39B-24

K. H. LEE¹, S. M. Lee, Y. H. Park, and K. C. Rhee. (1) Food Protein Research & Development Center, Texas A&M University System, Cater-Mattil Hall, College Station, TX 77843-2476

Justification: Soy protein products have long been used as major nutrient sources and functional components to enhance valuable properties of food products in the food industry. Emulsifying property is one of typical functional properties which soy protein products are known to have. Necessities in the industry are the results using real products commercially avaiable instead of pure soy proteins produced in the laboratories.

Objectives: To do this, it is needed to establish methods to be applicable easily and compare the results of various types of commercial soy protein products.

Methods: Emulsion was prepared by mixing 20% soybean oil in Sorval omnimixer at 8500 rpm for 5 min with 3% protein products in 0.1 M NaCl, pH 7.0 to make 100 ml. The emulsion was serially diluted with 0.1% SDS in 0.1 M NaCl by total 1/1000. Turbidity of the final solution was measured at 500 nm to calculate emulsifying activity index. Emulsion stability was evaluated by creaming after making emulsion in the same method but different in 0.3% protein products medium and 1 m mixing. The volume of the separated aqueous phase in the 100 ml mass cylinder was measured at time intervals.

Results: EAI(m2/g product) values ranged 7.02-30.8 in isolate products; 2.15-16.5 in concentrate products; 6.87-17.0 in flour products. Results of emulsion stability did not always coincide with results of emulsifying activity indexes. That meant emulsion formation is not always the same as emulsion maintenance, because many forces contribute to break emulsion like creaming, flocculation, and coalescence.

Significance: Real soy protein products commercially available show various capability in emulsion formation and stabilization.