[Protein concentrate from Amaranthus mantegazzianus. Physical, chemical and biological characterization].

The aim of this study was the obtainment of a protein concentrate (PC) from A. mantegazzianus seed powder and the evaluation of its percentual chemical composition, functional properties and biological protein quality. For this purpose, the optimal PC conditions assessed were: pH values for maximal and minimal solubility 11.5 and 5 respectively; flour/solvent ratio 1:20, stirring time 1.30 h at room temperature. A product exhibiting a protein content value of 55.3 g/ 100 g was obtained. The functional properties were evaluated by means of the following indexes Nitrogen Solubility Index (NSI) 94.9% at pH 11.5; emulsification activity (EA) 47 +/- 4.8; water absorption capacity (WAC) 2.1 +/- 0.3 and oil absorption capacity (AOAC) 0.8 +/- 0.1. The water and oil absorption index (WOAI) expressed as WAI/OAI was 2.6. These results render the product useful for bread baking due its high solubility, water absorption capacity and the OAI value which shows hydrophilic characteristics. The PC biological quality were calculated determining the net protein utilization (NPU): 64 +/- 7.4, true digestibility (tD): 88 +/- 7.6, biological value (BV): 73, intake: (I) 74 +/- 8.9 and weight gain (delta P) 23 +/- 4.5. The results of this study show a good nitrogen utilization, which plus the functional characterization let us infer that the A. mantegazzianus PC constitutes a good resource for the enrichment of bread baking products, preparing of diets for special regimens and protein complement for deficient foods.