Peanut flour optimizes texture.

New USDA-ARS findings about the thickening capacity of various forms of peanut flour will help scientists improve food texture. Researchers determined that ounce-per-ounce, low-fat, light-roasted peanut flours are able to promote more viscosity, or to thicken more effectively, than other peanut flours when they are dispersed in water and heated under controlled conditions.

Peanut flour is a dry powder formed after the partial extraction of oil from the roasted peanut seed. We use it to add flavor and protein to processed baked goods, nutrition bars and snacks, as well as to marinades, sauces and dressings. To gauge how effectively different commercial peanut flours thicken during heat processing, researchers applied different types of rheological tests to the flours. These tests relate to the human perception of texture.

Generally, peanut flours are offered at fat levels of 12% or 28%, and either as light, medium or dark roasts. ARS scientists found that regardless of roast color, lower-fat peanut flours thicken more effectively than higher-fat flours. While peanuts contain about 25% protein, peanut flour has about 50% protein. That's because the process of mechanically removing fatty oil from roasted peanuts enriches the levels of the remaining peanut components. The resulting flour is naturally low in fat, high in protein and relatively low in carbohydrates.

Thanks to the study, manufacturers have a guide as to which heating methods are appropriate for which peanut flours, and they will know how to maximize texture and nutrition in the finished product.

FYI: Peanut flour has been used to replace animal proteins in a variety of baked products. Peanut flour blends well with cereal flour to yield products with excellent flavor texture and color. Peanut flour can be used at levels up to 20% to provide protein supplementation without an off-flavor. Unfortunately, this flour is susceptible to lipid oxidation because of the high polyunsaturated fatty acid content in both the triglyceride and polar lipid portion. Even with defatting, there still remains a portion that will undergo oxidation. Roasting will decrease this problem as it will denature lipoxygenase, an enzyme that catalyzes the reaction.

Further information. Jack Davis, USDA-ARS Market Quality and Handling Research Unit, North Carolina State University, 224 Schaub Hall, Raleigh, NC 27695; phone: [phone]; fax: [phone]; email: [e-mail].