Refractometers are instruments designed to measure an optical constant called the refractive index, a characteristic of the sample and the particles dissolved in it. This is defined as the relationship between the speed of light in a vacuum and the speed of light in a substance, it is a property of the material that is not different from the boiling and melting points, but that facilitates the final identification.
The measurement of the refractive index allows one to make a graph that relates this property with the concentration of the sample, just need to know exactly how it varies depending on the amount of the species in the liquid. Once the relationship is established, any unknown composition can be determined. In most cases, the calibration is provided by the instrument itself, so that when measuring the sugar solution you can read the scale on the equipment. The measured refractive index is converted directly to percentage by weight of sucrose content (ºBRIX).
How the refractive index is measured in sugary mixtures
There is a directly proportional relationship between the refractive index and BRIX degrees since it measures 1 gram of sucrose per 100 grams of sample. This conversion is standardized by the International Commission for Uniform Methods of Sugar Analysis (ICUMSA). BRIX is defined as the percentage by weight of a pure sucrose solution. For any particle dissolved in a sweet substance it is possible to use the scale, but it counts as a relative measure or a reference value, such as the case of high fructose corn syrup (HFCS), which is a liquid sweetener extracted from corn starch that is mainly composed of fructose and D-glucose and can partially replace sucrose in beverages and soft drinks.
There are also other scales such as Baumé (°Be) and Oechle (°Oe) to measure the density of grape must, the Klosterneuburger Mostwaage (°KMW) grades used in Austria to determine the proportion of sugar in wine must; the Plato grade that was established to quantify the sugar content in the brewer must.
The measuring ranges vary according to the substance to be evaluated and depending on this the equipment to be used:
- 0-32% Brix: are usually used to measure the sugar content in juices.
- 28-62% Brix: Commonly used for jams and syrups
- 85-92% Brix: used in beekeeping.
It is also possible to obtain commercial equipment of 0-90% Brix, although these equipment are of wide range, also the measurement error is greater.
To make any measurement with the portable refractometer, it is necessary to ensure that the surface of the sample prism holder and the cover are clean. The instrument must then be calibrated to zero either with distilled water or with BRIX calibrating collusion. To make the measurement drop a few drops onto the prism, disperse the sample evenly, cover with the lid and take the measurement at room temperature.
Applications of refractometry in the measurement of sweet drinks
Some refractometer models offered by manufacturers are specifically designed to measure Brix degrees. Thanks to their practical and robust configuration they can be used in multiple ways in the field of application of sugar:
- Food industry: process control and quality.
- Food sector: the degree of ripeness can be determined (sugar of the fruit and vegetables), for natural juices, sweets, milk and its derivatives (condensed, evaporated, dairy products such as cheese and yogurt), for all types of sauces, among others.
- In the production of wine, must and alcohol.
- In Viticulture and Fruitculture.
- In beekeeping and honey production.
At KALSTEIN we are MANUFACTURERS, we offer high-end precision optical instruments, tailored to your requirements. We have portable refractometer scales as 0-10%, 0-32%, 0-50% and 58-92% BRIX. It is a simple model that avoids the conversion effort, since the refractive angle measured by the refractometer is recorded on the scale. For more information about our products HERE
