By Dr. John Michaelides
By Dr. John Michaelides
An Introduction to Enzymes
Question: What are enzymes, what is their function in baking, and what new types are available to help us improve our bakery products?
Answer: Enzymes are essentially proteins that catalyze (i.e., help to carry out) chemical and biological reactions in nature. Practically all interactions between chemicals that break down compounds or give rise to other chemicals in nature are mediated by catalysts. These catalysts are in some cases simple elements, such as nickel, or, in the case of many biochemical reactions, complex proteins in the form of enzymes. There are many thousands of enzymes in nature that help living organisms to digest and metabolize food. Many of these enzymes have been identified and are commercially produced for the chemicals industry as well as in food processing. Early in the history of their industrial utilization by humans, enzymes were applied to the detergent industry. Gradually, the enzyme industry evolved in the development of specific enzymes to help in the processing of foods.
In the baking industry, crude enzyme mixtures were originally used. For example, malt barley flour containing amylases and other enzymes was and is still being used to break down the starch in the flour and provide food for the yeast. Other crude sources included the proteases papain from the papaya and bromelain from pineapple. These crude substances are normally used in the bakery formulations at the per cent level.
Recently, the availability of specific enzymes has increased tremendously, with many new choices available for the food industry. Enzymes are now produced from many sources, such as plants, animals and microorganisms. They are also very specific, refined, and more powerful and, therefore, the amounts required in order to be effective in the various processes are minute, at the parts-per-million usage level.
Enzymes are usually named after the substrate they act on. For example amylase breaks down or modifies starch, protease affects protein, and lipase acts on lipids (fats).
In the baking process, enzymes help break down various components of the flour, releasing useful subcomponents. Amylase reduces the complex starch molecules to smaller groups of glucose units that can be absorbed by the yeast and provide food for the fermentation process. In addition, specialized amylases modify the starch in order to prevent or slow down the staling process. In the baking industry, there are three major sources of amylase: cereal, which is inherent in the wheat and other grains; fungal sources; and bacterial sources. These three types of amylase have different specific activities and different tolerances to temperature and pH and, therefore, careful selection of which type to use is very important. For example, using bacterial amylase will result in the retention of some of the activity after exposure to the temperatures of baking, whereas fungal amylase will be completely inactivated by these temperatures. If high amounts of bacterial amylases are used in bread, their activity will continue beyond baking and the crumb will become sticky and difficult to slice.
Proteases modify the protein component of the flour. This action can reduce the strength of the protein in the dough and, as a result, can control the height and spread of baked goods such as cookies.
Lipases, which are enzymes that either break down or modify the fat, are found in nature and in many cases are responsible for the fat’s oxidation and the subsequent rancidity. The lipases found in the kernel are normally dormant until the wheat is milled. In the process of milling, when the germ is separated, lipases become active and, as a result, will very quickly oxidize the lipids in the germ and produce the characteristic unpleasant rancid flavours. Lipases are also available commercially for use in baked goods to modify the small amounts of fat in flour and to increase the fats’ emulsification capacity, reducing the need for additional emulsifiers in bread dough and, at the same, time improving the quality of bread.
Lipases are also used in industrial processes to modify fats. They’ve been most recently used for the production of shortenings from oil without the harmful effect of the partial hydrogenation, which results in the undesirable production of high amounts of trans fats.
Pentosanases modify pentosans (fibre), which are found in flour, and improve dough’s water absorption and other functional properties, resulting in higher volumes and improved bread quality.
Other enzymes can cross-link, modify components, and mediate oxygen reactions to strengthen the function of flour.
Transglutaminase is a new enzyme in the market that cross-links proteins and therefore increases gluten fibril formation, subsequently increasing its strength. Specifically, it links the amino acids glutamine and lysine between different proteins. The activity of this enzyme will increase resistance to extension or elasticity of dough. It will improve the baking quality of weak flours and assist in the production of frozen dough, with much longer shelf life.
Glucose oxidase is a relatively new enzyme in the baking process and has been used in baked goods in Canada for the past few years as an oxidizing agent. Its basic activity is the mediation of the reaction of glucose and oxygen to form glucono-lactone and hydrogen peroxide. The reaction results in many beneficial properties that contribute to the baking process. It has been shown to increase stability and improve the machinability of dough. In addition, it results in bread loaves with higher volumes, and helps laminated dough formation, improving the performance of puff pastry.
Many choices of enzymes are available today that can help produce baked goods of consistently good quality. These enzymes play a very important role in the automated large-scale processes of today’s production environment.
For more information, or fee for service help with product or process development needs please contact the GFTC at (519) 821 1246, by fax at (519) 836 1281, or by e-mail at firstname.lastname@example.org