Enzymes are long-chain proteins that serve as natural catalysts, meaning that they allow chemical reactions to occur rapidly and efficiently. The building blocks for each enzyme are the 20 naturally occurring amino acids. Enzymes are commonly used in paper processing, food manufacture, medical device cleaning, ethanol manufacture, as well as many common household cleaning processes such as laundry and dishwashing. In laundry and dishwashing, enzymes break down the basic components of stains and soils so they can be washed away more easily. Since one enzyme molecule can act on many substrate molecules (such as soils and stains), a small amount of enzyme added to a laundry detergent can provide a significant cleaning benefit to the consumer.
Enzyme activities are highly-specific to the types of substrates they can work on. The catalytic function of each protein is determined by its 3-dimensional structure, as well as active sites that are dedicated to the particular substrate. Enzyme proteins are only active when the specified substrate is present. The various types of actions can be categorized into specific enzyme classes. The most common enzyme types used in the Household care industry are proteases, amylases, lipase, cellulases, mannanases, and pectinases. Each type may have many variations of the same protein structure that results in different preferences for conditions for peak performance. It has been found beneficial to combine different enzyme types to improve overall stain-fighting performance. Therefore, modern detergents typically contain several enzyme activity types to ensure optimal cleaning of complex soil substrates.
Enzyme products are available in liquid formulations with included stabilization systems for liquid detergent applications and also as encapsulated granulates for powder detergents and soap bars.
Proteases accelerate the breakdown of proteins into peptides and soluble amino acids. Proteases are basic ingredients in laundry detergents and are used worldwide because of their effectiveness on common stain components, such as food, grass, and blood. Some proteases have an affinity for specific protein soils and the target stain will determine which protease should be added to a detergent formulation.
Amylases accelerate the breakdown of starch-based stains from foods such as such as cereals, gravies, potato and pasta dishes, etc. In laundry, amylases ensure complete removal of starch at low wash temperatures.
Starch is a long chained carbohydrate consisting of glucose molecules bound together by alpha-1,4-glycosidic bonds. During wash, certain amylases catalyze the hydrolysis of alpha-1,4- bonds in starch, leading to the decomposition of starch into soluble dextrins and oligosaccharides. Unlike starch, dextrins and oligosaccharides are easily soluble in water and are therefore easier to remove from the fabrics during wash.
Lipases accelerate the breakdown of tri-glycerides (lipids) into fatty acids and glycerol and are applied in laundry detergents to improve the removal of body stains on collars and cuffs and non-mineral oil and fat, such as lipstick, butter, vegetable oil, and others, from fabric surfaces.
Fatty material trapped inside cotton fibers can give rise to discolored spots on laundry and cannot be removed effectively at medium-to-low washing temperatures without using lipase. With lipases the trapped fatty material trapped in the cotton fibers is hydrolyzed to less hydrophobic substances which are easier to remove.
Cellulases are used in laundry detergents to obtain cleaning and color care and improve overall cleanness. Cellulases also help maintain the brightness of colors on cotton fibers by reducing build-up of fuzz and pills on knitted garments that occurs due to normal wear and washing.
Repeated washing and wearing damages cotton fibers, resulting in areas with bristly cellulose microfibrils (“fuzz”). These microfibrils trap particulate dirt, for instance from outdoor soiling, during the wash. This prevents whites from staying white and makes colored and striped clothes look dull. Cellulases cleave off such damaged microfibrils and releases any captured dirt particles, preventing particulate soil from depositing and preventing fabric graying.
Not only can bristly cellulose fibers attract particulate soils during the wash, they can also make it more difficult for the other ingredients in the detergent to remove stains. Cellulases aid primary stain removal by modifying the surface of cellulosic fibers and fabrics, making it easier for the stain to come loose.
Cutting off fibrils that bind particulate soils also helps rejuvenate clothes, making them appear whiter and newer.
Mannanases remove mannan stains. Mannanases break down mannans and effectively remove food stains containing guar gum or locust bean gum, thereby, increasing in-depth cleaning by removing the adhesive mannan. Incomplete removal of these types of stains may result in fabric graying.
Mannans or galactomannans are polysaccharides consisting of a mannose backbone linked together by b-1,4-linkages with side-chains of galactose attached to the backbone by α-1,6 linkages.
During wash, Mannaway cleaves the b-1,4-linkages of mannans through hydrolysis, thus breaking down the gum polymer into smaller, more water-soluble carbohydrate fragments that can be siphoned out of the washing machine during the spin cycle.
Pectinases degrade pectin, a polysaccharide consisting mainly of α-1-4 linked polygalacturonic acid residues with varying side chain branching. During wash, pectinases alter the pectin structure by breaking the pectin backbone, and making them easier to remove from the fabrics during wash.
Pectinases can provide unique stain removal benefits on a wide range of pectin based stains from fresh fruits, such as tomatoes, oranges, bananas and berries. Extracted pectin is used in various processed foods, such as tomato sauces, jams, jellies, low-fat dairy products, and can cause the same type of staining potential in clothes.
Pectins are a family of complex polysaccharides that contain 1,4-linked α-D-galactosyluronic acid residues and are contained in the primary cell walls of terrestrial plants. Pectinases, catalyze the eliminative cleavage of (1->4)-alpha-D-galacturonan to give oligosaccharides with 4-deoxy-alpha-D-galact-4-enuronosyl groups at their non-reducing ends. This means that pectinases cleave the pectin into smaller molecular fragments to make it easier to remove during wash.
Many of the pectin-based stains, such as those from jams, jellies, berries, and processed tomato, are in general difficult to remove and bleach only masks these stains, thus increasing the risk of soil redeposition. Pectinases fully remove the stains by degrading the pectin, ensuring that clothes are really clean.
Enzymes were initially produced by extraction from glands of various animals; however, modern enzyme production is done through fermentation of various fungi and bacteria. The steps for production are fermentation, recovery, and standardization. Protein engineering and genetic modification of the production organism are employed in the industry to maximize the performance of the enzymes in conditions that may not be typically conducive, and improve production yields in the manufacturing process.
Fermentation to produce industrial enzymes starts with a vial of dried or frozen microorganisms called a production strain. This production strain is selected to produce large amounts of the enzyme(s) of interest.
Through multiples fermentation steps, where the microorganism is kept at optimal pH, temperature, and nutrient conditions, the desired amount of enzyme is produced. When the main fermentation is complete, the mixture of cells, nutrients, and enzymes, referred to as the broth, is ready for filtration and purification.
Following fermentation is the recovery step. A recovery process typically consists of a pretreatment followed by a primary separation of the enzyme from the biomass. Afterwards, the enzyme is concentrated by removal of water, and unwanted impurities are removed in a purification step.
Following recovery is a formulation or standardization step. Although much effort focuses on finding the right enzyme molecules for a given application, formulation plays a big role in the final use and success of the product. A new enzyme molecule with excellent performance can fail in the market if the enzyme is not stable during transportation and storage. The right formulation can remove these shortcomings, and the importance of having the right formulation should not therefore be underestimated.
The enzyme industry can cover a wide range of enzyme formulations, ranging from liquid products and various forms of solid products to immobilized enzymes.
Common formulations for the detergent industry are:
Granulates – dust-free handling
Granulates are considered the industry standard for the detergent industry and the formulations against which all other producers measure themselves. They are produced using a unique combination of high-shear granulation and various coating technologies. This results in an effective encapsulation of the enzyme, which isolates it from the environment until the moment the detergent product is dissolved into the washing solution. In addition to ensuring optimal stability of the enzyme while being stored within the detergent, the granulate form also prevents undesired exposures.
Liquid formulations – convenient to handle on both small and large scale
Most detergent enzymes are available in a liquid formulation. A liquid product is typically formulated and thus stabilized with polyols, sugars, and/or salts.
The key quality parameters for solid products are typically low dust, particle size, and stability of the enzyme activity. For liquid products, the enzymatic, physical, and microbial stabilities are the three main focus points in the product development.
Enzymes are an excellent solution for improving the sustainability profile of detergents. Since one globular enzyme protein is able to work on many molecules of substrate, small amounts of enzymes can offset larger amounts of conventional chemical ingredients. Modern formulas now take advantage of this benefit, typically incorporating more types of enzymes which allow some reduction in the amounts of other ingredients. In addition to high cleaning performance, consumers also benefit with more-compact products, and therefore reduced environmental impact.
Enzymes are stable at moderate pH and temperature.
This has benefited consumers by allowing the formulation of milder (and safer) detergent products. Related to this, many new “cold wash” products on the market rely on enzymes to provide good cleaning performance at lower washing temperatures, again providing environmental and economic benefits without sacrificing cleaning performance.
There is no standard formula for what amount of enzyme is required to improve the cleaning potential of a detergent or to substitute any other more harmful ingredients. However, that can be determined with the assistance of an enzyme manufacturer.
Increasing the sustainability profile of enzyme products, is the fact that they are naturally occurring and not derived from petroleum based ingredients.
Health and Safety
Through many years of testing it has been proven that enzymes have a very safe toxicological profile, lending to their sustainability profile. Enzymes are not mutagenic and not clastogenic. They are not reproductive or developmental toxins and have a low toxicity to aquatic systems.
As mentioned previously, enzymes have the potential to cause inhalation allergy in the occupational setting. This would occur only when the enzyme product is not handled appropriately, and if appropriate personal protective equipment is not employed. Enzyme manufacturers are able to guide formulators on what type of equipment should be used and how best to avoid exposures that may have negative effects. In addition, cleaning product formulators are strongly recommended to incorporate enzyme safety programs as part of their overall industrial hygiene programs in order to avoid any risks in their manufacturing plants. Responsible enzyme manufacturers should provide their customers with assistance in developing their enzyme safety handeling programs as well as guidance in evaluating safety of end-use products.