INFLUENCE OF MOIST HEAT ON SOLUBILITY AND EMULSIFICATION PROPERTIES OF SOY AND PEANUT FLOURS

Abstract

ABSTRACTNitrogen solubility and emulsifying properties of unheated and heated (live steam at 100°C for 10, 20, and 30 min) soy and peanut flours were determined. Results showed that each of these functional properties was reduced as heating time increased. Nitrogen solubility of soy flour was more sensitive to extension of heating time than peanut flour. However, emulsion‐forming and thickening properties of soy flour were not as adversely affected by moist heat treatment as peanut flour. Viscous, mayonnaise‐like emulsions (27,840–41,760 cps) were produced by unheated soy and peanut flours and soy flour heated for 10 or 20 min. Thick salad dressing‐like emulsions (9,520–14,960 cps) were produced by soy flour heated for 30 min and peanut flour heated for 10 or 20 min. Poor emulsifying properties were exhibited by peanut flour steamed for 30 min where a thin, pourable emulsion (2,400 cps) was formed. High levels of nitrogen solubility were not necessarily associated with maximum emulsifying capacity. Multiple regression analyses confirmed that heating time was the primary determinant in reduction of functionality of both flours and that flours derived from peanuts and soybeans responded differently to moist heat treatment.