Effect of germination on the main chemical compounds and 5-methyltetrahydrofolate metabolism of different quinoa varieties

•Germination increased the nutritional and phytochemical composition of quinoa.•PCA showed significant differences in chemicals among quinoa varieties.•The 5-MTHF content of the LL-1 and QL-2 varieties was highest in 6-day sprouts.•The expression of pterin synthesis genes regulated further accumulation of 5-MTHF.•The 6-day-old sprouts were the most superior quinoa sprouts for functional food.