Sugar production

Depending on the raw material used, sugar production yields either beet sugar or cane sugar. Powdered sugar is made by grinding sugar crystals into a fine powder and is primarily used in baking. Sugar cubes are used for coffee and tea because they are easy to portion out. They are made by mixing sugar crystals with a saturated sugar solution, which causes the crystals to stick together. It is then pressed, dried, and cut. The by-product of sugar production is molasses, a thick, brown, syrupy liquid. Molasses is used in the food industry as a flavouring agent and is also a key ingredient in the production of rum. In addition, due to its high energy content, it is also used as animal feed.

Sugar has long been a well-known and widely used sweetener. It was originally obtained from sugar cane, which was cultivated in India already in ancient times. In the 19th century, technological advances led to the beginning of industrial sugar production. The raw materials for sugar production, depending on the location of the growing area, are transported to the processing plant by road or rail, where they are processed immediately or after a short period of storage.

In temperate regions, the raw material for sugar production is sugar beet, whose root contains an average of 17–20 per cent sugar. Sugar beet cultivation requires good-quality soil and a high level of expertise. The countries that produce the most sugar beet include Russia, France, Germany, and the United States.

In the tropical regions, sugar cane is still the main raw material for sugar production today. Sugar cane is a tall grass that grows in tropical regions, with fibrous stalks containing a significant amount of sugar (13–15%). Brazil produces the largest amount of sugar cane and sugar in the world. In addition, India, China, and Pakistan also grow sugar cane in large quantities.

Sugar beet delivered to the factory is carried by conveyor belt to a beet washer, which removes the adhering soil. The cleaned sugar beet is cut into thin strips or slices by slicers. As a result of mechanical disintegration, juice extraction becomes easier, and sugars are more readily released from the cells. The sugars in the cells of the beet slices are extracted by diffusion using pure water. The slices are then transferred to a cossette mixer and subsequently to a diffusion tower, where counter-current hot water at 70–80 °C causes plasmolysis in the cells. This makes the cell membranes permeable, allowing the sugars to pass into the solution. This high-sugar content solution is called raw juice.

In the clarification tanks, milk of lime (Ca(OH)₂) is added, and in the carbonation tanks, carbon dioxide (CO₂) is introduced, causing non-sugar substances in the raw juice to precipitate and form an insoluble solid. Suspended impurities are removed in settling tanks and by filtration. The purified juice is called thin juice. The milk of lime (slaked lime) and carbon dioxide required for juice purification are obtained on-site from lime kilns, where limestone is calcined.

Freshly harvested sugar cane is first cleaned in a washing drum to remove adhering soil, leaves, and other impurities. The cleaned sugar cane is cut into smaller pieces with a shredder to increase the surface area and thereby facilitate juice extraction. The shredded sugar cane is pressed between milling rolls under high pressure, thereby extracting the sugar juice.

The extracted raw juice is warmed in heating tanks to 70–80 °C to increase cell permeability and promote plasmolysis, facilitating the release of sugars. Milk of lime (Ca(OH)₂) is added to the juice, which precipitates non-sugar substances. These impurities deposit in the settling tank, while the clarified sugar solution, the thin juice, rises to the top. The boiling and crystallisation processes are the same as those used in sugar production from sugar beet.