Effect of Heat on the Functional Properties of Pea Flour and Pea Protein Concentrate

Abstract

Pea seeds were pin-milled to pea flour (PF) and part of the PF was fractionated to yield a pea protein concentrate (PPC) by air- classification. Samples of PF and PPC were slurried with water, subjected to a range of heat treatments (50, 60, 70 and 98˚C) and freeze dried. Functional properties of heated and unheated samples are reported including data on nitrogen solubility index, water holding capacity, oil emulsification, oil absorption, foaming capacity and foam stability. The observed trends resulting from heat treatments of progressively increasing severity agreed qualitatively with the limited data for peas in the literature as well as with data concerning other protein sources such as soy and peanuts. Nitrogen solubility and oil emulsification both declined continuously; water holding capacity increased continuously; oil absorption increased to a maximum, then declined; foaming properties were adversely affected by all treatments except at 70˚. Globulins were isolated from both heated and unheated samples of pea material and examined by polyacrylamide gel electrophoresis and by sodium dodecylsulfate polyacrylamide gel electrophoresis. Both techniques revealed changes in the protein band pattern as a result of heating. The ratio of vici- lin to legumin decreased with increasing heat treatment.