Sugar begins life as a tall, bamboo-like grass called sugarcane. It thrives in warm, sunny places with plenty of water. Most of Australia’s sugar comes from sugarcane grown in North Queensland, Australia.
A sugarcane plant makes sugar in its leaves through the process of photosynthesis. The plant uses the sun’s energy to transform carbon dioxide and water into oxygen and glucose (a type of sugar). Any excess is stored in the form of a sweet juice found in the plant's fibrous stalks.
Growing and harvesting sugarcane
A sugar cane crop usually takes between 9 – 16 months to mature and can reach up to four metres. A machine plants sections of the stalk (called setts) underground, and these sprout into new plants after two to four weeks. After reaching maturity, the cane is harvested by machines that cut it into 30cm pieces called billets, which are collected and transported to the mill. Sugar cane can regrow 3 - 4 times, giving multiple harvests from a single plant!
Milling Sugar
Once the cane arrives at the mill it is shredded to break the fibrous stalks apart, crushing the cells of the plant that contain the sweet juice. The juice is separated and the leftover fibrous material fuels the mill's furnaces. Lime is added to the extracted juice and it is heated to remove impurities, then boiled down into a concentrated syrup.
Following this, the syrup is crystalised by spinning through a centrifuge. Once dried, the crystals are transferred to storage or transported to a refinery. The ‘raw’ sugar at this stage is not considered food grade yet.
Refining sugar
The 'raw' sugar from the mill arrives at the refinery where it is mixed with hot syrup to soften the hard molasses coating on the outside of the sugar. After this, the syrup is spun in another centrifuge which removes 50% of the colour from the raw sugar and it is melted into a liquor.
This liquor is then purified and cleaned, with any excess water being evaporated off. It passes through a UV light steriliser and goes through a final centrifuge to crystalise before being dried. The refinery is where raw sugar is converted into the many types of sugar products we know and use.
How much water is used to grow sugar cane?
Sugar cane is usually grown in areas with high-rainfall as this is what is needed for it to grow well. If rainfall is low, growers use irrigation to make sure the plant gets enough water, and many growers reuse their irrigation to conserve water. For every 100mm of soil water used by the sugarcane plant, about ten tonnes per hectare of sugarcane can be produced.
There’s a lot that goes into growing sugar cane, and sugar cane farmers work hard to use every part of the plant along with the by-products of production, in order to make production more sustainable.
Next time you’re enjoying a sweet treat, remember the long journey sugar makes from sun-soaked sugarcane fields to your plate. Sugar truly is a versatile ingredient, and its production is a fascinating example of agricultural science at work.
