Effect of Lactobacillus (L. acidophilus NCIB1899, L. casei CRL 431, L. paracasei LP33) fermentation on free and bound polyphenolic, antioxidant activities in three Chenopodium quinoa cultivars

The application of lactic acid bacteria (LAB) fermentation to the production of probiotic beverages is a common method for modifying the health-related functional characteristics and phytochemical content of such beverages. This study evaluated the effect of fermentation with Lactobacillus acidophilus NCIB1899, Lactobacillus casei CRL 431, and Lactobacillus paracasei LP33 on the total phenolic contents (PCs), flavonoid contents (FCs), phenolic profiles, and antioxidant capacities of the solvent-extractable (free) and cell-wall-bound (bound) fractions in quinoa varying in bran color. Compared with unfermented beverages, LAB fermentation significantly increased the free PCs and free FCs by 15.7%-79.4% and 7.6%-84.3%, respectively. The bound PCs increased, whereas bound FCs decreased in fermented black and red quinoa juice. The increments of procyanidin B2 , protocatechuic acid, p-hydroxybenzaldehyde, rutin, and kaempferol through 30 h fermentation exceeded 189%-622%, 13.8%-191%, 55.6%-100%, 48.5%-129%, and 120%-325%, respectively. However, the contents of catechin, procyanidin B1 , and ferulic acid decreased with fermentation. Overall, L. acidophilus NCIB1899, L. casei CRL431, and L. paracasei LP33 strains may be suitable for producing fermented quinoa probiotic beverages. L. acidophilus NCIB1899 was superior for fermentation to L. casei CRL431 and L. paracasei LP33. Red and black quinoa had significantly higher total (sum of free and bound) PC and FC concentrations and antioxidant capacities than white quinoa (p < 0.05) because of their higher concentrations of proanthocyanins and polyphenol, respectively. PRACTICAL APPLICATION: In this study, different LAB (L. acidophilus NCIB1899, L. casei CRL431, and L. paracasei LP33) were singly inoculated on aqueous solutions from quinoa to ferment probiotic beverage and to compare the metabolic capacity of LAB strains on nonnutritive phytochemicals (phenolic compounds). We observed that LAB fermentation greatly enhanced the phenolic and antioxidant activity of quinoa. The comparison indicated that the L. acidophilus NCIB1899 strain has the highest fermentation metabolic capacity.