Raw & Refined Sugar Quality
Quality of raw sugar plays very important role in manufacturing of refined sugar and as such the quality of raw sugar should be normally specified for price negotiations. The following criteria will represent the desired quality of raw sugar:-
Polarisation (Pol )
Raw sugar with a high moisture content cannot be stored because it is susceptible to microbial activity and sugar hardening during storage. The sugar-refi ning industry uses the ratio of water content (W) to nonsugars (NS) to calculate the safety factor (SF):
SF = W X 100 / NS = W X 100 / (100 – ( S + W ) )
Here, the S (sucrose content) refers to sucrose measurement by polarimetry, called polarimetric sugar or pol.
Concentration of specific impurity group
Colour value of whole crystals
Colour distribution within the crystals
Average crystal size
A suitable raw sugar has uniform crystals from 0.6 to 1.0 mm, preferably 0.8 mm. The grain size is determined by screening washed sugar through a 28 mesh screen.
Uniformity in crystal size
Crystal shape and Conglomerates
Wax, Gums and Starch Contents
The raw sugar is mainly divided into three types having following specifications. The proposed refinery will use VHP quality raw sugar as its raw material
Based on the quality of the raw sugar, you can calculate a theoretical (expected) recovery (yield). The recovery (R) is the percentage (on mass base) of the refined sugar produced per raw sugar processed. Sucrose (S), invert-sugar (I), and ash (A) content are used to judge the recovery of raw sugar. Different countries use different formulas for recovery estimation, as below table
In almost all countries, the price of raw cane sugar is calculated based on 96% sucrose content (polarimetric sucrose, PS). Raw sugar above the base level gets credit, and sugar below the limit is penalized. In the United States, the refi ners pay a premium up to 98.8% and deduct for sugars that contain less than 96% sucrose. In addition to the sugar content, moisture, ash, crystal size, dextran content, and color are included in the premium (or penalty). The adjustments are different according to the country.