By Allen Skillicorn
Fruit fillings and other fillings for pastries and pies
may seem simple enough. But when the equation changes from Mom making
a single cherry pie to the tons of fillings that large-scale commercial
production needs, it can get complicated.
A variety of factors influence the formulas of pies and
pastry fillings: flavor, texture, moisture, flowability, freeze/thaw
stability, shelf life, appearance, the amount of visible fruit, Brix
(the percent of sugars or solutes in solution), pH and titratable acid,
and microbial concerns.
Fillings for pastries and pies require the following attributes,
which can make the formulation and manufacturing processes challenging:
Cookie-bar fruit fillings require a firm consistency to
hold their shape in the finished product, and low aw to provide extended
shelf life and minimize moisture migration. These typically need to
be formulated with dehydrated fruit, such as low-moisture apples (24%
moisture) or similar products, to achieve a low finished-product moisture
level. A dehydrated fruit greatly increases the viscosity and prevents
boil out during baking. Many dehydrated fruits are treated
with sulfur dioxide or bisulfite to prevent enzymatic browning.
The type of fruit selected, the amount used and its process
characteristics, as well as cost restrictions, all affect how the finished
filling will look and taste. In addition to dehydrated forms, bulk frozen
fruit or individually quick frozen (IQF) fruit pieces can be added to
fillings. IQF processing provides a product that most closely approaches
fresh; the freezing process takes place relatively quickly, minimizing
fruit tissue damage by ice crystals. Frozen versions may come packaged
as 100% fruit or as a sugar-added type, such as a 5+1 form (five parts
fruit and one part sugar). The added sugar helps prevent ice-crystal
formation, decreasing damage to the fruits structure. Sugar can
help protect the fruits texture by depressing the freezing point.
This prevents the fruit cells from being frozen, protects against oxidation
and provides flavor. The higher sugar level reduces the amount of time
required for the solids in the finished filling to reach equilibrium.
It affects the specific gravity of the fruit pieces, which aids in their
Fruit whether its fresh off the tree, frozen 5+1, or dehydrated adds flavor, texture and natural nutrients. However, it is a natural ingredient, so it can vary in size and quality. To create a consistent product, manufacturers may have to make adjustments during production. Any changes, such as blending the fruit or fruit concentrate; adding sugars, acids or buffers; or using artificial colors to adjust the products color, must fall within legal guidelines. This is important, particularly since, in the past, questionable practices in regard to concentrates and purees have been employed. This is much less the case now with the improvements made in analytical chemistry.
U.S. Grade A or U.S. Fancy fruits are the very best quality,
with excellent color, and uniform size, weight and shape. Having the
proper ripeness and few or no blemishes, fruits of this grade are excellent
to use for special purposes where appearance, size and flavor are important.
Fruit of this grade is the most flavorful and attractive and
the most expensive. Much of the fruit processed into fillings is U.S.
Grade B or U.S. Choice. Only slightly less perfect than Grade A in color,
uniformity and texture, these fruits are of very good quality, have
a good flavor and are suitable for most uses. U.S. Grade C or U.S. Standard
fruits vary more in taste and appearance than the higher grades, and
have a lower cost. They are used where color and texture are not of
great importance, such as in pastry fillings that do not show piece
identity, jams, preserves, tarts and cobblers. They can also be processed
into fruit concentrates. A significant difference in price may exist
between the different grades, depending on supply and demand.
If the manufacturer is going to produce an apple pie with
big, visible apple pieces and the costs are recoverable, Grade A or
fancy-grade apples should be used. Conversely, it is cost-prohibitive
to use the same apples in a fast-food apple-pie-type product. Basically
an apple filling contained in a pastry coating, this type of inexpensive
product satisfies the consumers hunger and sweet tooth, but doesnt
require visible fruit pieces. Grade B or Grade C apples are more than
adequate in this type of application.
It is possible to use some apple-juice concentrate derived
from Grade C apples for flavor. These concentrates are not derived from
spoiled fruit, but are extracted from fruit that does have
defects. After juicing and evaporating, however, little difference will
exist between the concentrates juiced from Grade A apples and those
of the Grade C variety.
The least-expensive and lower-grade fruits are processed
into fruit-juice concentrate. Large amounts of apples and pears are
converted to fruit concentrates. Natural and inexpensive, fruit concentrates
retain their flavor but are in liquid form, consisting of water, sugar,
acids, flavor and some color. During concentrate processing, the moisture
is evaporated out in multistage evaporators. The aroma or essence of
the fruit is condensed out; concentrate suppliers can add the aroma
back to the concentrate or sell the essence separately.
Developers may also find size classifications used in
connection with the grade. For example, in the case of cultivated blueberries,
extra large has less than 90 berries/cup (250 ml); large is 90 to 129
berries/cup; medium is 130 to 189 berries/cup; and for small blueberries,
190 to 250 berries/cup. (It should also be noted that wild blueberries
are more flavorful, though they are smaller than cultivated blueberries.)
Apples are relatively inexpensive, a good fruit for fillings
and used by the food industry in great quantities. The U.S. crop is
picked in the late summer or fall. Apples receive a wash in dilute sodium-hydroxide
solution to clean and remove any pesticide residues. The apples are
then graded and sorted.
Through storage in a modified atmosphere, the shelf life
of apples can be extended before they undergo processing. The oxygen
content of the atmosphere is reduced and the carbon-dioxide level increased,
which slows down the apples respiration. The temperature is reduced
to 32º F and the relative humidity is increased to 90%.
After peeling, coring and slicing, most apples destined for canning, freezing or evaporation are treated with sodium sulfite, or a mixture of erythorbic acid, citric acid and salts (sulfite alternative). Large amounts of apples are sluiced and put through a drying oven, where the moisture is reduced to 22% to 26%. These apple pieces, called low-moisture apple dices or granules, come in many different sizes. The dehydrated fruit can be treated with antioxidants, such as sulfites and erythorbic acid. Low-moisture apples are relatively inexpensive, and store and ship well. They find themselves in everything from pies to relatively inexpensive pastry fillings where particle identity is not important.
Each component of the whole system adds to the flavor.
The flavor, sweeteners and acid bite all combine to make eating the
pie or pastry a pleasure. For each fruit-based filling type, a certain
ratio may exist between the titratable acidity and Brix. In nature,
different fruits have a normal Brix-to-acid ratio. If this is off, the
product may taste different. For example, due to variation in type and
the time of year that oranges are harvested, the fruits ratio
may vary. Using blends of different types of oranges or adding citric
acid may eliminate this problem.
The filling should have a characteristic fruit flavor, with good mouth-clearing properties and no artificial or chemical aftertaste. A good balance combining the sweetness of natural and added sugars, and the tart taste of acid helps bring out a full fruit flavor. Adding sugar reduces an acids tartness.
Citric acid and malic acid are the acidulants normally
used in fruit fillings, but formulations can contain other acids to
create the desired effect. Each has a different flavor-release profile.
Citric acid has a sharp, clean acid bite that quickly dissipates. This
makes it well-suited for a citrus-type flavor, but it can work in a
wide variety of fruit types. Malic acid is often used for apple-flavored
products and is found naturally in the fruit (malic means apple
in Latin). Its taste builds up and diminishes slowly. Tartaric acid,
used in small amounts to bring out grape flavors, produces a strong,
tart taste. Lactic acid is used in sour-cream or cream-cheese filling
for a number of reasons: it may be slightly better at lowering the pH
with less acid bite than the other organic acids; it is also the acid
most associated with dairy notes, giving a mildly acidic taste with
no sharpness. Phosphoric acid, which can be used in Bavarian cream fillings,
has a flat taste. This acid is not sharp, is slightly bitter and very
effective at lowering pH. Adipic acid has a delayed acid impact and
lingering high tartness.
An important relationship between the pH of a filling
and the total titratable acid exists that can affect the taste of the
final ingredient. As the pH decreases, the total titratable acid increases.
A pH meter will read the pH of a filling, but does not provide a reading
for the total acid in a product. The products total titratable
acid is measured by the titration of the acid with a standard solution
of sodium hydroxide (0.05N).
However, the pH may be changed by natural buffers in the
fruit or the addition of protein, sodium citrate, or preservatives.
When buffers, such as sodium citrate, are added, it buffers, or raises,
the pH. This creates a taste that is not as sharp, but is more well-rounded.
Preservatives are normally more effective at a lower pH.
Preservative systems may contain chemicals, such as sodium benzoate and potassium sorbate. While these preservatives are synthesized industrially, they also occur in nature. For example, sodium benzoate is found naturally in cranberries in the form of benzoic acid. Sodium benzoate is used in products in a low pH range the same range that fruit-based products normally fall into. It is considered effective at and below pH 3.8. Potassium sorbate is normally used at a higher pH range, and is effective at and below pH 4.3. These preservatives are effective against molds and yeasts, but less so against bacteria. Manufacturers should first dissolve these preservatives in water before acids are added. Preservatives are the least-soluble ingredient when added to a mix that contains acid, such as those found in the fruit or those added to the mixture.
Some of the different types of sweeteners include:
Corn syrup. Corn syrups
are categorized by DE (dextrose equivalents); they generally come in
24, 36 and 42 DE. The standard corn syrup used for fruit fillings is
42 DE. As the DE increases, the corn syrup becomes less viscous and
sweeter. The cost is also slightly higher because as the DE rises, more
processing is required to manufacture it. Storage in heated silos facilitates
pumping for the thicker corn syrups.
Beet and cane sugar (sucrose).
Normally used dry (although syrups are available), sugar has a higher
cost than corn syrup but is still used by some processors. The sweet
taste increases quickly and gradually declines. Sucrose is a disaccharide,
with two monosaccharides (glucose and fructose) forming one molecule,
and as a result, it has a higher molecular weight.
HFCS 42 DE and 55 DE. As
is the case with corn syrup, the higher the DE, the sweeter the HFCS
(a higher DE has more reducing sugars). Fructose lowers aw more than
an equivalent corn syrup. Consequently, HFCS normally lowers aw more
than corn syrup, as well.
Fructose. Sweeter than sugar
(sucrose), this crystalline monosaccharide, on a weight basis, lowers
aw more effectively. It is more expensive than sucrose and is normally
used only in bar fillings where low aw is critical.
These carbohydrate sweeteners add sweetness to pastry
filings and also control aw. The last thing a person wants is a soggy
crust and a dry pastry filling. The baked crust has relatively little
moisture and relatively small amounts of solutes (sugars). The filling
has a relatively large amount of water and a large amount of solutes.
The idea is to balance the aw in both the crust and the filling so that
there is not a great deal of difference between the two. This helps
minimize water migration. Designers should select sweeteners that prevent
sugar-crystal formation and growth. For example, if sucrose is the only
sugar in a bar filling, it could crystallize out. Using a corn-syrup
blend instead of sucrose prevents crystallization.
Using artificial, or high-intensity, sweeteners in place
of the aforementioned caloric sweeteners presents problems in preservation
and aw control. In some cases, sugar alcohols, such as sorbitol and
manitol, take the place of sugar or corn syrup. These are not metabolized
the same way as other sugars, and, therefore, provide fewer calories
than the sweeteners they replace. However, because they pass through
the gut, they can cause digestive problems (diarrhea) if consumed at
a high level. Despite these difficulties, these sweetener systems allow
the advantage of having a no sugar claim on a product label.
No one wants a grainy product. Blending sweeteners
in particular, corn syrup and HFCS will not exceed the solubility
limits of the sweeteners and helps prevent sugar crystallization.
Different types of corn syrup and other sweeteners have
different sweetness values, viscosity and ability to lower aw. The following
lists the relative sweetening power of the significant sweeteners used
in fruit preps compared to sugar at 1.
These values are only approximate, and will vary depending
on the individual tasting the sweeteners, concentration, temperature
and the product in which the ingredient is added.
The soluble solids can vary in the finished product for
each filling, but the approximate ranges are as follows:
Fruit fillings are normally colored with water-soluble
FD&C artificial colors, such as Red 40, Yellow 5, Yellow 6 and Blue
1. Designers may also combine colors to make different shades and blends.
All of these colors are water-soluble rather than oil-dispersable; this
requires an FD&C Lake (FD&C colors precipitated on aluminum
hydroxide). The American public has gotten used to a high level of color
in its fillings and other products, and, for the most part, people have
accepted artificial colors.
Natural (noncertified) colors, such as turmeric, grape-skin
extract, beet color and carmine, are also at the developers fingertips.
Grape-skin extract offers the possibility of some health benefits as
a result of the antioxidants found in the pigment. In some cases, carmine
a natural reddish-purple color derived from the bodies of an
insect is listed on the label of natural health-food products.
Sometimes, the cost of these natural colors prohibits their use for
An example of a color associated with flavor is a Bavarian cream filling. Bavarian cream consists of a simple starch paste containing water, sweeteners (such as corn syrup), modified starch, hydrogenated oil, flavor, phosphoric acid and colors. A combination of FD&C Red 40 and Yellow 6 creates a good, stable custard-yellow hue, which is very important without them, the mixture would appear as a semitranslucent white paste. Consumers eventually begin to associate Bavarian cream with a certain flavor and color even though nothing compares to it in nature.
The fruit texture of the prepared fruit-pie filling should
be firm, not hard or mushy. The filling should not show syneresis, or
watering-off. According to Cozy Helm, vice president of research and
development for St. Francis, WI-based Wixon Fontarome: Texture
is extremely important. There is a need to have a pie filling that is
not rubbery, but is able to be cut and served easily. There is a need
to have a pleasing appearance with sheen to the filling and fruit pieces.
Fruit pieces in satisfactory quantities are needed in the filling, but
not so much that it is cost-prohibitive.
A balance is necessary between all the filling ingredients
acidity, sweeteners, starch, gums and moisture. Too much stabilizer
or starch can tie up both the moisture and flavor.
Cold-processed fillings, sometimes used in bar fillings,
utilize factors other than cooking to produce a shelf-stable product.
High-solids fruit fillings (75% solids or more) rely on aw of 0.71 or
lower and low pH to protect against microbial growth. Developers need
to determine the shelf-stability of chocolate- or vanilla-flavored high-solids
fillings (these cold-processed fillings cannot contain a large amount
of acid) and adapt formulations as necessary to ensure this quality.
Fillings for breakfast bars, toaster pastries or cookies
may need to be fluid during pumping or depositing, but form a viscous,
short-textured gel during baking. An example would be a fruit-filled
cookie or tart, where the filling is injected into the cookie dough
before going into the oven. These are typically made with coextruder
equipment, such as a Rheon. The bar filling must be fluid enough to
be pumped or formed in the dough jacket and be flowable during the first
stage of baking to fill the voids in the pastry or cookie. Later on,
in the oven, the starch must gelatinize fully so that the filling does
not leak out of the pastry or enclosed cookie.
Finding the right starch to match the application can
help solve many of these potential problems. Jeff Jenniges, technical
director at Lawrence Foods, Inc., Elk Grove Village, IL, says: It
is important to design a filling that can be pumped through a spot depositor,
or be sheeted or extruded uniformly. The filling should be able to be
pumped without remixing. The starch selected should enable the filling
to undergo freeze/thaw cycling without gel rupture and syneresis and/or
Doris Dougherty, food scientist at the A.E. Staley Research
Center, Decatur, IL, notes that Staley offers a starch designed
to gelatinize in high sweetener solids and under baking conditions generally
used for these products. She adds that the company offers another
product that provides some initial viscosity to suspend particles
and prevent filling from flowing out of the product prior to baking,
when filling is cooked in the last stage on an oven conveyor belt.
Hydrocolloids, or gums, provide functionality similar to starch. When they work in combination with starches, the result is better than either ingredient can achieve alone. While gums may cost more on a weight basis than starch, they can be used at a lower level and create a functional synergy with starch. As a result, less starch can be used improving the flavor by reducing starchy flavor notes. Some of the gums used include pectin, guar, locust bean, gum arabic, xanthan, alginate, gellan and carrageenan. It should be pointed out that some of these gums are considered natural ingredients. Natural gums vary and, although gum suppliers take care to standardize the gum, it is important to read the specifications.
Once the water is poured in, starch is added and mixed
in well to create a slurry. The fruit or dehydrated fruit, along with
sugar, water and minor ingredients, are mixed in next. A portion of
the corn syrup or sugar is mixed in at this point, because starch hydrates
best if the Brix is under 50º; the other ingredients compete for the
available water if the Brix is over 50º. Because the 5+1 fruit contains
so much of the available water, it is necessary to add the fruit first
to cook the starch up properly.
Developers may add additional stabilizers, such as xanthan
gum and locust bean gum, to manage some of the water and produce a more
freeze/thaw-stable product. The gums are often first dispersed in sugar
to prevent lumping and then added under high-shear mixing to the water.
The rapid mixing disperses and hydrates the gums. The gum slurry is
added to the main mix. After this, the preservative can be added.
The mix is heated to 190º F with agitation and held there
for 5 to 10 minutes. It will thicken as the starch cooks out and gelatinizes.
The rest of the corn syrup is added at the end of the process, which
helps cool down the mix. Flavor is the very last ingredient added, mixed
in at this point to minimize the loss of volatiles.
For a hot-fill operation, the fruit filling is filled into containers at a minimum temperature of 165º F. This temperature can vary, depending on the size of container, the pH and aw. Finished fillings are placed in containers, such as No.10 cans; 3- or 5-gal. pails, which are inverted to sterilize the pail lids; totes; and ready-to-use plastic or foil pouches. A large bakery can pump fillings from a tote or barrel to equipment on a conveyor line, where it can be injected into doughnuts, filled into pie shells or added to fruit-topped pastries.
As a measure of the fruit content or the fruit identity, the fillings drained weight (of fruit pieces retained on sieves after washing findings with warm water) is often specd out and measured. In addition, the size of the pieces, as well as defects, such as haze, are checked.
It pays for the small bakery to outsource fruit-filling
needs to companies that specialize in it. This avoids the need for a
small cookie manufacturer to carry an inventory of different fruits
and special equipment. In products like Danish, bar fillings and
cookie fillings, it does not pay for a small bakery to make its own
specialized fillings, Jenniges says.
Food companies that use pie and pastry fillings need to be flexible and adapt to the changing needs and demands of the customer. By understanding those concerns and creating products that meet those requirements, creating great-tasting products with these ingredients is easy as pie.
Allen Skillicorn is a consultant to the food industry. He has served as project leader in fillings and toppings at Bunge Foods, Bradley, IL, and as a senior food scientist at Sterns & Lehman, Inc., Mansfield, OH. He can be reached at email@example.com.
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