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A beginner's guide to enzymes in detergents
Enzymes are increasingly important to detergent formulators for a wide range of tasks, including laundry, automatic dishwashing, and cleaning of industrial equipment used in the food industry. Key trends in the market are driving their usage, but there are some considerations for producers using enzymes in detergents.
By Peter Dybdahl Hede, M.Sc. (Chem. Eng.), Ph.D.
May 7, 2020
Although the detailed ingredient lists for detergents vary considerably across geographies and categories, the main detergency mechanisms are similar. Stains are removed by mechanical action assisted by enzymes, surfactants, polymers, and builders.
Surfactants of various kinds help wash liquor to wet fabrics, and they assist in removing various stains by lowering the surface tension at the interface between the wash liquor and the fabric. Anionic surfactants and polymers further increase the repulsive force between the original soil, the enzymatically degraded soil, and the fabric, which prevents the soil from redepositing on the fabric.
Builders act to chelate, precipitate calcium and magnesium components, to provide alkalinity and buffering capacity, and to inhibit corrosion. Enzymes in (heavy-duty) detergents degrade and thereby help solubilize substrate soils attached to fabrics or hard surfaces (e.g., dishes). Cellulases clean indirectly by gently hydrolyzing certain glycosidic bonds in cotton fibers. In this way, particulate soils attached to microfibrils are removed. A further desirable effect of cellulases is to impart greater softness and improved color brightness of worn cotton surfaces.
By helping to remove fuzz and pills on cotton fabrics, cellulases keep them looking new.
Many detergent brands are based on a blend of two or more enzymes - sometimes as much as eight different enzymes. One of the driving forces behind the development of new enzymes and the modification of existing ones for detergents is to make enzymes more tolerant of other ingredients, such as builders, surfactants, and bleaching chemicals, as well as of alkaline. The trend toward lower wash temperatures, in particular in Europe, has also increased the need for additional and more efficient enzymes. Starch and fat stains are relatively easy to remove in hot water, but the additional cleaning power provided by enzymes is required in cooler water.
Most widely used enzymes
The most widely used detergent enzymes are hydrolases, which remove protein, lipid, and polysaccharide soils. Research is currently being carried out with a view to extending the types of enzymes used in detergents. Many complex, stubborn stains come from a range of modern food products such as chocolate ice cream, baby food, desserts, dressings, and sauces. To help remove these stains as well as classic stains such as blood, grass, egg, and animal and vegetable fat, a number of different hydrolases are added to detergents.
The major classes are proteases, lipases, amylases, mannanases, cellulases, and pectinases. Historically, proteases were the first of these to be used extensively to increase the effectiveness of laundry detergents. Cellulases contribute to cleaning and overall fabric care by maintaining, or even rejuvenating, the appearance of washed cotton-based garments through selective reactions not previously available when washing clothes with surfactants unamended with enzymes.
Some lipases can act as alternatives to current surfactant technology by targeting greasy lipid-based stains.
Recent investigations show that multi-enzyme systems may replace up to 25% of a laundry detergent’s surfactant system without compromising the cleaning effect. This leads to a more sustainable detergent that allows cleaning at a low wash temperature.
Mannanases and pectinases are used for hard-to-remove stains of salad dressing, ketchup, mayonnaise, ice cream, frozen desserts, milkshakes, body lotions, and toothpaste as well as banana, tangerines, tomatoes, and fruit-containing products such as marmalades, juices, drinkable yoghurts, and low-fat dairy products.
The obvious advantages of enzymes make them acceptable for meeting consumer demands. Due to their catalytic nature, they are ingredients requiring only a small space in the formulation of the overall product. This is of particular value at a time where detergent manufacturers are trying to make their products more compact.
Washing with laundry bars.
In many parts of the world, strongly colored and stubborn stains from blood, sebum, food soils, cocoa, and grass are removed with the help of laundry detergent bars.
Such stain removal and washing by hand are one of the more time-consuming and physically demanding domestic tasks which can be made easier with the use of enzymes. After decades of very little performance enhancement for laundry bars, a specially formulated protease that empowers the producer to create products that stand out from non-enzymatic laundry detergent bars is now available, offering effective and effortless washing.
With the protease product Easyzyme® in laundry bars, washing is shortened by at least one rinse and requires much less scrubbing. In addition to obtaining a superior result, laundry bars containing the enzyme may be formulated to be milder to the hands than old-type bars without enzymes.
Most of the energy spent during a household machine wash is used to heat the water. Thus, the most efficient way to save energy and thereby reduce carbon dioxide emissions is to lower washing temperatures.
The wide spectrum of enzymes that are available today, combined with a choice of appropriate other ingredients such as surfactants and bleaching systems specifically selected to work at low temperatures, has enabled manufacturers to produce cold water detergents.
Enzymes in dishwashing
Modern dishwashing detergents face increasing consumer demands for efficient cleaning of tableware. Enzymes are key ingredients for effectively removing difficult and dried-on soils from dishes and leaving glassware shiny. Enzymes clean well under mild conditions and thereby assist to reduce clouding of glassware.
In addition, enzymes also enable environmentally friendly detergents. Phosphates have been used in the past in dishwashing detergents to get dishes clean, but they harm the aquatic environment and are increasingly being banned in detergents around the world. The combination of modifying detergent compositions and using multi-enzyme solutions enables detergent manufacturers to replace phosphates without compromising the cleaning performance. For removal of protein soils, proteases are used; and amylases are used to remove starch soils.
Proteases for cleaning dishes and cutlery.
Some of the more difficult soils on dishes and cutlery are blends of egg yolk/milk, egg yolk, whole egg, and egg white as well as minced meat and oatmeal. The reason for this is the content of protease inhibitors in these foods. The protease Blaze Evity® by Novozymes has been specifically engineered to overcome high levels of protease inhibitors from eggs. These inhibitors effectively inactivate detergent proteases, resulting in reduced cleaning performance not just on the egg stain itself, but on all protein-containing soils in the same dishwasher load.
Amylases for cleaning starch-containing soils from dishes.
In automatic dishwashing, most of the soil is physically washed off by the water jets. However, foods usually leave behind thin films of starch-/protein-containing soils. If they are not removed, these films will build up over time. Larger lumps of burnt-on and caked-on soils may also remain. These soils are the main target for enzymes.
Enzymes target thin films of starch-/protein-containing soils that can build up over time.
The history of enzymes in detergents
The first enzyme-containing detergent was introduced to the household market as early as 1913. Röhm & Haas in Germany added trypsin extracted from pig pancreas to their detergent Burnus, utilizing a patent of Dr. Otto Röhm.
As the protease trypsin had insufficient activity and poor stability in detergents, the enzyme concept did not catch on until 1963 when Novo launched a more alkali- and builder-stable bacterial protease called Alcalase®. Small detergent producers in Switzerland and the Netherlands were pioneers in the commercial use of Alcalase, which was initially considered useful only for washing blood-stained laundry from hospitals and slaughterhouses.
For almost 20 years, bacterial proteases from different suppliers were the only class of enzymes of real commercial importance. Then the use of amylases, lipases, and cellulases as detergent ingredients started to take off during the 1980s and grew steadily in importance during the 1990s. Just after the turn of the century, two new enzyme classes entered the detergent market: mannanases and pectate lyases.
Current trends for enzymes within detergents
The application of enzymes in detergents makes up the largest single segment of the world market for industrial enzymes. In 2003, the potential market for detergent enzymes was approximately US$700 million, of which Novozymes had a share of more than 56%. Enzymes on average constitute about 3-5 % of the total raw material costs of detergents – but very different from region to region. By far the largest volume of detergent enzymes is used in “heavy-duty” laundry detergents for household use (powders, liquids, and also tablets). There is also some penetration into “light-duty”laundry products for the washing of delicate fabrics although some enzymes are too aggressive for wool and silk. The main task of enzymes in laundry detergents is to remove stains of animal or plant origin. Another important task is to prevent soils from spreading throughout the laundry by redeposition.
This benefit is often referred to as “general cleaning” or “whiteness maintenance.”Enzymes also provide care effects by acting directly on cotton surfaces, helping garments look new longer. Repeatedly worn and washed laundry items are often contaminated with invisible residues, especially if they have been washed with detergents containing few enzymes. The residues make textile fibers sticky, attracting soil from the wash water, which results in incomplete cleaning. Multi-enzyme systems efficiently prevent this buildup of soil deposits. Automatic dishwashing detergents for household use are another increasingly important market segment. The enzyme penetration is highest in Europe, followed by the United States, where the market is growing. In industrialized countries the leading detergent brands typically contain more than one class of enzymes. Food stains are complex substrates containing protein, starch, and fat all mixed together. By combining different enzymes, soils are removed more efficiently, utilizing synergies between each enzyme’s cleaning abilities.
Trends driving enzyme usage
The importance of enzymatic detergency is expected to continue to increase, based on the following trends:
- Reduction of washing temperatures (mainly Europe)
- More detergents without bleach (e.g., color detergents and liquid detergents)
- More compact detergent formulations
- More cost-effective enzymes
Thanks to modern genetic engineering technology, enzymes are becoming increasingly cost efficient and offer higher yields. There are also possibilities to commercialize “custom-made” enzymes with improved economy and application properties.
On the other hand, detergents in most developed markets are facing price erosion, and consequently manufacturers are increasing their efforts to reduce ingredient costs. Competition between leading brands and cut-price supermarket-owned private label detergents may therefore limit the scope for further development in enzyme usage.
To some extent enzymes compete with surfactants; and considerable efforts are made by, for example, Novozymes to demonstrate that reducing enzymes in favor of surfactants typically does not pay off for customers. There are still sizable potential markets in developing countries where the penetration of enzymes is low, but these markets will gradually expand in line with the rising level of economic development.
Other markets where enzymes have low penetration are detergents for professional laundries and automatic dishwashing in institutions and restaurants. Owing to very high requirements for speed and cleaning efficiency, these market segments use strong chemicals, which have low compatibility with enzymes. Enzymes are, however, still used in their original application the prewashing of blood-stained laundry from hospitals and slaughterhouses.
Key Challenges for enzymes used in detergents
One of the key challenges of enzymes is that they are more sensitive to environmental factors than conventional surfactants and detergents and tend to lose their effectiveness when exposed to high temperatures and harsh chemicals. Both the producer and customer must take into account storage stability requirements such as stability of enzyme activity, microbial stability, physical stability, and the formulation of the enzyme product itself.
All modern detergents face a long journey before they actually are used in the consumers’ washing machines. The most important steps are:
- Production. In production, it is crucial that the detergent has the optimal formulation to reach its destination with performance intact.
- Warehouse. Storage conditions can be tough on detergent formulations. The detergent may sit in a warehouse for a long time, and conditions such as temperature and humidity may lead to efficiency loss.
- Transportation. Transportation time and storage conditions vary greatly for all detergents. And as in the warehouse, transportation conditions can affect detergent efficiency.
- Retailer. All detergent producers would like their product to move quickly. The reality, however, is that detergents can sit on the shelf for a long time before purchase, again leading to less efficiency.
- Consumer. At the final stage, it is crucial that the consumer stores the detergent under optimal conditions and uses it in the right way, for example, correct dosing, appropriate washing temperature, and correct washing cycle. Altogether, modern detergents are complex and innovative products. Promotional pack sizes, transportation, and storage mean that it may take a long time before the detergent is actually used, and this fact challenges producers to deliver a detergent that performs consistently after its long journey to the consumers’ washing machines.
Novel stability enzymes technology
Late in 2013, Novozymes introduced a new range of highly robust and stable enzymes enabling detergent producers to deliver more consistent wash performance. Th e range of new enzyme technology also gives manufacturers even greater formulation flexibility, and it has the brand name Evity®. Evity® is the brand for new range of robust and stable enzymes for liquid and powder detergents.
Protease inhibitor in liquid detergents
For liquid detergents Evity® has a new improved boron-free protease inhibitor. The new inhibitor solution makes the protease fully active in the detergent while inhibiting the enzyme while being in the bottle. Improvements in liquid stability have significant advantages for detergent producers, as they pave the way for leveraging enzymes in detergents. The new inhibitor developed by Novozymes is far more efficient than existing boron-based stabilization systems enabling the inclusion of multiple enzymes in the detergent as well as greater formulation flexibilities with other detergent ingredients.
Tests conducted by Novozymes on different European Union (EU) mid-tier liquid laundry detergents, washing under conditions of 40°C, 75 g/14 L wash, 15°dH - water hardness and samples stored at 30°C, show superior wash performance on individual protease stains after storage. In total, the novel enzyme technology from Novozymes provides these improvements for liquid detergents:
- Increased protease wash performance after storage
- Increased multi-enzyme performance after storage
- Greater formulation flexibility with other detergent ingredients
- Completely boron-free liquid detergent formulations with great performance
New granulate enzyme technology
For powder detergents, Evity® builds on a new granulate enzyme technology to improve stability of the detergent – laundry as well as automatic dishwash detergents. Granulate enzyme technology simply means that the enzyme concentrate is processed into a granule. This is done to prolong their working life; such immobilized enzymes may go on working for over a year—and even longer. Coating of the enzyme granulate protects the enzyme further from deactivation by other ingredients in the detergents, such as surfactants.
Tests conducted by Novozymes on an EU front-loader under conditions of 40°C, 15°dH, detergent containing bleach, dosage of 65 - 110 g/14 L wash found that standard protease shows great residual wash performance after regular accelerated storage conditions, while protease with the new stabilizer is superior also after tough accelerated conditions. With the new enzyme stabilization capabilities marketed by Novozymes starting in late 2013, these improvements for granulated enzymes used in detergents have been provided for the industry:
- Wash performance also after storage at tough conditions
- Consistent wash performance, which promotes brand loyalty for the detergent producer
- Longer-lasting, enhanced wash performance via single or multiple enzymes
- Visible and better performance—which is key for consumers.