Sensory and physico-chemical properties of commercially available kefir

M Sady,J Domagała,D Najgebauer-Lejko,T Grega

doi:10.2298/bah0702199s

M Sady, J Domagała + Show 2 more

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https://doi.org/10.2298/bah0702199s

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Abstract

The purpose of this work was to evaluate the quality of commercial kefir, obtained from the local market. Kefirs produced by eight manufacturers were analyzed. Four of them were classified as factory with large scale of production and signed: D1, D2, D3, and D4. Three kefirs marked: M1, M2, M3 originated from the local dairy cooperatives. One evaluated product signed T1 was sold as cheap brand in hypermarket. Kefirs were evaluated for the sensory properties, chemical composition (fat, protein, total solids, solid non fat - snf), flow curve and area of hysteresis loop between upward and downward curve of stirred kefir. Flow curves were described by two rheological models: Ostwad de Waele, and Casson, the apparent viscosity was calculated as well. Most of the analyzed kefirs were characterized by satisfactory sensory quality, but only the product D2 got the maximal note close to maximal 5.0. Unexpectively kefir D1 obtained from well known brand manufacturer was determined as the lowest sensory quality product. Fat content in evaluated kefirs showed that in three dairies the standardization of fat was done imprecisely. The highest discrepancy between the fat level declared by producer and determined was stated in kefir T1. As a result of protein and snf levels analysis, it was concluded that manufacturers D2, D3 and M2 have done standardization of those components, fortifying milk to 3.93-4.72% of protein and 9.72-11.7% snf. Kefirs D1 and D3 were characterized by the highest value of shear stress in the whole range of shear rate as well as other rheological parameters: consistency coefficient K, yield stress, Cassons viscosity, and apparent viscosity.

Highlights

Introduction and literature reviewKefir is fermented milk which originates from the Caucasus, where it has been manufactured for thousands of years
The chemical composition and sensory properties of commercial kefir are shown in table 1
Most of the analysed kefirs were characterised by satisfactory sensory quality, but only the product D2 got the note close to maximal 5.0

Summary

Introduction

Kefir is fermented milk which originates from the Caucasus, where it has been manufactured for thousands of years. Kefir was produced from sheep milk by fermentative activity of kefir grains called kefir fungi. Kefir grains are the products of lactic acid bacteria and yeast, and consist of the genera Lactococcus, Lactobacillus, Kuyveromyces fragilis and Candida kefir. Kefir has a double fermentation, acid and alcoholic that causes the drink’s particular taste (Irigoyen et al 2003). Because of its exceptional healthy properties, the consumption of kefir grows in other European countries as well. The therapeutic value of kefir results from antimicrobial properties of lactic and acetic acids produced during fermentation process. Kefir yeast is capable of synthesis of the B group vitamins. Kefir consists of metabolites preventing the accumulation of cholesterol, promoting better assimilation of protein and calcium and regulating overall metabolism (Wójtowski et al 2003, Simova et al 2002)

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