摘要：Study relative to strains of bacterium St. thermophilus isolated from dairy starter cultures, the effect of a certain quantity of beta-galactosidase enzyme on content of acid formed by bacterial cells in the course of lactose disintegration and the speed of milk coagulation was undertaken. The results indicate immediate connection between three mentioned variables. The temperature of 42 ° C proved to be optimal, and under such condition only 61% of the number of beta-galactosidase units per bacterial cell were determined and only 54% acid was produced using slow variant in comparison with the fast one. The lenght of milk coagulation was twice as long using slow variant instead of the fast one.
关键词：Str. thermophilus starter culture; beta-galactosidase; breaking up of lactose; amount of acid; length of milk coagulation
