Evaluation of Functional Properties of Four Soy Flours Produced in Iran

Soy flour is the least processed form of soy protein products which has become increasingly popular in food technology for its nutritional benefits, low cost and good functional properties. The aim of this study was to investigate functional properties of soy flours produced by four different industrial processes: defatted, defatted and toasted, low fat, and full fat soy flours. Because of different production procedure and degrees of heat treatment, soy flours had significant differences in protein dispersibilities (which determine the amount of residual trypsin inhibitors and use of the final products) and fat contents which affected on other functionalities. Soy flours with lower protein dispersibility indices (PDI) had lower foaming properties (capacity and stability), emulsification (activity and stability), water holding and fat binding capacities, and solid dispersibility indices. Comparison of low fat and full fat soy flour showed that fat content result in reduced functionalities such as water holding and fat binding capacities, emulsification stability, and solid dispersibility. Negative effects of fat content increase on functional properties are equal or more than PDI.