Investigation of Production and Anti-Diabetic Effects of Kefir Enriched with Paraprobiotics

This study investigated the physicochemical, microbiological, and consumer acceptance of kefir with and without paraprobiotics (inactivated kefir starter culture) and evaluated its effects on streptozotocin (STZ)-induced type 1 diabetes mellitus (T1DM) in Wistar rats. The pH, titratable acidity, and exopolysaccharide (EPS) values of the kefir samples ranged from 3.52 to 4.52, 0.71% to 1.58%, and 1.02 g/kg to 1.63 g/kg, respectively. The exopolysaccharide content of kefir samples produced by adding an inactive kefir starter culture before and after fermentation was higher than that of the control samples. The apparent viscosity values, flow behaviour index values, and consistency coefficient values of the kefir samples varied between 0.09 and 0.16 Pa·s, between 0.21 and 0.34, and between 1.44 and 2.79 Pa·sⁿ, respectively. During the storage period, the highest taste and overall acceptability scores were observed in kefir samples produced by adding inactive starter kefir culture before fermentation. In blood glucose measurements, although an increase was observed in the groups given kefir samples at the beginning, the values approached those of the control group by the end of the experiment. In the oral glucose tolerance test (OGTT) results, a significant reduction in glucose levels was determined in the kefir groups compared to the T1DM group, while no statistically significant difference was observed among the kefir groups. These findings indicate that kefir, particularly when enriched with inactivated kefir starter culture before fermentation, offers improved textural and sensory profiles. However, the anti-hyperglycaemic potential may be primarily attributed to the kefir matrix, regardless of the addition of paraprobiotics before or after.