Evaluation of the nutritional and functional properties of germinated quinoa and its protein isolate

Germination can help improve nutrient content, bioactive compounds, and bioavailability, as well as reduce antinutritional factors. Germinated quinoa is a promising alternative to cereal starches for the production of protein isolates of high nutritional and functional value. In this study, the quinoa varieties Tunkahuan and Excelencia were germinated and analyzed. Grain germination was carried out under controlled humidity and temperature conditions, the grain and rootlets were separated and protein isolates were obtained. The nutritional content of two varieties of desaponified quinoa, the germinated grain and the rootlets was determined. Yield, digestibility and anti-inflammatory activity of protein isolates from germinated grain and rootlets were determined. Germination significantly increased the concentration of protein (39.67 g and 35.55 g/100 g dry weight [dw] in the Tunkahuan and Excelencia varieties, respectively), fat (27.10 g and 29.80 g/100 g dw in the Tunkahuan and Excelencia varieties, respectively), and minerals, especially in the rootlets, which showed higher levels of bioavailable nutrients (e.g., phosphorus, potassium, zinc, iron and manganese) in both quinoa varieties. A better protein digestibility was recorded in the germinated grain isolates (85.91–86.87 g/100 g dw) compared to the root isolates (81.5 g/100 g dw) of both varieties. Furthermore, higher antioxidant, phenol, and flavonoid content was observed in the root isolates of both varieties. These results suggest that germination improves the nutrient content and bioactive properties of quinoa, highlighting the value of rootlets that constitute a valuable source for protein extraction and the development of new food ingredients.