Lacticaseibacillus rhamnosus GG and Lactobacillus casei Shirota Growth on a Medium Enriched with Rye Protein, and Assessment of DPP-IV Inhibitory Activity

Due to climate change and the development of sustainable foods, protein vegetable sources are being considered as promising food commodities. Fermentation is an ancient tool for obtaining bioactive compounds, and has been exploited for bioactive peptide production from different sources. Thus, this work aimed to evaluate growth and the antidiabetic peptides released from a rye-enriched medium fermented by probiotics. The culture was made with 7.5% rye protein isolate and 1% glucose, with buffering at pH = 6.8. Fermentation began with 1% inoculum addition and was performed for 24 h. The proposed medium allowed the growth of L. rhamnosus GG and L. casei Shirota to reach concentrations of 9.72 and 10.52 log cfu/mL, respectively, superior to those recommended to obtain beneficial effects on humans. In addition, the nitrogen demands of each strain tested produced peptides capable of inhibiting the DPP-IV enzyme at percentages between 20 and 27%, which converted the hydrolysates into an interesting tool for glycemic control. Finally, rye fermentation by probiotics is a promising process for developing plant-based products with functional properties.