Protective Effect of Using Biopreservative Culture in Kefir Production Against Eschericha coli and Enterococcus faecalis Contamination

Project no. 29644 · Status: Kapanmış · 2023

Summary

In this study, the protective effect of LABs with natural preservative properties was investigated in kefir production. Commercially available Lactiplantibacillus plantarum, Lacticaseibacillus rhamnosus, and Propionibacterium freudenreichii subsp. shermanii cultures were used as adjunct cultures in kefir production, and their protective effect was examined in cases of Enterococcus faecalis and Escherichia coli contamination.In the first stage, UHT milk samples inoculated with Enterococcus faecalis and Escherichia coli were inoculated with lactic acid bacteria selected as natural preservatives, including L. plantarum, L. rhamnosus, and P. shermanii, alongside the kefir culture. The produced kefirs were stored for 21 days, and the effect of the protective cultures on the aforementioned bacteria and on yeast-mold and bacteria present in the kefir culture was investigated on days 1, 7, 14, and 21.In the second stage, semi-skimmed UHT milk was used to produce kefir in four groups coded as CK, CR, CS, and CP. Commercial kefir culture KFC1 was inoculated in each group, and selected as protective cultures L. plantarum, L. rhamnosus, and Propionibacterium freudenreichii subsp. shermanii were inoculated accordingly.The results of the study indicate that protective cultures reduce E. coli and E. faecalis contamination in kefir, thereby enhancing product quality. The most effective culture was found to be Lacticaseibacillus rhamnosus (CR). Kefirs produced using Lactiplantibacillus plantarum and Propionibacterium subsp. shermanii exhibited lower contamination bacterial counts compared to control kefirs, thus demonstrating their protective properties. These findings underscore the effectiveness of protective cultures as a strategy to extend the shelf life of kefir.

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