Microbiological changes occurring during storage in kefirs with pomegranate (Punica granatum L.) juicy produced from cow’s milk

Abstract

This research was conducted to determine the microbiological changes that occur during storage (zeroth, 7th, 14th, 21st, 28th days) in kefirs produced by adding different concentrations of pomegranate (Punica granatum L.) juice (6.25%, 12.5%, 25%, 50%) to cow’s milk. Sterile cow’s milk, kefir grains, and Zivzik pomegranate juice were used in production. The highest total aerobic mesophilic microorganism (TAMM) count (9.00±0.35 log10 CFU/mL) was determined in sample at 50% concentration on the 14th day of storage. In the last stages of storage, TAMM counts decreased at all concentrations due to the inhibitory effect of pomegranate juice on microorganisms. The count of coliform group microorganism determined at 3 log10 CFU/mL levels in all concentrations also partially decreased during storage and Escherichia coli wasn’t encountered in samples. However, the count of Lactobacillus spp. increased due to increasing pomegranate juice concentrations and improved fermentation. A statistically significant relationship (p<0.01) was observed between Lactobacillus spp. and coliforms determined in kefir samples. During storage, fermentation has shown its effect on kefirs with pomegranate juicy and a significant relationship (p<0.01) was determined between yeast and mold count and pomegranate juice concentrations. As a result, it was observed that high concentrations of pomegranate juice in kefirs created an inhibitor effect on microorganisms in a generally. The fact that kefirs with pomegranate juicy comply with the criteria indicated in the Turkish Food Codex Fermented Dairy Products Communiqué and Microbiological Criteria Regulation in terms of E. coli shows that the consumption of these products during storage won’t pose any risk to public health. It is thought that individuals who have digestive system problems due to the count of Lactobacillus spp. detected above the level specified in the Turkish Food Codex Fermented Dairy Products Communiqué and increasing during storage can easily use these products containing probiotics. However, in the samples, a prominently mold growth occurred during the final days of storage and coliform group microorganisms thought to have originated from the kefir grains used in production were detected. Therefore, when quality and hygienic materials are used in production, kefirs with pomegranate juicy that comply with standards and have a shelf life of at least 21 days’ can be produced. Considering the taste and antioxidant activity of pomegranate juice, it is thought that kefirs with pomegranate juicy produced at hygienic conditions can be effective in healthy nutrition and these innovative products can contribute to econo mic development. © 2026, B Hallaç, H Sancak.