β-galactosidase is an enzyme which is highly important in dairy industry. The purpose of the enzyme is the hydrolysis of lactose. In addition to that it has other food applications. Due to the increasing incidence of lactose intolerance, this enzyme is gaining importance commercially. Many advancements have come with respect to this production of enzymes like biotechnological innovation and immobilization.
The people with lactose digestion problem varies widely per country. β-galactosidase involves in the hydrolysis of lactose with an improvement in the solubility and digestibility of final products. Lactosefree dairy products can provide essential nutrients present in milk to people who are lactose intolerant. Because of the thermostability, thermo acidophilic and thermoresistant properties, microbial β-galactosidase is of much interest (
Many advancements have come with respect to this production of enzymes like biotechnological innovation and immobilization and other applications are GOS production and dietary supplements (
β-galactosidases can catalyse both hydrolytic and transglycosylation reactions. Properties of microbial beta-galactosidases such as transglycosylation and transgalactosylation have been utilized for production of glucose, galactose, heteropolysaccharide, galactooligosaccharides. Through Immobilization, β-galactosidase can improve its stability and reusage (
Immobilization processes provide control of the matrix-enzyme interaction, allowing enzymes to be retained in a variety of orientations and conditions, which has remained a fundamental factor for their use in biotechnological sectors (
The hydrolysis of lactose into glucose and galactose will improve the solubility and digestibility of milk and milk products thus, β-galactosidase is highly important in dairy industry. Food with low lactose content, ideal for lactose-intolerant consumers is thus obtained. It also favours consumers who are less tolerant to dairy products crystallization such as milk candy, condensed milk, frozen concentrated milk, yoghurt and ice-cream mixes. It also produces oligosaccharides, the best biodegradability of whey second to lactose hydrolysis (
β-galactosidase (EC 3.1.2.23, β-D-galactoside galacto hydrolase) is often called by its trivial name lactase. It works in a relatively broad pH range enzymes from fungi act between pH 2.5-5.4, yeast and bacterial enzymes act between pH 6.0-7.0. β-galactosidases hydrolyse the disaccharide β-D-galactopyranosyl(1,4)-D-glucose (lactose) to β-D-galactose and D-glucose. The currently available commercial lactases differ widely in their properties, mainly with respect to their pH and temperature optima. Lactase which is present in the brush borders of the small intestine involves in the absorption of lactose. β-galactosidase enzyme produced by walls of small intestine and hydrolyse milk sugar lactose into glucose and galactose. Lack of lactase enzyme leads to lactose intolerance which shows symptoms such as abdominal pain, bloating, diarrhoea, gas and nausea (
Lactose intolerance is defined as a metabolic disorder when people are unable to digest significant amounts of lactose due to the genetically insufficient production of the lactase enzyme (β-galactosidase) (
Lactose intolerance is caused by a lack of β-galactosidase, which is not mediated by the immune system. Lactose is not digested into its component monosaccharides in the absence of this enzyme in the digestive tract, and instead travels into the colon, where bacteria metabolise the sugar. Lactose intolerance is caused by the products of this fermentation (CO2, H2, and H2O), which cause gastrointestinal irritation (
Lactase deficiency can be classified into three categories: primary, congenital, and secondary. People aged 2 to 20 years suffer from primary lactase insufficiency. A more prevalent type of lactase insufficiency is primary lactase deficit, which occurs when β-galactosidase production is diminished along the brush boundaries of the small intestine (lactase). The second form of lactase deficiency is congenital lactase deficiency, which is caused by a genetic defect that results in either a very tiny amount of this enzyme in patients or the enzyme being completely absent in affected persons. The third form, known as secondary lactase deficiency, is caused by low amounts of this enzyme as a result of an underlying GI tract illness (
Because of its numerous roles, which include digestion, lysosomal degradation, and catabolism, β-galactosidase is widely distributed in nature (
Although a wide range of bacteria can generate β-galactosidase,
In
Two types of β-galactosidases are of increasing significance in industrial processing. They are thermostable and cold-active β-galactosidases. The thermostable β-galactosidase from
The disaccharide β-D-galactopyranosyl-(1/4)-Dglucose (lactose) is hydrolysed by β-galactosidases into β-D-galactose and D-glucose. The mechanism of action of
The immobilization of enzymes is a widely used approach for obtaining reusable enzyme derivatives which reduces the high enzyme cost associated with their production and purification (
For the production of lactose hydrolysed UHT milk, β-galactosidase enzyme is used in a process in which lactase was sterile filtered into the package after the UHT treatment. Lactose crystallization in frozen and condensed milk products can be prevented by hydrolysis of lactose in milk for food processing. Enzymatic hydrolysis of lactose in yogurt mixes would reduce the lactose content and make the yogurt more digestible by lactose-sensitive, lactase-deficient individuals. Lactose hydrolysis by β-galactosidase found in whey can be used to make sweet syrup (used as a source of sugar in confectionary, feedstuffs, soft drinks, sweets, baking, ice-cream, dairy desserts, molasses). Other products like flavoured milk, dairy powders, heat desiccated products such as khoa were also prepared by lactose hydrolysed milk.
Microbial β-galactosidase production is an important area in whey utilization and treatment or bioconversion of whey into commercially important products are gaining importance. In biotechnological processes, an ultrasonication method is widely used for laboratory scale work. Sonication resulted in release of higher β-galactosidase activity from lactic acid bacterial cells. Galactooligosaccharides (GOS) are produced simultaneously during lactose hydrolysis due to transgalactosylation activity of β-galactosidase. GOS are currently used as low-calorie sweeteners, food ingredients, and cosmetic additives. Acid lactase are used as dietary supplements.
Lactase (β-galactosidase) is permitted as a nutraceutical ingredient at the level 3,000-9,000 IU (or FCC units) / day (
Low lactose milk shall have less than 1% lactose and lactose free milk shall have less than 0.1% lactose (
Lactose free milk produced using immobilized lactase enzyme showed maximum activity at a concentration of 39.33 IU/mg at 50°C and pH 9 and the lactase enzyme (64.53 IU/ml) was isolated from
β-galactosidase was used for production of lactosehydrolysed UHT milk in a process where lactase was sterile filtered into the package after UHT treatment with limited degree of hydrolysis between 80 and 90% to avoid excessive sweetness (
Compared to normal yoghurt lactose hydrolysed yoghurt have higher rate of lactic acid production, reduced whey separation and improved flavour, body and texture. Enzymatic hydrolysis of lactose in yogurt mixes make the yogurt more digestible by lactose-sensitive, lactase-deficient individuals. Lactose hydrolysed yoghurt have several advantages over normal yoghurt. Lactose hydrolysed yoghurt have increased sweetness and flavour acceptance and faster acid development or a shorter coagulation time compared to normal yoghurt (Dekker, 2019).
In frozen dairy products there will be decrease in the freezing point due to lactose hydrolysis. Thus, it can improve smoothness and scoopability of the product (Dekker, 2019). β-galactosidase prevented the crystallization of lactose by breaking into glucose and galactose and reduced sandiness. Replacement of 75% of MSNF with lactose hydrolysed demineralized whey powder, gave acceptable product with improved creaminess (
Hydrolysis of whey using β-D-galactosidase have an important application of enzyme technology in food industry. In soft drinks and canned fruit syrup, concentrated hydrolysed whey or whey permeates can be used as a sweetener. Sweet syrup obtained by the hydrolysis of whey can be used in confectionary, feedstuffs, sweets, baking, ice-cream, dairy dessert, molasses (
Cheese whey consists 0.7% (w/v) protein, 5% (w/v) lactose, 93% (w/v) water and 0.5% (w/v) minerals. Whey is a highly polluting substance in the cheese industry. It is cheap and a readily available substrate for microbial cell cultivation after the hydrolysis of lactose using β-galactosidase (
Cheese maturation or cheese ripening is a process carried out for developing unique flavour, aroma and texture in cheese. Ripening of cheese is done for usually 6 months to 2 years depending upon the variety of cheese (
Flavoured lactose-free milk has much less problems with Maillard-related off-flavours and browning than regular lactose-free UHT milk because it has strong flavour and colour. Dairy powders can be produced from milk or whey that is made lactose-free by lactase. Lactose hydrolysis into glucose and galactose affect the drying of milk products by promoting greater adhesion to equipment, greater tendency to browning and decreased solubility and modification of microstructure (
Disposal of whey which contain high BOD (5-6% dissolved solids) is a major problem in dairy industry. Bioconversion of whey by β-galactosidase is an important area in the utilization of whey. Ethanol production using β-galactosidase synthesized by
Production and purification of β-galactosidase enzyme from safe
Utilization of 20% lactose hydrolysed paneer whey (60% hydrolysis) in the bun gave desirable colour and flavour. Concentrated (20%) and lactose hydrolysed (60%) paneer whey and wheat flour (25% replacement of maida) could be successfully utilized for the production of buns (
Skim milk solids are used in bread, contributing about 1.5% lactose. Lactose so incorporated is not yeastfermentable and imparts no additional sweetness on an overall basis. Hydrolysis by β-galactosidase impart sweetness. The hydrolysis products glucose and galactose can be useful for fermentation and crust colour formation respectively (
GOS are nondigestible prebiotics, aid to modify intestinal microflora for human health. In human milk GOS influences growth of
Enzyme hydrolysis of lactose is a common biotechnological approach as the hydrolysed products can be consumed by lactose maldigesters. To improve the flavour of lactose-hydrolyzed milk, β-galactosidase is immobilized in liposomes. Coldactive β-galactosidase hydrolyses lactose and it is an important food-industrial enzyme. Thermophilic β-galactosidases are useful alternative to the mesophilic enzymes used in the industrial processing of dairy products along with heat treatment to sterilize the product. Whole cells as a source of β-galactosidase used for the lactose hydrolysis through permeabilization technology. Saccharification of milk whey using ethanol permeabilized cells in packed bed bioreactors indicated that permeabilization increases the lactose hydrolysis rate and 99.5% of milk whey lactose was hydrolysed at 30°C for 30h. Sonication resulted in release of higher β-galactosidase activity from lactic acid bacterial cells. Whey proteins are ultrafiltered and hydrolyzed to produce a variety of valuable pharmaceutical products (
Acid lactase are used as dietary supplements and most commonly used acid lactase is obtained from
Neutral lactases are sold by companies like DSM Food-Specialties (Maxilact® neutral lactase enzymes), DuPont (GODO-YNL2), Chr. Hansen (HA-LACTASE™), Kerry (BiolactaseTM lactase enzyme), Novozymes (Lactozyme®) Amano Enzyme Inc. (Lactase 14-DS.) and Shin Nihon, and DSM Nutritional Ingredients (ToleraseTM L, an acid lactase).
β-galactosidase is a key enzyme in the food processing industry, with nutritional, technological, and environmental uses. Because of their beneficial effect on the gut bacterial microflora, they are widely used in a range of foods. Enzyme immobilization allows for enzyme reutilization and, in some cases, improved activity by supplying the enzyme with a more favourable micro-environment.