Refractometer

Ohio State University Extension explains that refractometers measure how light bends through a liquid to estimate its soluble solids. Handheld models suit on-the-spot degrees Brix measurements, while lab units are more costly and not portable but return data quickly.

The Brix scale reflects the percent of dissolved solids in a solution. Because sugars are usually the most abundant soluble solid in fruit and vegetable juices, a Brix reading mainly estimates sugar content, which relates to sweetness. For bakers and confectioners, that makes it a quick way to check a juice, fruit puree or syrup.

The extension fact sheet adds that a high reading does not guarantee a sweet taste, since other flavor components can outweigh sweetness, and that results are only as good as the sampling and the instrument.