From the Forbidden Fruit in the Garden of Eden to today's fruit-filled bakery foods, consumers have been tempted by many taste, textural and health benefits derived from fruit. These benefits appear to grow daily as scientific research discovers more healthful properties found in fruit. However, without the proper handling, fruit and fruit fillings can discolor and destabilize bakery foods.
Fruit fillings consist of many ingredients, including fruit; water; stabilizers such as starches and gums; and sweeteners such as sugar and high fructose corn syrup. These ingredients play an important role in achieving the ideal fruit filling.
When manufacturing fruit-filled bakery foods, high-volume bakers can either purchase ready-to-use fruit fillings from an ingredient supplier or create their own fillings using fruit, stabilizers and an assortment of other ingredients.
When using fruit fillings, bakers must be familiar with the filling's brix level. Brix is the measure of the percentage of soluble solids (primarily sugar solids) of a liquid fruit filling or a particulate piece. Brix levels are measured using a refractometer. The higher the brix level, the more dissolved solids the filling will have. "Different baked goods require certain filling brix levels to ensure final product quality," one fruit filling supplier says. "For instance, some cake, cookie, or donut fillings will require total soluble solids levels of around 70% to 80% to reduce the water activity and prevent water migration from the filling into the bakery item, while some pie fillings can be lower at around 30% to 50% solids."
As a key ingredient in fruit fillings, water has to be managed carefully. Selecting the wrong stabilizer system or using incorrect levels not only causes syneresis or weeping upon storage, but it also leads to problems during processing due to fillings that are too thick or too thin. Bakers can stabilize their fruit fillings by using starches, gums or a combination of the two.
Popular gums for baking applications include xanthan, carboxymethylcellulose (CMC), carrageenan, locust bean gum, gellan and pectin.
According to one supplier of fruit fillings, starches are typically used at 1% to 5% of total weight, which is higher than gums. The supplier says that this causes more masking of a product's flavor than gums. Bakers also can use a combination of starches and gums to reap the advantages of both types of stabilizers.
"Pectin alone does not work well when heated and tends to boil out, but it does give a cleaner flavor release," one fruit filling supplier says. "Combinations of starch and gum work well together in the oven to give bakery stable fillings that will not run or boil out."
Along with stabilizers, sweeteners represent another important ingredient in fruit fillings. Sugar, 42 DE corn syrups and high fructose corn syrups (HFCS) provide bulk solids and typically make up 40% to 50% of the total weight of a filling.
"Fruits can be infused with different materials such as corn syrup, fructose, sucrose, and even sugarless polyols such as sorbitol or maltitol to make shelf-stable individual pieces, which can add an upscale image to many baked goods," one fruit filling supplier says. "Fruits such as berries, which start out with only 10% to 12% solids, can be transformed into products with much higher total solids levels and reduced water activities."
For example, the supplier says that fruit pieces ranging from 40 to 60 brix can be used for muffins, and pieces with much higher solids levels (64 to 68 brix) are ideal for breads due to their low moisture content.
Syrups are less expensive than granulated sugar, dextrose, or fructose, but do contain a higher moisture level. High intensity sweeteners such as aspartame, sucralose, and acesulfame-K also can be used. Sucrose is a reducing sugar so it will undergo browning reactions and cause filling discoloration during heating. The ideal formulation requires the blending of sugars in the correct ratios for cost effectiveness and maximum functionality.
Besides formulating ideal fillings, bakers also must consider a variety of challenges that arise when using fruit fillings in bakery foods. The real test for fruit fillings is in the oven. The filling must be stable under conditions of oven time and oven temperature. The fillings also must not expand out of the crust and boil out, or create excess steam pressure, which would cause unsightly cracks. Maintenance of piece integrity, if applicable, and a pleasing color, gloss, mouthfeel and aroma, also are valuable sensory attributes. Fruit fillings that are deposited onto the top of cookies and cakes should be devoid of bubbles and should be of sufficient viscosity to remain in place.
Water activity measures the free unbound water available for bacterial growth in foods. Most bacteria are unable to grow below a water activity of 0.90. Most spoilage yeasts and molds are inhibited at an water activity below 0.80, and no molds can grow below 0.60. For a longer shelf-life, bakery fillings should have a water activity less than 0.75. Lower water activity fillings are typically found in cereal bars and fruit-filled cookies. "An important issue in controlling sogginess in baked products containing fillings is to control the water activity," notes one filling supplier. "With cake or cookie fillings or pastries, it is not desirable to have the moisture migrate out of the filling and into the dough or vice-versa. It is best to have the filling and dough at similar water activity levels. Otherwise, water migration will occur on storage and lead to textural and microbiological stability problems down the road."
Another issue when using fruit fillings in bakery foods is their potential to discolor a product. Although some bakers view this as a detriment to a product, others see it as an opportunity.
"Some bakers prefer to add a percentage of the IQF berries into their batter and let sit overnight. They will add the balance of the frozen berries the next morning and then bake," a fruit filling supplier says. "Color bleeding can add color and flavor swirls into the batter and make muffins and other baked goods look more appetizing."
A pH level of 3.4 to 3.8 is common for fruit fillings and it is recommended to have the pH below 4.5 to prevent spoilage. Increasing the acidity (lowering the pH) will enhance the fruit flavors. Citric acid is the most common acidulent used. A higher pH level reduces color stability and causes a loss of fruit brilliance, especially for berries, one supplier says.
Cut the fat
Simply stated, incorporating any type of fruit, including fruit fillings, IQF fruits, fruit bits or fruit pieces, can be a profitable decision. Fruits add color, sweetness, flavor, and their all-natural status adds to an appealing ingredient label. Additionally, fruits provide health-conscious consumers with a variety of vitamins, minerals and soluble dietary fiber. Berries and plums contain several bright red and blue pigments known as anthocyanins. Some fruits also contain other antioxidants such as flavonoids, which have potent anti-cancer and disease fighting properties.
Some fruits, including apples, plums, dates, raisins, figs, pears, white grapes and cherries, can be used as fat replacers in various bakery applications. For example, dried plums are an ideal fat replacer because of their high levels of total dietary fiber (8%); sorbitol content (roughly 17%), which serves as an all-natural humectant and helps lower water activity; and malic acid, which acts as a flavor enhancer and preservative.
The benefits of fruit are innumerable. As a result, incorporating the ideal type of fruit into a bakery food formula has the potential to attract a large segment of consumers, including health conscious eaters and buyers that are simply looking for an indulgent treat.
An apple a day...
In specialty breads and bagels, one apple supplier recommends using infused apple pieces dried to 5% to 12% moisture. These pieces can be prepared using either high fructose corn syrups, fruit juice concentrate or other humectants, the supplier says.
Apple powder or evaporated apples can enhance other fruit fillings to make them more functional. "These products can help build solids and lower water activity levels, and because the color and flavor of apples is subtle, they will take on the characteristics of whatever fruit they are blended with. Since apples are a natural humectant, incorporating them as the base fruit in a filling also can help prevent the filling from drying out and extend its shelf life," notes the supplier.
However, when using apples with high malic acid contents in a formula that requires leavening, adjustments may be needed to compensate for the high levels of acid, which trigger excess carbon dioxide production prior to baking.