Properties of protein concentrates and hydrolysates from Amaranthus and Buckwheat

Abstract

Protein concentrates and pepsin hydrolysates were made after isoelectric precipitation of the proteinaceous liquor from wet-milling of grain of five Amaranthus and one buckwheat genotype. The Amaranthus protein concentrates exhibited better solubility, foaming, and emulsification than two commercial soy protein controls. Many protein properties depend on solubility, and Amaranthus protein concentrates were more soluble than soy protein isolate. The buckwheat protein concentrate was highly soluble with excellent emulsification, but poor foaming ability. Partial pepsin hydrolysis further improved solubility of the protein concentrates and also altered their foaming property. Fractionation and subsequent characterization of protein concentrates revealed that glutelins, albumins, and globulins predominated, with prolamins present in minor quantity. SDS-PAGE showed that globulins and glutelins were comprised of several subunits with varying molecular weights from relatively high to low while albumins were mostly of low molecular weight. The prolamin fraction of the buckwheat concentrate was comprised of intermediate to low molecular weight subunits while those of Amaranthus concentrates were only of low molecular weight. This study demonstrated the feasibility of producing potentially useful functional protein concentrates as by-product of Amaranthus and buckwheat starch extraction.