Maxiren® is the cheese-making enzyme chymosin (also known as rennin). It is identical to the animal product but is obtained instead from a genetically-modified dairy yeast, Kluyveromyces lactis. (This, or a similar enzyme obtained from another GM source is used to make about 90% of the cheese produced in the UK.)



Maxiren® is produced by a genetically-modified strain of Kluyveromyces lactis.



Maxiren® is used instead of calf chymosin for coagulating milk proteins during cheese-making. Its performance and properties are identical to calf chymosin. The majority of cheese sold in the UK is made using chymosin from genetically-modified K. lactis.



A classic school activity is to add chymosin to whole milk, incubate the mixture, and time how long it takes for the milk to gel. The effect of calcium ion concentration on the coagulation of milk proteins can be studied by adding calcium chloride to milk. The effect of temperature, pH, enzyme concentration, type of milk, etc can be investigated (see link to practical protocol above left).



Maxiren® induces milk-clotting through hydrolysis of the phenylalanine–methionine linkage of kappa casein. In the presence of calcium ions, aggregates of calcium paracaseinate then form, making cheese 'curds'. When the curd is cut, liquid whey is released. The coagulation time is inversely proportional to the enzyme concentration. The optimum activity for raw milk is reached at 42.5 °C and pH 6.6; and for pasteurised milk at 45 °C and pH 6.5. Chymosin is inactive at temperatures above 55 °C and below 15 °C. Additional information about the properties of Maxiren® is provided with the enzyme.



Maxiren® should be stored in a fridge at 3–5 °C. Do not freeze.



GHS08 pictogram

DANGER. May cause allergy or asthma symptoms or breathing difficulties if inhaled. See Safety Data Sheet for further advice.



Maxiren® ..... 100 mL ..... *£19.00 (GBP)

*Maxiren® is currently zero-rated for VAT.



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.

Copyright © NCBE, University of Reading, 2018

Enzymes for education


A computer-generated model of bovine chymosin.

PCR of chloroplast DNA RUdevice

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.

DSM Maxiren®

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