You’ve seen the vivid images of coffee cherries, transforming from clusters of light green to bright orange and red.
While the colour tells us what stage the coffee cherry is in, it doesn’t always accurately determine what chemical changes are occurring inside.
That’s where Brix (°Bx) comes into the picture.
It measures the percentage of soluble compounds within the cherry, which helps coffee producers know when it’s ready for harvesting.
Granted, the Brix reading alone cannot guarantee coffee maturity, as it’s meant to be assessed alongside visual markers.
What a Brix Reading Actually Tells You
To get the Brix measurement, juice is extracted from the coffee cherry and evaluated using an electronic tool called the refractometer.
The Brix reading derived from this provides a quantitative measurement. For instance, specialty coffee is known to measure between 18° and 24° Brix.
A higher reading doesn’t automatically mean higher-quality coffee. It indicates the total soluble compounds present in the coffee cherry, including sugars, amino acids, minerals, salt, etc.
The Brix measurement changes as the coffee cherry develops. The fruit transforms carbohydrates and other compounds during the maturation process. And so, Brix helps producers know how mature the coffee cherry is.
Why There isn't a “Perfect Brix” Number
There is no one universal Brix measurement that is applicable for all coffees across all coffee farms in the world. There are a few reasons for this.
-
Cultivar - The genetic makeup of a coffee influences both its chemical properties and appearance. Different cultivars follow different patterns of development as they ripen. That is to say, two coffees that are at similar developmental stages can have varied Brix readings. If we were to go by a fixed Brix threshold, it’s not guaranteed that both coffees would be equally ripe.
-
Environment - Factors like sunlight, rainfall, altitude, and temperature affect coffee development. Even cherries on the same farm can be influenced by different microclimates. So a reading from one lot shouldn’t be treated as a benchmark for another lot on the farm or even the same lot at a different time.
As you can see, it is better for coffee producers to sample coffee and get insights into how the Brix readings are changing rather than wait for all coffee to reach a universal Brix number.
A series of continuous Brix tests provides useful information about coffee maturation and harvest window.
Brix vs Colour: What Happens When the Two Disagree?
The most convenient way to check coffee maturity is the colour of the coffee cherry. It doesn’t require equipment and can be implemented quickly.
However, it isn’t always the most accurate. Research shows that there are considerable differences in the soluble sugar present in coffee across different levels of redness.
This shows us that red doesn’t always mean the coffee is ready or that a darker colour means the coffee is overly ripe. Yellow, orange, and pink coffee cherries can all represent ripe fruit depending on genetics.
The Brix reading adds another dimension to what the coffee producers can infer. For instance, a coffee cherry that appears to be overripe may not represent a significant drop in sensory or chemical structure.
Apart from sugars and organic acids, studies show that compounds like caffeine and trigonelline are also associated with specific stages of development.
The Brix test is a significant part of coffee cultivation. It provides a glimpse into what is happening inside the fruit.
It isn’t an activity that is conducted once around harvest season but is done periodically when the coffee cherries start transforming.
For coffee producers, assessing Brix along with a broader context like the colour of the coffee cherry, visual characteristics, cultivar type, and field conditions is where the real value lies.
Eventually, forming connections between this and the cup profile helps them focus on producing quality coffee.