Which instrument is used to measure sugar content in fruit juice?

• A. Refractometer
• B. Hydrometer
• C. Viscometer
• D. Thermometer

Answer: (A)

Measuring sugar content in fruit juice is best done with a refractometer because dissolved sugars change how light bends through a liquid, and that change is directly translated into a Brix reading. The refractometer uses a drop of juice on a prism and shows the sugar concentration as a percent by weight, giving a quick and direct measure of sweetness that’s widely used in fruit processing and quality control.

A hydrometer, by contrast, gauges density to infer sugar content, but density is affected by many other dissolved substances and by temperature, making the result less direct and requiring more calibration. A viscometer measures how thick or viscous the liquid is, which doesn’t tell you sugar content on its own. A thermometer simply measures temperature and has no direct connection to how much sugar is in the juice.