OPTIMIZATION OF PERMEABILIZATION PROCESS FOR LACTOSE HYDROLYSIS IN WHEY USING RESPONSE SURFACE METHODOLOGY

Abstract

ABSTRACT To overcome the permeability barrier and prepare whole cell biocatalysts with high activities, permeabilization of Kluyveromyces marxianus var. lactis NCIM 3566 in relation toβ‐galactosidase activity was optimized using cetyltrimethylammonium bromide (CTAB) as permeabilizing agent. Permeabilized whole cells can be advantageous over pure enzyme preparations in terms of cost‐effectiveness and increased stability maintained by the intracellular environment. Response surface methodology (RSM) was applied to optimize concentration of CTAB, temperature and the treatment time for maximum permeabilization of yeast cells. The optimum operating conditions for permeabilization process to achieve maximum enzyme activity obtained by RSM were 0.06% (w/v) CTAB concentration, 28C temperature and process duration of 14 min. At these conditions of process variables, the maximum value of enzyme activity was found to be 1,334 IU/g. The permeabilized yeast cells were highly effective and resulted in 90.5% lactose hydrolysis in whey.PRACTICAL APPLICATION β‐Galactosidase is one of the most promising enzymes, which has several applications in the food, fermentation and dairy industry. However, the industrial applications of β‐galactosidase have been hampered by the costs involved in downstream processing. The present investigation was focused on developing the low‐cost technology for lactose hydrolysis based on permeabilization process. Disposal of lactose in whey and whey permeates is one of the most significant problems with regard to economics and environmental impact faced by the dairy industries. Keeping this in view, lactose hydrolysis in whey has been successfully performed using permeabilized Kluyveromyces marxianus cells. Hydrolysis of lactose using β‐galactosidase converts whey into a potentially very useful food ingredient, which has immense applications in food industries. Its use has increased significantly in recent years, mainly in the dairy products and in digestive preparations. Lactose hydrolysis causes several potential changes in the manufacture and marketing of dairy products, including increased solubility, sweetness and broader fermentation possibilities.