SOP: Holde Test for Mineral Oil in Edible Oils

GIFSQ — Global Institute for Food Safety & Quality

Principle

Mineral oil is not saponifiable. When the oil is saponified with alcoholic KOH and diluted with hot water, any mineral oil present produces a distinct turbidity. The method is sensitive when the mineral oil content is 0.5% or more. For quantitative estimation, the method for the determination of unsaponifiable matter is followed.

Apparatus required

• Conical flask
• Reflux assembly

Reagents

a. 0.5 N alcoholic KOH solution.

b. Hot distilled water.

Procedure

To 1.0 ml of oil or melted fat in a conical flask, add 25 ml of 0.5 N alcoholic KOH solution

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Boil under reflux for about 5 min, or until saponification is complete

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Add 25 ml of hot distilled water

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In the presence of mineral oil, distinct turbidity appears

Calculation

For quantitative estimation, follow the method for the determination of unsaponifiable matter (SOP on unsaponifiable matter in oils and fats).

References

Ranganna, S., Handbook of Analysis and Quality Control for Fruit and Vegetable Products, 2nd edition.