Rheological properties and microbiological characteristics of kefir produced from different milk types

Abstract Kefir is a refreshing fermented dairy product which has flowing consistency, uniform and bright appearance with mild yeast taste and flavor. Traditional or industrial methods can be applied for the production of kefir using kefir grains or lyophilized culture. Changes in product rheology caused by the using different types of milk and different incubation temperatures in kefir production are effective on selecting the equipment such as pump, pipeline, mixer, filling machine. In this study, microbiological flora and rheological properties of kefir were investigated for cow, sheep or goat milks with kefir grain or lyophilized culture. The pasteurized cow, sheep and goat milk were cooled to 28 °C and fermented with kefir grain and incubated at 20 °C, 25 °C or 30 °C for 24 hours. Then, the grains were filtered and stored at + 4 °C for 24 hours. At the end of the storage period, rheological and microbiological analyzes were carried out on kefir samples. The same procedures and analyzes were carried out lyophilized culture. It was found that the incubation application at different temperatures was effective on the consistency coefficient even in the fluid type unchangeable samples.