Dry fractionation to produce functional fractions from mung bean, yellow pea and cowpea flour

Abstract

Dry fractionation of mung bean, yellow pea, and cowpea was performed to investigate the compositions and functional properties of the obtained fractions. Dry fractionation consisted of milling and subsequent air classification using three air classifier wheel speeds. Water holding capacity, gelation, and rheological properties of all fractions were studied. Separation between protein and starch granules was successfully performed by air classifying, as visualized with SEM images. Protein contents in fine fractions ranged from 42% to 58% (w/w), which was dependent on classifier wheel speed and material source. The correlation between water holding capacity and protein content was dependent on material source. Gelation of fine fractions occurred at lower concentrations than flours and coarse fractions. Fine fractions of all materials formed gels with higher elastic modulus (G') than the flour and coarse fractions, while the flour and coarse fractions formed more solid-like gels (lower tan δ). The need for functional plant protein ingredients for food applications is growing continuously. It is thus important to study sustainable methods for plant protein extraction. Dry fractionation is often considered an efficient alternative to the conventional wet fractionation process, that preserves the native functionality of the proteins in addition. For the application of ingredients produced from dry fractionation in food products, it is important to understand their functional properties. Therefore, the functional properties of dry fractionated ingredients produced from three different legumes are evaluated in this manuscript.