SOP: Determination of Curcumin in Turmeric (Spices)

GIFSQ — Global Institute for Food Safety & Quality

1. Principle

Curcumin is extracted by refluxing the sample with the alcohol for about 3 hours. After dilution, concentration of curcumin is measured by spectrophotometer at 425 nm against the alcohol blank.

2. Application

This method is applicable to determine curcumin in spices.

3. Apparatus

1. Flask, extraction, flat bottom, 100 mL
2. Condenser
3. Volumetric flask, 100 mL and 25 mL
4. Spectrophotometer capable of accurately measuring absorbance at 425 nm

4. Reagents

Ethyl alcohol 95%.

Standard curcumin solution — weigh 25 mg of standard curcumin into a 100 mL volumetric flask. Dissolve and dilute to mark with the alcohol. Transfer 1 mL of the solution to a 100 mL volumetric flask and dilute to mark with alcohol. This standard solution contains 0.0025 g/L.

5. Procedure

Take 0.1 g sample with 30 mL alcohol

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Reflux for 2.5 hours and cool

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Filter and wash thoroughly with alcohol into a 100 mL volumetric flask

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Pipette 2 mL of the extract into a 25 mL volumetric flask

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Dilute up to mark with the alcohol

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Measure the absorbance of the extract and the standard solution at 425 nm in 1 cm cells against an alcohol blank

6. Calculation

Absorptivity of curcumin, a = Absorbance of standard solution at 425 nm ÷ [Cell length (cm) × concentration (g/L)]

% curcumin in turmeric = [Absorbance of extract at 425 nm × 125] ÷ [Cell length (cm) × a × sample wt (g) × 140]

7. Precautions

• After refluxing, wall of extraction flask should be washed thoroughly with alcohol.
• Cuvette should be well rinsed with sample solution whose absorbance is to be measured.
• Outer walls of cuvette should be cleaned by tissue paper before inserting into the spectrophotometer.

8. Limit of Detection

By this method, solution having absorbance about 1 can be estimated more accurately. In case of more intensely colored solution, determination should be done by dilution. In general, amount of curcumin in any natural variety of turmeric can be determined by the above mentioned procedure.

References

FSSAI (2016), Manual of method of analysis of foods — spices and condiments; Method no 16.4.