Enzymes are produced by all living cells as catalysts for specific chemical reactions. Not surprisingly enzymes are present in all foods at some time, and play an increasingly important role in food processing techniques. Enzymes, although not recognized as such, have played an essential part in some food processes, notably the making of cheese, leavened bread, wine and beer, for thousands of years.

Enzymes are commonly used in food processing and in the production of food ingredients. Enzymes traditionally isolated from culturable microorganisms, plants, and mammalian tissues are often not well-adapted to the conditions used in modern food production methods. The use of recombinant DNA technology has made it possible to manufacture novel enzymes suitable for specific food-processing conditions. Such enzymes may be discovered by screening microorganisms sampled from diverse environments or developed by modification of known enzymes using modern methods of protein engineering or molecular evolution. As a result, several important food-processing enzymes such as amylases and lipases with properties tailored to particular food applications have become available.