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Enzymes

Martino Verga

Clerici Sacco Group, Cadorago, Italy

Introduction

The production of cheese started thousands of years ago. Perhaps the first cheese was obtained by chance. The stomach of an animal was used to transport some milk in summer. The warm temperature and the digestive enzymes released by the stomach wall cells clotted the milk. Since then, a lot of milk has been clotted and transformed into cheese, and an amazing variety of cheeses have appeared. Our diets have been enriched by these wonderful products.

People used enzymes without knowing what they were. We had to wait until 1897, when E. Buchner purified the first enzyme obtained from yeast cells, to realize that they are molecules able to work outside the cells and not a sort of “living” material. Since then, a continuous progress has led to the discovery of thousands of enzymes, many of them used for food application.

The enzymes used in dairy production are quite few in comparison to the exterminate number of enzymes acting in nature. The first enzymes used were animal rennet enzymes and, to a much more minor extent, vegetal rennet enzymes. They are still in use, and chymosin (obtained nowadays not only from animal tissues but also by genetically modified organisms—GMO—technique) is the most used enzyme in milk curdling. Animal lipase too dates back many centuries for the production of piquant cheeses.

About 50 years ago, the first microbial coagulants obtained from molds appeared on the market. Their use nowadays represents 30% of the total milk clotting enzymes. More recently, the dairy technique started using lysozyme, lactase, proteases, and transglutaminase to solve specific problems or to extend the market of dairy products to people who didn't consume these foods due, for example, to lactose intolerance.

Some efforts have been made to accelerate cheese ripening using enzymes. The results obtained so far have not been applicable to every type of cheese. Few (in reality, very few) enzymes are used for natural cheese ripening acceleration so far, since they do not work well. They produce a bitter or off flavor, bad texture, and other unfavorable results. Nonetheless, they are used a lot for enzyme modified cheeses, where cheese flavor is developed through the action of highly active microbial enzymes added to cheese slurries and then stopped by heat treatment before they take on a bad flavor. One

Advances in Dairy Products, First Edition.

Edited by Francesco Conto, Matteo A. Del Nobile, Michele Faccia, Angelo V. Zambrini, and Amalia Conte.

© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

example is the Rhizomucor miehei/pusillus lipase that in natural cheeses gives good flavor for 4+/-2 months—before, unfortunately, turning into oil paint and turpentine. However, in enzyme-modified cheeses, lipolitic activity can be stopped at the right moment before off-flavor formation.

There are useful solutions based on lactic acid bacteria: Lc. cremoris concentrates may be partly lysed, and when added in the cheese they are able to show a high peptidase activity associated with de-bittering. However, they are still too costly compared to use a good starter.

 
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