All about sugar
Ever wondered what exactly sugar is, where it's from or how it gets to your table? Here's where you can find out all you ever wanted to know.
What is sugar?
Sugars are simple carbohydrates, such as glucose, fructose, lactose, or sucrose, produced naturally and commonly found in fruit, milk, and sugar cane. Sucrose is the sugar that is commonly sold in our supermarkets, as it is easily extracted from sugar cane or sugar beet.
Sugar's chemical composition
In chemistry terms sugar (sucrose) is a disaccharide; in other words it is a double molecule comprising one molecule of fructose and one of glucose. Breaking the bonding by the process of inversion yields a 50:50 mix of monosaccharides (single molecules) of glucose and fructose, together known as "invert sugar".
The origins of sugar
We are the UK's only cane sugar manufacturer. Sugar-cane is a tropical grass which grows up to five metres high and requires copious amounts of sun and water. Sugar-cane is grown from short lengths of cane called 'setts'. The sugar-canes produce large amounts of sugar in their palm-like leaves, which is stored in the stalk.
How sugar is harvested
The setts are ready for harvesting after 11 – 18 months. Harvesting is carried out mechanically or by hand, with the dry leaves or 'trash' often being removed beforehand to assist the subsequent processing.
The sugar process
The canes are cleaned, crushed and shredded, then sprayed with hot water to extract the juice. The juice is filtered, concentrated by evaporation under vacuum, and crystallised, before being removed from the remaining liquid by centrifuge.
The remaining liquid is known as 'molasses'. This is a useful co-product which can be used for fermentation processes or animal feed. Bagasse, the residual fibre from the cane, is mainly used as boiler fuel at the factory.
At this point, the sugar is partly purified and in a concentrated, crystallised, microbiologically stable form suitable for bulk handling, storage and transport to refineries around the world.
Reaching the factories
The raw cane sugar is despatched by bulk carriers to refining plants. The storage shed at our Thames refinery in London can hold up to 70,000 tonnes – sufficient to supply the refinery for about 20 days of normal production.
Turning raw cane into table sugar
The raw cane undergoes five processes:
- Affination and Melting
- Carbonation and Filtration
- Decolourisation
- Evaporation and Crystallisation
- Separation and Drying
(If you want to know more about these processes, please click here)
White sugar
The raw sugar is washed (dissolved) then it is passed over various ion exchange resins (this pulls out the unattractive colour and any impurities). It's then given a final polish by passing active carbon. This absorbs some of the remaining colour molecules derived from the original cane and also some heavy metal ions. The result is a natural sparkling white sugar free from any inorganic or other particles!
Brown sugar
Brown sugars are made by mixing the white sugar with a specially prepared 'mingling syrup'. The mingling syrup is made from a blend of intermediate syrups or molasses produced when sugar is refined and clarified before mingling. By blending in this way we can control the colour and flavour to produce our two brown sugars: light brown soft, which has a mellow flavour and colour; and dark brown soft, which has a rich colour and flavour.
Making sugar cubes
Granulated sugar or demerara sugar is mixed with about 1.5% water and the resulting mixture is compressed into cube shaped moulds and pushed out onto a steel band. They then pass into a drying oven. After drying, the cubes are firm and ready to pack.
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