Also, the formed lactic acid, not acting as yeasts inhibitor, generates
hydrogen bonds with hydroxyl groups of cellulose and
leaves the liquid medium (Rhee and Tanaka, 2000). This explains
why whey is fermented in reduced fermentation time by porous
cellulose supported kefir cells as compared with free cells
(Golfinopoulos et al., 2011). Recently it was observed that lactose
uptake rate by free kefir cells was strongly correlated to
lactose fermentation rate in synthetic media containing lactose
(Golfinopoulos et al., 2009), as well as in whey (Golfinopoulos
et al., 2011). Also, new results indicated that the use of kefir
immobilized on GP and DCM reduced sharply whey fermentation
time and increased lactose uptake rate (Golfinopoulos et al.,
2012). As Fig. 1 illustrates the aforementioned results were verified
and also lactose uptake rate by kefir cells immobilized on BSG or
MSR was correlated to lactose fermentation rate during whey
fermentation too.