Sugar is one of the world’s purest natural ingredients and is used globally and in almost every food category.
Grown in more than 100 countries, more than 170 million metric tons of sugar are produced each year. But how is it extracted from sugarcane and processed as a crystal?
In a sugar mill or sugar facility, sugarcane undergoes various processing stages. The result is a sugar crystal. The processing of sugarcane in a mill requires different phases to extract sugar from sugarcane, which are explained below:
Extraction
Once the cane has been sorted, it is washed to remove impurities before being processed. Cane cleaning can be done wet or dry. Dry cleaning is the preferred method, as it is more environmentally friendly and does not affect the TRS (total recoverable/reducing sugars) content.
After the cane has dried, it is cut before being crushed in large roller mills. This process removes the sugarcane juice. The juice is the valuable extract, as it is used to produce sugar and ethanol. The sugarcane residue, which is known as “bagasse”, is used as fuel to generate electricity in the power plant.
Clarification
Sugarcane juice is sent for clarification, a process in which precipitates are removed through coagulation and sedimentation. This eliminates sand, clay, and other substances. Almost 90% of the weight of sugarcane is juice, which contains up to 17% sucrose (common sugar) and small amounts of dextrose and fructose.
To avoid decomposition of the sucrose, the juice undergoes a pH correction process. Once this is done, it is mainly water, mineral salts, and sugars.
Boiling
The juice undergoes a boiling process, where the moisture is boiled off. During the boiling and evaporation process about 75% of the water is removed, resulting in a thicker syrup concentrate. The syrup is cooked so that crystallization and sucrose recovery can take place.
Crystallization
The syrup is placed in large containers where it is slowly rotated, allowing it to cool evenly. Seeding then takes place, where small seed crystals are added to the syrup to catalyze the crystallization process. The molasses is separated from the crystals and the liquid is ready for the next stage.
Centrifugation
To complete the previous step, centrifugation is carried out. During this stage, the crystallized syrup is separated from the sugar and dried by placing it in centrifuges. This produces raw sugar.
For every 100 tons of cane processed, about 12 tons of VHP (Very High Polarity) sugar and 4 tons of molasses are produced.
The amount of molasses, which is the solution left over from sugar processing, that is left in the crystals or added back to the sugar crystals determines what type of sugar is produced.
In addition to white granulated sugar, there are light and dark brown sugars that have a higher molasses content and are often produced for specialized use. Generally, at this stage, cane sugar is not food grade.
Source: CZAPP