Processi

Processing and refining of sugar

Processing and refining of sugar cane and beet

Once sugar cane and sugar beets have completed their journey from the farm to the mill processing or refining facilities, the transformation into the familiar sweet crystals we use in our daily lives begins. 

How is sugar produced?

Sugar is produced naturally in sugar beet and sugar cane plants. The plants are harvested, washed, and the juice extracted. The juice is then boiled, refined to remove the impurities, and finally the natural sugars contained within the extracted juice are crystallised. 

What gives sugar its white colour?

Sugar is naturally white. It is the naturally-occurring molasses, which give brown sugar its colour. These molasses are extracted during the refining of white sugar.

Discover below how sugar is processed and refined.

Cane factory

Sugar cane

At the mill, sugar cane stalks are washed, cut and the shreds are pressed (1). This process releases juices, which are then clarified, concentrated, and crystalized. The remaining product is spun in a centrifuge, a machine that spins rapidly and separates out the sugar from the liquid. The raw sugar is then transported to a sugar refinery (usually via a dry bulk ship) where it is further purified. At the refinery, cane sugar is further refined to remove the final impurities (1). Molasses, which is a thick, dark syrup byproduct from the production of sugar, is removed by blending the raw sugar with hot water, and then placing it in a centrifuge. The dark molasses is spun off, leaving white sugar crystals. These crystals are then dissolved and filtered. This process produces a colourless water and sugar syrup. The sugar syrup goes through evaporation and "seed" crystals are added. Over time, larger sugar crystals form. These crystals, which are naturally white, are then dried and stored. Finally, prior to packaging, the sugar crystals are sieved to produce the range of sugars that we buy in the shops (e.g. granulated, fine, superfine (caster), and powdered (confectioners’)).
Beet harvesting

Sugar beets

When harvested, sugar beet root contains 12-20% sugar. The rest of the crop is made up of water (75%) and pulp (5%) (2). The beets therefore need to be processed, to extract the sugar from the crop. At the sugar refinery, after washing, the sugar beet is sliced into thin strips called cossettes. The cossettes are mixed with hot water to help extract the sugar (3). Similarly to the process for cane sugar, above, the syrup produced is then filtered and heated, and sugar crystals form. Once large enough, the crystals are removed, then washed, dried and cooled.

References

  1. Institute of Food Technologists. How sugar is processed. 2020. https://www.ift.org/news-and-publications/food-technology-magazine/issues/2020/july/columns/processing-how-sugar-is-processed 
  2. FAO. Agribusiness Handbook - Sugar Beet, White Sugar. 2009. https://www.fao.org/fileadmin/user_upload/tci/docs/AH1-(eng)Sugar%20beet%20white%20sugar.pdf 
  3. Misra, V., Shrivastava, A.K. Understanding the Sugar Beet Crop and Its Physiology. In: Misra, V., Srivastava, S., Mall, A.K. (eds) Sugar Beet Cultivation, Management and Processing. 2022. Springer, Singapore. https://doi.org/10.1007/978-981-19-2730-0_2
     

Copyright

Sugar processing image and sugar beets image on this page are copyright Dennis Möbus/Südzucker.