Edamame protein hydrolysis using Lactococcus lactis, Lactobacillus bulgaricus and Lactobacillus paracasei produce short peptides with higher antioxidant potential

Abstract

Abstract. Anggraeni SL, Jayus J, Ratnadewi AAI, Nurhayati N. 2022. Edamame protein hydrolysis using Lactococcus lactis, Lactobacillus bulgaricus and Lactobacillus paracasei produce short peptides with higher antioxidant potential. Biodiversitas 23: 3604-3613. The high demand for protein sources for functional vegetable foods, especially proteins that have ACE (Angiotensin-Converting Enzyme) inhibitory activity has encouraged efforts to meet this need through exploration of potential protein sources and the development of food processing technology to modify the protein into derivative compounds in the form of short peptides to promote higher bioactivity than the native protein. This research focused on the hydrolysis of edamame proteins into shorter peptides through a fermentation process using a group of Lactic Acid Bacteria (LABs), that is Lactococcus lactis, Lactobacillus bulgaricus and L. paracasei, to gain a higher functional activity of its protein hydrolysate. Edamame milk was fermented with that LABs as starter culture until 24 hours at 37ºC. The activity of the protease released by the LABs was confirmed using the agar diffusion method based on the emergence of a clear zone surrounding the culture, while the antioxidant activity was confirmed with the ABTS and hydroxyl radical scavenging methods. The results exhibited that the population density of starter culture in edamame milk reached 10⁸ CFU/mL, and the pH decreased from 6.75 to 4.15. All LABs used in fermentation were able to hydrolyze protein as indicated by the increasing degree of hydrolysis and changes in protein profile of SDS-PAGE analysis. In addition, when compared to the unfermented edamame milk, the protein hydrolysate from LABs fermentation showed an increase of ABTS and hydroxyl radical inhibitory activity, in which the highest IC₅₀ values ??of 8.96 and 13.33 g/mL of each were found in edamame milk fermented by Lc. lactis InaCC B187. An increase in ACE inhibitory activity was also observed in edamame milk fermented using this microbe (9.80 g/µL). These findings indicate that Lc. lactis InaCC B187, L. delbrueckii subspecies bulgaricus FNCC41, and L. paracasei InaCC B145 have the potency as an effective starter culture to increase bioactive peptides in edamame soybeans potential for functional food sources.