Treatment of soy milk with Debaryomyces hansenii cells immobilised in alginate

Whole cells of Debaryomyces hansenii UFV-1 were permeabilised with ethanol and immobilised in calcium alginate hydrogel. The optimum pH and temperature for alpha-galactosidase activities of permeabilised free (PFC) and permeabilised immobilised cells (PIC) were 4.5 and 60 degrees C; and 4.0 and 70 degrees C, respectively. PIC alpha-galactosidase was more stable than that of PFC. The incubation of PIC at 60 and 70 degrees C promoted an increase in alpha-galactosidase activity. The alpha-galactosidase activity was maintained when PIC was used in three repeated batches. The K-m values for PIC and PFC alpha-galactosidases, with pNP alpha GaL were 0.82 mM and 0.30 mM, respectively. Soy milk treatment with PIC for 6 h at 60 degrees C promoted 100% hydrolysis of raffinose oligosaccharides. (c) 2008 Elsevier Ltd. All rights reserved.