SOP: Determination of Oil Content in Oil and Sweet Pickles

GIFSQ — Global Institute for Food Safety & Quality

Principle

The oil is separated from the dried pickle sample by solvent extraction. In the routine procedure the sample is dried and the oil extracted in a Soxhlet apparatus with petroleum ether; the more accurate procedure extracts with a chloroform–methanol mixture, and the oil so obtained can be used for further characterization and analysis.

Apparatus required

• Hot air oven
• Soxhlet extraction apparatus

Reagents

a. Petroleum ether, 40–60° C.

b. Chloroform–methanol mixture (for the more accurate procedure).

Procedure

Dry a known weight of the composite sample in a hot air oven by the procedure described for the determination of moisture

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Extract the oil from the dried sample in a Soxhlet extraction apparatus using petroleum ether of 40–60° C

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For the more accurate determination, extract the sample using the chloroform–methanol extraction procedure

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Use the oil extracted by the chloroform–methanol procedure for further characterization and analysis

Precautions

• Dry the sample fully before extraction so that moisture does not interfere with the Soxhlet extraction.
• Recover and measure the oil quantitatively; losses during transfer lower the result.

References

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