Brix testing: How We Measure Sugar Content

Brix testing: How We Measure Sugar Content

As our customers know, not all fruit is created equal. The balance of sugar, acid, texture, and aroma all play into what makes a piece of fruit something delightful versus just something to eat. Our taste buds are the ultimate judge of what is exceptional, and we do a lot of tasting around here to be sure, but there is another way to measure the quality of our fruit: the Brix test.

Farmer Al brixing Moro blood oranges

If you follow us on Instagram, you’ll likely have heard the term Brix. Brix is the ratio of Total Soluble Solids (TSS) to water in solution. Degrees Brix (°Bx) measures the total amount of “sucrose” in a standard amount of plant juice. In its most basic definition,°Bx measures the sugar or sucrose within a fruit. The higher a Brix measurement, the more sugar, and thus the sweeter the fruit. But °Bx measures more than just sucrose – levels of fructose, minerals, vitamins, proteins, amino acids, and hormones also constitute the solids that are measured.


Our fruit, and the fruit of our partner growers, will measure much higher than fruit you will find through most other channels. This means that you get exceptionally sweet and delicious fruit and that you are getting a higher concentration of vitamins and minerals in the fruits you eat. A myriad of factors determines a fruit’s Brix, but two of the most critical are soil quality and ripeness.


Soil is the foundation for a plant’s total health. A soil rich and diverse in microbial life allows for a plant to grow healthy, strong, and be more resistant to disease and pests. Plants grown in soil complex in microbial life have higher Brix measurements and are more resistant to disease and pests.


The longer a piece of fruit hangs on the tree, the riper it becomes. Ripe fruit has higher concentrations of the sugars that make them taste so delicious, as well as all of the minerals, amino acids, and vitamins that make them so good for you. At Frog Hollow, we use Brix measurements to determine the readiness of fruit to be harvested. Over the years, we’ve established a minimum threshold of ripeness for each of the varieties we grow because each variety has its own nuances and capacities. Our blood oranges are a great example of this. Blood oranges, even at their most tree-ripened state, will never have as high of a Brix rating as a high-quality navel orange. But with the experience of growing blood oranges, measuring their Brix, and of course, tasting them, we know when they have reached a minimum level of Brix to be sweet enough for harvest. The blood oranges may not Brix as high as navels. Still, we think comparing those two varieties of oranges is more akin to comparing apples to oranges than oranges to oranges because their flavor profiles are very different.

As we get into the harvest season of our stone fruit, you will be hearing more about ripeness in fruit and Brix levels. Stay tuned!

Brixing Moro blood oranges using a refractometer

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