Sugar refinement is a multi-step process that transforms raw sugar extracted from sugar cane or sugar beets into the white, granulated sugar commonly found in households. Here's a breakdown of the general process:
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Extraction and Washing: Sugar canes (or beets) are harvested and thoroughly washed to remove dirt and debris.
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Juice Extraction: The sugar cane is crushed or sliced to extract its juice. In the case of sugar beets, they are sliced into thin strips called cossettes, and then the sugar is extracted with hot water.
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Clarification: The extracted juice contains impurities, including mud, soil, and plant matter. The juice is clarified using various methods, such as:
- Lime Treatment: Lime (calcium hydroxide) is added to the juice, causing the impurities to precipitate out.
- Carbonatation: Carbon dioxide is bubbled through the limed juice, further removing impurities as calcium carbonate precipitates.
- Filtration: The clarified juice is filtered to remove any remaining suspended solids.
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Evaporation: The clarified juice is then evaporated under vacuum to concentrate the sugar content and create a syrup. This reduces the water content significantly.
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Crystallization: The syrup is further concentrated and seeded with sugar crystals to encourage crystallization. The process is carefully controlled to produce sugar crystals of the desired size.
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Centrifugation: The resulting mixture of sugar crystals and molasses (the remaining liquid) is spun in centrifuges. The spinning action separates the molasses from the sugar crystals.
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Drying: The separated sugar crystals are dried to remove any residual moisture. Hot air is often used for this purpose.
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Refining (Optional, but Common): This step further purifies the sugar. This may involve:
- Affination: Washing the raw sugar crystals with a concentrated syrup to remove the outer layer of molasses, which contains impurities and color.
- Melting: The washed sugar crystals are melted to form a sugar liquor.
- Decolorization: The sugar liquor is then decolorized, often using activated carbon (bone char can also be used, though this makes the sugar unsuitable for vegetarians/vegans). This removes colored impurities.
- Recrystallization: The decolorized sugar liquor is recrystallized to produce white sugar crystals.
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Grading and Screening: The refined sugar crystals are sorted by size into different grades, such as granulated, powdered, and brown sugar.
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Packaging: The refined sugar is then packaged for distribution and sale.
In summary, sugar refinement involves extracting juice, removing impurities through clarification, concentrating the juice via evaporation, forming sugar crystals through crystallization, separating the crystals from molasses via centrifugation, drying the crystals, and, optionally, further purifying the sugar through affination, melting, decolorization, and recrystallization.
