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55 2016

Journal of Food and Nutrition Research
Súhrny čísla 2 / 2016

Pop, C. R. – Salanţă, L. – Rotar, A. M. – Semeniuc, C. A. – Socaciu, C.  – Sindic, M.
Influence of extraction conditions on characteristics of microbial polysaccharide kefiran isolated from kefir grains biomass
Journal of Food and Nutrition Research, 55, 2016, č. 2, s. 121-130

Carmen R. Pop, Department of Food Engineering, Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Mănăştur Street 3-5, 400372 Cluj-Napoca, Romania.

Received 22 September 2015; 1st revised 25 January 2016; accepted 18 February 2016; published online 26 March 2016.

Súhrn: Kefiran is a water-soluble polysaccharide, which can be isolated from kefir grains biomass. Rheological behaviour and physico-chemical characteristics of kefiran solutions were influenced by the extraction parameters. Degradation of the polymer chain occurred at the highest temperature tested (100 °C). The intrinsic viscosity of kefiran solutions (0.1 g·ml-1) varied between 8.24 mPa at 100 °C to 19.32 mPa at 80 °C. Regarding rheological properties, kefiran solutions had characteristics of a Newtonian behaviour in diluted solutions and pseudoplastic at higher concentrations. High-performance liquid chromatography analysis of monosaccharides revealed that kefiran is composed of glucose and galactose in a relative molar ratio of 0.94–1.1. Infrared spectra of kefiran suggested the structure of alpha- and beta-configurations in pyranose-form carbohydrates, which indicated a purified structure of kefiran. The molecular weight of kefiran polymer was between 2.4 × 106 Da and 1.5 × 107 Da, the values of molecular weight depending on extraction conditions. This polysaccharide was found to have higher intrinsic viscosity and higher apparent viscosity in aqueous solutions, which brings a perspective for its use as thickening or gelling agent in food, or as a matrix in film-forming solutions.

Kľúčové slová: kefir grains; lactic acid bacteria; kefiran; rheological properties

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