🍷 Refractometer

A refractometer is a handheld instrument that shows how much sugar is in grape juice. The grower squeezes a drop of juice from a berry onto the glass of the instrument, closes the lid and looks into the eyepiece. The scale shows the sweetness of the juice.

The instrument works because light bends differently in liquids of different density. The more sugar in the juice, the more the light ray bends. The result is shown in degrees Brix (percent sugar) or other scales. The device is small, fits in a pocket and is convenient right in the vineyard.

It is used to follow grape ripeness before harvest. When enough sugar has accumulated and acidity has not dropped too low, it is time to pick. A refractometer does not replace taste: berries are also tasted and the seeds are examined. But sweetness can be measured quickly and precisely. For wine, which ferments from sugar, this is a very important number.