Q. Determine the acid value and free fatty acids?

This activity will help you to:

• know the acidity in given sample of fat/oil, and

• determine the free fatty acid composition in the sample provided for analysis.

Principle

The acid value is determined by directly titrating the material in an alcoholic medium with aqueous sodium or potassium hydroxide solution. Free fatty acid is calculated as oleic, lauric, ricinoleic or palmitic acids (refer to section 4.2 of this practical). The materials required and the procedure for the determination of acid value and free fatty acid is given herewith.

A) For Acid Value

Materials Required

Sample of oil/fats namely any refined oil or hydrogenated fat. Reagents - ethyl alcohol (95%), phenolphthalein indicator solution, standard aqueous sodium or potassium hydroxide solution (0.1 N or 0.5 N)

Pipette (10 ml)

Conical flask

Procedure

Carry out the experiment following the procedure given herewith:

1) Mix the oil or melted fat thoroughly before weighing.

2) Weigh accurately a suitable quantity of the cooled oil/fat in a 200 ml conical flask.

3) Add 50-100 ml of the freshly neutralized hot ethyl alcohol (i.e ethyl alcohol with pH 7).

4) Boil the mixture for about 5 minutes and titrate while as hot as possible with the standard aqueous alkali solution shaking the solution vigorously during titration. Continue the titration till the solution turns pink, which is the end point.