REVIEW The Role of Enzymes in Modern Detergency Hans Sejr Olsen* and Per Falholt Enzyme Development & Application, Enzyme Business, Novo Nordisk A/S, DK-2880 Bagsvaerd, Denmark ABSTRACT: Enzymes have effectively assisted the develop- lulases, the foundations were already laid in 1913 for the ment and improvement of modern household and industrial de- commercial use of enzymes that continues to be important tergents. The major classes of detergent enzymes—proteases, li- today. pases, amylases, and cellulases—each provide specific benefits Today the most widely used industrial enzymes are hy- for application in laundry and automatic dishwashing. Histori- drolases, which remove soils based on proteins, lipids, and cally, proteases were first to be used extensively in laundry de- polysaccharides. Cellulolytic enzymes are another class of tergents. In addition to raising the level of cleaning, they have hydrolases that provide fabric care through selective reac- also provided environmental benefits by reducing energy con- sumption through shorter washing times, lower washing tem- tions not previously possible on fabrics. Research is cur- peratures, and reduced water consumption. Today proteases are rently underway into the possibility of using redox en- joined by lipases and amylases in improving detergent efficacy zymes—oxidases or peroxidases—for bleaching colored especially for household laundering at lower temperatures and, components (2). in industrial cleaning operations, at lower pH levels. Cellulases To support the 18–19-million -ton global annual market contribute to overall fabric care by rejuvenating or maintaining for laundry and dishwashing detergents (3), the world- the new appearance of washed garments. Enzymes are pro- wide consumption of detergent enzymes amounted to duced by fermentation technologies that utilize renewable re- ca. U.S. $500 million in 1995 (4). The principal producers sources. of enzymes are Novo Nordisk A/S (headquartered in JSD 1, 555–567 (1998). Bagsvaerd, Denmark) and Genencor International Inc. (headquartered in Rochester, NY), serving the market with KEY WORDS: Amylases, automatic dishwashing, cellulases, enzymes in detergents, industrial cleaning, laundry, lipases, more than 90% of the total volume of detergent enzyme proteases, storage stability, wash performance. products. THE ROLES PLAYED BY ENZYMES IN DETERGENTS The field of enzymology is an important branch of bio- process technology. Developments in submerged fermen- Over the years, enzymes have been an important factor in tation processes and genetic engineering have resulted in the development and improvement of detergent products. great progress in the manufacture of industrial enzymes. In laundering, dishwashing, and in industrial and institu- Enzymes find use as functional ingredients in deter- tional (I&I) cleaning, they have contributed to shortening gents and contribute to cleaning of laundry and dishes in washing times, reducing energy and water consumption an efficient, environmentally mild, and energy-saving by lowering washing temperatures, providing environ- manner. This largest of all industrial enzyme applications mentally friendlier wash-water effluents, lowering pH lev- began slowly in the early 1930s, based on Röhm’s 1913 els in wash liquors, and providing fabric care. Enzymes patent of the use of pancreatic enzymes in presoak solu- themselves are environmentally attractive since they are tions (1). Pancreatic enzymes include protease (trypsin and derived from renewable sources. They are also highly chymotrypsin), carboxypeptidase, α-amylase, lactase, su- space-efficient and are thus of particular advantage in con- crase, maltase, and lipase. Thus, with the exception of cel- centrated detergent formulations. Developments in genetic and protein engineering have contributed to long-needed *To whom correspondence should be addressed at Enzyme Develop- ment & Application, Enzyme Business, Novo Nordisk A/S, Novo improvements in the stability, economy, specificity, and Allé, DK-2880 Bagsvaerd, Denmark. E-mail: [email protected] overall potential of industrial enzyme products. Copyright © 1998 by AOCS Press Journal of Surfactants and Detergents, Vol. 1, No. 4 (October 1998) 555 556 REVIEW TABLE 1 Consumption During the Washing of Fabrics (European data) (Refs. 5–9) Consumption/kg 1943–44 1965 1975 1985 1990–95 dry fabric (manual) (machine) (machine) (machine) (machine) Chemicals (g) Conventional 109 ca. 50 ca. 50 38–48 32 Compact 0 0 0 0 16–21 Water (L) 31 37 31 21 10–12 Energy for heating (kWh) 1.45 0.6 0.4 0.25 0.2 (to heat water) Energy for motors and pumps (kWh) 0 0.4 0.2 0.15 0.1 Detergent mechanism based on enzymes. From an enzyme zymes were introduced by Lion Corp. in 1979, and in the point of view, detergents on the international market con- United States the resurrection of enzymes began in the tain principal ingredients that operate by almost identical 1980s after health problems with factory workers had ar- detergency mechanisms. Soil and stains are removed by rested the initial introduction in 1971 (3). mechanical action assisted by surfactants, builders, and en- Throughout the period covered in Table 1, the develop- zymes. Alkaline proteases, amylases, or lipases in heavy- ment of new ingredient combinations (builders and bleach duty detergents hydrolyze and solubilize substrate soil at- systems) and machines was optimized in conjunction with tached to fabrics or hard surfaces (e.g., dishes). Cellulases the improved cleaning properties offered by enzyme sys- clean by hydrolysis of glycosidic bonds which removes tems. At the same time, the development of new enzyme particulate soils attached to cotton microfibers. Key effects systems was influenced by the new compositions of deter- of cellulases are to soften and improve the color brightness gent mixes. of worn textile surfaces. Surfactants lower the surface ten- A comparison of calculated cost distributions for sion at interfaces and enhance the repulsive force between washes from 1943 (5) and 1997 (10) reflects many dramatic the original soil, enzymatically degraded soil, and the fab- changes in society and also indicates the benefits of new ric. Builders act to chelate, precipitate or ion-exchange cal- developments. Table 2 shows the annual cost of washing cium and magnesium salts, to provide alkalinity, to pre- on a family basis for the 2 yr. Interestingly, the proportion vent soil redeposition, to provide buffering capacity, and of the costs attributable to the detergents has not changed. to inhibit corrosion. The energy part of the washing costs has been reduced sig- Laundry. Over the past 35 yr the role of enzymes in de- nificantly, but the costs for water have increased consider- tergents has changed from one of a minor additive to be- ably due to the increasing shortage of clean water and coming a key ingredient. The largest application in which heavy taxation of environmental resources. the use of enzymes has grown is household laundry. Table 2 explains, to some degree, the developments seen Before the introduction of modern detergent formula- in laundry technology over the years from 1943 to 1997. tions, soap and sodium carbonate were the principal deter- New detergent compositions and enzymes made possible gent constituents, and the cleaning effect in laundering was a lowering of washing temperatures and hence of energy dependent mainly on mechanical action. Table 1 shows a consumption. Thus it is easy to understand the current comparison of the consumption of chemicals, water, and trend of washing machine design heading in the direction energy over the last 50 yr. The advent of washing machines of reducing water consumption. brought a considerable reduction in the consumption of Dishwashing. Automatic dishwashing machines have chemicals over that in manual washing. In the period of been in use for almost as long as washing machines but not 1967–1970 (5), a reduction in energy consumption of about as widely. Today, automatic dishwashers are found in 40% was brought about by the successful introduction of 50–60% of households in the United States, West Germany, enzymatic detergents. In 1969, at least 50% of European de- tergents were offering “biological attack” (proteolytic en- zymes), which resulted in the energy-savings shown (3). TABLE 2 The move away from 95°C washes to 60°C washes, and Yearly Costs (DKK—Danish crowns) and Cost Distribution later to 40°C washes became more common. Furthermore, for Washing in a Danish Model Family prewashes and overnight soaking could be eliminated. The 1943 (Ref. 5) 1997 (Ref. 10) additional energy reduction resulted from a combination of Component DKK % distribution DKK % distribution more diverse enzyme ingredients (cellulases, amylases, and Electricity 14.5 12 368 27 lipases), more mechanically efficient washing machines (jet- Fuel 47 39 spray and cascade systems), better-managed machine elec- Water 9.7 8 415 31 tronics, and compact detergents. In Japan, proteolytic en- Detergents 48.8 41 565 42 Journal of Surfactants and Detergents, Vol. 1, No. 4 (October 1998) REVIEW 557 Norway, Sweden, and Denmark, and in ca. 30% of the from 2.8 to 1.5 kWh (13). Chlorine or hypochlorite-releas- households in France and Italy, while in other European ing bleach compounds (e.g., chloroisocyanurates) have countries like The Netherlands and Spain distribution is been deemed essential to remove certain stains, e.g., tea less than 20% (4,11). In Japan, automatic dishwashers are stains in cups. found in fewer than 5% of domestic households