Vol. 7, Issue 2, Part B (2025)

Quinoa (Chenopodium quinoa Willd.) has emerged as a globally significant pseudocereal due to its high protein quality, gluten-free nature, and resilience under diverse agroecological conditions. Despite increasing recognition of its nutritional value, comparative bioscientific evaluations of its amino acid composition across different varieties remain limited. This study aimed to assess the proximate composition, essential amino acid (EAA) profile, and protein quality scores of three quinoa varieties—white, red, and black—while examining the effects of saponin removal and providing practical nutritional insights. Grains were harvested under controlled field conditions, processed to reduce saponin content, milled, and subjected to proximate and amino acid analyses using AOAC official methods and high-performance liquid chromatography (HPLC). Protein quality was evaluated through amino acid scores (AAS), protein digestibility-corrected amino acid scores (PDCAAS), and digestible indispensable amino acid scores (DIAAS). Statistical analyses included one-way ANOVA, Tukey’s HSD, Pearson’s correlation, and principal component analysis (PCA).

Results revealed significant varietal differences (p < 0.05) in protein and lipid content, with black quinoa showing the highest protein (16.2%) and lysine (65.1 mg/g protein), followed by red (15.1%; 62.3 mg/g protein) and white (13.4%; 59.8 mg/g protein). Lysine values exceeded FAO/WHO reference patterns, confirming quinoa’s advantage over traditional cereals, while methionine + cystine were consistently first limiting (AAS 0.89-0.97). PDCAAS values ranged from 0.78 to 0.82, placing quinoa above most cereals and close to animal-derived proteins. Saponin removal did not significantly alter amino acid composition, validating consumer acceptable processing methods. PCA separated pigmented from white varieties, with protein and lysine contributing to varietal clustering.

In conclusion, quinoa represents a nutritionally superior pseudocereal with considerable potential for addressing protein-energy malnutrition, enhancing gluten-free and functional food formulations, and strengthening sustainable food systems. Promoting pigmented quinoa varieties, dietary complementation with methionine-rich foods, and integration of quinoa into public nutrition programs are recommended to maximize its health benefits.