Improvement of nutritional value, bioactivity and volatile constituents of quinoa seeds by fermentation with Lactobacillus casei

The effect of fermentation with Lactobacillus casei on selected parameters of quinoa seeds (QS) was studied. The protein, free amino acids, carbohydrate, ash, thiamin (B1) and riboflavin (B2) of fermented quinoa seeds (FQS) were significantly (p < 0.05) higher than QS. Fermentation of quinoa seeds increased the DPPH radical scavenging activity, reducing ability and Fe2+-chelating activity in comparison with QS. However, the contents of fat and dietary fibre decreased by 52.05% and 45.87%, respectively. FQS showed a higher (p < 0.05) total phenolic content (16.53 mg gallic acid equivalent (GAE) g−1 extract, dry weight) than QS (13.85 mg GAE g−1). Fermentation resulted in an increase in free phenolics and a decrease in bound phenolics. With regard to amino acid compositions, FQS showed higher essential amino acids and an essential amino acid index than QS. The percentages of protein <180 kDa fractions increased from 39.31% to 61.94% after fermentation. FQS showed an increase of total volatile compounds from 30 to 47 after fermentation, and they belong to different kinds of volatile compounds: acids, aldehydes, alcohols, ketones, phenols, alkanes, alkene and esters. The L. casei fermentation could be recommended as a promising method to improve the quality of quinoa seeds.