Brix Explained

Although Brix is often equated to the concentration of many different kinds of sweeteners, extracts or solids, it is actually defined as the number of grams of sucrose in 100 grams of sample. Understanding how a Brix result is influenced by ingredients other than sucrose is crucial to developing a useful correlation to be used for quality control during production.

The term Brix is often used as a quality control parameter in many different food and beverage industries. Some examples of these products include juice, soft drinks, sugar, frostings and wine, among others. Generally speaking, the value obtained from a Brix measurement is used to determine if the product contains the correct amount of sweetener. It is important to note that although Brix is used with many different types of sweeteners, it is actually a value that corresponds to the number of grams of sucrose in 100 grams of sample. Therefore, when a Brix value is determined for a product containing a different sweetener, for example High Fructose Corn Syrup (HFCS), only a relative concentration is calculated, not an exact value.

Differences between digital refractometers and density meters

Historical tables exist that are used to convert certain measured physical properties of a solution to a Brix value. The two most common of these measurements are density and refractive index. When a solution of sucrose dissolved in water is measured, both density and refractive index will provide the same Brix value. If the sample contains any other components, like when measuring a soft drink, the density and refractive index are changed and the resulting Brix values are influenced differently. The same holds true for a sweetener other than sucrose.

As seen in the table below, a 40.0 % HFCS-55 solution has a refractive index that is the same value for a 39.5 % solution of sucrose in water and therefore a refractometer would show a value of 39.5 °Brix.

Sucrose Concentration = 39.5 % HFCS-55 Concentration = 40.0 %
Refractive Index = 1.39884 nD at 20 °C
Brix Value from Refractometer = 39.5 °Brix

The density of a 40.0 % HFCS-55 solution is the same value as a 39.8 % sucrose solution and thus a density meter would provide a result of 39.8 °Brix, as shown in the following table.

Sucrose Concentration = 39.8 % HFCS-55 Concentration = 40.0 %
Density = 1.17558 g/cm3 at 20 °C
Brix Value from Density Meter = 39.8 °Brix

Since different values for Brix are given by each instrument when measuring samples other than sucrose, it is important to establish separate quality control limits for each device. This is particularly important when comparing results with other laboratories where a different measuring technique may be used. To assist with this issue, the term “Refractive Brix” is sometimes used to indicate when a sample was measured with a Refractometer.

Special application: Using Brix to monitor a fermentation process

Understanding where Brix comes from and what changes its value allows us to obtain useful information, even when the “wrong” type of sample is measured. A great example of this is Wine. Before fermentation, the Brix value provides information about the amount of sugar in the juice. Once yeast is added to the juice the sugar is converted to alcohol which causes the density to decrease and thus leads to a lower Brix value. In fact, as fermentation continues and more ethanol is produced, the density drops to a value below pure water which results in a negative Brix value. Even though no real concentration information can be obtained, winemakers can use this changing in Brix value to monitor the fermentation process using target values.

Examples of specific instruments that are commonly used for Brix analysis are Anton Paar DMA Generation M density meters , Abbemat Performance and Performance Plus refractometers and Soft Drink Analyzer M density and sound velocity meter for additional information on the sugar inversion process.

The refractometers as well as the density meters are widely used in industrial quality control, research, at authorities and standards organizations.

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