12th IFDC 2017 Special Issue - Influence of germination of quinoa (Chenopodium quinoa) and amaranth (Amaranthus) grains on nutritional and techno-functional properties of their flours

摘要

The germination process produces changes in grains that may affect the nutritional properties and technological characteristics of their flours. The aim of this work was to determine nutritional changes in quinoa (Chenopodium quinoa) and amaranth (Amaranthus) flours, induced by germination under controlled conditions. Proximate composition, protein digestibility, starch and fiber were determined by AOAC methods. Total and reducing sugars (dinitrosalicylic acid method) and protein fractions (SDS-PAGE) were determined in flours. Amylose content (spectrophotometric method) was determined in starch. Thermal behavior of flour was studied by DSC. Protein content and digestibility, and reducing and total sugars were increased by germination. Protein degradation was observed in fractions with molecular weights higher than 24 kDa in quinoa, while in amaranths the degradation was in all the molecular weight range 14-66 kDa. Apparent amylose content increased, possibly due to the formation of dextrins and linear chains of glucans from amylopectin. Gelatinization temperatures were similar between samples before and after germination. Gelatinization enthalpies of flours were significantly lower in sprouted than unsprouted grains; also a greater tendency to retrogradation was determined. Germination improved the nutritional contributions of quinoa and amaranth flours, but the starch content decreased and the gel became more unstable, important features if they are to be used as ingredients in food formulations.