The kefir culture (5 UC) had been previously
distributed in sterile soymilk and immediately frozen in vials prior
to use. To be incorporated into the soymilk, the bottles were
thawed at room temperature and the required amount was
aseptically added, followed by manual shaking. Kefir culture
(0.02 UC/L) was applied to the soymilk at 25 C. Fermentation
occurred in sterile plastic bottles of 100 mL placed in BOD
incubator at 25 C for 30 h, with semiopen cover. At 15 h, samples
were collected at 2.5-h interval and, from 15 to 30 h, in 5-h
interval for determination of cell viability, pH and acidity,
a-galactosidase and b-glucosidase activity, determination of sugar
and isoflavone content. In the soymilk control, kefir culture was
not applied.