• Type of soil to be removed
• Cleaning method required
• Cleaning equipment available
• Will disinfection be required
• Time window
• Water hardness
• Chemical concentration required
• Water temperature
• Materials of construction
• Operator safety
• Risk to food safety
• Cost

Detergent types:

•  Alkaline and Caustic detergents
  

Alkaline and Caustic detergents are probably the most common detergents used throughout the food industry as they have good fat and protein removal properties and they can be used across a wide spectrum of food manufacturing environments. Both contain sodium hydroxide boosted with surfactants and sequestrants. Caustic detergents contain higher levels of Sodium Hydroxide and generally have higher risk classifications than alkaline detergents. They are corrosive to skin and should always be used in conjunction with the correct Personal Protective Equipment. They may also attack soft metals such as aluminium, tin, brass etc.

•  Acid detergents

These are used mainly for protein, mineral and vegetable deposit removal and typically contain phosphoric acid.  Acids must never be allowed to come into contact with chlorine compounds because of the consequential release of chlorine gas, which can prove to be fatal.

•  Neutral Detergents
  

These are generally blends of surfactants used for manual dishwashing and manual cleaning.  They are generally safe to use and are found predominantly in domestic and light industrial use.  Gloves should still be worn to avoid de-fatting of the skin and to reduce the risk of dermatitis.

Types of Soil

• Organic – These are derived from living matter and include animal fat, vegetable oils, starch, sugars, and proteins from milk, egg, meat or blood.  Normally they can be removed by using neutral or alkaline detergents, but if heated, dried or allowed to remain for a prolonged period then caustic detergents may be required to remove them.
  

When removing liquid protein deposits such as egg, blood or meat it is best practice to begin with a cold water rinse first to prevent “cooking” of the protein. When grease or oil is heated it will form a resolute, dark, sticky polymerised deposit, which can generally be removed with an alkaline detergent.  If the polymerised deposit is heated further it results in the formation of carbon, which generally has to be removed by a more aggressive caustic alkali detergent such as sodium hydroxide.

•  Inorganic – These include water hardness salts (scale), oxidised metals (rust), uric acid salts (urinal stains), beerstone and calcium salts deposited from milk (milkstone).  These types of soils are usually removed with acids such as hydrochloric and phosphoric.
  

Soils are very rarely made up of one component, for example a hard scale in a meat processing area may be a complex of a mineral scale and protein.