Fermentation has shown to be an effective technique in bioactive peptides release. That is why in this study antihypertensive, antithrombotic, and antioxidant activity was evaluated during amaranth proteins fermentation with Lactobacillus casei Shirota and Streptococcus thermophilus 54102 in mono and combined culture. During fermentation an increase of free amine groups was observed, and no statistical differences among monocultures were shown, getting higher concentration in combined culture. This was related to antihypertensive and antioxidant activities, where the highest values were also found in the combined process (45% of angiotensin-converting enzyme inhibition, and 168 μmol Trolox equivalents per liter [TE/L] for 2,2-diphenyl-1-picrylhydrazyl, 268 μmol TE/L for 2,2'-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid, and 381 μmol Fe2E/L for ferric reducing ability of plasma). On the contrary, antithrombotic activity was not related to free amine groups during fermentation, having the highest bioactivity in different moments in each experiment. L. casei Shirota and S. thermophilus 54102 are strains that are able to release bioactive peptides from amaranth protein, although amaranth is not a common matrix for the development of lactic acid bacteria. In addition, in this study it was observed for the first time that lactic acid strains are able to release bioactive peptides from amaranth protein. In addition, this methodology could be part for the development of fermented beverages, different from fermented milk, to diversify matrix to obtain a novel functional food.
Keywords: acid lactic bacteria; amaranth protein; bioactive peptides; fermentation.