Peanut concentrate could be alternative emulsifier.

It appears that peanut protein concentrate could provide food processors with an alternative emulsifying ingredient. Research by scientists at North Carolina A&T State University indicates that this concentrate could be used in formulations that necessitate a high emulsifying capacity. However, it wouldn't be geared toward uses that require high water retention and foaming capacity.

Peanut flours and peanut protein concentrate are functional because of their soluble protein content. Proteins with high oil and water binding are desirable for use in meats, sausages, breads and cakes. Proteins with high emulsifying capacity are good for sausages, bologna, soups and salad dressings. Fermented peanut flour and the derived protein concentrate showed better functional properties--water-holding and emulsifying capacity--than did the unfermented flour and protein concentrate.

Not only does peanut flour add protein and flavor to processed foods such as baked goods, nutrition bars and snacks, it also functions as a dependable thickener in sauces and dressings. As you may know, the flour is the dry powder formed after the partial extraction of oil from roasted peanut seed.

In experiments, the scientists used peanut protein concentrate prepared and dried by the spray- or vacuum-drying of defatted peanut flour. The researchers compared protein solubility, water-oil binding capacity, emulsifying capacity, foaming capacity and viscosity to the raw defatted peanut flour and a soy protein isolate. In contrast to the defatted flour's protein content of 50%, the concentrate contained more than 85% protein, and it exceeded the solubility of the flour. Spray-dried concentrate also showed comparable oil binding and foaming capacity to commercially available soy protein isolate.

While peanuts themselves contain about 25% protein, peanut flour has about 50%. Peanut flour is sold containing different levels of fat--generally 12% or 28%--and as light-, medium- or dark-roasted flour. Processors must decide which of these flours will give their various products the best texture.

Since rheological tests often relate to consumer perceptions of texture, USDA-ARS researchers have run a variety of tests to see how different kinds of peanut flour affect flow behavior and form changes in model systems under controlled heating conditions. The investigators found that lower-fat, light-roasted peanut flours promoted more viscosity, ounce for ounce, than did other types of flour. The test data will help processors optimize texture in both existing and new products containing peanut flour.

Further information. Jianmei Yu, Food and Nutritional Sciences, North Carolina A&T State University, Department of Human Environment and Family Sciences, 161 Carver Hall, Greensboro, NC 27411; phone: 336-334-7963; fax: 336-334-7239; email: jyu@ncat.edu. Jack Davis, USDA-ARS Market Quality and Handling Research Unit, North Carolina State University, 224 Schaub Hall, Raleigh, NC 27695; phone: 919-515-6312; fax: 919-513-8023; email: jpdavis3@ncsu.edu.