What is the Brix scale and how is it linked to fruit quality?

The quality of a fruit is a multi-dimensional notion, and the aspects of quality we take into account differ according to the context. When we are studying how end consumers make fruit-buying decisions, then the appearance of the fruit is crucial. The added value that the consumption of a fruit has to offer, though, is mainly driven by its nutritional value and taste. That is what dictates the enjoyment of its consumption. 

Taste is mostly affected by the sweetness of the fruit, which in turn is linked to the level of soluble solids in it. The most prevalent among them are of course sugars, and the rest of them are mainly made of pectins, organic acids, and amino acids. A consumer would be hesitant to buy fruits from a vendor that has sold them bad-tasting fruits even once. That is why sellers and farmers nowadays cater for measuring the sweetness of their product, and a dedicated scientific scale has been developed for this purpose, the Brix scale. The higher the brix degrees of a fruit, the better its taste and the higher its nutritional value, so a quality-conscious consumer would be more eager to buy again from vendors that offer them such fruit. 

The most widely used method of measuring Brix degrees in a fruit is by squeezing its juice on a refractometer. This method leaves the fruit in non-marketable condition, so it is called “destructive”. In the last years, “non-destructive” methods have been developed, so that the Brix degrees can be measured by inspecting the fruit’s interaction with special light sent into it. 

It is worth noting that apart from serving as the key quality indicator for fresh produce, minimum BRIX degree measurements are also imposed in some cases to dictate the minimum legal marketable conditions that specific fresh fruits need to satisfy before they can be harvested or enter the distribution chain. Taking kiwifruit as an example, to satisfy the minimum development and ripeness requirements for harvesting, it must bear a BRIX degree of at least 6.2, and, before the fruit can enter distribution chains, it must have reached a BRIX score of at least 9.5 degrees. 

Link to the European Legislation: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX%3A32011R0543