Digestibilidad gastrointestinal in vitro y actividad antioxidante de la proteína aislada de una mezcla de harinas precocidas de quinua (Chenopodium quinoa Willd) y amaranto (Amaranthus caudatus)

Abstract

Quinoa (Chenopodium quinoa Willd) and amaranth (Amaranthus caudatus) are pseudocereals rich in protein and contain all the essential amino acids, considered complete proteins. In Ecuador, the consumption of precooked flours has increased because they offer a quick and easy option for preparing various dishes. Food transformation processes can affect the initial nutritional characteristics of the raw material. In the present investigation, three mixtures of defatted precooked flour and mixtures of defatted raw flour were used as controls. The mixtures were made with a quinoa: amaranth ratio of 25:75, 50:50 and 75:25. The isolated protein was obtained by isoelectric precipitation at pH 8.0 for solubilization and pHs 4.0 and 5.0 for protein precipitation. Simulated digestibility was performed in gastric and duodenal phase, and SDS-PAGE electrophoresis was used for protein characterization and hydrolysis progress. On the other hand, the presence of antioxidant activity was evaluated by the TBARS method. Finally, we worked with the mixture of 25 percent quinoa flour and 75 percent amaranth flour and pH 4.0, due to its higher yield and protein quantification. In the protein concentrates, the presence of 7S and 11S globulins and 2S albumins was observed. After in vitro gastrointestinal digestibility, a higher duodenal digestibility of protein from precooked versus raw flours was observed. In addition, the analysis of antioxidant activity established a higher activity in precooked flours compared to raw flours.