SOP: Piperine in Pepper Oleoresin

GIFSQ — Global Institute for Food Safety & Quality

Principle

Piperine is determined either by finding the total nitrogen by the Kjeldahl procedure and converting it to piperine, or spectrophotometrically by measuring the absorbance of the oleoresin solution at 341–342 nm against a calibration curve prepared from purified piperine.

Apparatus required

• Kjeldahl digestion and distillation apparatus
• Spectrophotometer with 1 cm silica cells

Reagents

a. Paraffin (a small amount, to reduce frothing during digestion, if necessary).

b. Standard piperine solution: purify piperine (m.p. 129–130 °C) by repeated crystallizations using isopropanol; prepare standards containing 0 to 1 mg of piperine per 100 ml in ethylene dichloride.

c. Ethylene dichloride.

Procedure

By determining nitrogen:

Determine the nitrogen content using 1 g of sample by the Kjeldahl digestion and distillation procedure given in Chapter 1; if necessary, add a small amount of paraffin to reduce frothing

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Calculate the total nitrogen content as given in the procedure — to calculate the piperine content, substitute 28.51 in place of 14 in the formula

Spectrophotometric procedure:

Measure the absorbance of the piperine standard solutions at 341 to 342 nm in a spectrophotometer using 1 cm silica cells, and plot absorbance vs. concentration to obtain the calibration curve

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Take 25 g of the oleoresin, heat to 100 °C with stirring on a boiling water bath or oven, but not on a hot plate

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Weigh 100 mg of the oleoresin, dilute to 100 ml with ethylene dichloride, and dissolve

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Take a 1 ml aliquot of this solution and dilute to 100 ml with ethylene dichloride

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Measure the absorbance immediately using a 1 cm cell at 341–342 nm

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From the calibration curve, note the piperine concentration

Calculation

% Piperine = (Piperine concentration from graph (mg/100 ml) × 100) / Weight of sample (mg/100 ml)

Where,

• Piperine concentration from graph (mg/100 ml) = piperine read from the calibration curve in the measured solution
• Weight of sample (mg/100 ml) = weight of the oleoresin present per 100 ml of the measured solution (1 mg/100 ml with the dilutions given)

References

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