Kefir: composition and evaluation of in situ antagonistic activity against Staphylococcus aureus and Escherichia coli.

Abstract

The aim of this study was to investigate whether produced kefir meets the identity and quality standards for
fermented milks, to check the possibility of assigning a nutrition declaration, and to evaluate the antagonistic activity of the
fermented milk against Staphylococcus aureus and Escherichia coli. Two different formulations of kefir (Kefir 1 and Kefir
2) were prepared to determine the percentage composition, minerals, pH, total lactic acid bacteria, and antagonistic activity
against Staphylococcus aureus and Escherichia coli. The results of the physicochemical evaluation indicated a statistically
significant difference between the formulations, except for the percentage of lipids, Ca, K, Mg and Na. The formulations met
the parameters of identity and quality in the fermented milks under evaluation. Possible nutrition declarations for Kefir 1 are
‘source of proteins’ and ‘reduced calorie’, and for Kefir 2, ‘high protein content’ and ‘high zinc content’. The fermented milks
showed significant antagonistic activity against the tested microorganisms (> 24 h), with no activity seen after this period.
Further studies involving kefir are suggested, exploring its potential as a probiotic food, and its inclusion in the diet of the
population.