SOP: Determination of Sugar-Acid Ratio

GIFSQ — Global Institute for Food Safety & Quality

Principle

The sugar-acid ratio is an important criterion of quality from the standpoint of taste appeal, especially in juices. It is the ratio of the sugar value, determined with a refractometer, to the grams of acid content determined by titration.

Apparatus required

• Refractometer
• Titration assembly for total acidity

Procedure

Determine the sugar value of the product with a refractometer

↓

Determine the total acid content of the product by titration, in grams of acid

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Calculate the ratio of the sugar value to the grams of acid

Calculation

Sugar-acid ratio = (sugar value by refractometer) : (grams of acid by titration)

Where,

• For quality control purposes, the ratio is placed at 40:1 for apple products and 10:1 for orange juices.

Precautions

• Determine sugar and acidity on the same representative sample.

References

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