Functional Properties of Peanut and Soybean Proteins as Influenced by Processing Method1

Abstract

Abstract Proteins were extracted from defatted Florunner peanuts and Cobb soybeans and dried using different methods. Freshly prepared peanut protein isolates contained 73.9 to 81.3% protein and 1.4 to 4.3% fat. The corresponding values for soybeans were 54.7 to 61.6% and 2.7 to 4.5%. Spray dried peanut protein isolate contained 69.1% protein after 36 months storage and exhibited less solubility than those stored for 24 months or freshly prepared. Freeze dried soybean isolate contained more soluble protein man the freeze dried peanut protein isolate. The reverse was true for the spray dried peanut and soybean isolates. Protein solubility, emulsifying capacity, foaming capacity and foam stability of peanut and soybean protein isolates were higher for the spray dried and freeze dried than the drum dried preparations. Heat treatment of peanuts (107°C for 20 min.) did not influence protein solubility or emulsifying capacity but decreased foaming capacity and foam stability. Storage of peanut isolates resulted in a loss of emulsifying capacity, especially for the freeze dried peanut preparation.