Practical 6: Sugar Content and °Brix

What is the Dubois method for sugar analysis?

A phenol-sulphuric acid method detects all sugars via colorimetry. It involves treating a sugar solution with phenol and sulfuric acid, which produces a colored complex that can be measured spectrophotometrically to determine the concentration of sugars.

Why is a standard glucose curve needed?

To quantify sugar concentration from absorbance readings.

Define °Brix.

It is the % (w/w) of sugar in a solution, measured by refractometer.

How does a refractometer determine total soluble solids?

By measuring light refraction, which changes with solute concentration.

Name other methods for carbohydrate analysis.

DNS method, HPLC, enzymatic assays.