Currently, 64% of Americans are overweight or obese. According to the National Bureau of Economic Research (NBER), Cambridge, Mass., and the Economic Research Service, Washington, D.C., their caloric intake has increased 12%—about 300 calories per day—since the 1980s. Americans have a net calorie imbalance of 100 to 150 calories daily, and the extra calories are coming from snacks, which contribute about 20% of Americans' daily caloric intake.
Soy protein is a useful ingredient for high-protein snacks such as bars and snack mixes. Understanding the various soy ingredients enables developers to give consumers healthful, high-protein snacks, while allowing the processor to optimize product nutrition, functionality and cost.
Soybeans have over 40 different nutritional compounds. Various soy ingredients are made from the soybean. These ingredients have different nutritional and functional properties. In the production process the soybean is cleaned, cracked and dehulled. The cracked soybean is rolled into full-fat soy flakes. The full-fat soy flake can be made into full-fat soy flour or the oil can be extracted, yielding a defatted flake. The oil is the primary product of the crushing process. This defatted flake is the product that remains from the soy oil extraction step and is the starting point for many soy ingredients.
Soy Flour: Full-fat flakes or defatted soy flakes are ground into soy flour. Depending on the heat treatment, particle size and amount of fat, different soy flours result. The processing and heat treatment will affect the functionality of the soy flour. Typical soy flours available are 20, 70 and 90 PDI. The PDI is the Protein Dispersibility Index and indicates the amount of heat treatment the flour received. Soy flour is 40-50% protein.
Relecithinated Soy Flour: A blend of fluid lecithin and refined soybean oil are added to defatted soy flour to yield a relecithinated soy flour with a fat content of 3-15%. This flour has emulsification and dispersibility functions.
Textured Soy Flour/Concentrate: Is sometimes called Textured Soy Protein (TSP). Soy flour or concentrate are processed through an extruder and yield a porous TSP with a particle size from small bits to chunks. Rehydrating the TSP yields a chewy, meat-like texture. TSP is useful in meat extenders, savory imitation bacon bits, and as meat replacers.
Enzyme Active Soy Flour: This soy flour has been minimally heat treated, so it has high levels of naturally occurring enzymes. The enzyme active flour is useful as a whitener in bakery products such as bread.
Soy Grits: Toasted soy flour that has a larger particle size.
Soy Protein Concentrate: SPC is made from defatted soy flakes by extracting the soluble carbohydrates and other components. Concentrates are about 65% protein and retain most of the dietary fiber. SPC can be made by three basic processing methods: aqueous alcohol wash, water extraction and acid leaching. The processing affects nutrient content and the amount of phytochemicals retained.
Soy Isoflavones: Are obtained from one of the product streams in soy processing. Less refined soy ingredients, like soy flour, retain the highest levels of soy isoflavones.
Isolated Soy Protein: ISP has most of the non-protein components removed from the defatted flake. ISP is the most concentrated form of soy protein and is about 90% protein. Isolates are highly dispersible amino acids, usually sold as a fine powder. Isolates can be lecithinated to improve dispersibility or extruded to yield a wet fibrous protein. New processing methods have improved the flavor of the isolates. Choose an isolate with a reduced beany flavor. Processing method affects the functionality, so different isolates will have various viscosities, emulsification and whipping properties.
Soy is a healthful solution to adding nutrition value to snacks and is a useful ingredient to help reduce the obesity epidemic. Be sure to choose the correct soy ingredient for your product application.
For more information:
Patricia Godfrey R.D., L.D. at 952-742-5920
pat_godfrey@cargill.com
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