Soap noodles are sodium salt of fatty acids. Soap noodles are generated from vegetable oil or animal fats that are used as the primary ingredient in soap bars. Saponification of neutral fats and oils, neutralisation of fatty acids, and saponification of methyl esters are all used to make it.
Saponification is the process of making soap from alkali and fat (or oil). Vegetable oils and animal fats are fatty esters in the form of triglycerides. The alkali breaks the ester bond and releases the fatty acid salt and glycerol. If necessary, soaps may be precipitated by salting out with saturated sodium chloride. Usually, sodium hydroxide is used in formation of hard soap while potassium hydroxide is used in case of soft soap.