Determination of bioactive peptide production performance and antimicrobial effect spectrum in kefir with lactic acid bacteria

In this study, kefir samples obtained by the traditional production method; Lactobacillus delbrueckii ssp. bulgaricus ATCC 11842 (A), Lactobacillus helveticus ATCC 15009 (B), Lactobacillus plantarum ATCC 14917 (C) and control (K) samples were added by adding only kefir grain and matured for 28 days at + 4 ° C. The pH and titratable acidity values of the kefir supplementary culture were different; There was also significant difference in water-soluble and nitrogen soluble in 12% TCA (P <0.05). When the RP-HPLC chromatograms were examined, the addition culture in the production of kefir produced similar peaks in the formation and concentrations of the peptides during the ripening period. It was found that the K sample was distinctly separated from the other samples. Lactobacillus spp. kefir produced by ancillary cultures were found to have a higher total FAA value than control kefir samples. The free amino acid values of kefir samples were increased during the storage of Trp, Asn, Ala, Gly contents in B and K samples. In the B, C and K samples, the Ile content increased while the Val content decreased during the ripening period. At the end of storage, the highest ACE-inhibition activity was observed at day 28 Lb. plantarum. Peptide fractions of Kefir samples have been found to have an antimicrobial effect on Staphylococcus aureus, Staphylococcus warneri and Staphylococcus hominis. In antimicrobial effect kefir samples; It was determined against Staphylococcus aureus and Enterococcus faecalis, but it was observed that kefir samples and peptide fractions did not inhibit Candida albicans ATCC 04055. It was determined that Lactobacillus spp. cultures in the increasing functional properties of kefir have the potential as additional culture. KEY WORDS: Bioactive peptide, functional food, kefir, antimicrobial activity, ACE-i activity