Efeito do método de produção de kefir na vida de prateleira e na infecção experimental com Salmonella Typhimurium em camundongos

Abstract

Kefir is a carbonated fermented milk with a slightly acidic flavor. It is traditionally produced by the kefir's grain inoculation in milk. However the amount and species of microorganisms in kefir grains may change after successive productions, becoming difficult to standardize the drink quality. There are evidences that the kefir produces beneficial effects for the immune and gastrointestinal systems, however there are a fewpublished studies about animals and human experiments proving it. In this work we analyzed the stability of physicochemical, microbiological and sensory characteristics of tradicional kefir and starter-culture kefir aside from the possibility of the kefir protection against a Salmonella enterica sorovar Typhimurium infection in mice. The starter-culturekefir revealed the lowest pH and the highest acidity. The starter-culture kefir have had the lowest syneresis and the higher viscosity during storage. The counts of lactic acid bacteria on the traditional and starter-culture kefir has changed from 9.19 to 8.37 log CFU/mL andfrom 9.37 to 9.78 log CFU/mL, respectively, while the yeast has changed from 6.34 to 6.52 log CFU/mL and 5.75 to 6.10 log CFU/mL. The storage time has influenced the presence of foam, acid and alcoholic flavors and off-flavor in both samples. The lumpiness, acid flavor and creaminess were the most important attributes to distinguish the traditional andthe starter-culture kefir. In the mortality tests the survival rate of the traditional kefir (30%) and the starter-culture kefir (20%) were statistically identical to the control group (21.1%). The group threatened with traditional kefir have not gotten injured liver and colon in mostpart of the animals. The starter-culture fermentation method of kefir was technologically better because it produced a drink with better constant quality and a bigger shelfile while preserving the sensory characteristics of the traditional kefir. Nonetheless, while none of kefir showed a protective effect on infection with Salmonella Typhimurium in mice.