Allyl Iso Thiocyanate Lab Report

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4.1) Pungency Test
Aim: Determination of allyl iso-thiocyanate (PUNGENCY TEST)
Theory: The oil obtained from black mustard seeds contains sinigrin and myrosin which, after maceration with water yields a volatile oil, the major constituent of which is allyl iso-thiocyanate. The oil obtained from white mustard seeds contains acrinyl iso-thiocyanate which is much less volatile than allyl iso-thiocyanate. The presence of ally iso-thiocyanate is responsible for the pungent nature of mustard oil. Generally customers associate this pungency of the mustard oil with the quality of oil.
Method: The allyl iso-thiocyanate in the oil is steam distilled into a known excess of silver nitrate solution, and the excess of silver nitrate solution is determined
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Theory: The acid value can be defined as the number of milligrams of potassium hydroxide required to neutralize the free fatty acids present in one gram of fat. It tells about the measure of rancidity as free fatty acids are normally formed by the decomposition of oil glycerides. The acid value is expressed as percent of oleic acid, lauric or palmitic acid.
The determination of acid value is based on the principle of directly titrating the oil in an alcoholic medium against potassium hydroxide or sodium hydroxide solution.
Analytical importance:
The value is the relative measure of the amount of fatty acids that have been liberated due to the hydrolysis of the glycerides as a result of action of moisture, temperature and/or lypolytic enzyme lipase.
• 250ml conical flask
• Ethyl alcohol: 95% alcohol or rectified spirit neutral to phenolphthalein indicator.
• Phenolphthalein indicator solution.
• Standard aqueous potassium hydroxide or sodium hydroxide solution 0.1N or 0.5N. The solution should be stored in a brown glass bottle and colorless. Procedure:
1. Mix the mustard oil thoroughly before weighing.
2. Weigh approximately about 5 to 10 g of oil sample in a 250 ml conical
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Add 50 to 100 ml of freshly neutralized hot ethyl alcohol and about one ml of phenolphthalein indicator solution.
4. Boil the mixture for about five minutes and titrate it against the standard alkali solution while shaking vigorously during the

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