Preparation of lactose hydrolysed milk using β-galactosidase enzyme extracted from potential Lactobacillus cultures

Abstract

In the study, pH 6.5 and 40°C were selected on the basis of maximum β-galactosidase activity produced by L.helveticus MTCC 5463 (V3), L.rhamnosus (NK2) and L.casei (NK9) during optimizing the pH and temperatures using Response Surface Methodology (RSM). During evaluation of lactose hydrolysis using partially purified β-galactosidase enzyme, V3 showed highest reduction of lactose and maximum production of glucose and galactose at 2 % rate of β-galactosidase upto 12h of incubation. Partially purified β-galactosidase enzyme showed maximum lactose hydrolysis at 2% rate of addition in sterilized reconstituted skim milk for V3, NK2 & NK9 cultures up to 12h of incubation. Lactose hydrolysed milk which were prepared using partially purified enzyme were added @2% in sterilized reconstituted skim milk for 12h at 37°C. Based on sensory scores, B (Commercially available enzyme sample), A (Reconstituted sterilized skim milk), and C (Partially purified β-galactosidase produced from V3) showed highest sensory score and were more acceptable compared to D (NK2), E (NK9) and F (Market sample: Lactose free milk) after 12h of incubation at 37°C by adding 2% partially purified β-galactosidase enzyme in sterilized reconstituted skim milk.