SOP: Nonvolatile Ether Extract in Spices — Alternate Soxhlet Method

GIFSQ — Global Institute for Food Safety & Quality

Principle

The spice is extracted with diethyl ether in a Soxhlet apparatus; after drying the total residue, the portion still soluble in cold ether is removed by decantation, so that the nonvolatile ether extract is found from the difference between the total residue and the ether-insoluble residue left behind.

Apparatus required

• Soxhlet extraction apparatus
• Water bath
• Hot air oven (110 ± 1 °C)

Reagents

a. Diethyl ether.

Procedure

Note the tare weight of the receiver flask of the Soxhlet extraction apparatus, A

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Extract 2 g of the ground material with diethyl ether in a Soxhlet extraction apparatus for 18 hr

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Remove the ether by distillation and the last traces by blowing air into the flask on a water bath

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Dry in a hot air oven at 110 ± 1 °C until the loss in weight between two successive weighings is less than 2 mg; note this weight, B

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Shake the residue with 2 or 3 ml of ether at room temperature, allow to settle, and decant the ether; repeat the extraction until no more of the residue dissolves

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Dry the flask again until the loss in weight between two successive weighings is less than 2 mg; note the lowest weight, C

Calculation

Weight of total residue = B − A = W₁

Weight of ether-insoluble residue after decantation = C − A = W₂

Weight of sample taken for extraction = W

% Nonvolatile ether extract = ((W₁ − W₂) × 100) / W

Where,

• A = tare weight of the receiver flask
• B = weight of flask plus dried residue after extraction
• C = weight of flask plus ether-insoluble residue after decantation
• W₁ = weight of the total residue
• W₂ = weight of the ether-insoluble residue left after decantation with ether
• W = weight of the sample taken for extraction

References

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