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Understanding Industry Terminology
By Aziz Ullah, Ph.D., MBA
October 01, 2012
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Uses of enzymes in detergents was first patented in 1913 but were not commercially exploited until the 1960s.
The early enzymes were derived from the pancreatic extract of dead animals, and were finicky and sensitive and broke down easily. The newer enzymes are derived by fermentation using specific strains of bacteria, and are highly resistant to higher temperatures and alkalinity.
Since enzyme dust can cause allergic reactions, the newer enzymes are encapsulated.
Enzyme confusion
There is a common misconception about the nature of enzymes, and this is perhaps reinforced by some of the terminology used when describing their action.
Enzymes, despite their derivation from living things, are not living organisms themselves. They are protein structures, of varying complexity.
Enzyme action is often explained by the analogy of lock and key. The substrate (material to be broken down like protein) must fit a portion of the enzyme, called the active site, quite precisely just as a key must fit a tumbler lock in order to open it (see "The lock-and-key model for enzyme action" illustration to the right).
Not only must the enzyme and the substrate fit precisely, but they likely are held together by electrical action. Formation of new bonds to the enzyme by the substrate weakens bonds within the substrate. These weakened bonds can then be more easily broken to form products that can be removed during cleaning.
All enzymes are water-soluble. Water is an essential medium for proper functioning of all enzymes. Enzymes provide enhanced cleaning performance by breaking down specific kinds of soils like proteins and starches.
What they do
Enzymes in cleaning are protein molecules that speed up chemical reactions by helping to break down large insoluble soils and other target molecules into smaller pieces, which are then rinsed out of the fabrics. Enzymes provide enhanced cleaning performance by breaking down, at a greatly accelerated rate, specific kinds of soils like proteins and starches that, under normal conditions, would simply not occur.
Protein stains from sources such as milk, cocoa, blood, egg yolk and grass are just as resistant to removal from fibers by simple detergents as are bleachable stains, particularly after the stains have dried. However, proteolytic (protein cleaving) enzymes — also called proteases — are usually capable of eliminating such soil without difficulty during the course of cleaning.
Proteolytic enzymes are the most widely used enzymes in cleaning. Protein stains such as blood, egg, grass and sebum are difficult to remove because they tend to coagulate. Their sticky nature also causes particulate material to stick to the stained area. If they are not thoroughly removed they can oxidize, denature the fibers and become permanent.
Specific application
All enzymes are specific for a particular application, as each type can break down a particular type of stain.
Proteases, the first enzymes to be introduced into detergent formulations, are still used to clean difficult to remove protein-based stains such as blood, egg, milk and grass. Amylases (enzymes that breaks down starches) in detergent formulations are used to remove starch-based stains such as gravy, pudding and potato. Lipases (enzymes that break down oils and fats) demonstrate their cleaning advantages on oil and fat based stains, such as margarine and oil.
Like a key for a particular lock, enzymes are very specific. A proteolytic enzyme will not break down starch, and an amylase will not attack oil. Lipases will not break a protein stain like egg, but egg stains will be broken down by proteolytic enzymes.
Most recently, cellulases have been used for color maintenance or restoration benefits on cotton textiles.
Usage guidelines
As all types of enzymes are made of proteins, if different types of enzymes are used or mixed as ingredients in a cleaning product, the effectiveness is neutralized. For example, mixing the protein-attacking enzyme protease with the starch-attacking enzyme amylase doesn't mean your resulting chemical product will remove both types of soils. Instead, they neutralize each other and are ineffective as cleaning products.
Enzymes work best under mild conditions, such as in the range of temperature of 100 to 140 degrees Fahrenheit. Keeping the pH between four and eight is best. Enzymes have now been developed that can also perform under more extreme conditions.
Notable cautions
As mentioned, enzyme-based products should not be exposed to high temperatures, and extreme pH values or agents — which can inactivate enzymes — should be avoided.
Cationic surfactants and chlorine releasing agents should not be used with enzymes.
Proteolytic enzymes are active protein-decomposing agents, and precautions should be taken to avoid direct contact with skin, which is a protein.
Inhalation of enzyme dust must be avoided, as it may cause allergies in sensitive persons.
