The Sugar beet reference article from the English Wikipedia on 24-Jul-2004
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Sugar beet

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Sugar beet Beta vulgaris L., one of the Goosefoot (Chenopodiaceae) family, is a plant that contains a very high concentration of sucrose, and is grown commercially for sugar.

A geneticist evaluates sugar beet plants for resistance to the fungal disease Rhizoctonia root rotEnlarge

A geneticist evaluates sugar beet plants for resistance to the fungal disease Rhizoctonia root rot

Sugar beets are grown in mainly in Europe, the United States, and China [1]. Beet sugar accounts for 30% of the world's sugar production.

Sugar extraction

The beets are harvested in the autumn, washed carefully, peeled and chipped, and then placed in a machine called a diffuser to extract their sugar content. The diffuser is a large horizontal or vertical tank in which the beets slices slowly work their way from one end to the other while the water is agitated in the opposite direction. This is called a counter-current flow, and it extracts more sugar from the chips than if they were merely sitting in a hot water bath. Once the beet chips have passed through the diffuser they still contain sugary liquid, so they are pressed in a screw press to extract the last juices. The remaining beet pulp is turned into animal feed, and the beet juice is further processed.

The next stage in the processing is carbonation. The sugar juice contains many impurities that must be removed before it can be dehydrated, so small clusters of chalk are grown in the liquid. The chalk extracts the impurities from the mix, leaving a pure, if weak, sugar solution. This sugar solution is then concentrated in a multi-stage evaporating machine.

Finally, the syrup is boiled in large vats to concentrate the solution and create sugar crystals. These crystals are removed from the liquid in a centrifuge and dried out using hot air.

Discovery

Beets (and carrots) were identified as potential sources of sugar by the Prussian chemist Andreas Sigismund Marggraf in 1747, but he thought that commercial extraction would be uneconomic. His former pupil and successor Franz Carl Achard began selectively breeding sugar beet from the White Silesian fodder beet in 1784.

Achard was the first to start producing beet sugar commercially in 1802, following the opening of the world's first beet sugar factory in Kunern, Germany in 1801. At the time his beet was approximately 5% to 6% sugar, compared to around 20% in modern varieties. The development spread rapidly in France and Germany, encouraged by the imposition in 1807 of a blockade by the English in the Napoleonic Wars.

Related topics

Other economically important members of the Chenopodiaceae family: