Microbiological, physicochemical evaluation and sensory acceptance of kefir with graviola pulp

Abstract

Kefir is a product obtained by fermentation of milk with kefir grains and cultures prepared from the grains. Considering the functional qualities of kefir and seeking the use of fruits from the Amazon region, a kefir beverage was produced with graviola pulp and its microbiological and physicochemical characteristics were evaluated during the storage period under refrigeration, as well as its acceptability. The main groups of microorganisms presented in kefir were Lactobacillus, Lactococcus, yeast and acetic bacteria quantified in specific broths. The total number of microorganisms was similar for all groups, around 10⁹cfu/g. At the end of 28 days of storage it was reduced to 10⁷cfu/g. It was verified that the addition of graviola pulp and sugar to the natural kefir did not influence the behavior of its microbiota. Nine lactic acid bacteria were isolated from the kefir grains and were characterized as Lactococcuslactissubps. lactis. The pH value did not change significantly during 21 days of storage. The pH statistically increased  only on the 28^th day of storage under refrigeration. The acidity (% of lactic acid) increased gradually during the storage period. The sensory analysis of kefir with graviola pulp showed an excellent acceptability.