GIFSQ Tools · Module 2 — Food Chemistry & Physicochemical Testing · Tool 24 of 500
Divide soluble solids (°Brix) by titratable acidity (%) to get the sugar-acid ratio — the maturity index used for citrus and other fruit.
Try sample values — fills the form with the worked example below.
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Sugar-acid ratio (:1)
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Soluble solids (°Bx)
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Titratable acidity (%)
Equation: Sugar-acid ratio = soluble solids (°Brix) ÷ titratable acidity (%).
Method: Brix by refractometer (AOAC 932.12) and acidity by titration (AOAC 942.15) on the same sample; the ratio is the maturity index used in citrus grading. The common minimum for oranges is 10:1 — variety and market minima differ, so check the grade standard for your fruit.
Assumptions: Brix and acidity were measured on the same sample at the same stage of ripeness; acidity is reported as the fruit's main acid.
Limitations: the ratio alone does not prove flavour or eating quality — aroma, colour and texture are not in the number. A high ratio can come from low acid as well as from high sugar.
Rounding: ratio to 2 decimal places; inputs to 2 decimal places.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Brix by refractometer (AOAC 932.12) and acidity by titration (AOAC 942.15) on the same sample; the ratio is the maturity index used in citrus grading. The common minimum for oranges is 10:1 — variety and market minima differ, so check the grade standard for your fruit.
Assumptions: Brix and acidity were measured on the same sample at the same stage of ripeness; acidity is reported as the fruit's main acid.
Limitations: the ratio alone does not prove flavour or eating quality — aroma, colour and texture are not in the number. A high ratio can come from low acid as well as from high sugar.
Rounding: ratio to 2 decimal places; inputs to 2 decimal places.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: An orange juice sample measures 12.0 °Brix and 0.80 % titratable acidity as citric acid. Sugar-acid ratio = 12.0 ÷ 0.80 = 15.00:1, above the common 10:1 maturity minimum for oranges.
Enter values above to see results.
Typical ratios at harvest: oranges 12–20:1, grapefruit 7–10:1, lemons 1–2:1, apples 15–25:1, grapes 25–35:1. Use Tool 22 for the acidity and Tool 23 for the Brix correction first. Tool 24 of 500 — GIFSQ
