SOP: Estimation of Approximate Fruit Content of Fruit-Sugar Mixtures

GIFSQ — Global Institute for Food Safety & Quality

Principle

In a mixture of fruit and dry sugar, the fruit content is calculated from the soluble solids of the mixture and the known soluble solids content of the fruit used: the added dry sugar is taken as 100% solids, and the fruit fraction is obtained by difference.

Apparatus required

• High speed blender
• Refractometer (Abbe type)

Sample preparation

Allow the sample to thaw and attain room temperature in the original package.

Procedure

Mix the sample thoroughly in a high speed blender and filter

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Determine the soluble solids (as sucrose) using the refractometer, as in the total soluble solids determination

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Correct the reading to 20°C

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Calculate the approximate fruit content using the expression in the Calculation section

Calculation

Fruit content, % = [(100 − Soluble solids in fruit-sugar mixture) / (100 − Soluble solids content of fruit used)] × 100

• Where,
• Soluble solids in fruit-sugar mixture = refractometer reading of the mixture, corrected to 20°C, % w/w as sucrose
• Soluble solids content of fruit used = soluble solids of the fruit before sugar addition, % w/w as sucrose

Note: the printed layout of this formula is garbled in the available copy (the second “100” term reads as “te 70”); the expression above is read from the printed variables and from the arithmetic of a fruit–dry-sugar mixture, flagged for checking against the printed book.

Precautions

• This formula does not hold good in the case of fruits packed in sugar syrup and frozen.

References

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