215 RESEARCH FOR RURAL DEVELOPMENT 2017, VOLUME 1 THE COMPARISON OF COMMERCIALLY AVAILABLE β-GALACTOSIDASES FOR DAIRY INDUSTRY: REVIEW Kristine Zolnere, Inga Ciprovica Latvia University of Agriculture k.zolnere@gmail.com Abstract β-Galactosidase (EC 3.2.1.23) is one of the widely used enzymes for lactose-free milk production and whey permeate treatment. Enzymes can be obtained from microorganisms, plants and animals. Nowadays, microorganisms are becoming an important source for production of commercially available enzymes, which are of great interest and ofer several advantages such as easy handling and high production yield. The aim of this review was to summarize fndings of research articles on the application of commercially available β-galactosidase preparates in dairy industry, to analyse and compare the most suitable β-galactosidase commercial preparates for lactose hydrolysis. The results showed that the main factor to choose an appropriate β-galactosidase for lactose hydrolysis was reaction condition. Enzymes from microorganisms contain a wide range of optimal pH from 4.0 (Penicillium simplicissimum and Aspergillus niger) to 8.5 (Bacillus subtilis). The greatest commercial potential have enzymes obtained from fungi (Aspergillus oryzae and Aspergillus niger) and yeasts (Kluyveromyces lactis and Kluyveromyces fragilis). Fungal origin enzymes are more suitable for the hydrolysis of lactose in acid whey due to its acidic pH but yeasts origin enzymes for milk and sweet whey. In the study, commercial preparates from diferent suppliers with the purpose to analyse their lactose hydrolysis potential and give more detailed characteristics of each preparate advantages and drawbacks were also summarized. Key words: β-Galactosidase, lactose hydrolysis, commercial preparates. Introduction The scientists worldwide are searching for new biotechnological tools which promote the use of dairy by-products (whey, buttermilk and other) for obtaining compounds with new perspective or products with high added value (De Jesus et al., 2015). Enzymes are protein molecules which are working as catalysts for chemical reactions (Chaudhary et al., 2015) and are entirely involved to change and develop the nutritional, functional and sensory properties of ingredients and products, and have found extensive application in processing and production of food products (Oort, 2010). Important segment of food enzymes industry are dairy enzymes, which are used for the developing and improving sensory characteristics (aroma, favour and colour) and functional properties of milk products (Singh et al., 2016). Dairy industry is one of the largest markets for commercial enzymes application (Kelly & Fox, 2012) and one of the highly used enzymes is β-galactosidase (EC 3.2.1.23) (Grosová, Rosenberg, & Rebroš, 2008). β-Galactosidase is known as lactase, which hydrolyses lactose into glucose and galactose (Panesar, Kumari, & Panesar, 2010). The enzyme is used to produce lactose-free products for people who are lactose-intolerant (Shu et al., 2014). Lactose is a disaccharide and major sugar in milk. This sugar may afect favours and odours absorption and leads to many faults in refrigerated foods such as formation of crystals, deposit and sandy or gritty texture. There is another reaction where β-galactosidase can be used and it is in transglycosylation of lactose for galacto-oligosaccharides (GOSs) synthesis. These are the nondigestible oligosaccharides, which in the upper intestinal tract are not hydrolyzed or absorbed (Panesar, Kumari & Panesar, 2010). β-Galactosidase has animal, plant and microbial (bacteria, fungi, and yeasts) origin; for reducing production costs, mostly microbial enzymes, which represent a higher activity than others are used. Enzyme used in food production must come from microorganisms which have been approved by Generally Recognized as Safe (GRAS) (Dutra Rosolen et al., 2015). GRAS provides unhampered usage of their enzymes without any profuse and expensive purifcation (Carević et al., 2015). The greatest commercial potential shows enzymes which are obtained from fungi and yeasts (Dutra Rosolen et al., 2015). The aim of this review was to summarize fndings of research articles on the application of commercially available β-galactosidase preparates in dairy industry, to analyse and compare the most suitable β-galactosidase commercial preparates for dairy production. Materials and Methods Monographic method was used in this study. The review summarizes the research fndings on commercially available β-galactosidase that is used for the hydrolysis of lactose. Enzyme properties and suitability for dairy products production, commercial preparates for industrial and research tasks, as well as lactose hydrolysis potential has been studied. Results and Discussion Characterisation of β-galactosidase The commercially available β-galactosidase is derived from a variety of microorganisms which are FOOD SCIENCE DOI:10.22616/rrd.23.2017.032