Effect of kefir addition on the microbiological, chemical and sensory properties of buffalo milk mozzarella cheese

The aim of this study was to determine the effects of kefir prepared using a commercial kefir starter culture on the microbiological, chemical, and sensory properties of mozzarella cheese produced from buffalo milk. In this study, kefir prepared using a lyophilized commercial kefir starter culture with a defined microbial composition was used. The culture contained Lactococcus lactis subsp. lactis, L. cremoris, L. lactis var. diacetylactis, Leuconostoc mesenteroides subsp. cremoris, Streptococcus thermophilus, Kluyveromyces marxianus, and Debaryomyces hansenii. A control group (without kefir addition) and four experimental groups supplemented with 0.5%, 1.0%, 1.5%, and 2.0% kefir were prepared. The cheeses were produced under laboratory conditions, vacuum-packed in PA/PE material, and stored at 4°C for 56 days. Microbiological, chemical, and sensory analyses were performed on days 0, 1, 7, 14, 21, 28, 42, and 56 of storage. Microbiological analyses included total aerobic, anaerobic, and psychrophilic bacterial counts, lactic acid bacteria (LAB), Lactococcus spp., yeasts, proteolytic, and lipolytic microorganisms. Chemical analyses involved pH, titratable acidity, fat, and dry matter determinations. The addition of kefir did not cause statistically significant differences in microbiological or chemical parameters (p > 0.05). However, kefir-supplemented cheeses exhibited a numerical increase in LAB and Lactococcus populations, lower pH values, and higher titratable acidity compared with the control. No significant differences were observed in fat and dry matter contents. Sensory evaluation showed numerically higher scores for appearance, texture, flavor, and sliceability in kefir-treated groups compared with the control. Statistical analysis revealed that only texture and sliceability scores were significantly higher in kefir-treated groups than in the control (p < 0.05). Kefir addition was associated with higher texture-related sensory scores without adversely affecting the microbiological quality or chemical composition of mozzarella cheese. These findings suggest that kefir prepared using a commercial kefir starter culture can be evaluated as a natural and functional starter culture alternative for buffalo milk mozzarella cheese production.