Shortenings, especially those with partially hydrogenated oil, are receiving a bad rap, but these functional fats are essential for the texture and flavor of baked products.
About 200 companies comprise the edible oils manufacturing industry, worth $38 billion in annual revenue, with the top 50 companies grabbing the lion's share. These suppliers offer a vast array of functional fats.
The functional fats category for baked products includes shortenings derived from a variety of sources, both vegetable and animal, such as palm, soy or dairy. Each fat has a different functional and nutritional profile, which affects the finished product.
The many bakery functions of shortening fall into four general categories. The first is texture. Shortening helps make pastries, pie crusts and breads tender and flaky by preventing the cohesion of wheat gluten strands during mixing, which makes the gluten strands shorter, hence the term shortening. The shorter wheat gluten strands become less elastic and sticky for a more tender texture.
The second function of shortening is for frying applications. Shortening behaves in a different manner than frying oils. As a semisolid substance, shortening affects the texture and body of the fried product.
Thirdly, shortening can add flavor and richness to breads and other baked products. European-style butter, for instance, has higher butterfat content than standard butter and produces a more flavorful ingredient, beneficial for baking.
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| Above) Cakes’ light, airy cell structure can be attributed to the amount of air trapped during the creaming step. (Below) Donuts benefit from frying in a solid fat, as the oil sets quickly without weeping through packaging. Photo Courtesy of multifoods. |
The fourth characteristic of shortening is “creaming power” in making icings and fillings. When beaten with sugar, shortening incorporates large volumes of air bubbles to produce a fine, delicate structure.
For some baking applications, such as flaky croissants and puff pastries, butter lends both pleasant flavor and functionality well suited for laminated dough applications.
European-style butter can be used at higher temperatures, without burning, to produce a lighter, flakier pastry. In a laminated dough system, the slightly higher fat content of European butter cuts back on the 18 percent water common to most American-style butters to create crisper, lighter doughs. It melts more slowly as well, an advantage in rolling multi-layered doughs, such as laminates. Any fat used in laminated dough must be able to maintain its unique texture during the temperature variations that occur in the pastry making process. In addition to butter, bakers have found success using a blend of palm fractions and soybean oil.
Plasticity, in addition to melting point, stability and solid fat index, is among the most important functional properties of shortening. Shortening, with a narrow plastic range, melts rapidly and is useful in a product where the formulator wants it to melt near body temperature to assist in flavor release. A wide plastic range shortening contains 15 percent to 30 percent solids across a broad temperature range and resists breakdown during creaming. A more plastic fat will spread readily and combine thoroughly with other solids or liquids without cracking, breaking or having liquid oil separate from crystalline fat.
Butter possesses excellent plasticity. Its semisolid state, when beaten, can hold air bubbles within its malleable mass and act as a spacer in pie crust, for example. Plastic fats contribute to baked products' structure by coating and shortening gluten strands, retarding gluten development and contributing to tenderization. This ability to cream or aerate batter is directly related to crystal size within the fat. Most fats used in baking will have similar crystal sizes.
Liquid fats, such as oils, coat flour particles, produce smooth dough and mix easily into formulations. They also prevent some gluten development, but according to some sources, not as effectively as plastic fats. Oil does not aerate well when creamed with sugar. Its lack of solids content inhibits its air holding properties, affecting texture, crumb development and rise and increasing spread in cookies, for example.
All of these characteristics, the solids content, plasticity, etc., relate to dough rheology. “Typically, for example, cookie manufacturers shy away from liquid or semisolid shortenings because of a negative effect on dough rheology, particularly in a rotary-moulded cookie where controlling spread to preserve moulded imprints is of primary importance,” says Frank Stynes, senior vice president, Ventura Foods LLC, Brea, Calif. Ventura offers a pumpable shortening, among other types, that functions like a solid shortening to help control dough rheology.
The pumpable, fluid shortening mimics the properties of a solid fat, containing 23 percent solids, which compares to standard, all-purpose shortening with solids of 25 percent to 28 percent.
Palm oil is a solid fat, and blending palm oil with other liquid oils, such as soybean or canola, creates semisolid or solid shortenings.
The U.S. bakery market requires many different fats in order to make its diverse product range. Palm oil is a highly versatile raw material easily converted into many different forms using fractionation. Fractions blended in different proportions produce a wide variety of ingredients, each with different functional properties that can be tailored to meet client specifications.
Palm oil and fractions are naturally highly stable and impart a long shelf life. Palm oil's natural antioxidant content — tocotrienols — protects against off flavors.
The main saturated fat in palm oil is palmitic acid, which naturally crystallizes into a very small, stable form called beta prime. This small crystal “is ideal for imparting a smooth texture to baked products and is effective in entrapping and stabilizing small air bubbles,” says Gerald McNeill, Ph.D., vice president, R&D and marketing, Loders Croklaan, Channahon, Ill. Proper aeration is essential to the texture of most baking products. Cookies, with a rough mouthfeel, contain a relatively small amount of air while cakes, which are smoother in texture, are highly aerated.
“Donuts, for example, benefit from frying in a solid fat, such as palm oil,” McNeill adds. “The oil sets quickly on cooling for a firm donut with good structure that will not weep oil into the packaging. It also lends itself well to icing or sugar coatings. And different blends of palm oil fractions even can impart different textures to donuts, imparting a more dry or more moist characteristic, depending upon the product specifications.”
While common public opinion labels palm oil a saturated fat, it actually consists of a balance of saturated and unsaturated fat, about 50 percent of each. According to McNeill, “Dietary research published in the last 10 years has not been able to show a clear link between saturates and heart disease. It appears saturated fats in general may be neither good nor bad, having only a small effect on risk of heart disease.”
High-stearic soybean oil can be used as an alternative to partially hydrogenated oils, which are used to formulate a wide range of shortening products. The American Heart Association has indicated stearic acid may not affect or may even lower blood cholesterol.
As soybean oil currently serves as a source of omega-3 fatty acids, when it is used as the liquid portion of a blended shortening, the levels of omega-3 and omega-6 fatty acids in the resultant shortening provide a healthful benefit. Researchers are currently developing soybeans even richer in omega-3s.
Interesterification is a process that rearranges fatty acids on the triglyceride molecule. The resulting fat's properties, such as its melting point, can be improved for structural stability. Zero-trans and reduced-trans oils and fats can be produced via interesterification.
Interesterified soybean oil has been shown to work well in cookie and Danish applications. The combinations of solids from stearic acid and polyunsaturated fatty acids (PUFAs) from soybean oil produce cookies and Danish with some degree of structure and a degree of tenderness. The balance of saturates and PUFAs helps define the textural equilibrium, says Tom Tiffany, senior technical sales manager, Food Oils Division, ADM, Decatur, Ill.
Whether a baking operation wishes to manufacture product with special claims or just special flavor and texture, maintaining product equilibrium involves an important choice in shortening selection.