Look at any dish detergent, and it'll probably boast its ability to "cut through grease." To dispose of grease and oil, detergents use surfactants—chemicals that make oil and water miscible, so they can be rinsed out. But surfactants are at best half the story in modern washing machine and dishwasher detergents, and definitely the less interesting half at that. To break down organic stains, most modern detergents recruit nature’s nano-machines to help: enzymes.
An “enzyme” is a protein that works as a catalyst, helping to facilitate biochemical reactions. Enzymes are made up of at least one amino acid chain, which can be as short as three amino acids to over 34,000 amino acids long. These chains then fold in 3 dimensional space based on complex interactions between the amino acids that make up the chain. Some repel each other, some attract each other, and others bond for life. Once properly folded into a unique shape, an enzyme can accomodate corresponding molecules like a lock and key. When in place, the enzyme usually precipitates a chemical reaction, which can be anything from breaking down milk sugars or getting the alcohol out of your system. If you're come across anything that ends in "ase," you're probably reading about an enzyme.
In the context of detergents, the most relevant class of enzymes are the digestive enzymes, which help us and other organisms break down our food. Eventually, all organic matter degrades into its components due to entropy, but not everyone has time for that. Think about those fries you had for lunch. It takes a very long time for a fried piece of potato to fully disintegrate without outside influences, and even with stomach acid, those spuds would hang around for days.
Anyone who has worked at a fast food restaurant will attest to the fact that fries last way longer outside of a stomach, than inside of one. In order to speed up the digestion process, our stomachs secrete digestive enzymes that assist with the breakdown on the microscopic level. To accomplish this daunting task, these enzymes "unlock" bonds in the molecules to whittle down food. By the time the enzyme is done, all that remains are small organic molecules, like sugars, amino acids and nucleotides, which can then be transported into cells to be made into energy, other proteins, and more essentials.
Enzymes in Detergents
Since the food on our plates is identical to the food in our stomachs—unless you're three and your plate is littered with crusts—appliances don't need to reinvent the wheel. Detergent manufacturers have been taking advantage of digestive enzymes for almost a century, adding proteases, amylases, and lipases to help remove protein, carbohydrate, and oil-based stains, turning dishwashers and washing machines into stomach stand-ins. It wasn't easy to alter the stomach's proteins that operate in the highly acidic stomach at body temperature to work in the alkaline, cold water conditions in washing machines. But today these detergents are better than ever at removing stains using these tactics, doing so with minimal use of caustic or toxic chemicals, which is good for your health, clothes, dishes, and the environment.
To digestive enzymes, the tomato sauce on your favorite shirt is simply a collection of proteins, fats and carbohydrates, which can be chewed up into their most basic components. Once the enzymes are done breaking down the stain, the leftover components are easily dissolved in water or removed by mechanical force—all that is left is the fabric on which it was deposited.
Better Living Through Biochemistry
Protein science has come a long way since the early 20th century when enzymes were first introduced into detergents, but we are still a few decades away from making designer proteins to do our bidding. In the meantime, we are borrowing already existing enzymes and altering them slightly to maximize their performance in their new settings like the inside of a washing machine. Next time you do laundry or the dishes, just picture the billion tiny enzymes eating away the stains and realize just how cool of a process is going on right there behind closed hatches.
Contributing Author: Ethan Wolff-Mann