Bio-hydrolysis Study of Lactose in Produced Yoghurt by β-Galactosidase from Lactobacillus fermentum

Abstract

The present study investigated the physicochemical and biohydrolysis of lactose in conventional and locally produced yoghurt drinks, respectively. Physicochemical properties of the conventional yoghurt in the presence of the locally produced one were: pH 3.0; 4.0, titratable acid 1.14; 1.04, conductivity 2751.54, 2204, viscosity 71.11; 112.14, TDS 1788.5; 1433, TSS 781; 654, TS 3532.54; 2087, Mg 11.06; 34.19, Ca 28.76; 45.21, TOC 155.23; 145.23 and TOM 190.93, 178.63 for yoghurt sample I and II respectively. Lactose concentrations of the respective yoghurts were: 2.12 and 1.79 Mg/ml. β-galactosidase was produced from isolated Lactobacillus sp under submerged fermentation system after 12 days of incubation. 60% ammonium sulphate was found suitable for precipitation of proteins with highest enzyme activity, the precipitate was desalted through reverse osmosis using dialysis bag. Optimum biohydrolysis was achieved after 20 hours of incubation with residual sugar concentration of 0.51 mg/ml while the control experiment had 0.93 mg/ml of the residual sugar. Optimum pH and temperature of hydrolysis were: 5.0 and 70°C respectively. Rate of hydrolysis proceed linearly as the enzyme concentration increases from 0-20% v/v. the present study has shown exclusively the nutritional components of yoghurts drinks commercially sold in the market, it went further to show hope for the metabolic compromised individuals with intolerance to lactose as the enzyme lactase produced from non noscomial organism showed great potentials of hydrolysis.