Cereal Chem 43:400 - 407.  |  VIEW ARTICLE

Rate Studies on Atmospheric Steaming and Immersion Cooking of Soybeans.

W. J. Albrecht, G. C. Mustakas, and J. E. McGhee. Copyright 1966 by the American Association of Cereal Chemists, Inc. 

Simple methods for adequately cooking soybeans to produce a full-fat flour would enable populations in many of the developing countries to have a food that would provide needed protein in their diet. Rate studies were made on two such cooking procedures - atmospheric steaming and immersion in boiling water. Variables of initial moisture, particle size, and hull removal were correlated with rate of cooking as defined by change of urease activity and nitrogen solubility index (NSI). Trypsin inhibitor assays were correlated with urease enzyme activity. Conditions were established for both methods that enabled rapid cooking of soybeans. The experiments demonstrated that initial moisture of the soybean fraction is a major factor influencing cooking rate. High initial moisture (62-65%) promotes rapid decrease in both NSI and urease. Small particle size influences the reduction of urease activity, but has little influence on the rate of NSI reduction. Therefore, by steaming a soybean fraction of small particle size (under 20-mesh) and low moisture (8%), it is practicable to destroy urease activity and retain high NSI if this is desired in the cooked product. Restricted timing (5-7 min.) of the immersion cooking of soaked whole soybeans can also retain high NSI value while destroying urease. Trypsin inhibitor activity is destroyed at approximately the same rate as urease by both cooking methods.