How do I make that frothy milk that coffee shops use to make lattes?

They aren't just frothing the milk, they're also stretching the milk. Stretching it is what gives a latte its unique texture (though the micro bubbles add to that). If you want a good latte, focus first on stretching it - you can use a small whisk to get air into the milk if need be.

You want a small stainless steel pitcher, most look like this:

Put 2/3 of the amount of cold milk you actually want in your latte in that, then put it on a heat source (small burner is okay). Hold your hand around the pitcher while it heats, and use the other hand to stir the milk. You can also use one hand and just swirl the milk around in the pitcher - do what feels comfortable, just keep the milk moving.

As soon as the pitcher becomes just less than too hot for your hand, pull it. Swirl it around a little bit and look inside. Does the milk have a kind of gloss to it similar to Elmer's glue (or any other paste you used in school)? If not, Put it back on the heat for 20 - 30 seconds, swirling it as you do. Once it's got that gloss, and the milk has expanded a bit, it's stretched properly.

An electric burner is ideal for this, but there are also metal overlays for gas burners that just provide a hot surface.

At that point you can use a hand whisk, or any number of the frothing gadgets that you can find in any cooking store (brick-and-mortar or online).

You can, of course, just froth the milk, but what you're essentially doing is aerating it. That's fine, it's going to make a tasty drink, but it might fall short of your expectations if you don't stretch the milk as well. The process is what makes the milk and the coffee fall in love and give birth to a latte.

The steam wand on espresso machines heats the milk and adds the air, giving you a lot more control over the process. However, this will work almost as well.

Tips:

Don't ever let the milk get close to simmering. It'll burn very quickly.
Use the handle if you have to put the pitcher back on the heat (as naturally, you took it off because it was approaching too hot to hold)
You want to get the milk in the coffee as soon as possible once it has that gloss. Don't let it cool down too much while frothing (work fast)
It's going to take some practice

Total for this would be about $15 for the stainless steel pitcher, $10 - $15 for the frother, so all total around 30 bucks. You could use a sauce pan, but it's much harder to gauge how hot the milk is if you do, and much harder to control when you pour.


Is all Ethiopian coffee considered Specialty Grade 1? If so, where can I buy some in Canada?

Ethiopian coffee is all over the place. “Specialty” is a coffee that scores over 80 in the SCA scoring system. As such, it is not referred to as a “Grade”.


Is soap/water enough to get safely clean coffee mold from my mug?

I would feel confident drinking out of a ceramic mug after a good scrubbing with soap and water.  Smooth (glazed) ceramic surfaces are more easily cleaned than rough ones, so perhaps the rough ones deserves extra effort.

If there is a concern about sanitizing the mug, putting water in the mug and leaving it in the microwave on high until the water boils should kill any mold.  According to this 2012 Penn State Extension bulletin on important temperatures for food safety:

  Processing foods in a boiling water bath will kill most bacteria, molds and yeasts.


What effect does portafilter diameter have on espresso?

MT San talks about portafilters and the resulting differences between these portafilters that are different in size.

I will discuss the differences in espresso extraction as a result of portafilter and subsequent basket size.

Assuming that the only variable here is basket diameter:

Scientifically, pressure applied is normally measured as force per unit surface area. Taking the bed of coffee as a flat surface, and we assume traditional extraction pressure of 8 bar, the net extraction force upon the coffee puck will be greater for larger surfaces.

8 bar = 800kPa = 800 kN/m2

Now given two different basket sizes 58mm and 52mm which are 0.058m and 0.052m respectively, the net force on the surface of bed of coffee will be:

For 58mm:

Surface area: πr2 = π*0.0292 = 0.00264207942

Net force on area: pressure x area = 800*0.00264 = 2.11 kN

For 52mm:

Surface area: πr2 = π*0.0262 = 0.00212371663

Net force on area: pressure x area = 800*0.00212 = 1.7 kN

We can see that the larger portafilter is subject to a higher force of extraction with the same pressure. What this amounts to in practice is very much dependent on your setup. However it should tend towards better consistency in extraction. This is because, for a given dose, more of the coffee is in contact with the water at the bed surface and so has a more direct pressure gradient through the puck as it will be comparatively thin in the larger basket helping to reduce probability of channeling.

However, observable effects in practice will be slight to none as many other variables will take precedence in affecting shot flavour and the difference in extraction force will be accounted for silently in your dial-in process.


Is harvest time important for coffee quality?

Yes, it does, but it's much more complex than that :-)

Harvest times vary greatly depending on the latitude, altitude and variety of beans being harvested. There is a very large table here which illustrates the variety of harvest/shipping seasons, as well as the optimum points of both.

In general, December-February is best, but some countries vary anywhere from June to October. Some countries with a larger variety of crops have a lot of different 'Best' points, e.g. Kenya:

(The top brown/red line indicates harvest times, Red Bs indicate the optimum harvest times.)


By checking if it grinds.

Let's think about the mechanism of a grinder. Why grinders may get damaged if you adjust them when the burrs are not rotating?

A perfect coffee grinder design is a very serious engineering problem.

You need to have two very rigid burrs. When you don't have this rigidity, burrs may be damaged under high pressure of stuck coffee beans. Also, you don't want them to change their ideal shape in time.
You want the burrs to rotate in opposite directions when they are so close to each other. The distance of the burrs must be equal at every rotational position to produce consistent ground. In practice, every grinder is a bit skewed from the ideal position. So, burrs are closer to each other at one angular position and more apart at another position.
You want a heat conducting material to keep the beans from burning after all the friction in between the burrs. Also, you don't want the heat deposit on the burrs.

The caution you've noticed is mostly relevant to the second bullet. If, by mistake, you squeeze the burrs so close to each other they may damage each other in the next run. So, they can grind each other. While the grinder is running, even if you want to, you cannot squeeze till they touch. Even if you do, you suddenly hear a loud noise to release the setting a bit. However, if the grinder stops at an (somewhat) apart position and you squeeze them to touch, you cannot notice that.

If it grinds consistently, probably it is OK. But do not gamble again.


How should I order an espresso to get a less sour shot?

Here's a few thoughts based on what causes sourness/acidity in coffee and ways to temper it.

Order an espresso lungo. Sourness (acidity) is characteristic of the "stuff" that is extracted relatively early in the brewing process. In other brewing methods that take longer to perform (e.g., coffee press, drip, or pour-over) this can be balanced by the more bitter notes that take somewhat longer to fully extract. For this reason, you might get a result that is more appealing to you by ordering an espresso that takes longer to pull, i.e., espresso lungo. Not everyone behind every coffee counter will be immediately familiar with this, but at good cafes with good machines an espresso lungo should be no problem.

Try a darker roast. Darker roast coffees tend to be less acidic than lighter roasts, at the expense of losing more of the varietal/regional notes. Many cafes have really only one bean/roast that they use for every espresso (often because of the practical considerations of having several grinder hoppers full of beans), but if you have an option, try a darker-roasted bean.

Try beans from a different region. To my taste, Indonesian coffees tend to have less pronounced acidic notes than African or American coffees. Again, if multiple coffees are available for espresso, pick a coffee that you like (or find less sour) for any other preparation.

Pick beans further off of the roast. This is really only for completeness, but beans that were very freshly/recently roasted (i.e., less than a few days) can have accentuated acidity because some undesirable volatiles haven't yet had a chance to leach out. This is more toward what @daniel noted; this is the kind of thing you shouldn't need to be concerned about at a cafe -- they should!

A cafe affiliated with a local roaster (or any specialty cafe) should be able to tell you lots of things about the coffee when asked, such as region, varietal, roast level, and roast date. Here's a Serious Eats article about "problems" and related solutions that touch on some of the things I talked about above. Here's another link from Coffee Cuppers about regional and roast considerations in general.


What is a good recipe for high quality coffee beans that are no longer fresh?

One option is a somewhat obscure preparation method, but one that works best with older-ish beans: Nel drip (nel pot) preparation recommends beans that are a few weeks old; here's a Nel preparation guide from Blue Bottle. I don't know why older beans are recommended, except perhaps tradition.

See also other questions tagged nel-drip including another question of mine on Nel.


Conversion of Krups Nespresso Machine to Ground Coffee?

You could get a reusable nespresso capsule Like this.
Its a little bit more effort when you want to make your espresso but it would be the simplest and probably cheapest option for you.  But this comes with some disadvantages too, like the capsule can only hold 5 grams of coffee, maybe 6.


Completely reusable, stainless-steel, zero-waste Nespresso pods any good?

TL;DR:
Depends if the coffee style matches the pod design.
How a Nespresso machine works:

pod put in the machine gets pierced on the upper side
hot water is released into the pod
pressure rises inside the pod
due to high pressure a membrane burst at the bottom of the pod
brewed coffee is released

By modifying the membrane to burst at a higher or lower pressure, other flavors will be extracted from the coffee, like pour over and espresso.


How do flavors like vanilla and hazelnut get into coffee

In a coffee shop (assuming both places like Starbucks or non-chain versions), flavour syrups are a staple. Some have their own range, others use generic manufacturer's that are also used in other cooking or bartending applications.

I'd assume a dash or two of these are added to your coffee and voilá: Vanilla (hazelnut/caramel/...) coffee.

Another option are flavoured coffee beans, but for a coffee shop, that's pretty unlikely, as they would have to keep various beans at hand and switch between orders.


I'm not really an expert, but in basic terms:

Roast darkness:

Roughly how long was the coffee roasted, much like toast, a longer roast usually brings about a darker flavor. Darker roast coffees tend to have a slightly burnt caramelized flavor.

Body:

I usually think of this as more of a texture than a flavor, probably more easily noticed at the extremes. A "full bodied" coffee sort of coats the tongue causing the flavor to linger while "medium bodied" coffees tend to be a little lighter with a cleaner finish.

Acidity:

Acidity is basically what it sounds like, lower acid coffees are often referred to as "smooth" and higher acid coffees referred to as "bright".

Now as mentioned in the comments these terms are really painfully relative, and somewhat rendered meaningless by an onslaught of advertisers claiming that their coffee is "smooth dark and full-bodied" regardless of the real characteristics.


Do coffee connoisseurs add anything to their coffee when tasting a new coffee?

Your intuition is correct, modifiers like sugar or creme will only obscure a lot of nuance so connoisseurs, professionals & judges will try new coffees or espresso as brewed without adding anything.

Depending on the quality of coffee and a person's preferences they may sometimes add something after the initial taste. And some connoisseurs may order something like an espresso macchiato (espresso with a tiny amount of textured milk) or routinely add e.g. one sugar when drinking a coffee that they are familiar with or just for variety. But in general the better the quality of coffee and the more serious the connoisseur, the less likely they are to be adding anything to their coffee.

Certainly if you are trying to discern what a new coffee tastes like, you shouldn't be adding anything initially (coffee roasters and buyers have a special method for tasting nuances in new coffees called cupping). Even if you customarily like to add something if you want to learn more about coffee and improve your palate you should at least have a sip before adding anything so that you develop a better ability to discern subtle differences.

Espresso like scotch can be an acquired taste for some and they may find that they add less sweetener over time as the intense taste grows on them. And it's worth noting that high quality coffee has a rich, winey base overlaid with desirable flavours and little, if any bitterness. And properly textured milk in lattes is already quite sweet and creamy in texture so there is little, if any need for additional sweetness.


Caffeine is only mildly addictive and only shows minor physical dependence. It does not threaten physical, social or economic health the way truly addictive drugs will.
"Withdrawal" or skipping your morning cup might give you a mild headache.
Here is a link to a brief description of caffeine addiction.

http://www.m.webmd.com/a-to-z-guides/caffeine-myths-and-facts


Does instant coffee give a lesser buzz/high than conventional filter/french press coffee?

Caffeine content varies greatly by preparation and brew method.  Instant coffee is generally designed to produce something close to a cup of drip coffee.  "Cups" is unfortunately not well defined and may vary based on it's usage.  Beyond that, percolated and french press coffee is generally prepared stronger (more concentrated) that regular drip coffee (and probably much stronger than the watered down concentration instant is designed for).  It's also very likely that some amount of caffeine is lost during the freeze dry process since it is so water soluble.

TL;DR Yes.  Real brewed coffee will generally have a higher caffeine concentration than coffee that has been brewed, dehydrated, then re-hydrated.


Do what comes up in your mind. I like to add cinnamon and Jamaican pepper. They don't change the flavor but brings a lot of aroma.


Ground beans have a much larger surface area by weight than whole beans. When the surface of the bean is exposed to air chemical reactions take place. I doubt that these reactions have been completely characterized but at a minimum they include some loss of aromatic oils. In other words, the processes that lead to a judgment that coffee is "old" happen faster in ground coffee.

You can do the experiment easily and cheaply by comparing the results of coffee made with freshly-ground and pre-ground versions of same brand/date coffee. You can always borrow a grinder.

The experiment might not work if both samples of coffee are old (or poor quality). Otherwise I think you would notice a difference. Whether the difference is worth paying for is a different question; but the only costs are a grinder and time to grind the beans.

A short answer to the question about brands might be: good, fresh Arabica beans are similar in many ways, up to roasting. Some people prefer a light roast, others medium or dark. Once you decide, find a brand that does what you like consistently.


Shelf-Stable Half and Half - How stable?

If the curdles swim on top and are without much structure it is likely milk fat.
If they are fluffy it could be proteins.

Breakdown due to germs is unlikely as a shelf life of several months wouldn't be possible with fresh milk. Manufacturing errors excluded.


The easiest would be to service the machine. Think of it as bringing your car to the shop or going to a physician / dentist yourself, so a professional can check some things that might be indicative of problems and do some basic maintenance.

You can try to find a (video) guide for your specific model, try it yourself (with or without a guide) or have it done by some shop.

Generally, you'll want to look for obvious problems like small leaks, rust and mould. Other things you might be able to do is replacing the gaskets that seal of different tubes. For that, you'd need to know which ones you need exactly.


When to use stirring to increase extraction?

Stirring should be used if the grounds were not evenly dispersed in the beginning of the process for some reason (in immersion brewing methods).  For instance, when I am using my pour over at work, if my initial pour leaves some dry spots floating on top.  The Aeropress uses stirring prior to extraction presumably because the short time combined with the tube shape (narrow with all the grounds at the bottom) demand a good mixing.  I've seen many badly designed drip brewers that leave a chunk of dry grounds in the basket when done.  This is because the drip isn't dispersing water evenly and some of the grounds end up wasted,  finer grind, longer brew and temp won't necessarily help bad engineering in that case.


Qm76 Evo Quick machine building up pressure

You have an upscale espresso machine with a standard, non-pressurized portafilter. So as you know there normally isn't any pressure in the portafilter when you go to remove it after a shot.

Backflushing can only be done on machines like yours that have a 3-way valve. And it's basically just putting a blind (sealed) basket or rubber disc into the portafilter and pulling three short shot cycles. That is put the portafilter, with a blind basket into the group then let the pump run for about 8 seconds, then stop the pump for a few seconds. Then repeat two more times before removing the portafilter.

This flushes out the brew path. Backflushing with water is safe but you shouldn't do a frequent chemical backflush on an E61 type machine. Most of the time this can be resolved by doing a backflush (sometimes you may need to do two or three backflushes) which will clean the brew path. When was the last time you did a backflush on the machine? You should be backflushing with plain water weekly. And with a food safe detergent every 200 shots.

When the portafilter does remain under pressure it means that the "3 way over-pressure valve" that normally relieves the group pressure is sticking. Or more precisely something in the expansion chamber is sticking or the internal E61 cam isn't moving completely smoothly.

The easiest way to check for scale (mineral) buildup on an E61 machine like yours is to remove the gicleur chamber nut and mushroom at the top of the E61 assembly and visually inspect the removed parts and the group head internals which will now be visible.


What grind to use for a Phin (Vietnamese Coffee Maker)?

For a phin, most websites recommend using a grind that you would use for a standard drip machine or a grind that is slightly coarser. Because every phin is different, it is necessary to experiment with the grind and find the result that fits your tastes best.

For someone who cannot drink strong coffee, it is best to err on the side of caution and make their grind slightly coarser and adjust to a finer grind slowly. The best taste profile will be found this way.

Useful resources:

Coffee Geek Phin Guide for Iced Coffee
Trung Nguyen Online Phin Guide


Are reused glass jars ever fit for storing ground coffee?

The Short answer  to this is no. You should not use a glass jar for storing coffee.

Why? The base of the answer can be found here: When Does Coffee Go Off?

Coffee goes stale relatively quickly, and the transfer to a glass jar will:

Increase the coffee's interaction and exposure to oxygen
Increase the coffee's exposure to light, which will cause rancidification of the oils

Furthermore, you should only be purchasing and storing whole bean coffee - as pre-ground coffee is already stale.


Is it possible to Cold Brew using an Aeropress?

Don't brew in the Aeropress itself. Brew in a jar like in classic methods and use the Aeropress only for fast and easy straining, taking care not to stir up the grounds from the bottom of the jar as you're pouring. Most of the coffees you strain out this way should be an absolute breeze. Only the last one you make (assuming a bigger jar) should give you any plunging force trouble, and that's if you insist on getting every last drop out (I know I do).


I believe heat and humidity play a key role in the role of energy transference in the roaster. I roast (professionally)in a very dry climate and find it easier (more forgiving) to roast in a climate that generally has a more humidity.

Here is a link to a conversation about heating and humidity that hopefully will help answer your question.

I think the 3rd answer is the most appropriate in its relation to heat transfer and "other" objects in a room (i.e. Coffee beans).

How air humidity affects how much time is needed for heating the air?


Is there a group identity for coffee drinkers who care, but compromise?

Based on the wording of your question; I believe there is no current classification for this denomination in the coffee market.

When you compare this with the electronics market; there are devices developed for the "prosumer" market which are targeted at professional consumers (average Joe that can make it rain), but are not used to their full capacity. For example, I can buy the latest Macbook Pro laptop and only use it for iTunes, or buy a high powered Microsoft Surface Studio PC and only use Microsoft Paint because Photoshop is too expensive.

To start generating momentum to classify this marketing group, you could say that this group of people (without trying to be offensive) would be classified as lazy prosumers?


It's a French press.

Put ground coffee inside it, pour hot water, stir a little bit, and then wait for 2 to 4 minutes (or longer if you want a strong and bitter coffee).

After waiting, use the pump to filter the ground from the coffee and pour the coffee into your mug.

I recommend using coarse or medium ground coffee, otherwise, the coffee will go through the filter and will end up in your cup (and mouth).

Some extra information here.


This may be heresy: An espresso machine plus a grinder is overkill for a one cup a day person. Try Nespresso Vertuo. Their coffee is excellent and comes in a wide selection of tastes. In my opinion, much better than anything from Kuerig. I own two Vertuo machines, one for office, one for home. I'm not in any way connected to Nespresso except as a satisfied customer.


How do I brew french roast coffee, so that it doesn't taste like ash

Starbucks' dark roasts are very dark. It tastes like ash because it contains ash. There's no way around that.
That said, you can minimize the ashy notes in your brew by using the below suggestions:

Lower the brew temperature--cold brew in particular works well for this purpose

Use a coarser grind setting when grinding

If using a hot brew method, reduce the time you let the coffee brew

Use just the first or some combination of all three. It'll take experimentation to get it right.


Is it possible to burn coffee while brewing?

Burn? I've heard that some large chains "burn" their beans while roasting :-) But not while brewing.

A major coffee chain, seen on almost every other corner in some places, is known for their very dark, "burnt" roast. Many people like this sharp taste and associate it with caffeine and their morning pick-me up.

Other people find this "burnt" roast to be overwhelming and consider this heavy roast to be destructive when using high-quality beans. In any case the burning happens at roast - not when brewing.


Amount of money I should spend on a Grinder

Depends on if you want to be able to grind true espresso grinds.  My daily grinder I received as a wedding present and it suits me just fine, a Cuisinart for about $40 dollars.  If I want to grind for espresso, this is completely incapable of doing so, so I ended up getting a $180 dollar unit that is capable of timed grinding and grinding to espresso level grind.  This unit is a Breville with a cone burr, which I honestly really like because it doesn't have the static of the Cuisinart.

This is very much a personal choice type of question.  If you have $10000 burning a hole in your pocket, I'm sure you could find a grinder to match, or if you are worried about keeping the lights on, you could probably find one to suit your needs as well.

Here are a few recommendations..

Low End:
Cuisinart DBM-8 -- Does good coarse grind, to a reasonably fine grind.  Drip brewers and pour over are right in the middle of its standard grind range.  Biggest con is it is a flat disc grinder and generates quite a bit of static so be aware that it will make a bit of a mess.  Cannot grind espresso.

Mid Range (150-250) -- The Baratza Encore is really popular and a pretty good price.  It has conical burrs and gearing specifically intended to reduce static and heat.  I personally use a Breville Dose Control Pro which is about the least expensive grinder I could find with the portafilter holder and timed grinding.  Thus far I've been happy with it, low static, very very fine grind level for espresso if needed, but I am seeing some reviews about how the internal components tend to fail after extended use.  Someone may be able to comment on the feasibility of the Encore for espresso grind better than I.  Breville can grind espresso, someone please comment on Encore / Virtuoso espresso grind capability!

High Range --  The sky is the limit here.  You could go with a higher end Baratza going all the way to the 1000 dollar range and probably higher, if you've got that $10,000 dollars burning a hole in your pocket you could go big with a 60 lb EK43 (and then send me a big tip!).. just kidding.  The EK43 runs about 2500 and is a shop grinder, although it is now a barista favorite for competition.  When you start getting into the super high end machines, personally my favorite is Mahlkonig but really.. there's no reason for this caliber of grinder at home.

Again, how much to spend is a tricky question.  I would say a minimum of $40 and a max of however much you want to spend.  If you have the money, and want a solid reliable workhorse, I would probably go with either the Baratza Encore or Baratza Virtuoso.  Baratza is one of the higher quality, and popular home grinders that don't completely break the bank.


How can I emphasize the sweet, fruity notes of my coffee?

Lighter roasts are going to have more of these flavors but it obviously depends on the bean as well. If all you are going to change is the method of brewing the coffee, I would recommend making sure you don't use too hot of a water temperature and trying to use a pour over. I find pour over allows for more delicate flavors you are describing, rather than something like aeropress which can approach more espresso type coffee.


From anecdotal experience freshness and flavor begins to fade within ~7 days with regular storage methods. Many people brewing cold brew online state between 5 days and 2 weeks is okay to keep cold brew for. In my opinion you will have coffee that you won't want to drink long before you run into harmful bacteria as long as you are keeping things sanitary.

How you store the coffee will determine how long it keeps.
To improve storage look into bottling it in individual bottles with little headspace, or even kegging the coffee. Exposing coffee to oxygen will negatively impact flavor and expose coffee to more bacteria. Creating a concentrate of the coffee may help to prevent bacteria from forming. Splitting batches up into multiple sterile containers and keeping them sealed may also help it to last longer.

Getting your coffee to last you a full month is almost definitely going to be much more of a hassle than brewing coffee more frequently. The taste will always be better from fresher coffee and cold brewing coffee is one of the simplest methods. Unless you absolutely can't make coffee more frequently I would recommend making smaller batches you can consume quickly.


Used Keurig smells and tastes like cigarettes

First of all, note that the smell of the machine itself is unlikely to come from the interior of the parts that heat and transport water -- after all, they are regularly cleaned with hot water and smoke has a hard time getting there.

So running vinegar through the machine won't change that. Rather, it is the other surfaces that cause problems. Thoroughly cleaning all surfaces of the machine may help a little bit (including the easily accessible ones behind the cover), and storing it in a room that is thoroughly aired for some months should also help to some extent. Depending on the temperature, a garage may also be an option. You need to be careful to not break the machine during cleaning and airing, though.


Akin to the simultaneous fates of Schrödinger's Cat, answers to your question include no, maybe, and it doesn't matter. I have furthermore been unable to avoid philosophical diversion and hypothetical questions in this answer; please forgive me. :)
As @EricPlaton noted in comments, the answer depends on a slightly different question: What characteristics define real espresso? Here I merely compare the beverages produced by the following:

a traditional espresso machine (See this history of espresso machines and production techniques for one view of what is traditionally espresso), and
capsule-based "espresso" systems. There are several capsule-based espresso machines (here's a review of Nespresso and three others). You place a small coffee-filled capsule (a.k.a. "pod", made of aluminium, plastic, paper-wrapped, compressed puck, or other material) into the machine and press a button; seconds later it produces a coffee beverage.

My answers:
No.
In simple point of fact, espresso is not traditionally made with a coffee-filled capsule, so the beverage produced by capsule-based machines might be disqualified from being called espresso on that trivial issue alone. :)
If you subscribe to the INEI being a benchmark of espresso production standards (PDF), capsule systems may not meet INEI parameters... so if they don't, they're not an espresso on technicality alone, with regard to "Certified Italian Espresso" at least. For example:

quantity of coffee (e.g., Nespresso might be light);
hot water should be used for espresso (some do use pressurized water; but it's not INEI espresso if the capsule system uses steam);
Some capsule systems (as noted by @EricPlaton below) do produce espresso-machine pressures, but there could be benefit (or problems) by using pressure that is too high, or on the other hand too low for extraction and crema. That said, it seems that AeroPress can create crema at lower pressures, so perhaps the capsule systems produce a beverage more like AeroPress than espresso.[1]

Maybe.
There have been several taste-tests of questionable "legitimacy" between capsule-based machines and traditional espresso machines. One four-subject test gave higher marks to the beverage produced from a capsule-based machine than a traditional espresso machine. This one agrees. Another test disagreed, giving a capsule-based machine a scathing review. Maybe there are better reviews out there; these are mostly useful for anecdotes.
As you note, the resulting beverage from a capsule-based espresso system is similar to traditional espresso, crema and all. However, if you ordered an espresso from a proper cafe, and they gave you a beverage that was brewed using a capsule-based machine, would you feel cheated on principle? What if the beverage was indistinguishable from traditional espresso... or if you like the capsule-based system's result better?
It doesn't matter.
This is my personal conclusion. The result of the beverage produced by a capsule-based system is a decent replica of proper espresso. Capsule systems also are likely to produce a consistent result. If you like the beverage that results (see above...), what difference does it make if it's "real" espresso or not?
[1] Is AeroPress espresso? I think not (and @Chris in AK agreed and notes "Aerpresso" in comments!), but that's a separate question also...


It's not that just heated milk is wrong or tastes bad.
It's only that there are some (popular) coffee drinks that uses steamed or frothed milk (are not the same, read this) by traditional way.

On those popular drinks you can find the cappuccino, latte, etc... (as you can see on this infographic), but at home you always can add regular hot milk to your coffee (but we all agree that it isn't feel and taste like the regular way).

Last, why are those techniques important for a coffee? I think that gives a different flavour and tasting to the drink, due to its consistency (and of course, that let you to do some pretty nice latte art)


Approximately how many cups (by volume) are in a pound of ground coffee beans?

In case the question is relevant to the coffee beverage:

The well-known recipe for the ground coffee to coffee beverage ratio is around 1:20.

One pound is equivalent of 453.6 grams. Therefore; you may expect to have 9072 grams of brewed beverage. When you assume that a cm3 coffee beverage is around 1 grams, yo should have a bit more than 9 liters of beverage. Again, this makes around 320 oz. beverage. If you assume that your cups are 10 oz, you should end up with 32 cups of beverage from 1 pound of ground coffee.

I admit that, using such a unit system makes it way harder than stating "1 kg coffee ends up two hundred 100 ml cups", at once.

In case the question is relevant to the density of coffee:

(Updated after Paul's comment)

The solution is simpler as it depends solely on the density of coffee. Still, we may require a series of unit conversions.

The density of ground coffee is around 0.32 gr/cm3. This means, 453.6 grams (one pound) of coffee has a volume around 1.42 l. This volume is roughly 50 oz. Finally, a cup is 8 to 12 oz, let's say 10 oz on average. Therefore, a pound of coffee should be more or less 5 cups of coffee.

Note: This density is for ground beans. Green coffee beans has a density around 0.56 gr/cm3.


Why is it not recommended to drink coffee immediately after it's roasted?

Fresh off the roast, coffee has high levels of carbon dioxide and nitrogen (based?) gasses. These gasses will greatly contribute to retro-nasal activity as well as initial flavors (think carbonated water). The most apparent flavor one gets from this is metallic. At my work, 4 days is considered minimum for serving and tasting, although there's always exceptions.


How hot should the water be for instant coffee?

There's an answer to this question at Seasoned Advice: see What water temperature should be used for instant coffee?

A brief summary, taken from @PatrickSebastien's answer:

Use water at whatever temperature you like to drink your coffee at, or
Use water just below boiling, around 95-99 degrees Celsius (~205-210 F).

Other articles like this one from WikiHow also recommend using filtered water that is just off the boil.

See also that same SA answer, and this question, for a discussion and additional context about how instant coffee powder is produced.


What factors determine coffee bean size?

The single biggest factor in the size of a coffee bean is the botanical variety of the plant. There is no amount of nutrition or growing conditions that can overcome the effect of genetics.

In this picture from our garden at Coffea Diversa you can see two examples at the extreme.

On one hand you have mokka, this variety has the smallest bean of all
coffee varieties.
On the other hand you have Maragogype, this variety has the largest
bean of all coffee varieties.

There is no amount of fertilizer that you can give to a mokka grain to make it even come close to the size of a ripe Maragogype bean (and viceversa).

The difference in sizes between your blend and peruvian coffees are probably due to the botanical varieties of the beans.


Does coffee help if you are tired because you have over slept?

Coffee is an excellent countermeasure against drowsiness in general. The main and best understood mechanism of action of caffeine is that it blocks the receptors of adenosine in your brain. Adenosine is responsible for the feeling of drowsiness. It accumulates throughout the day and would act to make you feel increasingly tired. In addition caffeine likely has effects on your dopamine, serotonin and noradrenaline levels. They are all chemicals  considered to be excitatory neurotransmitters. Nehlig et al. (1992) made an extensive review of the action mechanisms of caffeine. A more recent review was published by MacLellan et al. (2016).

Drowsiness from oversleeping occasionally probably stems from a disruption of your cycadian rhythm. If you wake up in the middle of a sleep cycle before completing it, you will feel groggy and tired. Caffeine will certainly have some effect through the stimulation of your central nervous system and the increased release of stimulating neurotransmitters. But so would a morning work out or a walk in the sun. Which one is more effective for you, you will have to trial and error. I'd combine them I guess.

Chronic oversleeping however should be considered a medical issue. Hypersomnia could be a symptom for many other, more serious issues ranging from sleep apnea to depression and other neurological diseases. In these cases caffeine might have positive or negative effects. But that is a question you should ask to your physicians.

References

McLellan, T. M., Caldwell, J. A., & Lieberman, H. R. (2016). A review of caffeine’s effects on cognitive, physical and occupational performance. Neuroscience & Biobehavioral Reviews, 71, 294-312.
Nehlig, A., Daval, J. L., & Debry, G. (1992). Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Brain Research Reviews, 17(2), 139-170.


I'd agree with you.  There isn't a brew happening because the solution was already created.  What you are performing is a rehydration.  However, "let me rehydrate some coffee" is a pretty awkward turn off phrase.


What is the right coffee ground size for an espresso coffee machine?

Practically speaking, an arbitrary number can only get you so far. What you need to focus on is what we would call 'dialling in'. This is a term to describe the process by which we find the most suitable parameters for making the 'best' cup of coffee. 'Dialling in' can mean a multitude of things but in your case it will simply refer to finding the right grind size and/or dosage.

The problem you seem to have is directly because you are shooting far above and below the the 'right' grind size assuming that you are using the exact same mass of coffee every time.

To find the right grind size, you must have a decent enough grinder that grinds to a uniform level and can be adjusted to a high degree, you should only be adjusting in small amounts. If you do not have a grinder, it will be very hard if not impossible to find a pre-ground bag that works perfectly for you. If you are choking the machine because the particle size is too small, adjust coarser gradually and keep making shots to observe the change in extraction times and flavours. If you are extracting very fast and water is rushing out causing under-extraction, adjust finer. Repeat until you achieve the 'best' flavour you can.

At this point, if your coffee still tastes off then your problem may lie in your dosage. You may be using too much or too little coffee causing hindrance to a uniform extraction. Once again, simply adjusting your dosage above and below your current amount in small increments will help you find the spot where the extraction performs the best.

If your coffee still tastes off you may be having temperature stability issues, water quality issues, coffee freshness issues, unstable brew-head pressure issues, poor basket distribution and tamping or any combination of the above.

Since the 'right' grind size for espresso, or any brew method for that matter, is never the same and is dependent on, at the very least, the coffee bean itself which is still a variable even if brewing from the same bag, finding the 'right' grind size is always going to be a chase and 'dialling in' will be an exercise you will almost always have to do if you want the best coffee you can extract from what you have.

MT San's answer provides a link to a more generic explanation and reference to the different general grind sizes for the different brew methods if you are completely in the dark.


I have used a regular old Moka Express (the simpler version without the "crema" thingie) for years, and always on an electric stove. But the same should apply for your Brikka.

1. An electric stove is fine.
If you are starting with boiling water, go medium-to-low, reduce heat to a minimum once the coffee starts to rise/appear - or even turn it off, see 2. below. If you are starting with cold water (I can't be fiddling with a hot metal vessel after a short night and without sufficient caffeine in my system - see here and here),initially go full-speed to minimize the not-so-hot water trickling through phase, then proceed as described above.

2. Violent frothing may be a sign of different things.
My first suspicion would be you missing the sweet spot of turning the heat down in time - or too much residual heat in your stove top. Note that electric plates are a lot slower to react that gas, where you can instantly cut the heat. Learn to "play" your specific stove, and as an emergency measure, simply lift the Brikka off the stove.
A second issue could be the grind. While a Moka needs a finer grind than drip, a true espresso grind is too fine (and a common beginner's mistake when making "stovetop espresso"). In the best case, a too-fine grind will just be over-extracted and give you a lot of dregs in the cup. But the fine grid will also compact more, so that your machine will be working at a higher-than intended pressure. It may be enough to trigger the valve, but it may also be ever so slightly below the critical value, still giving you a rather forceful "volcanic action" (as I observed in the context of this question).


Backflushing is a fairly straightforward procedure. You only need two things:

a backflushing disc
coffee machine detergent

The procedure needs repeating a few times (3-4):

Install the disc in the portafilter
Add in a bit of cleaning detergent.
Turn on the coffee machine until you hear the pump start to labour, once this happens turn the pump off, and the hot water with detergent will spray out of your 3-way valve. This is quite likely to cause spraying so try to be careful.

After you've done this, repeat the procedure without detergent to flush the soap suds from the machine.

Normally you would do this about once a month. This is highly dependant on how you feel the machine is doing, but it's definitely recommended that you do this if you use the machine a lot (Some people recommend doing it around every 30th espresso).

After this it is a good idea to run one espresso shot through the machine to clear everything out and not leave any residue.

You can find further details here


When the espresso begins to pour it takes about 3-5 secound to reach the right presure, what can I do?

This is completely normal, this is the pre-infusion phase.

Pre-infusion is used to wet the grounds before starting ideal espresso extraction. Wetting with hot water helps the grounds to release initial CO2, therefore enables more and even extraction surface. It somewhat resembles blooming in pour-over manual filtering.

As a result, you should feel lucky that you have this feature on your machine. By the way, I take a look and found this explanation on Sage's website:

  Pre Infusion Function:
  Gradually increases water pressure to gently expand grinds for an even extraction.

And a final note to enhance your cup of espresso...

As I can  see, you end up in 22.4 - 5 = 17.4 seconds, which is pretty fast. The common practice is 1 ml in 1 second; therefore you should fill a 30 ml espresso in 30 seconds (with double spouts a doppio will take the same amount of time 60 ml in 30 seconds.) I recommend you try to fix timing first to see if you can get better results.


As suggested by several previous comments, there's several things that could be called "white coffee."

According to the white coffee article on Wikipedia, and other sources (e.g., coffeefaq, Nescafé); others listed below.

Simply referring to coffee with whitener (e.g., milk, creamer, etc.);
A Lebanese drink ahweh bayda, made from water, orange blossom water, and (perhaps) sugar (more here)
Something called Ipoh white coffee; of Malaysian origin, this refers to beans that are lightly roasted with margarine (and perhaps sugar and wheat), brewed and served with sweetened condensed milk.
Coffee beans that are roasted to the "yellow" roast level, then ground and prepared as espresso; the result is a pale yellow brew with a nutty flavour and assertive acidity.
A beverage originating in Yemen, probably from the literal translation qahwa bayda. I've never had this, and can't find consistent information on it, but things that I have seen suggest that it's any number of different preparations, including the following: coffee made from lightly roasted beans plus spices; or a spiced coffee cherry tea (e.g., qishr); or even something non-coffee similar to the Lebanese variety above.
A longer shot (so to speak...) is that it could indicate a flat white, which is a coffee drink similar to a cappuccino or latte but with higher proportion of milk.
There is also a company called White Coffee Corporation, but perhpas not what you're looking for.

I hope this is a reasonable (albeit, perhaps not acutely helpful) summary.


Beans can smell like dirt, especially if they are beans that are known for having an earthy flavor profile. What you want to avoid are rancid smelling beans that can get that way due to the oils being over-oxidized over time. Alway check the roasted-on date and don't drink coffee that is several months old. If the bag has an expiration date instead of a roasted-on date, that means they don't want you know how long ago it was roasted. Don't buy those.


What is the impact of espresso tamper base shape?

If you only use a double (14g) portafilter basket then you're best to use a 58mm convex tamper. This is because if you look at the basket, in most cases, the sides will slope in. Therefore, if you had a flat 58mm tamper then the you are compressing to outer more than the inner. Obviously the whole point of tamping is to compress the grounds consistently throughout the whole puck, so this would achieve this the best. If you want to use a flat tamper for any reason in this situation, you would be best using a 57mm flat tamper and tap the edge of the portafilter to knock any loose grounds back down into the basket and then rotate the tamper over to produce a flat surface for the water to pass through.

If, however, you are using a single (7g) portafilter basket then the 58mm tamper would probably be too wide to compress the grounds evenly as it may not go far enough down in the portafilter basket to tamp it at all. Therefore, you would be best using a 57mm tamper.

If you're using a triple basket then a 58mm convex rules would apply the same as the double basket.

This is all based on the assumption that the basket is 58mm. This is the most common size but other sizes do crop up, commonly on older machines which may use a 53mm basket. In this case the flat/convex rules still apply, just with the smaller diameter.


Cold brew it! Make sure you start with very cold water and a coarse grind. Cold-temp chemistry has a better chance of taking what's good and leaving what's bad.


It is good for my health to drink coffee 10 times a day?

Caffeine content of coffee varies widely depending on many factors. How much caffeine does your 10 cups contain? And how much is too much? The Mayo Clinic website has addressed exactly what you are concerned about in their detailed article which can be read here:

https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/caffeine/art-20045678

Important extracts:

  How much is too much?
  Up to 400 milligrams (mg) of caffeine a day appears to be safe for most healthy adults. That's roughly the amount of caffeine in four cups of brewed coffee, 10 cans of cola or two "energy shot" drinks. Keep in mind that the actual caffeine content in beverages varies widely, especially among energy drinks.

  [...]

  You may want to cut back if you're drinking more than 4 cups of caffeinated coffee a day (or the equivalent) and you're experiencing side effects such as:

  Migraine headache

  Insomnia

  Nervousness

  Irritability

  Restlessness

  Frequent urination or inability to control urination

  Stomach upset

  Fast heartbeat

  Muscle tremors

  [...]

  Most adults need seven to eight hours of sleep each night. But caffeine, even in the afternoon, can interfere with this much-needed sleep.

  Chronically losing sleep — whether it's from work, travel, stress or too much caffeine — results in sleep deprivation. Sleep loss is cumulative, and even small nightly decreases can add up and disturb your daytime alertness and performance.

  Using caffeine to mask sleep deprivation can create an unwelcome cycle. For example, you may drink caffeinated beverages because you have trouble staying awake during the day. But the caffeine keeps you from falling asleep at night, shortening the length of time you sleep.

That's also my personal experience as a long-time coffee 'addict', though I am also very sensitive to caffeine and therefore I can tolerate just 2 cups a day before I lose sleep and begin to experience strong physical effects. The key thing is to make sure you don't experience symptoms of caffeine excess, and that you get adequate sleep every day, which also varies from person to person.

If you feel the need to reduce your coffee intake, the same article linked above provides some useful guidelines.


Coffee can cause some sweating when consumed in very high dosages. Your core temperature increases because of central nervous system activation and your body tries to regulate temperature. However 5 cups a day don't seem close to an overdose unless your caffeine tolerance is very low and studies have shown that normal dosages of caffeine intake don't alter core temperature or increase sweating to an extent where it would affect your hydration (see e.g. McLellan et. al 2016 for a Review). It still might be noticeable if you sweat a lot in general. I would just trial and error it by not drinking coffee for a few days. You might notice increased sweating for a day or two from withdrawal but that should pass after a couple of days. However these "health" websites have a lot of misinformation on them that are not scientifically supported.

References:

McLellan, T. M., Caldwell, J. A., & Lieberman, H. R. (2016). A review of caffeine’s effects on cognitive, physical and occupational performance. Neuroscience & Biobehavioral Reviews, 71, 294-312.


Is coffee a pro-oxidant or an antioxidant?

In Spain one study showed that Brazilian Arabica 100% (A100) roasted samples presented lower antioxidant capacity (less efficient antioxidants) than Robusta coffee varieties (could be due to the higher percentage of chlorogenic acids in Robusta ground coffee than in Arabica) therefore Brazilian Arabica 100% (A100) presented the highest value of pro-oxidant activity.

However higher antioxidant activity was observed in Colombian coffees than in conventional roasted coffee blends. On the other hand, when the percentage of torrefacto coffee was increased, an increase of the antioxidant activity and a slight tendency to decrease the pro-oxidant activity were observed. Therefore addition of sugar at the end of the torrefacto roasting process may influence the antioxidant and pro-oxidant properties of coffee because sugar is one of the main precursors the Maillard reaction.

In summary, we can say that antioxidant and pro-oxidant capacity of ground coffee can be affected by several factors such as coffee variety, roasting process (e.g. torrefacto), growing climate, storage, etc. The details of the studies for further reading can be found below.

Sources:

(study) Comparison of antioxidant and pro-oxidant activity in coffee beverages prepared with conventional and “Torrefacto” coffee at Science Direct
(study) Influence of torrefacto roast on antioxidant and pro-oxidant activity of coffee at Research Gate


How to prevent calcium loss when drinking a lot of coffee?

Apparently, drinking caffeinated beverages shouldn't affect you calcium level if you get your recommended daily intake of calcium. According to this review of the literature on the subject:

  There is no evidence that caffeine has any harmful effect on bone
  status or on the calcium economy in individuals who ingest the
  currently recommended daily allowances of calcium.

That said, there does seem to be a connection between high caffeiene intake and low calcium intake, meaning that there is significant overlap between individuals who drink caffeinated beverages and don't get enough calcium from their diets, but implying a causal relationship is dubious. Luckily,

  ...the negative effect of caffeine on calcium absorption is small enough
  to be fully offset by as little as 1-2 tablespoons of milk.

Most milk alternatives (like soy or almond milks) are fortified with calcium and other nutrients and drinking them in place of milk should do the trick, just be mindful of the high sugar content of many of the milk alternatives available.

Also, I wouldn't worry about your daily coffee dose, 1.4 billion cups of coffee [2] are poured every day and if there were serious health risks associated with daily caffeine ingestion, we'd know about them!


Please Help find Moka Pot Gasket Replacement

We can’t give you shopping advice, it will depend on your location through which channels you can obtain a replacement part.

What we can help you with is to determine what size of pot you have - and based on that, you can pick the correct size.

First, you can measure the diameter of the “no longer there” gasket, some web shops may actually list that value.
If they simply sell by pot size, measure the amount of water that goes into the lower compartment. For my Bialetti models, the three-cup one takes about 140-150 ml, the six-cup around 300-310 ml. That translates to about 50 ml per cup (will be less after brewing, as some water will be absorbed by the grounds).


Why do some grounds float and others sink when brewing by pour over

Bean density varies dramatically with roast level.  The more roasted a bean is, the less dense it becomes.  My guess would be that less dense beans would have more of a tendency to float and more dense beans would have a tendency to sink.  However, I imagine that there are other factors as well.  Grind size would affect the mass vs surface size of the grounds and have some say as well.  Age could also be a factor since freshly roasted beans still contain/give off some amount of gas.  That degassing time can also vary with roast level and bean variety, so just time since roast may not always be a consistent measure.  Overall I'd guess there are four plus factors affecting the "float" of your grounds.  And that's not to even say anything about the content of the water itself.


how often should I replace the metal filter on a Bialetti Moka Express 6-cup?

Welcome to CoffeeSE!
You do not need to replace the filter that often, it is just metal  after all. As long as you can clean it properly and it functions normally there is no need to replace it just because you're replacing the gasket, especially when there's no visible corrosion or damage.
There are some people who use their Moka Pot very often, don't clean it properly and almost neglect it. They can go through gaskets fairly quickly, my mother used to change it every few months, but she just replaced the filter just once, and that was because she lost the original one. For those people getting a few gaskets for a cheaper price per gasket makes sense. For others, getting just one is fine. I have even seen a pack of 6 gaskets and one filter not long ago.
Clean your Moka Pot after every use (or at least rinse it thoroughly and clean it properly every few days) and you filter should last you quite a long time.


My Handpresso got leakage after leave it with some air pressure built in. Could it be worse?

Pressure may have built up as a consequence of the residual water and such inside the device and environmental temperature/pressure changes.

It should be okay, and it seems to still be working. Make sure you thoroughly clean it just because you left it for a couple of days. Other than checking for any visible deformities (especially around the silicone sealed areas), if its still working it and tastes fine it likely is not broken.


how to make French Press coffee the right way?

Is it possible that you read a few posts on the Internet the wrong way?

The grounds will not disappear, if anything they will appear "more", volume-wise because they swell in the hot water.
There are two points about "grounds on the bottom":

In the bottom of your cup, indicating a too fine grind of the beans or a hole in the filter mesh. Some very fine "dust" is ok, though. This is french press, not filtered coffee.
Coffee sitting on the grounds after pushing the plunger for too long can negatively influence the taste of the last cup, making it excessively bitter, for example. So drink / pour the coffee shortly after you finished brewing. The time threshold depends on your beans and personal taste.


Is there more caffeine with an AeroPress?

Aeropress coffee (hearby called Aerpresso in this post) is more concentrated than regular drip coffee.  However, if you are using similar amounts of grounds as you would in a drip machine, you shouldn't notice any difference.  Caffeine is highly soluble in hot water and most any extraction method utilizing hot water will result in nearly full extraction of caffeine from grounds.

Aerpresso ends up somewhere in caffeine concentration between espresso (very concentrated) and drip coffee (less concentrated).  However, the total amount of caffeine is dependent more on the amount of grounds used that the extraction method (with the above listed methods).

So the the final answer is no.  There isn't more caffeine, but the Aerpresso is more concentrated.


This is a pretty good way to ruin a burr grinder. Worst case scenario, your burrs jam up so much that they can't spin and burn out your motor. A blade could help, but I'd argue that the inconsistent grind you'd get wouldn't be much of an improvement in cup quality anyway. Realistically you'd end up with some of your grinds unchanged, some at the size you want and some ground to dust. The different sized particles would extract unevenly and the dust is likely to clog the filter.

That said, you're not going to break a blade grinder by regrinding, so give it a shot and see how you like the results. At most you're out 20-50g of coffee.


Where can I find a stand-alone coffee wand for home use?

If you want to save money, look to the technology of 60 years ago and seek out a stovetop steamer. Possibly easier to find at a thrift store than online, at least at a bargain.

Then again, you may well find a thrift-store "espresso" machine that you could dedicate to only using the steam wand on, even if you'd never dream of making coffee with it. May also depend on the thrift store, or the week (given that stock varies with what they get.)


I mainly used Toddy and other full immersion techniques.

In the place I work we just use the Toddy. For big batches it is in my opinion the best alternative. We have a drip stand (Hario or some other fancy wooden thing) as well, but it's just not as good, because the water is dripping on the same spot of coffee grounds constantly. You can mitigate that by placing a round paper filter on the grounds (from Aeropress e.g.), however there will still be some uneven extraction. An alternative is the Filtron system, which is basically the same thing. What you could do as well is just brew it in big jars or barrels and then filter it in 3 levels with a restrainer, cheese cloth and coffee filters.
Here is a nice little comparison by Stumptown coffee, that places the Filtron and Toddy system on the top.
To be honest, cold brew works best with washed Ethiopian/Kenian light roasted coffees in my opinion, which really brings out a lot of sweetness and a nice floral flavor. Cold brew generally reduces acidity, so it works well with high acidity (african) coffees. Sumatran coffees, which would match your flavor requests, are already very low in acidity so the cold brew method can't really shine here. You can also try natural processed african coffees, they would be more full bodied, chocolaty and with notes of red berries (had an amazing ethiopian natural that tasted incredibly like strawberries). They are not really my thing though, a bit flavor overkill most of the times.
Central American coffees usually work quite well as well, with a bit more nutty, caramel and chocolaty flavors.
I've written something on this in this question already. In any case I use very high coffee to water ratios and don't dilute the concentrate (just served on a lot if ice). However for many people that is too strong and they dilute it with water or even add a little milk, which works quite well with this kind of concentrate.
Depends on your taste and the best recommendation anyone can give you here is to try a lot of different coffees and recipes until you find your style. You should definitely do some testing before you sell, so you actually like what you are selling and understand what it is. Generally longer contact time means higher extraction, 12 to 14 hours is what I do at home (in a mason jar) and I like it most. In the shop we do faster brews though.

Well I hope that helped, I'm happy about comments and suggestions how to improve the post.


Is an Americano the same as drip coffee?

Differences

Crema: an espresso has crema whereas drip brew coffee doesn't. The reason for this is that an espresso is pulled under pressure.
Paper filtered: drip brew tends to be filtered by paper of cloth, filtering out oily components. From Comparison of nine common coffee extraction methods: instrumental and sensory analysis (where the French press is similar to espresso in that it isn't paper filtered):

  The most efficient extraction of fatty acids was performed with French Press extraction. Brewing with a paper filter resulted in coffee with the lowest fatty acid content, which is consistent with the findings of Peters.

Of course, this doesn't apply to all drip brews, metal filters don't filter out oily components.

(Possible) similarities

Strength: since an Americano is a diluted  espresso, you can make it the same strength as a drip brew coffee by adding an appropriate amount of water. The opposite isn't true, you cannot make a drip coffee that has espresso-strength.
Ingredients: both are made using roasted coffee and water only.


What's the theory behind using thin spouted kettles when making drip/pour over coffee

By having a thin spout, you can more finely control the flow rate and where the water lands.    When making pour-over coffee, you want to control the water level in the cone to control the brew time and evenly extract coffee.  Also, water needs to be poured carefully onto the middle of the cone so that the water doesn't run down the side of the cone without touching the coffee grounds.


Which is better for grinding coffee: Food processor or blender?

I guess both food processors and blenders would act like big blade grinders. Blade grinders give particles of a wide range of sizes, from fine dust to chunks.  This gives uneven flavor extraction (if you can taste it), and requires the use of the finest filter.  If I had to choose, a small food processor might be superior, since the blades on blenders are pitched to stir more than to cut.

Lacking a burr grinder, which gives more consistent particle size and therefore predictable extraction, I'd repurpose an old pepper grinder!


Making instant coffee is the same process as making a cup of coffee from grinding your own beans - at least the first part of it before the drying.

How is instant coffee made

So if I want a mild cup of coffee, I use less coffee grind. There are other variables that can be played with along with the amount of grind: extraction time, extraction temperature, bean roast level.

You can probably make your cup of instant less mild by adding an extra spoon or so of instant. Simulating (?) more coffee grind.


What is the best way to clean a refractometer?

I'm sure there are instructions on maintenance and cleaning in the refractometers manual. However with distilled water and soft towels/tissues and/or Q-tips for the edges (be careful not to scratch the prism with the plastic handle) you can get rid of all the residue. Don't use alcohol or something like that. If the oils don't come off or if it's really dirty you could use a little bit of mild detergent in the water and wipe it with distilled water at the end to get rid of any detergent residue.


How do I know when to stop pulling my shot?

I generally judge when to stop my shot based off when blonding begins to occur. This is when the espresso changes to a noticeably lighter, yellowish color. At this stage, only bitter flavors are being extracted from the coffee, and any more extraction will only degrade the flavor of your shot.

It takes a bit of practice to notice blonding, and can be made more obvious by using a bottomless portafilter. I also suggest using a stopwatch to determine how long it takes before blonding occurs, so you can see how consistent the rest of your process is.


Replaced gasket on moka pot and it misbehaves - should the gasket be treated with anything?

It sounds like you know your Moka pot well, and it is true that it is an easy way to get deliciously strong coffee. That being said, it can also be very nuanced in how it works. First, your new gasket should seal perfectly well and as long as there is no sputtering from the screw joint, it is good.

Sputtering means that you are forcing too much steam too quickly through the grounds and into the pot. Try using a high heat to get the coffee flowing, then adjust the heat to keep an even flow into the top chamber. It's possible that with a bad seal, extra pressure was being release from the screw joint and now it is all being directed through the "tower".

Hope this helps!


Is it necessary to keep a portafilter in the grouphead when not in use?

Keeping the portafilter warm (and receiving / tamping a dose within a warm portafilter) is supposed to result in additional oils being released in the extraction, which in theory leads to a fuller pull and more crema. It's also supposed to add to the benefits of pre-infusion.

I have experimented at length with this, and can detect positively no difference between a shot extracted from a cold filter, and one extracted from a warmed one. It might only be noticeable on higher-end (larger) machines, or simply larger filters.

Mechanically, it's a sound enough practice as it would help keep the group head and portafilter from warping independently, even ever so slightly. Even though the seal they make is assisted by the inclined plane the filter travles to reach the head, it's still good for the filter to mate properly with the machine.

I asked my barista about this after Joel mentioned it, and he also said it's a good practice to keep.

tl;dr; It can't hurt, and it might help, but YMMV on lesser machines.

edit

Experiments in various presses, and the amount of crema they produce have shown that pre-warming metal filters produces more crema. This eluded me because I own a pretty good machine that heats the filter quickly after it has been attached to the machine.

The accuracy would depend on your machine. The result could be more crema, and everything that a fuller extraction entails.

suggestion

Try it on your machine and see if it makes a detectable difference.


French press vs simple filter, is French press equipment really necessary?

The simple answer is, no. You don't really need the exact French-press equipment to prepare a drinkable cup of French-press coffee.

However, the equipment is very likely to ease your preparation. Otherwise, you should take care about

timing
amount of water (and maybe setting the coffee/water ratio)
filter-size
act of filtering quickly and properly

all by yourself to have a decent cup. If you aren't experimenting or looking for adventure I advise you to pay 5 bucks for the equipment.


What are my options for approximating espresso at work?

I don't want to provide any specific product links here since they may change in the future and I also don't want to advertise specific stores.

However there are some options I can think of. There are electric Moka pots that have the stove already built into them. Bialetti is the go to brand for Moka pots. I'm certain that they will fit in your office, even on your desk if need be. Alternatively you can get a small electric stove for the Moka pot you already have. It will also fit on your desk.

Another option would be portable espresso makers. Handpresso Wild Hybrid and Wacaco are the only ones I know of. I've heard good things about the Handpresso, but can't attest to them since I haven't tried one yet. They work with pressure, which the Moka pots don't do, so they should come closer to Espresso from a machine.

However I personally would stick with the AeroPress. In my opinion it makes by far better, more complex coffee than the other options.There are also some tweaks, like using two filter papers, using a metal filter, very fine grind size, tamping the coffee, high coffee to water ratio and tweaks/constructions to apply more pressure, that make a more espresso like drink. Note however that the AeroPress is not built to withstand several bars of pressure and constructions like the one in the video are neither practical, nor safe. The other tweaks mentioned however can safely increase pressure to a point where you get pretty neat, espresso like results.


How to choose coffee that's the most stimulating without the anxiety

Have you tried mushroom coffee? It has the effect you're looking for. 4 Sigmatic have a good range to choose from with varying effects. I find the ones with lion's mane mushroom help with focus but don't give me the jitters!


How can I make french press coffee taste less acidic?

Without any more specific information about the coffee you use and what recipe you use for the french press, we won't be able to give you a specific answer with a solution to your problem. However too acidic probably means that your coffee is underextracted. That means the water hasn't had enough time or wasn't hot enough to extract the flavor compounds you want out of the ground coffee.

There are a few variables that will influence extraction with french press. I already mentioned time and heat. A recipe that I have used with very good results is 6g coffee per 100ml of water, ground to the size of coarse salt with a steep time of 4min. At first you only add a little water (just off the boil), twice to three times the weight of coffee grounds and let sit for 1min. Then give it a stir (there will be grounds on the top forming a crust), add the rest of the water and wait until 4min. Plunge and immediately transfer your coffee to a preheated vessel, either your mugs or a jug. Important here is that you don't let the coffee sit as it will continue to extract and taste bitter after a few minutes.

This should give you an even, full bodied extraction. If you feel like it's still too acidic, you could vary the variables involved. If you grind slightly finer the extraction will be higher. Same thing if you increase the brew time a bit. I suggest you just play around and keep in mind that these variables are not independent of each other. Finer grind means faster extraction for example. With a basic understanding of how extraction works you should get the hang of it quickly.

If the coffee still tastes too acidic although you have tried all suggestions check if the roast is too light, since light roasts tend to have more acidity. Also the origin of your coffee is a factor, african coffees (there are many different regions and processing methods so this is a big generalization) tend to be more acidic, while sumatran coffees are considered the least acidic. Central and South American coffees will often have acidity levels in the middle range.
It might also be sour because the coffee is stale (around 4 weeks after roasting for whole beans, much much much faster for preground) or it might just be shitty coffee.

This is a good little intro in the world of extraction (or rather which tastes are associated with different levels of extraction):
Coffee Extraction and How to Taste It.

This is a very nice little graphic with explanations that helps identifying which extraction problem you have and how to solve it:
The Coffee Compass.

Cheers and enjoy a nice cup of coffee.


Based on the cezve shown by @IgorTatarnikov, I can say the options are really limited.

The cezve presented here is an electrical Turkish coffee pot with proper quality.

Decoction brewing technique (mixing grounds and water together, then heat them up) and their alternatives are the only ones you can do. Worse, you cannot slow down heating in an electrical pot. Actually, quick heating is something desired for good Turkish coffee. But, you cannot use this for mırra, for example.

Adding flavors may be an option. Like cardamom, mastic, etc. to diversify the Turkish coffee.

Another option which is rarely made in Turkey is adding milk after preparing the coffee. First, you need to wait a while for the grounds settle down. Then, pour the non-grounded part on another cup and add warm milk. It resembles Indian coffee, but without sugar. And you cannot use their fancy filtering equipment. This may resemble latte a bit. But, I can't think of any other options.

One side note... Such an electrical pot is a cool device to quickly heat up water. So, if you also place a few more cups and grab some filters you can filter your own coffee. When I was a student, I used to use this a lot. I used a similar machine to prepare Turkish coffee at the same time I directly filter my grounds with a Melitta filter on my cup.


Would drinking excessive coffee reduce blood hemoglobin content?

coffee reduces iron uptake. parts of hemoglobin are comprised of iron. if hemoglobin becomes low the oxygen rate to other parts of your body decrease. causing low energy and fatigue. the low iron could also cause anemia.


Which type of coffee grinder is the quietest?

First, lets ignore blade grinders entirely.  Any grinder that doesn't have a motor will be relatively quiet.  You'll be at the mercy of the crunching beans, but that's it.  Add to this that the more the grinder weighs, or the more "heft" it has to it, the quieter it will typically be due to the additional mass damping any vibration.  When adding a motor to the mix, each step between the motor and the burrs adds an opportunity for noise.  As such, a direct drive grinder will typically be quieter than anything involving a gearbox.

The pecking order is basically...

Hand Grinder --> Direct Drive Flat Burr --> Direct Drive Conical Burr --> Gear-Reduced Burr

While Decibel ratings are available from most manufacturers, they're difficult to translate into a subjective estimate of "harshness."  I deal with these regularly and found that some of my favorite grinders are technically louder than several others, including the Baratza Vario. The difference is that they have a much more mellow drone rather than the gear motor's quieter whine.


How do I judge the quality of 'green' beans?

I have been purchasing everything from cheap beans to rather pricey beans and what i discovered while buying the more pricey (and higher quality) beans was that the fragrance of the bean is somewhat stronger and can actually smell of more than just the usual grassy fragrance. Notes from fruits and nuts are not unusual and could be a indicator of somewhat higher quality coffee.

I have no scientific proof of this, and while even expensive coffee can be bad, it is my empirical approach to determine what could be a step up in coffee quality.

Apart from that i have to admit that its hard to determine the quality of the bean before it has been roasted.


Is it possible to feel any effects after chewing one coffee bean?

First I want to draw a comparison between how much caffeine is in a coffee bean versus a cup of coffee, a cup of tea, or a double espresso.

In a standard cup of coffee, there is approximately 150 mg of caffeine. In a cup of black tea, steeped for 3 - 5 minutes there is approximately 50 mg of caffeine. In a double espresso there is approximately 60 - 90 mg of caffeine depending on the roast, grind, extraction time, etc.

In one dark roasted espresso bean there is approximately 6 mg of caffeine according to this source.

If a person is extremely sensitive to caffeine, they would probably be able to feel the effect of 6 mg of caffeine. However, if someone is a coffee drinker, the likelihood that this caffeine is actually affecting them is very unlikely.

If your friend never ingests soda, coffee, tea, or caffeine in any form then he may have felt some of the effects. In my opinion, the majority of the way your colleague was feeling was probably a placebo effect.

Edit: Coming back to this answer, I neglected to mention the effect of the taste of the coffee bean. Taste and aroma can powerfully affect and stimulate the brain. Due to the relatively strong taste resulting from chewing up a roasted coffee bean, this may have also contributed to the reported feeling of stimulation.


Piece that goes screwed in my steam wand

Is it a wand with a single tip at the end?

To get microfoam, you only have to produce a little foam at the start of steaming, a few light 'rips' of bubbles, then the rest of the time is spent whirling this into the milk. Keep the wand tip just below the milk and a little to the side while keeping the pitcher flat. This will create a whirlpool that helps mix everything else up. Hope this helps.


Coffee passing through filter during bloom

The drip-through of water during the bloom process isn't itself a cause for worry of a 'bad' brew as this process is meant to aid degassing of the beans prior to the main brew pour. The amount of drip-through you're experiencing is completely fine as long as the entire bed of coffee has been wet by the bloom pour.

However, if you reckon there is too much coming through, make sure you're not using too much water relative to your total brew weight in the bloom. If a significant fraction of your water is used during the bloom, and therefore less being used during actual extraction, it will affect the resulting flavour.

I'd argue that as long as the amount of water used for the bloom is less than 1/4 of the total brew water weight and the entire bed is being wet by it, no matter how much filters through, it should not affect the brew significantly.


What is this tamper/filter thing that came with my moka pot for?

OK, I've worked this one out. This little thing is called a reducer.

What you can do is put the reducer into the funnel. It should sit on the indentation half way down. You then put coffee on top of it. This allows you to make less coffee with a larger pot.

However, although I haven't tried it yet, it seems that most people complain that the quality of the coffee reduces (!) significantly. Many complain of a weaker brew. It's probably better to use a smaller pot if you regularly want to make less coffee.


Like @Shiri said in comments above (and hopes that I'm not answer-sniping), most recipes for cold-brew are concentrates. Within reason, try brewing with a smaller amount of water! Compare guides like Kicking Horse, Stumptown, Blue Bottle.

In my experience (except for the problems that I've had with filtering) brewing a lower volume of water generates very similar results when diluted. Said the other way, brewing with a higher ratio of coffee :: water, then diluting, is my preferred way of brewing, storing, and consuming.

That said, do store in a neutral vessel that is easy to clean (my preference is a wide-mouth glass jar). Stored in the fridge, it will last several days (maybe a week) and still taste okay. In a plastic jug (or so) it might 1- start to obtain bad tastes from the container, and 2- infect the jug with stale coffee taste over time. Coffee oils (etc.) can be hard to remove especially when cold.

Some additional information is in related questions are about ratios and concentration and a concentration table in this answer.


Whole Bean Coffee Degradation Over Time

Whole bean coffee will go stale within 14 days - on average. The graph below shows the quick 1.5 standard deviation drop in quality within the first 14 days (marked in red). *See note below for details

Staling in the context of coffee has a commonly agreed on definition - the loss of volatile aromatic compounds and the oxidation of surface oils on the roasted coffee beans. The loss of aromatics affects the flavor profile because: 1) they are both part of the same degradation process and 2) the majority of what you taste in coffee is flavors from volatile aromatics through retronasal olfactory sensation.

This graph was created using data from Analytical Flavor Systems where we build quality control and flavor profiling tools for craft beverage producers. Perceived Quality is a non-hedonic assessment of a product's quality. This time series is taken from a degradation study.

Ground coffee, on the other hand, will stale within minutes. 70 cc of ambient air is enough to render one pound of coffee stale. On average, this process takes seven minutes.

Interestingly, the degradation curve looks about the same!

Data Analysis Minutia (notes)

This time series model was segmented using daily Perceived Quality means from a random selection of 15,000 coffee reviews. All coffees included are whole bean, freshly ground, third wave coffee brewed in a Chemex with a bleached filter.

Certain other brewing methods, particularly methods optimized for older coffee such a Nel, may show a different degradation curve.

The staling point was selected by a parametric statistical change point analysis, which searches for shifts in the mean and variance of a time series. This time series was modeled for change point analysis using a Poisson distribution as  we're searching for the average number of coffees that go stale within a specific time-point, and the model was set to find at most one change.


Office bean-to-cup machine tastes acidic in the morning

My thought is that once you turn on the machine, the machine starts to heat the water. Often the heating system is regulated by a PID regulation (Maybe on-off regulation). The machine will heat the water fast to make sure you can get your cup of coffee:) Once the water is heated it will stabilize to the intended temperature. If the water is heated above the intended temperature it will cause acidic compounds to be extracted from the beans. After a while the temperature is stabilized and you will experience that the coffee is no longer acidic.

Another theory is that the pipes within the machine are not clean.

You can test both.

Try turning on the machine an hour before making the first cup. If this helps it is probably a temperature issue.

If not try to clean the machine by running through hot water before making the first cup.

Hope one of these solutions will help you with your issue.

"Life is too short for bad coffee"


How do I make an espresso shot in a moka pot?

You can create more pressure if you will use finer grind (but be careful). I even tamp a bit (but be careful again). You can also buy Bialetti Brikka, which has a pressure valve - it helps to build higher pressure and create crema. However, with moka pot you'll never get real espresso, you can only try to brew something similar.


When accounting for bloom, why is the common instruction to stir with very little water?

Blooming is the outgassing of CO2 (carbon dioxide) from the ground coffee in response to hot water being added.  The more recently the coffee has been roasted, the more bloom you can expect.  It doesn't make a huge difference ultimately if this is done quickly or slowly when you brew your coffee.  What I have noticed myself is that it's sometimes diffcult to predict how much foam is going to be produced when the water is poured over the grounds.  More than once I have misjudged the amount of bloom and made a foamy brown mess on my countertop.  If you just add enough water to wet the grounds first, you accomplish two things.

First, all the coffee is wetted at nearly the same time which better controls how the flavors are extracted, since different flavor profiles extract at different rates.  Sometimes adding all the water at once creates lumps of dry coffee mixed in with the bloom and wetted coffee and it takes a bit of stirring to get all that wetted.

Secondly, adding a small amount of water controls how quickly the bloom will occur. You'll get most of the bloom done well within the pot and you'll avoid the huge foam ball at the top of your brew that might overflow the pot (or AeroPress in my case), but really this is more of a technique thing than a chemistry thing.


What is an optimal coffee to water ratio for pour-overs?

This is going to be unpopular but my routine doesn't really involve measuring much.  I want get the brewing over with ASAP so I can drink my coffee.

Prime the filter with hot water and pour out water
Put in ground coffee, I just use 6 TBSP for the 8 cup classic
Prime grounds by pouring just enough in to stir them up and get wet
Wait for gas to release (should have a nice cone of grounds)
Pour water into the center of the grinds and then circulate as water rises
Wait until brewed coffee gets to the belly button of the chemex
Pour more water in until it is about 1/4 inch to the top
Let drain out and enjoy

I just go a bit bigger with my scoops if I'm looking for more of dark brew.  My goal here is to control the output so that when finished I have enough coffee for about two pint glasses.  Thy key is that belly button which I'm guessing is the half-way mark.


In short: Very probably, you will lose the very best part of your coffee.

Caffeine is highly soluble, yes. But, also the other lipids and aromatics, too. So, you cannot obtain the benefits of specialty coffee if you ruin that first brew. The main taste we gain from coffee grounds are received from the soluble aromatic oils in the coffee. You don't want to loose them by pouring.

Normally, decaffeination process is made when the beans are green. That's why the aromatics are kept inside the beans when the beans are over-hydrated and then dried (in the Swiss process, which is the common way recently) a few times in a cycle to near completely remove the caffeine.

You can check the decaffeination process in the following question:

How is decaffeinated coffee made?

And also watch a nice explanatory animation here.

Still, if you wonder how to use the grounds for a second time, please see this discussion:

Brewing with the same coffee grounds twice?


What is going wrong with this Espresso shot?

I don't think anyone can really give a definitive answer to this but I'd like to chime in to try to help. It's almost impossible to find your answer because of how many different variables are at play here. You should first focus on minimising the variance in your methods.

You describe the shop shot as being a 'longer pull' and thereby expecting more bitter results. The problem with that assumption is that you can only truly compare shot times if you have extracted the same output weight in both cases. Since you have not, you have not only extracted much less in your shop shot, but, like you noted, it also took longer. I normally only ever measure my shots by weight because that's the number that tells me how much water got through and thereby how much real contact and subsequent extraction occurred.
I use time as a secondary reference to diagnose other problems in my shot. If I suddenly start extracting a same weight shot in half the time that I normally do, I know something is definitely off. Since your shop shot extracted much less output weight, the sourness is clearly due to some level of underextraction from being stopped too early (relative to your home shot). In any case, I always try to aim for 30g in 30s, which means you probably need to grind slightly finer in the shop to be able to extract more and try to hit the same balance as your home shot.
You mention your water sources being different. This is huge! You will never find the same shot if you are using filtered at home and unfiltered at the shop depending on how hard the water is when unfiltered.

Compare shot times as a secondary to consistent output weight and see how grinding finer in the shop would fare.

Higher boiler pressure does not necessarily point directly towards higher temperatures. Also, higher pressures could impact the puck suddenly when the valve is opened which could crack and cause channeling and therefore underextraction and sourness. Your main issues here are still in point 1.
Weight difference is purely by choice. Crema production is mostly dependent on freshness of beans and less to do with specifics in extraction method. If preset weight quantities are being used as part of a single button-press on a machine, then your problem starts there. You need to weigh every shot and choose when to stop the shot yourself. Without this control, you're simply relinquishing responsibility of the shot and you are at the mercy of the machine, yet another variable to consider in being able to find the right shot.

In conclusion, you MUST minimise variables. Make sure your grind sizes are the same at both locations, ensure your input and output weight are identical, analyse differences in taste and extraction time at same output weight, ensure your sources of water are identical, make sure your tamp pressures are the same. At this point the only real differences will be the machines and then you can start investigating how each machine is affecting the shots. Try to use bottomless portafilters in order to diagnose whether your distribution of your coffee bed was poor and whether channeling occurs during extraction.

Combine all of the parameters above with the taste of your output shots and you'll know the next steps you need to take in finding the problem in your shot.


What purpose have those grooves inside the dripper?

These grooves are for improving the flow of coffee through the filter. The grooves create space between the filter and the cone to permit little channels for the coffee to flow into the vessel after passing through the filter paper. I think the ridges also help "wick" the coffee away from the filter paper, helping the filter paper drain better.

If the ridges are absent (as in Chemex cones, for example) the brewed coffee sometimes wells up between the filter paper and the cone. See also this question and my answer that compares the two styles of cones.

As for the shape and location of the grooves, some are spiral-shaped, others are straight, staggered, etc. I don't notice any advantage of any style as long as they're present, and I suspect the shape and location is purely aesthetic or marketing, not significantly different in any functional way.

EDIT: this article from Serious Eats suggests that the grooves additionally help "keep water distributed evenly among the bed of coffee grounds." Presumably this is related to the drainage I mention above, but was a more-legitimate source than my theories above, so I wanted to include.


Coffee cannot taste like distilled water. It's not possible.

I think what you mean is that the coffee in question tastes too clean or too dry. That can be caused by using filtered water with too low dissolved solids or water with too high sodium content. The best water to use for brewing is generally thought to be hard water rich in magnesium and calcium, with no chlorine and low sodium content. If the dry, flat taste of coffee bothers you, try using mineral water, or, if you really want to experiment, buy water additive made specifically for making brewing water like Third Wave (you can find it on Amazon). You mix this additive with distilled water to create mineral water. You can also make your own water additive with 0.75g epsom salt and 0.36g baking soda per gallon of distilled water.

Water quality is very likely the problem if coffee consistently tastes flat, dry, or "clean". The only way to test this is to try the same brew with different water.


I used empty capsules to fill my own coffee and brew it using a Nespresso machine. I would say the result largely depends on the coffee you use, but not the capsules itself. It takes several tries until you get the right amount of coffee into one capsule (I had to stuff one brand of coffee quite tight to get a crema at all), and the amount differs very much from coffee to coffee. Of course, the grind matters a lot, but you can compensate with the amount of coffee.

The only problem I had with the capsules is that sometimes they got stuck when discharging, but you can usually fiddle them out using a fork or so.


It really depends on how much coffee you grind per day. Say, If you're going through about 100 gm (or lower even) of coffee every day, you should clean

The beans chute and the burrs once a month or two.

The grinds catch around once a week. Your grinds catch needs cleaning more often than the chute and the burrs themselves.

Also for the chute or any of the internals (especially the burrs), Don't use water for cleaning.
TLDR: Clean the grinds catch often and rest once a month or two for regular coffee use.


If the coffee is, (ground or not) sealed directly after roasting, the coffee will still gas out, releasing CO2 as a result from the roasting process wich leads to inflated bags. On many coffee bags, especially from "smaller" roasters there is a little valve integrated to let this excess CO2 escape rahter than blow up the bag.
This happens for up to two weeks after roasting, the most of it shortly after.

It is rather a sign of freshness, but that depends on where you got your coffee so I can only speculate if it is fresh and that that is the cause ;-)


Why does my Moka pot sometimes produce GREAT coffee and sometimes awful coffee?

Actually, this question is self explanatory. I assume you only need some guidance and confirmation for what's going wrong.

A better known fact is:

if your coffee is underextracted, it tastes sour.
if your coffee is overextracted, it tastes bitter.

Now, let's tie up this to grind size:

if your grounds are finer, your coffee overextracts if other conditions are kept stable.
if your grounds are coarser, your coffee underextracts if other conditions are kept stable.

It's known that Moka pots are not controllable devices. So, all the other conditions (temperature, pressure, etc.) are nearly same each time. Thus, it's obvious that your grinding directly affects the taste of your cup. You should be consistent about your grounds. :)

And a final note, one of the jewels of this site is this extraction chart that you may check.


Dragon curve floating on freshly brewed coffee

It's probably not a dragon curve, but the fractal projection of the Brownian motion of coffee lipids on the surface of your tasty beverage.

Brownian motion is best explained by statistical physics. Small atoms or molecules collide each other continuously in very high speeds in the liquids even if they seem serene. However, as the total effect (average) of these collisions are quite stable, we see a still surface.

The small particles, which are very light in mass, can be affected by these collisions. So, they may move with respect to these collisions. So, you can observe these collisions as Brownian motions if you put some very light powder or lipid on top of the surface of a liquid. Very probably, this is what you have experienced.

Here you can find a very comprehensive list of fractal sketches, including the ones related to Brownian motion. Do any of them look similar?


You can actually get all-in-one moka pots that plug directly into the mains, e.g.:

http://www.amazon.com/Delonghi-EMK6-Alicia-Electric-Espresso/dp/B00009W5F0

I've used one similar to this before, the results aren't bad!


Does coffee taste different when it is ground at home?

I bypass the first question.

Yes, ground size considerably affects the taste of the final cup. In general, there's a common rule of five component for a good cup of coffee. Each component must require its precedent.

Good beans
Good roasting
Homogenously/correct-sized grinding
Correct equipment
Skilled cook

(Italians mostly merge first two articles and name it as 4M for espresso.)

As stated above, the grounds must be all at the same size. Moreover they must be the correct size. The finest for Turkish, a bit less fine for espresso, boulders are good for French press, etc.