Influence of extraction method on inherent properties and techno‐functional behavior of quinoa protein ingredients

Abstract

AbstractThis study investigated the structural modification and functional properties of quinoa protein ingredients using dry and wet fractionation techniques. Alkali extraction at pH 9.0 produced a quinoa protein isolate (QPI) with 76.2% wt/wt protein (dry basis) and a concentrate (QPC) with 55.9% protein. However, the protein separation efficiencies (PSE) were 32.1% and 58.5%, respectively. In contrast, dry fractionation produced a quinoa protein rich fraction (QPRF) containing 24.7% wt/wt protein, but higher PSE at 69.9%. Despite varying final protein concentrations, SDS‐PAGE showed similar relative abundance of 11S, 7S, and 2S proteins among the ingredients and quinoa whole meal. Mass spectrometry revealed different levels of oxidative modifications to proteins, with QPI showing more pronounced oxidation. In starch pasting experiments, QPRF exhibited significantly higher viscosity than QPI and QPC, attributed to low starch content and the formation of protein–starch and protein–lipid complexes in QPI and QPC. Solubility over pH 2.0–9.0 followed a U‐shaped trend for all ingredients, with QPC showing lower solubility at pH >7.0. Furthermore, foaming capacity and stability of foams converged at high ingredients concentration (3% wt/vol), while increasing protein refinement gave high foam stability at lower concentration (0.5–1% wt/vol). Similarly, emulsion activity index was favored at high purity (QPI), while emulsion stability was promoted at low protein purity (QPRF). This study demonstrated that dry fractionation enabled the retention of techno‐functional properties of the protein while enhancing quinoa bioresource recovery.