Refractometers for Food and Beverage Processing

Refractometers commonly used to detect sugar levels and properties of jams juices, beverages, dairy products and much more.

Electron Machine Corporation developed the first in-line process refractometer more than 50 years ago when orange juice was first concentrated. Since that time, their refractometers have been successfully applied on many more applications including the production of sucrose, fructose, dextrose, soft drinks, fruit juices, dairy, apple sauce, jams, jellies, beer, wine, coffee, tea, vegetable oils, tomato paste, ice cream and honey.

With an extremely durable Sapphire prism as its foundation, the Electron Machine MPR E-Scan combines accurate measurements with ruggedized components in the sensing head combining for years of of dependable and accurate service in harsh food production environments.

What is Refraction?

Diagram 1

Light rays travel through space in a straight line at approximately 300,000 km/s. As light passes through a transparent medium, such as water or glass, its speed is decreased.

For glass, its reduced to 200,000 kilometers per second, and for water the speed is 225,000 kilometers per second.

If the light enters into a medium perpendicular to the surface, it passes straight through but at a slower speed. However if the light beam arrives at the medium surface at an angle, not only will it speed be reduced, but it will bend due to a process called refraction.

To better visualize this phenomenon let's look at Diagram 1. As a beam of light reaches the surface of a medium the lower portion enters first and is slow down. However, the upper portion is still traveling at the speed of light until it arrives at the surface and enters.
 
This speed difference at the top and bottom aspects of the light path causes it to pivot, bending toward what is referred to as the normal. This is an imaginary line drawn perpendicularly to the surface of the material.
   
Transparent materials have what is called a refractive index. This is the speed at which light travels in a medium compared to like traveling in a vacuum.
     
For example, typical glass has a refractive index of 1.33. This is calculated by dividing the speed of light in a vacuum (300,000 km/s) by the speed of light in glass (225,000 km/s).
     
The refractive index of air is 1.0003. Anytime a light beam travels from a medium with a low index of refraction, like air, to a medium with a higher index of refraction, like glass, the beam of light will bend toward the normal.
     
Likewise when the beam of light exits a highly refractive medium into a medium with the low index of refraction, the process is reversed.
     
The bottom portion of the beam of light exits first, and resumes at the speed of light, with the top portion still at the speed determined by the medium. This causes the beam to pivot away from the normal line.

Applying Process Refractometers in Sugar Cane Processing

Raw and final product of sugar refining

Sugar cane, after harvesting, requires processing within a limited time window to avoid sugar loss by inversion to glucose and fructose. The traditional two stage process, milling and processing, may be combined in a single modern production facility. Process refractometers can be found in both operations, making an optical measurement of a solution’s refractive index used to determine the concentration of dissolved solids.

To achieve high quality liquid and crystal sugars and contain production cost, refractometers are employed to deliver accurate in-line Brix and other measurements in the cane sugar refining and milling processes. 

Specific uses of refractometers in sugar production are:

• Product flow adaptation to evaporator capacity to achieve energy savings.
• Extraction process optimization, minimizing the use of water that will need to be removed at the evaporator.
• Separation column feed juice control to adjust concentration to match capacity.
• Quality assurance check on liquid bulk sugar and molasses.
• Vacuum pan automatic and accurate seeding.
• Monitor supersaturation over complete strike of crystallization.

Share your refractometry challenges and applications with the experts at Electron Machine Corporation for effective solutions.

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