Formation of gal-sorbitol during lactose hydrolysis with β-galactosidase

The objective of the work was to determine the effect of selected parameters: content of dry matter in reaction mixture, temperature, pH and concentration of NaCl on the enzymic synthesis of gal-sorbitol with β-galactosidase from Kluyveromyces lactis. The highest content of gal-sorbitol (16.8% w/w in dry matter) was obtained using 35% (w/v) solution of lactose and sorbitol (1:1). Temperature had a minimal effect on the amount of the sorbitol derivative synthesised. An increase in pH from 6.5 to 9.0 caused approximately a 9% increase in the amount of gal-sorbitol. The presence of 0.25–0.75 M NaCl caused approximately an 11% increase in the amount of the product synthesised. An increase in pH and an addition of NaCl caused an increase in the process duration.