Characterising the composition and physicochemical properties of legume and oilseed protein concentrates to evaluate their potential for high-moisture extrusion processing

This study represents the initial phase of a larger entity evaluating the applicability of plant protein concentrates from pea, faba bean, flaxseed, and hempseed for high-moisture extrusion processing (HMEP), in which chemical composition and functional properties of the ingredients were analysed. Wheat gluten and pea protein isolate were used as benchmark ingredients. The main emphasis was on properties potentially important for creating fibrous structures in HMEP, although the levels of specific chemical compounds and endogenous enzymes that might influence the nutritional quality and flavour of the extrudates were also analysed. Significant variation was observed among the ingredients, with hemp showing the most similarities to protein isolates in terms of high protein content, low dietary fibre content, and low protein extractability. Flax was comparable to hemp but had a lower protein content. The high protein extractability of legume concentrates may be a barrier for their application in HMEP. The presence of elevated levels of phytic acid, raffinose family oligosaccharides, and lipid-modifying enzymes in certain ingredients need mitigation for HMEP. The findings of this study will serve as a foundation for a subsequent investigation, where the performance of these emerging ingredients will be evaluated in actual HMEP trials.