Lactase (β-galactosidase)
Lactozym® Pure is a preparation of lactase (β-galactosidase). It breaks down (hydrolyses) the disaccharide lactose to the sweeter-tasting monosaccharides glucose and galactose. Lactase is widely used in the manufacture of dairy products such as fermented milks, ice cream, milk drinks and even lactose-reduced milk for cats.
PRACTICAL PROTOCOL
SOURCE
Lactozym® is produced by the dairy yeast Kluyveromyces lactis.
COMMERCIAL USES
Sweet milk and low-lactose milk products
Lactase is used in the production of lactose-reduced milk for people who are intolerant of lactose. The enzyme is also used to make a special low-lactose milk for domestic cats for similar reasons. When flavoured milk drinks are made from lactase-treated milk, the amount of sweetener required can be reduced without reducing the sweetness of the finished product. This is because glucose and galactose are sweeter than lactose. The amount of flavouring required can often be reduced too. In the production of condensed milk, lactose crystallisation can be avoided by lactase treatment, and the risk of undesirable thickening caused by casein coagulation on lactose crystals is thus reduced. Such products are made by injecting the enzyme into the milk or by treating the milk with an immobilised enzyme preparation.
Cultured milk products
Generally, lactose is fermented more slowly than glucose or galactose. Consequently, when lactase-treated milk is used for cottage cheese or yoghurt production, the period from the addition of the starter culture to obtaining the desired low pH will be shortened. In addition, for the reason stated above, the yoghurt is sweeter and the shelf-life is prolonged. With fruit yoghurt, the amount of sweetener can also be reduced, resulting in a product with fewer calories.
Ice cream
If ice cream is made from lactase-treated milk (or whey), or if the ice cream mix is treated with the enzyme, no lactose crystals are formed and the common defect ‘sandiness’, due to lactose crystallisation, will not occur. Hydrolysis of lactose also improves ‘scoopability’ and texture significantly, as well as making the ice cream more palatable to those who are lactose intolerant.
Treatment of whey
After lactase treatment, whey may be purified and concentrated to form syrups for use as a sweetener in various food products.
EDUCATIONAL USES
Immobilised lactase
Instructions for this popular school practical procedure can be downloaded from the link on the left, above.
Lactase persistence and human evolution
The Howard Hugues Medical Institute has produced some excellent free resources on lactase persistence in humans: www.hhmi.org/biointeractive/making-fittest-got-lactase-co-evolution-genes-and-culture
ACTIVITY
When lactase reacts with lactose, a mixture of glucose and galactose is formed. Some oligosaccharides (e.g., galactobiose, galactotriose) are also produced at the initial stage of the reaction and at high lactose concentrations. Lactase is competitively inhibited by one of the products of the reaction (galactose).
Lactozym® Pure is typically used at pH 6–7.5 and has an optimum activity at pH 6.5. It works well between 10 and about 50 °C, but at the higher temperatures the enzyme is not particularly stable. You are therefore advised to consult the data sheets that are supplied with the enzyme preparation before deciding upon the conditions of use.
STORAGE
When stored at 5 °C, Lactozym® Pure maintains its declared activity (see data sheet provided with the enzyme preparation) for at least 6 months. Do not freeze.
SAFETY
DANGER. May cause allergy or asthma symptoms or breathing difficulties if inhaled. See the Safety Data Sheet for further advice.
SAFETY DATA SHEET
ORDERING
All of the prices on this page are in GBP and do not include Value Added Tax (VAT). This tax applies within the European Union only. Postage and handling must also be paid on orders from outside the United Kingdom. Details of how to order are given on the price list and on the Ordering web page.
Please note: We are unable to supply this product to addresses in the United States of America.
PLEASE NOTE: THE NCBE SUPPLIES THESE ENZYMES TO SCHOOLS AND COLLEGES FOR EDUCATIONAL USE ONLY. COMMERCIAL USERS OF ENZYMES OR THOSE WHO REQUIRE ENZYMES FOR RESEARCH PURPOSES SHOULD CONTACT THE ENZYME MANUFACTURERS OR OTHER SUPPLIERS, NOT THE NCBE.