Role of Soy Flour Type and Production Procedure on Chemical and Functional Properties of Its Protein Concentrate

Soy protein concentrate (SPC) which is one of the well known food ingredients, is produced especially from defatted soy flour and flash desolventized white flour with maximum PDI, but other soy flours may also be used to produce products with different properties. In this study, four different soy flours including defatted soy flour (fat content 3.67, PDI 55.10), defatted and toasted soy flour (fat content 3.78, PDI 10.72), low fat soy flour (fat content 14.34, PDI 32.71), and full fat soy flour (fat content 22.08, PDI 28.72) were used to produce SPC by two washing methods (alcohol washing and acid washing) and chemical properties and key protein functionalities were determined. SPC from full fat soy flour had higher yield but lower protein content due to its residual oil. Alcohol washing had higher yield whereas fat, protein, and fiber contents were decreased. PDI of alcohol washed SPCs had lower content and, in contrast to acid washed SPCs, did not relate to PDI of starting materials. Under the same washing condition, SPC from defatted soy flour had higher water holding capacity, fat binding capacity, emulsification, and foaming properties. SPC from acid wash procedure had higher emulsifying and foaming properties while alcohol washing enhanced water holding and fat binding capacities.