Saponification value determination method is the process by which the fatty acids in the glycerides of the oil are hydrolyzed by an alkali. Saponification value unit is the amount (mg) of alkali required to saponify a definite quantity (1g) of an oil or fat.
Saponification value unit is useful for a comparative study of the fatty acid chain length in oils. Saponification value unit is important to the industrial user for saponification value unit helps to know the amount of free fatty acid that is present in a food material.
Principle of Saponification Value
The saponification value is the number of milligrams of potassium hydroxide necessary to neutralise the free fatty acids and to saponify the esters present in 1g of the substance. Saponification value determination is an index of mean molecular weight of the fatty acids of the glycerides.
Lower saponification value indicates higher molecular weight of fatty acids and vice-versa. The oil sample is saponified by refluxing with a known excess of ethanolic KOH. The alkali required for saponification value determination by titration of the excess potassium hydroxide with standard hydrochloric acid.
Saponification Value Requirements
1. Oil or Fat
2. Conical Flask
4. Water bath
1. Hydrochloric acid 0.5N,
2. Alcoholic KOH
3. Phenolphthalein Indicator
Saponification Value Procedure
1. If the sample isn’t already liquid, melt it and sift it through paper to remove any remaining contaminants and moisture. The sample must be totally devoid of moisture.
2. Fill the flask with a 4-5g sample. Allow 50mL of alcoholic KOH to drain from the burette for a specific amount of time.
3. Prepare a blank by pouring 50mL of alcoholic KOH into a separate container and leaving it to drain for the same amount of time. Connect the air condenser to the flasks and gently boil them for 1 hour.
4. Rinse the inside of the condenser with distilled H2O when the flask and condenser have cooled, and then remove the condenser. Titrate against 0.5N HCl with roughly 1mL of indicator until the pink hue fades completely.