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

Derya Saygili,Cem Karagözlü,Deniz Döner,Filiz İçi̇er

doi:10.1590/fst.32520

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.

Highlights

Kefir whose origin is the Caucasian Mountains is an important fermented milk beverage
The results of microbiological analysis of kefir samples produced with sheep and goat milk were in agreement with the results reported by Chen et al (2005)
Kefir samples produced from cow milk by grain and culture were found to fit the Hershel-Bulkley model even at different incubation temperatures, whereas only kefir incubated at 20 °C fitted the Exponential model

Summary

Introduction

Kefir whose origin is the Caucasian Mountains is an important fermented milk beverage. The kefir grain has a diverse spectrum of species including especially lactic acid bacteria (Lactococci, Lactobacilli, Leuconostoc). It has a spectrum of certain yeasts (Saccharomyces, Kluyveromyces and Candida) and acetic acid bacteria (Acetobacter). The rheological properties are important to determine different interactions in new kefir formulation. The addition of caseinates have important effect on rheological properties of kefir. The effect of the production method of kefir and the composition of the milks were emphasized when the flow behavior was determined (Arı et al, 2012)

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