Saponification of Fats
Saponification is the reaction between a fat or oil and a strong base in water that produces soap (fatty acid salts) and glycerol.
Animal and vegetable fats are mostly triglycerides: three fatty acids bonded to glycerol by ester bonds. A strong base, such as sodium or potassium hydroxide, breaks those bonds (alkaline hydrolysis). The fatty acids end up as soaps, which are water-soluble and have surfactant properties, and the glycerol is released. That is why alkaline detergents and degreasers are effective against kitchen grease and fats of animal origin: they turn part of the soil into products that water carries away with rinsing. The reaction proceeds faster at high temperature and alkalinity. The saponification value expresses the milligrams of KOH needed to saponify one gram of fat.
Not all fats saponify. Mineral oils and hydrocarbons have no ester bonds, so alkalinity does not transform them: they are removed by emulsification with surfactants or with solvents. In addition, strong alkalinity attacks metals such as aluminium, so the technical data sheet must be checked to see which materials each product can be used on.
Alkaline Instaquim products indicated for grease, according to their technical data sheets:
- Prein (pH 1 %: 11.8; 10–20 g/kg of dry laundry): pre-wash detergent with alkalis and sequestrants; the data sheet attributes to it «great wetting, saponifying and sequestering power» and recommends it for heavily soiled laundry.
- Deplac (pH 1 %: 12.5; neat or diluted up to 10 %): cleaning of kitchen griddles and ovens with burnt-on grease; not suitable for aluminium.
- Gras Foam (pH 1 %: 12.2; 2–6 % at 20–60 °C): degreaser for heavily greased floors, walls and surfaces in the food industry, applied with foam, spraying, immersion or by hand; not suitable for aluminium.