Farmer's Weekly (South Africa)
Fundamentals of Brix
This unit of measurement is valuable to crop and livestock producers.
The Brix value tells you how much dissolved sugar is in a liquid solution. This value is indicated in °Brix (°Bx), and 1°Bx = 1g of sucrose in 100g of solution. That is, when measuring a solution solely made up of sugar and water, the Brix reading should match the actual concentration. The higher the Brix value, the sweeter the liquid solution. This means that the Brix value is important for the taste and quality of your end product.
For one, it will tell you if your fruit or vegetables are ripe. All you need is a little sample of sap and a handheld refractometer. You then compare the results to a chart showing the desirable readings.
This will differ from crop to crop, of course. Cabbage is ready for picking at 10°Bx to 12°Bx, lemons at 8°Bx to 12°Bx, onions at 8°Bx to 10°Bx, and so forth.
Named after the 19th century Austrian scientist Adolf Brix, the measurement is widely used in the food and drinks industry. In winemaking, for example, the alcohol concentration of the finished product is calculated by multiplying the °Bx of the grape juice by 0,55.
There are a few ways of measuring Brix, but the most common involves using a refractometer. When light enters a liquid it changes direction; this is called refraction. Handheld refractometers measure the degree to which the light changes direction (the angle of refraction). This is compared with a database of established refractive index values to determine the concentration of a particular solution.
CALIBRATION
A Brix refractometer is calibrated to give the percentage value of the dissolved sucrose-to-water ratio in a solution at 20°C.
While it is helpful to take the measurement when the ambient temperature is as close to 20°C as possible, most digital refractometers have temperature compensation.
The juice from fruit or vegetable samples (about 0,2mℓ) is dropped straight onto the measuring surface and measured immediately.
Knowing the sugar content of forage is important for livestock farmers. Simply put, ruminants are generally unable to convert grass proteins into milk proteins, only achieving a 20% to 25% conversion efficiency.
On top of this, some proteins are not well used by the animal.
The total milk output of a cow can be increased by either improving this conversion efficiency or increasing the cow’s total grass intake; research shows that high-sugar grasses have a positive effect on the efficiency of milk production in an animal.
Grass is broken down in the rumen of a cow, generating amino acids that are later used for the production of milk.
When the diet lacks readily available energy such as sugars, rumen microbes either cannot grow or they use amino acids to provide energy, which means less milk is produced.
A cheap way to increase the efficiency of the rumen is to use sugars that naturally occur in forage.
Higher-sugar grasses increase animal performance, boost feed nitrogen utilisation, and reduce nitrogen excretion.
In addition, according to research, animals’ live-weight gain can also be improved by using high-sugar grasses.
Forages are composed of many soluble and non-soluble compounds. Water-soluble compounds (WSC) include sucrose, fructans, minerals, proteins, lipids, pectins and acids. A refractometer can be used to take a Brix measurement of these water-soluble compounds in multiple grass samples collected throughout a camp paddock and thus provide an estimate of the average WSC content in the pasture. This allows you to monitor the pasture’s changing sugar content and correct it where necessary.
A pasture sample is usually done by picking a variety of forages similar to those a ruminant would eat. This grass is then squeezed onto the refractometer’s measuring surface using a garlic press.
• Sources: plagron.com > search ‘What is the Brix value?’; coleparmer. com > search ‘Brix’.
YOU CAN TELL WHETHER YOUR FRUIT IS RIPE BY TAKING ITS BRIX MEASUREMENT