Development of an Improved Electrical Resistance Method for Determining Emulsifying Capacity of Pulse and Soy Materials1

An electrical resistance method for objectively measuring oil emulsifying capacity (EC) of pulse and soy flours or their protein concentrates and isolates was modified to provide great improvement in precision. The electrical resistance method is based on the fact that oil is a nonconductor, whereas combinations of pulse or soy protein and water are good conductors. EC was determined at the inversion point at which an oil-in-water emulsion turns into a water-in-oil emulsion, as indicated by a sudden drop in conductivity. Measurement conditions (material concentration, blending speed, and oil addition rate) for the modified method were standardized. The modified method was found to be precise with an average coefficient of variation of 3.1%. The application of the modified method to various pulse and soy materials revealed differences in EC values among the samples evaluated. The modified method for measuring EC was simple, objective, precise, and reliable, and it can be applied to a variety of pulse and s...