EMULSIFICATION, FOAMING AND PROTEIN SOLUBILITY PROPERTIES OF DEFATTED SOYBEAN, PEANUT, FIELD PEA AND PECAN FLOURS

ABSTRACT

Defatted soybean, peanut, field pea and pecan flours were blended as 8% suspensions (w/v) with distilled water and characterized for emulsion and foam capacity, emulsion viscosity, protein solubility, and gel electrophoretic properties. Flour suspensions were evaluated for these properties at their natural pH, at pH 4.0, 8.2 and after a two-step sequential adjustment from the natural pH to 4.0 to 8.2. Maximum functionality of suspensions was noted as follows: (a) soybean flour, very thick mayonnaise-like emulsions (> 160,000 cps) and egg white-type foams at natural pH; (b) peanut flour, semi-thick mayonnaise-like emulsions (70,880 cps) and thick egg white-type foams after two-step adjustment to pH 8.2; (c) field pea flour, semi-thick mayonnaise-like emulsions (66,240 cps) and medium-thick foams after adjusting the pH directly to 8.2; and (d) pecan flour, very thick mayonnaise-like emulsions (> 160,000 cps) after two-step adjustment to pH 8.2. Protein solubility seems to be more closely associated with improved quality of emulsions and foams formed than with increased quantity of oil or air that could be bound by flour suspensions. Data from gel electrophoretic studies suggested that the major seed storage proteins were important in functionality tests, although other seed constituents, such as carbohydrates, may be equally involved.