1. IB2.17.3 Enzymes and detergents © Oxford University Press 2011 Enzymes and detergents

2. IB2.17.3 Enzymes and detergents © Oxford University Press 2011 The enzymes  Biological washing powders contain detergent and have enzymes added to them.  The enzymes break down stains on clothes.  These stains contain fats (such as grease or sweat) and protein (such as egg yolk or blood).  The enzymes added to washing powders are proteases and lipases.  Washing powders are highly alkaline, so the enzymes added to them must work well at solutions with a high pH.  The enzymes must also work at a range of temperatures between 10°C and 90°C.

3. IB2.17.3 Enzymes and detergents © Oxford University Press 2011 Low-temperature enzymes  Some enzymes added to washing powders are denatured at high temperatures: they work well at low temperatures.  These washing powders are designed to be used at temperatures up to 40 °C. They remove stains better than other types of detergents at this lower temperature.

4. IB2.17.3 Enzymes and detergents © Oxford University Press 2011 The process  The enzymes added to washing powders break down the large protein and fat molecules into smaller molecules which dissolve into the water and can be washed away during the wash cycle.  Protease enzymes break down proteins; lipase enzymes break down fats.  The enzymes are contained within the granules of washing powder and are released once the powder becomes wet.