Effect of process parameters on the ?-galactosidase hydrolysis of lactose and galactooligosaccharide formation in concentrated skim milk

The study aimed at evaluation of beta-galactosidase activity for lactose hydrolysis (DH) and galactooligosaccharide (GOS) formation at 7 degrees C. beta-galactosidase derived from K. lactis was more effective than B. lichenformis for DH and GOS formation in 16% lactose solution. beta-galactosidase from K. lactis exhibited 96.61% DH and 7.28% GOS production after 12 h of reaction and hence was utilized for lactose hydrolysis in concentrated skim milk (40% total solids). Use of 9.53 U/mL enzyme resulted in significantly high DH (97.06%) after 12 h with 4.90 g/L of residual lactose. However, maximum GOS formation of 12.01% with 94.74% DH was obtained after 4 h. Further increase in reaction time up to 12 h resulted in breakdown of tri and tetrasaccharide GOS, thereby, reducing GOS content. Hence, reaction time of 12 h was finalized to obtain maximum DH along with additional benefit of GOS formation.

Automated summary

This study evaluated the activity of β-galactosidase for lactose hydrolysis and galactooligosaccharide formation at 7 degrees C. The enzyme derived from K. lactis was more effective than B. lichenformis. When used in concentrated skim milk, the enzyme concentration of 9.53 U/mL resulted in the highest hydrolysis rate and the maximum formation of galactooligosaccharides was obtained after 4 hours.