Bioprotective and Functional Activities of Postbiotics From Lactic Acid Bacteria Derived From Artisanal Dairy...

Postbiotics have been reported as a more stable and safer alternative to live microorganisms for industrial food applications. This study demonstrates the use of cell-free supernatant and cell-wall components derived from 10 native Lactic Acid Bacteria (LAB) as a functional and bioprotective agent, emphasizing its potential as a preservative in pasteurized milk. These species were from Lactiplantibacillus (L. plantarum, L. paraplantarum), Loigolactobacillus (L. coryniformis), Levilactobacillus (Lb. brevis), Lactobacillus (Lb. helveticus, and Lb. bulgaricus), Enterococcus (E. faecium and E. faecalis), Lactococcus (Lc. lactis), and Streptococcus (St. thermophilus) genera. Postbiotics, obtained as cell-free extract and cell-wall components, were combined and subjected to biopreservation and in vitro functional analyses, including antioxidant and antimicrobial activities, as well as their phenolic and organic acid contents. To assess their bioprotective effects, these postbiotics were applied to pasteurized milk, both with and without E. coli (ATCC 25922). According to the results, L. plantarum, L. paraplantarum, E. faecalis, E. faecium, L. brevis, and Lc. lactis were found to produce high levels of antioxidants and phenolic compounds. This is believed to contribute to the higher antimicrobial activity exhibited by their postbiotics. In pasteurized milk, all postbiotics demonstrated a reduction in the E. coli count, highlighting their bioprotective potential. However, this decrease was particularly significant in the presence of postbiotics from E. faecium, Lb. helveticus, and Lc. lactis, which are also determined as producers of acetic and formic acids. It is suggested that the specific desired properties of the final product can guide the selection of the appropriate strain for obtaining postbiotics.