Refractometer for Juice Concentrate

Fruit juice concentration line

Reprinted with permission from K-Patents

Introduction

Fruit juice concentration requires the partial removal of water content so that all the solid components such as fruit sugars, minerals and vitamins are left in a more concentrated solution. The purpose of concentration is to ensure longer storage life and easier transportation.

Chemical curve

Application

Typical end products: Fruit and vegetable juice concentrate (apple, orange, grapefruit, pineapple, tomato, passion fruit, mango, carrot, grape, cherry, cranberry, guava, pomegranate etc.)

After juice extraction, screening and centrifugal purification, the juice goes to a primary tank. At this stage, the juice concentration is inconsistent, varying from 9 to 12 Brix. The concentration depends on various factors such as fruit quality and annual rainfall. The juice is then fed to the evaporation plant.

For fruit juice concentration, a three-stage falling film evaporation plant is commonly used. The evaporators have a constant boiling rate. In the evaporation process, the concentration value is typically increased from 10 to 65 Brix.

Installation

The K-Patents Sanitary Refractometer PR-23-AC is mounted on the evaporator outlet. It provides a signal to a controller regulating the Brix value by varying the evaporator inlet flow.

If the Brix value increases, the valve allows a product flow rate increase through evaporators. This brings the Brix value back to the set-point. Typical measurement range is 30-80 Brix.

Solution

K-Patents Sanitary Compact Refractometer PR-23-AC for small pipe line sizes of 2.5 inch and smaller.  

K-Patents Sanitary
Compact Refractometer
PR-23-AC

• The PR-23-AC sensor is installed in the pipe bend. It is angle mounted on the outer corner of the pipe bend directly, or by a flow cell using a 3A Sanitary clamp or Varivent® connection.
• Measurement range: Refractive Index (nD) 1.3200 – 1.5300, corresponding to 0-100 Brix. 

Using Process Refractometers in the Processing of Sugar Cane

Sanitary process refractometer
(courtesy of K-Patents)

After sugar cane has been harvested, it must be processed in under 24 hours to avoid sugar loss by inversion to glucose and fructose. Traditionally, sugar cane processing requires two stages, milling and refining, but this two stages are slowly combining into on production facility. Process refractometers are commonly used to determine the concentration of a dissolved solids by making an optical measurement of a solution’s refractive index (nD).

In cane sugar refining and milling process, refractometers are used for accurate in-line Brix and concentration measurements with the purpose is to achieve high quality liquid and crystal sugars and to minimize costs of production. 

Specific uses of refractometers in sugar production are:

• Optimize extraction process and to minimize usage of water that needs to be removed from sugar juice later at the evaporator stage.
• Adapt product flow to the capacity of the evaporators in order to save energy.
• Make sure that liquid bulk sugar and molasses meet specifications.
• Control feed juice to adjust the concentration with the capacity of the separation columns. This leads to longer intervals between Recovering cycles and longer lifetime of the columns.
• Monitor supersaturation over complete strike of crystallization.
• Implement automatic and accurate seeding of the vacuum pan.

Refractometers (in red) used in sugar milling

Refractometers (in red) used in sugar refining

Download the complete Process Refractometer Application Note for Cane Sugar here.

For more information on process refractometers, contact:
Instrument Specialties Inc.
3885 St. Johns Parkway
Sanford, FL 32771
phone 407.324.7800
fax 407.324.1104
e-mail: offices@isisales.com