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Brix is a rough measure of a food’s nutrition that can be done in the field using a simple tool called a refractometer. The tool is commonly used by vineyards to measure the sugar content of their grapes and determine when to harvest. Each type of produce has its own range on the brix scale so the measure is relative. Good asparagus may have a brix of 6 while a tasty apple may have a brix of 14.
Brix is measured by squeezing a couple drops of a plant’s sap or juice onto the bevelled edge and closing the top flap. Looking through the refractometer one sees the degree of refraction that light undergoes as it passes through the sap. The degree of deflection indicates the amount of disolved solids in the solution – primarily sugar and minerals with lots of other chemicals present in small quantities. A grower with a sense of what an average brix reading should look like for each crop can get a general sense of how their crops are doing as the season progresses. This can be done on leaves as well as fruit. This is not necessarily a good tool for consumers to use to gauge food quality. Produce begins to lose water after harvest which will make brix increase even as nutrition falls off.