Refractometer is used to determine

A refractometer is used to determine T. S. S. (total soluble solids).
The refractometer is a well-established instrument used for measuring the water content of liquids. It measures the refractive index of the liquid, which changes according to the moisture content.
The destructive method of TSS measurement is usually performed by a refractometer. The measurement is done by dripping the liquid fruit extract on the detector. TSS value is expressed by %Brix, the value displayed is based on a ratio of the speed of light in a vacuum and the speed of light through the sample.