GIFSQ Tools · Module 2 — Food Chemistry & Physicochemical Testing · Tool 32 of 500
Correct a refractive index reading to 20 °C and read off the matching sucrose (Brix) value from the ICUMSA table.
Try sample values — fills the form with the worked example below.
–
Refractive index at 20 °C
–
Sucrose (°Brix)
–
Temperature correction
Equation: nD20 = nDT + k × (T − 20), where k = 0.00045 per °C. Brix is read from the ICUMSA sucrose table (nD20: 0 °Brix 1.3330, 10 °Brix 1.3478, 20 °Brix 1.3638, 30 °Brix 1.3812, 40 °Brix 1.3999, 50 °Brix 1.4201, 60 °Brix 1.4419) by straight-line interpolation between the two nearest table points.
Method: Refractometry, AOAC 932.12 / ISO 2173 — refractive index of a solution at the sodium D line, corrected to 20 °C, then converted to soluble solids by the ICUMSA sucrose table.
Assumptions: the temperature coefficient 0.00045 per °C applies to the sample (the usual value for sugar solutions near 20 °C); the sample behaves like a sucrose solution for the Brix reading.
Limitations: Brix is a sucrose equivalent, not a true sugar assay — other dissolved solids (salts, acids, alcohol) shift the reading; the table covers 0–60 °Brix only; interpolation between table points is an estimate, not a table value.
Rounding: refractive index to 4 decimal places, Brix to 2 decimal places, correction to 4 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Refractometry, AOAC 932.12 / ISO 2173 — refractive index of a solution at the sodium D line, corrected to 20 °C, then converted to soluble solids by the ICUMSA sucrose table.
Assumptions: the temperature coefficient 0.00045 per °C applies to the sample (the usual value for sugar solutions near 20 °C); the sample behaves like a sucrose solution for the Brix reading.
Limitations: Brix is a sucrose equivalent, not a true sugar assay — other dissolved solids (salts, acids, alcohol) shift the reading; the table covers 0–60 °Brix only; interpolation between table points is an estimate, not a table value.
Rounding: refractive index to 4 decimal places, Brix to 2 decimal places, correction to 4 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: A juice reads nD = 1.3630 at 25 °C. Correction = 0.00045 × (25 − 20) = 0.00225, so nD20 = 1.3653. Between 20 °Brix (1.3638) and 30 °Brix (1.3812), that gives 20.83 °Brix.
Enter values above to see results.
Typical nD20: water 1.3330, apple juice about 1.3478 (10 °Brix), honey about 1.4900 — outside this table, so honey needs its own table. Record the temperature with every reading. Tool 32 of 500 — GIFSQ
