Physicochemical and Microbial Profiling of Kefir from Cow and Buffalo Milk; Implications for Probiotic Use

Abstract

Kefir, a traditional fermented dairy product, is valued for its unique taste, thickness, and health benefits attributed to its rich microbial diversity. This study aimed to investigate the processing, physiochemical properties, and probiotic profile of kefir, particularly focusing on its therapeutic potential. The introduction highlights kefir's historical and contemporary significance, including its increasing popularity as a functional food. The problem statement addresses the rising prevalence of digestive issues and the need for effective dietary interventions like kefir. Kefir, with its high probiotic content, offers potential health benefits, including improved gastrointestinal health and immune function. The specific objectives include producing kefir using traditional fermentation methods, identifying the microbial strains present, and characterizing their probiotic properties. The study utilized traditional kefir fermentation methods with kefir grains. Physiochemical analyses of kefir and metagenomic profiling of lactic acid bacteria and yeasts from kefir were conducted. This study investigated the isolation, identification, and probiotic characterization of lactic acid bacteria (LAB) and yeast from kefir, identifying strains such as Lactobacillus helveticus, Lactobacillus rhamnosus, Lactobacillus fermentum, Kazachstania martinaie, and Pichia chibdodasensis. The isolates exhibited distinct morphological, biochemical, and genetic characteristics, confirmed through PCR amplification of the 16S rRNA and 18S rRNA genes. Among the LAB, Lactobacillus helveticus showed the highest acid tolerance at lower pH levels (2.5 and 3), while L. rhamnosus performed best at mildly acidic to neutral conditions (pH 5.6). L. helveticus also demonstrated superior bile salt tolerance, autoaggregation (65%), coaggregation (30%), and hydrophobicity (40%). All strains tolerated lower salt concentrations (2% and 5%) well, with L. rhamnosus showing the highest overall salt tolerance. L. fermentum exhibited the highest phenol tolerance, while L. rhamnosus and L. fermentum formed biofilms, unlike L. helveticus. Lastly, L. helveticus displayed the highest bile salt hydrolase activity (+++), followed by moderate activity in L. rhamnosus and L. fermentum (++). L. helveticus showed superior antibiotic susceptibility, and notable antimicrobial activity, particularly against E. coli and Staphylococcus aureus. In contrast, L. rhamnosus exhibited effectiveness against Pseudomonas aeruginosa. These findings indicate L. helveticus as a promising probiotic candidate, suggesting its application in enhancing gastrointestinal health. Buffalo milk kefir differs notably from cow dairy milk kefir in pH, acidity, Degree Brix, and HPLC-measured concentrations of organic acids and sugars. Buffalo milk kefir shows higher pH (4.7 ± 0.082), lower acidity (1.37 ± 0.024%), and higher lactose content (32.92 ± 0.088 mg/ml) compared to cow dairy milk kefir, which has lower pH (4.5 ± 0.082), higher acidity (1.96 ± 0.033%), and lower lactose content (18.02 ± 0.061 mg/ml). Significant yeast growth, essential for ethanol production, was observed in buffalo milk kefir, contributing to its distinctive flavor and aroma. The findings confirmed kefir's rich probiotic content and beneficial physiochemical properties. These findings support the broader use of kefir in dietary interventions aimed at improving overall health. Further research should focus on standardizing kefir production methods and conducting clinical trials to substantiate its health benefits. Additionally, promoting kefir consumption could help address common digestive health issues, especially in regions with limited access to healthcare.

Keywords : Kefir, fermented dairy product, probiotics, therapeutic potential, digestive health, lactic acid bacteria (LAB), yeasts, antimicrobial activity, functional food, dietary interventions, HPLC, lactic acid.