There are three methods to determine the acidity of animal and vegetable oils: hot ethanol method, cold solvent method and potentiometric titration, in which the hot ethanol method is the reference standard method and the cold solvent method is only suitable for light-colored oils. Potentiometric titration uses a pH meter to determine the titration end point, and then calculates the acid value of oil according to the amount of potassium hydroxide needed for titration.
acid value
It is a sign of free fatty acid content in fat. During long-term storage, fat is slowly hydrolyzed by microorganisms, enzymes and heat to produce free fatty acids. The quality of fat is related to the content of free fatty acids. Generally speaking, acid value is one of the commonly used measures. Under the condition of fat production, acid value can be used as an index of hydrolysis degree, and under its preservation condition, it can be used as an index of rancidity. The smaller the acid value, the better the oil quality, the better the freshness and refining degree.
Refer to the above content: Baidu Encyclopedia-Acid Price