Caracterização microbiológica e química da bebida Kefir de leite e açúcar mascavo

Abstract

Two beverages fermented with kefir grains that are commonly consumed in Brazil were studied. The grains were inoculated in milk and a brown sugar solution. The objective of the study was the microbiological identification and characterization of the chemical compounds formed during the beverage fermentation. The kefir grains cultured in milk presented a symbiotic association of microorganisms belonging to several species including lactic acid bacteria (Lactobacillus, Lactococcus, Leuconostoc), yeasts and acetic acid bacteria. The kefir cultured in brown sugar also consisted of a symbiotic association of yeasts and bacteria. The kefir cultured in brown sugar and cultured in milk are similar in microbiological constitution, culture procedures, structure and chemical constitution, but differ in visual appearance. The characterization of microorganisms in the kefir beverages indicated the presence of lactic bacteria (Lactobacilllus, Lactococcus, Leuconostoc), Gram positive bacteria, Gram negative bacteria and yeasts. The Lactobacillus genus predominated throughout the fermentation period in both the beverages and was therefore an important group present in the kefir beverages. The dominant species were Lactobacillus fermentum, Lactobacillus paracasei ssp. paracasei 1 and Candida kunwiensis. The kefir grains in brown sugar and milk indicated a greater colonization of bacteria and yeasts on the external surface, in analyzes using Electronic Scanning Microscopy. Chemical analyses showed lactic and acetic acid. Ethanol was also detected. Three types of fermentation (lactic, alcoholic and acetic) were observed during the beverage preparation. The study was important for understanding the microbiota, fermentation process and chemical constitution of the milk and brown sugar fermented kefir beverages consumed in Brazil.