Showing posts with label refractive index. Show all posts
Showing posts with label refractive index. Show all posts

°Brix Measurement with Inline Refractometers

Refractometers measure Brix in juice
Refractometers are used to measure Brix in various juices.
A wide variety of food and beverage products rely on sweetness as a standard of consistency and quality. The unit of measurement to determine the concentration of sugar in food and beverage is °Brix (degrees Brix). Commercial processors of juices, wine, beer, soft drinks, tomato products, dairy, maple syrup, honey, jams and jellies implement the use of some form of refractometry to determine °Brix in their products.

°Brix (symbol °Bx) is the percentage of sugar dissolved in the subject product. One degree Brix equals 1 gram of sucrose in 100 grams of solution. °Bx is a degree scale from 1-100. A solution that is 15°Bx is 15 percent sucrose by weight. Measuring °Bx is based on the index of refraction or the density of the process media at specific reference temperatures of 20°C.

inline industrial refractometers
Inline industrial refractometer with control electronics.
One type of instrument used to measure °Bx is called a refractometer. Smaller food and beverage producers use hand-held refractometers to determine °Brix in product batches. Large scale producers, with continuous processing or high volume batches, use highly accurate, rugged, inline industrial refractometers which are installed on the process piping and become part of their overall control scheme.

All refractometers use the refractive index (RI) of the food/beverage concentration as the measurement method to determine °Bx.  The refractive index (or index of refraction) of a material is a dimensionless number that describes how fast light propagates through the material, or in other words, how much the path of light is bent, or refracted, when entering a material.

Refractometers often require some type of correction or linearization based upon the substance they are measuring. To account for other undissolved solids, organic acids or ethanol in the process media, specialized curves must be used. Inline process refractometers include these custom curves in the microprocessor programming, and can be selected through the refractometers user interface for varying product runs.

For more information about the measurement and control of °Brix using inline refractometers, contact Electron Machine Corporation.


What Is An Inline Process Refractometer?

Inline sensing head
Inline sensing head
Inline process refractometers are used in the food processing, beverage, pulp and paper processing, chemical, power, and primary metal industries. Inline process refractometers save labor costs, streamline the manufacturing process, and improve quality by detecting inconsistencies in a product early in the production phase. They continuously monitor, control and report the on Degrees Brix, Percent Solids, Dissolved Solids, SGU, and refractive index of a brand variety of solutions.

Inline process refractometers are made up of three main components:
Control console
Control console
  1. The inline sensing head, which is inserted to a pipe and is exposed the the product for direct measurement. The sensor is connected by a cable to the second main component, the control console.
  2. The control console, which houses the display, electronics, power supply and output connections. Both the sensor and the control module are designed for high accuracy and precise control. Their housing and cabling are often specialized for use in varying extreme conditions and very demanding environments.
  3. The process adapter, which connects the sensor mechanically to the process piping. Adapters are configured for the pipe size and application they are used on and are available in many configurations. Some of the more common adapter options are:
    • Lined - For extremely corrosive applications.
      Mounting adapters
      Mounting adapters
    • Inline - For most applications with pipeline sizes less than 2”.
    • Isolation - For critical process lines that cannot normally be shut down.
    • Sanitary - For applications on a sanitary pipeline.
    • Spool - For most applications with pipeline sizes greater than 2”.
    • Vessel - For applications where the sensing head is to be mounted directly onto a vessel or vacuum pan.
    • Weld-in - For economical mounting.

The Basics of Process Refractometers

Light refractionA refractometer is a process instrument capable of determining a solution's refractive index. Light bends and changes velocity as it travels from one media into another through the media interface. When light traveling through air enters liquid, the light rays change direction by an amount determined by the liquid's density.

Angle of refraction refers to the magnitude the light bends as it exits one media and enters the interface of another. With the angle of refraction defined by their densities, different liquids display different amounts of refraction - for example, a higher density juice such as orange juice will have significantly different refraction than cranberry juice, because of its higher density.

Light refraction
Light bends when traveling through
different media. That's why this pencil
appears to be "broken" when it enters
the water.
A liquid's refractive index relates to the amount of light bending that liquid displays. The greater the bending, the greater the refractive index. The lower the bending, the lower the refractive index.

Standard tables are available that correlate refractive index to a variety of materials. These same tables also correlate refractive index to varying concentrations of particular liquid media at a particular temperature. Take corn syrup for example. Different refractive indexes are observed for different corn syrup samples of different concentrations. Therefore, by using a process refractometer to observe the refractive index of a particular corn syrup sample, a determination of the concentration of that particular sample can be made. By referring to the table or scale that correlates the refractive index to concentration at a particular fixed temperature, liquid concentration can be determined.

The refraction index of the liquid medium readings will vary at different temperatures, and therefore, the sample's temperature must be measured and compensated for in order for refractive index readings to be accurate and repeatable.

Refractive index measurements have been used for process control in the food, juice and beverage industries for decades, with the most common applications being the measurement of sugars (Brix) and total dissolved solids (TDS). Large scale production and processing of fruit juices, jams, tomato products, wine, beer, coffee, and many other products rely on industrial refractometers for quality and consistency.

For more information contact Electron Machine Corporation by visiting or by calling 352-669-3101.

Measuring Total Soluble Solids with Refractometers

Inline, process refractometer for beverage production
Inline, process refractometer for beverage production.
Just as weight is expressed in pounds, the level of soluble solids in a solution is measured in degrees Brix (symbol °Bx).  The Brix scale is based on a solution of pure sucrose diluted with water. Adolf Brix first developed the Brix scale in the 1800s. For example, a 100 gram solution with a Brix 50 reading contains 50 grams of sugar (and other dissolved solids) and 50 grams of water.

Fruit juices, wine, nectars, and other beverages all contain soluble solids. Total Soluble Solids (TSS) refers to the total amount of soluble constituents of the juice, wine or other beverage. These are mainly sugars, with smaller amounts of amino acids, pectin, and organic acids. For example, approximately 85% of the total soluble solids of citrus fruit are sugars. Because sugar is the most abundant soluble solid, the Brix scale is used by the beverage industry in determining the sucrose equivalent of soluble solids in their products. The term "Brix" or "degrees Brix" is used interchangeably with % sucrose or % soluble solids by weight.

Refractometers are instruments that determine soluble solid concentration by evaluating the solution's refractive index. Changes in direction of a light beam passing through the solution correlate to the amount of dissolved solids in the solution. Basically, the higher the level of soluble solids in the solution, the greater the bending of the light beam. In large scale beverage plants, inline process refractometers are used to control quality and consistency by continuous monitoring of the soluble solid concentration.

For more information about measuring TSS and/or Brix in a commercial beverage production facility, contact Electron Machine by visiting or calling 352-669-3101.