<p>It doesn't actually matter!</p>

<p>The valve on the bag is there to let gas out without letting gas in. The reason for this is that freshly roasted beans will continue to give off a bit of CO2 for a little while. Coffee that's packaged immediately after roasting will give off a bit in the bag, hence the need for a valve.</p>

<p>Oxygen causes coffee to go off, which is why we keep our coffee in airtight containers to preserve it as long as possible. It's why the valve on the bag is designed to prevent air from the outside getting in.</p>

<p>The CO2 that's accumulating in the bags is essentially inert, and won't cause the coffee beans to go off. It makes no difference whether you squeeze it out or not!</p>

CC BY-SA 3.0
2015-02-26T11:52:19.290Z
Agreed, and also... *still don't squeeze!* I don't fully trust the "one-way-ness" of one-way valves in cheap, one-time-use packaging. In fact, I put the whole thing (original packaging and all, whether opened or not) nested in *an additional bag* (like a zip-top plastic bag with extra air exhausted) to further minimise the gas exchange.
hoc_age
CC BY-SA 3.0
2015-02-26T11:53:09.070Z
@hoc_age Yeah. To be honest, the positive pressure in an inflated bag is probably a good way to make sure no extra oxygen is getting in!
fredley
CC BY-SA 3.0
2015-02-26T11:56:48.153Z
Indeed. Sometimes the bags are flushed with more-inert gas (e.g., nitrogen, CO2) to evacuate the less-inert stuff in regular air. Anything that's in there already is better than anything that might seep in!
hoc_age
CC BY-SA 3.0
2015-02-26T22:07:44.983Z
Got email from the roaster and they said essentially the same thing. If the coffee is being consumed within 21 days it really has no effect one way or the other.
Francisco
CC BY-SA 3.0
2015-02-26T09:50:31.967Z
2015-02-26T09:50:31.967Z
fredley
<p>I buy 2-3 bags of fresh roasted beans and after a few days the bags balloon out. Should I squeeze the gases out or let the gases seep out naturally? </p>

CC BY-SA 3.0
2015-02-26T17:09:39.800Z
Only vaguely related, this actually proves that you are getting fresh coffee.
Suspended User
<beans><storage><whole-bean>
The one-way valve, to squeeze or not to squeeze?
Francisco
# The one-way valve, to squeeze or not to squeeze?

(Asked by: username_0 on 2015-02-26)

I buy 2-3 bags of fresh roasted beans and after a few days the bags balloon out. Should I squeeze the gases out or let the gases seep out naturally?

**Tags:** beans, storage, whole-bean

> **Comments:**
> **username_1**: Only vaguely related, this actually proves that you are getting fresh coffee.  

---

## 1 answers

### Answer by username_2 on 2015-02-26. Score: 7 | Accepted answer

It doesn't actually matter!

The valve on the bag is there to let gas out without letting gas in. The reason for this is that freshly roasted beans will continue to give off a bit of CO2 for a little while. Coffee that's packaged immediately after roasting will give off a bit in the bag, hence the need for a valve.

Oxygen causes coffee to go off, which is why we keep our coffee in airtight containers to preserve it as long as possible. It's why the valve on the bag is designed to prevent air from the outside getting in.

The CO2 that's accumulating in the bags is essentially inert, and won't cause the coffee beans to go off. It makes no difference whether you squeeze it out or not!

> **Comments:**
> **username_3**: Agreed, and also... *still don't squeeze!* I don't fully trust the "one-way-ness" of one-way valves in cheap, one-time-use packaging. In fact, I put the whole thing (original packaging and all, whether opened or not) nested in *an additional bag* (like a zip-top plastic bag with extra air exhausted) to further minimise the gas exchange.  
> **username_2**: @username_3 Yeah. To be honest, the positive pressure in an inflated bag is probably a good way to make sure no extra oxygen is getting in!  
> **username_3**: Indeed. Sometimes the bags are flushed with more-inert gas (e.g., nitrogen, CO2) to evacuate the less-inert stuff in regular air. Anything that's in there already is better than anything that might seep in!  
> **username_0**: Got email from the roaster and they said essentially the same thing. If the coffee is being consumed within 21 days it really has no effect one way or the other.  

---

