Department of Nutrition and Health, Federal University of Viçosa, Brazil.
Quinoa flour has been used as a food ingredient or for dietary enrichment. Therefore, this study aimed to evaluate the protein quality of two varieties of quinoa, the BRS Piabiru (cultivated in Brazil) and the Real (cultivated in Peru). The biological assay was approved by the Ethics Committee on Animal Research of the Federal University of Viçosa (UFV), Brazil (protocol n0 24/2013). Thirty-two male Wistar rats, recently weaned, with body weight range between 50-60 g, were used. The diets were based on the AIN-93G, using 9.5% protein. Aproteic, casein, BRS quinoa and Real quinoa diets were prepared. The animals received experimental diets and deionized water ad libitum, during 28 days. In vivo true digestibility, the essential amino acid composition, the protein digestibility-corrected amino acid score (PDCAAS) and the anti-nutritional factors were determined. Statistical analyzes using either Duncan or t tests (p<0.05) were performed. There was no difference (p>0.05) for the true digestibility among the casein, BRS quinoa and Real quinoa groups. Phytic acid, tannins, trypsin inhibitors and nitrate did not present difference (p>0.05) among the quinoa varieties. Regarding the essential amino acid composition (mg/g protein), only Phe + Tyr, His and Thr reached at least 1.0 as score, as recommended for 2 to 5 years old children, according to FAO/WHO. The BRS quinoa presented 47.4 (Phe + Tyr), 24.3 (His) and 27.4 (Thr) mg amino acid/ g protein while Real quinoa presented 54.6 (Phe + Tyr), 25.2 (His) and 30.2 (Thr) mg amino acid/g protein. Methionine was the primary limiting amino acid in the two varieties of quinoa. The PDCAA values were 53.4% for BRS quinoa and 57.4% for real quinoa. Thus, the varieties of quinoa showed similar protein quality and low PDCAA, possibly due to the presence of anti-nutritional factors. Financial Support: CAPES, CNPq, FAPEMIG.