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How is sugar made from sugarcane?

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Quick answer

Sugarcane stalks are shredded and crushed between heavy rollers to extract their sweet juice. The juice is cleaned with lime and heat, boiled down in evaporators, then concentrated in vacuum pans until sucrose crystals form. Centrifuges spin the dark molasses away, and the remaining crystals are dried and packed as sugar.

Sugar is made from sugarcane by crushing the stalks to squeeze out sweet juice, cleaning that juice with lime and heat, and boiling it down until sucrose crystals form. A centrifuge then spins the crystals free of the dark syrup called molasses, and the crystals are dried into sugar.

Step by step

  1. Mature sugarcane is harvested, cut into pieces and shredded so the juice-filled cells are opened up.
  2. Heavy roller mills crush the shredded cane while water is sprayed on, extracting juice and leaving fibrous bagasse.
  3. The juice is heated and mixed with lime so impurities clump and settle, leaving a clear, golden liquid.
  4. Multiple evaporators boil off most of the water, and vacuum pans thicken the syrup until sugar crystals grow in it.
  5. Centrifuges spin off the molasses, and the damp crystals are dried with warm air before being graded and bagged.

Key things to understand

  1. Sugarcane stores sucrose in the juicy tissue of its stalks, made by photosynthesis in the leaves and moved downward.
  2. Mills shred the cut cane and press it through heavy rollers, separating sweet juice from the fibrous leftover called bagasse.
  3. The juice is heated and treated with lime, which makes soil, wax and other impurities settle out as mud.
  4. Evaporators boil off most of the water, and vacuum pans concentrate the syrup further until sucrose crystals grow.
  5. Centrifuges spin the crystal-syrup mix so molasses passes through a fine screen, leaving raw sugar crystals behind for drying.

Labelled diagram

  1. Crushing

    Roller mills squeeze juice from shredded cane, leaving fibrous bagasse behind.

  2. Clarifying

    Lime and heat make impurities settle out of the raw juice as mud.

  3. Evaporating

    Boiling removes most of the water, turning thin juice into thick syrup.

  4. Vacuum pan

    Syrup boils at low temperature until sucrose crystals grow to the right size.

  5. Centrifuge

    Fast spinning flings molasses off, leaving sugar crystals to be dried and packed.

From cane stalk to sugar crystal

Real-world examples

  • Sugar mills in Uttar Pradesh and Maharashtra crush cane during the winter season to produce much of India's sugar.
  • Village kolhus in India boil fresh cane juice in wide open pans to make jaggery instead of white sugar.
  • Molasses from sugar mills is fermented in distilleries to make ethanol for blending into petrol.
  • Brazil, the world's largest sugar producer, also channels much of its cane juice into ethanol fuel.

Common mistake

✗ Myth: Brown sugar is unrefined and much healthier than white sugar.

✓ Fact: Most commercial brown sugar is refined white sugar with a little molasses added back for colour and flavour. Its extra minerals are tiny, and its calories and effect on blood sugar are almost the same as white sugar.

People also ask

What is molasses and how is it made?
Molasses is the thick, dark syrup left after sugar crystals are separated from boiled cane juice in a centrifuge. It holds the sugar that would not crystallise, along with minerals and plant compounds. Mills often re-boil it to recover more sugar, and the final molasses is used for ethanol, animal feed and baking.
How much sugar comes from one tonne of sugarcane?
A tonne of sugarcane typically yields roughly 100 to 120 kilograms of sugar, depending on the cane variety, its maturity and the mill's efficiency. Sugar recovery in India is often around 10 to 11 percent. The rest becomes bagasse, molasses, filter mud and water evaporated during processing.
Is jaggery healthier than sugar?
Jaggery contains small amounts of minerals such as iron and potassium because the molasses is not removed, so it is slightly less refined. However, it is still mostly sucrose and supplies similar calories. It raises blood sugar much like white sugar, so people managing diabetes should treat both cautiously and seek a doctor's advice.
Why is sugar boiled under vacuum?
Lowering the pressure lets the syrup boil at a much lower temperature, around 65 to 70 °C. That avoids scorching and browning the sugar while still evaporating water fast enough to grow clean crystals.
What happens to the bagasse?
The dry fibre left after crushing is usually burned in the mill's own boilers to produce steam and electricity. It can also be turned into paper, board or biodegradable food containers.
How is jaggery different from white sugar?
Jaggery, or gur, is cane juice boiled down in open pans until it solidifies, without separating the molasses. It keeps its minerals and brown colour, while white sugar is almost pure crystallised sucrose.
How does white sugar become so white?
Colour comes from molasses and plant compounds clinging to raw crystals. Refining washes, filters and decolourises the sugar, often using carbon or other treatments, then recrystallises it into pure white sucrose.

Part of the guide: Food & Kitchen Science →