Production of table sugar

The production of sugar from sugar cane juice is based on the ability of sucrose to crystallize from thick syrup while glucose and fructose remain dissolved.

Major steps in the production of raw sugar crystals include:
*Harvest and transport of cane to the sugar factory
*Juice extraction
*Purification of the juice
*Evaporation of water
*Crystallization of sucrose and the production of massecuite
*Storage of sugar and molasses

The cane is first prepare for grinding by revolving knives that cut the stalks into chips, by hammer-mills shredders that shred the cane but extract no juice, by heavily grooved crusher rolls that break the cane and express a large part of the juice.

Crushers are two roll mills which were formerly use extensively for preparation of cane before further crushing on three roller mills. A well operated crusher should give 50% juice extraction.

By a combination of cane preparation, blanket compression and dewatering of the fiber, the first mill following should give an additional 27% juice extraction, giving a total of 77% by dry crushing.
Production of table sugar

Processing of sugar cane

After harvesting, the cane goes through a series of processing steps for conversion to the final sugar product.

It is first washed to remove dirt and trash; then cut cane is chopped to remove the top section which has low sugar content, the leaves are removed and the remaining stem is chopped into short lengths for crushing.

Cane entering the mill is prepared by chopping, shredding or crushing and after one or a combination of these procedures is completed, the remaining juice is extracted by passing the prepared cane though series of mills containing three to five rollers.

The other method of extracting juice is by diffusion where the sugar is leached out by water and thin juices.

The raw cane use contains soluble solids other than sucrose and is clarified before concentration, a very important step in facilitating subsequent recovery of the sucrose.

To remove both insoluble and the soluble impurities from the juice, the juice is limed, heated and sent to clarifiers.

Clarification and neutralization of the mildly acidic, raw extract (pH 4.8-5.0) is done by treatment with lime or lime and carbon dioxide.

The juice is heated to approximately 100 degree C which coagulates suspended solids and proteins, inactivates enzymes systems such as invertase and destroys bacteria, thus stabilizing the system.

The clarified juice, which contains only 12 to 13 % of sucrose, is sent to evaporators, while the juice containing precipitate is sent to rotary-drum vacuum filters to extract the juice leaving the filter cake for disposal.

The syrup is used to produce crystals (raw sugar) and syrup (molasses). The whole process is energy self sufficient as the remaining cane fiber is used to fire the boilers.

The raw sugar is shipped from the mill to a refinery, where it is decolorized with activated charcoal, or put through a column beef bone.

After being crystallized and dried the end product of sugar refining is white and nearly pure, sucrose.
Processing of sugar cane