MICROBIOLOGICAL AND RHEOLOGICAL STUDIES ON PORTUGUESE KEFIR GRAINS

The native bacteria and yeasts present in Portuguese kefir grains stor ed under four distinct sets of environmental conditions have been isol ated and identified on the basis of morphology and biochemical tests. The microbial population of the kefir grains as a whole has been chara cterized in terms of rates of biomass production and formation of lact ic acid and ethanol. The rheological properties of the purified polysa ccharide (kefiran) produced by the microflora of the grains and accumu lated therein were studied in a low water activity solvent and as a co mponent of a binary gel containing either kappa-carrageenan or xanthan gum.