Which of the following test is used for distinguishing among dry oils, semi-drying oils and non drying oils ?

ANS:A - Elaiden test

The Elaidin test, also known as the Elaidinization test, is a chemical test used to differentiate between unsaturated and saturated fats or oils based on their ability to undergo cis-trans isomerization when treated with a strong alkali like sodium hydroxide (NaOH) in the presence of hydrogen gas. Explanation:

1. Principle: The Elaidin test takes advantage of the ability of unsaturated fats and oils to undergo cis-trans isomerization in the presence of a strong alkali and hydrogen gas. During this process, the double bonds in the unsaturated fatty acids are converted from the cis configuration (common in natural unsaturated fats) to the trans configuration.
2. Procedure: In the Elaidin test, the sample of fat or oil is mixed with a solution of sodium hydroxide (NaOH) in the presence of hydrogen gas. The mixture is heated under reflux (where the vapors are condensed and returned to the reaction flask) for a certain period.
3. Observation: If the fat or oil sample contains cis double bonds (typical of natural unsaturated fats), the cis-double bonds will isomerize to trans double bonds during the reaction, resulting in the formation of a solid or semi-solid product. This solidification or increase in viscosity of the reaction mixture indicates a positive result for unsaturation.
4. Interpretation: A positive Elaidin test indicates the presence of cis double bonds in the original fat or oil sample, confirming its unsaturated nature. In contrast, saturated fats or oils, which lack double bonds, will not show any change in consistency or solidification during the test.
5. Applications: The Elaidin test is commonly used in the food industry to determine the degree of unsaturation in fats and oils, which affects their physical properties and suitability for various applications such as cooking, baking, and food processing. It is also used in lipid chemistry research to characterize and analyze fatty acid compositions.