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The characteristics of polysaccharides isolated from milk and soymilk kefir grains, and the composition of flavor and volatile compounds from soymilk kefic were investigated. Soymilk kefir grains revealed lower polysaccharide content than milk kefir grains, with a polysaccharide profile consisting primarily of glucose and galactose, with the former predominating. The apparent molecular weight of the polysaccharide was estimated at 1.7 × 10 4 Da. In comparison to nonfermented sbymilk, the concentrations of the key volatile compounds for soymilk kefir (such as acetaldehyde, acetone, diacetyl, and ethanol) increased, while n-hexanal concentration decreased. The acetaldehyde level for soymilk kefir was slightly higher, but levels for the other volatile compounds were lower than for milk kefir. Les polyosides et composes volatils responsables de la flaveur du kefir provenant de lait ou de lait de soja fermente sont compares. La teneur en glucides est plus faible dans les grains de kefir de lait du lait de soja (glucose et galactose). La teneur en composes volatils est superieure dans le lait de soja fermente que dans le produit non fermente.

The effects of added glucose, lactose, and sucrose on microbial growth, acid, and ethanol production, and galactosidase activity in soymilk fermented with kefir grains were studied. Immediately after the addition of kefir grains to soymilk, the lactic-acid bacterial counts were higher, but the yeast counts were lower than in milk kefir. After fermentation for 32 h, the concentrations of yeast, lactic acid, and ethanol in soymilk were significantly lower than those in milk kefir. Addition of 1% glucose to soymilk stimulated growth of lactic-acid bacteria and yeast, the production of lactic acid and ethanol, and the β-galactosidase activity. Nevertheless α- galactosidase activity was suppressed by 1% glucose.