Enzymes are proteins that act as catalysts in all living organisms - microorganisms, plants, animals, and humans. Catalysts are compounds that increase the rate of chemical reactions in biological systems. Very small quantities of enzymes can increase the rate of reactions up to ten million times. Enzymes operate within a narrow set of conditions, such as temperature and pH (acidity), and are subject to inhibition by various means.
Enzymes are classified by the type of reaction they catalyse and the substance (called a substrate) they act upon. It is customary to attach the suffix "ase" to the name of the principle substrate upon which the enzyme acts. For example, lactose is acted upon by lactase, proteins by proteases, and lipids by lipases. Additionally, many long-used enzymes have common names, such as papain, from papaya, which is used to tenderize meat.
Enzymes extracted from edible plants and the tissues of food animals, as well as those produced by microorganisms (bacteria, yeasts, and fungi), have been used for centuries in food manufacturing. Rennet is an example of a natural enzyme mixture from the stomach of calves or other domestic animals that has been used in cheese making for centuries. Rennet contains a protease enzyme that coagulates milk, causing it to separate into solids (curds) and liquids (whey). Alternatively, for centuries enzymes produced by yeast have been used to ferment grape juice in order to make wine.
In the twentieth century, enzymes began to be isolated from living cells, which led to their large-scale commercial production and wider application in the food industry. Today, microorganisms are the most important source of commercial enzymes. Although microorganisms do not contain the same enzymes as plants or animals, a microorganism can usually be found that produces a related enzyme that will catalyse the desired reaction. Enzyme manufacturers have optimized microorganisms for the production of enzymes through natural selection and classical breeding techniques.
Direct genetic modification (biotechnology) encompasses the most precise methods for optimizing microorganisms for the production of enzymes. These methods are used to obtain high-yielding production organisms. Biotechnology also provides the tools to have a genetic sequence from a plant, animal, or a microorganism, from which commercial scale enzyme production is not adequate, to be transferred to a microorganism that has a safe history of enzyme production for food use.
Although the production organism is genetically modified the enzyme it produces is not. Enzymes produced through biotechnology are identical to those found in nature. Additionally, enzymes produced by microorganisms are extracted and purified before they are used in food manufacturing. Genetically modified microorganisms are useful from a commercial standpoint but would not survive in nature.
In Canada, enzymes that are used in food processing are regulated as food additives. An enzyme meets the definition of a food additive, as set out in section B.01.001 of the Food and Drug Regulations, when it affects the characteristics of the food and/or it or its by-products become part of the food. It is the physical enzyme residues, not enzyme activity, that are considered in determining if enzyme residues remain in or on a food.
As with other food additives, Health Canada is responsible for conducting the pre-market safety assessment of enzymes and approving their use in foods. Enzymes permitted for use in foods sold in Canada are listed in Table V of Division 16 of the Food and Drug Regulations, along with the permitted sources for each enzyme.
The safety of the source organism is the primary consideration in assessing an enzyme product. Food animals and edible plants have a history of safe use as sources of enzymes for the food industry. A microorganism used for food enzyme production must be well-characterized and not produce any pathogens, toxins, or antibiotics. These are usually soil microorganisms to which humans are commonly exposed to through their environment and diet, and which have a history of safe use in food enzyme manufacture. Health Canada's safety assessment considers toxicity tests on the enzyme product and the process used to commercially produce the enzyme.
The safety assessment of an enzyme produced by a genetically modified microorganism expands on the approach above. In this case, Health Canada also reviews the technique used to transfer the genetic material along with the safety of the genetic material that has been introduced and expressed in the production microorganism. The genome of the production microorganism must be fully characterized for a safety review to be completed.