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Cut sugarcane stalks

Turning sugarcane into sugar crystals at the mill: how to produce sugar 

10/10/2024 By Ben Eastick in What we do Crystallines, Sourcing, Syrups

When the harvested sugarcane arrives at the sugar mill, it undergoes multiple processes to turn it into crystalline sugar that Ragus manufactures into pure sugar ingredients for our industrial customers. In this article, we highlight the stages that occur to turn raw sugarcane into a functional crystalline sugar.  

Crushing the cane and extracting the juice 

The sugarcane arrives at the mill without leaves, as these have already been removed by the harvester, and the stalks remain. These stalks are washed, cut up and shredded before they are crushed to extract as much sugar juice as possible.  

Sugarcane being crushed in an industrial mill.

The sugarcane stalks are shredded and crushed to extract the juice.

The sugar juice is extracted from the stalks using high-pressure rollers that are capable of extreme loads. Hot water is added to improve juice extraction and maximise the amount of juice from the dry stalks, or bagasse.  

Excess bagasse is burned in the mill’s boilers to produce electricity, with the excess supplied to the local grid. The recycling of all parts of the sugarcane plant makes the processing of sugarcane for sugar products more sustainable. 

Heating and purifying the juice

Once all the juice is extracted, it needs to be purified. To do this, the juice is heated to a temperature of approximately 80°C. Lime is added to neutralise any impurities. Fine fibre particles form as scum on the surface of the juice and, along with other mineral matter, flocculate to the lime and settle as sediment. 

Industrial equipment in a mill or factory

Juice heaters are used at the purification stage to purify the juice.

Industrial equipment

The raw sugarcane passes through many processes before it becomes a product we recognise.

Evaporating to a syrup 

Once the juice has been purified, it is boiled to reduce its volume and turn it into a more concentrated, thicker liquid. Industrial evaporators boil the juice in a vacuum of between 70°C and 130°C for up to two hours. The natural water in the extracted sugar juice evaporates, leaving a thicker juice that has a more intense amber colour. This process increases the concentration of sugar in the juice, turning it into a syrup. 

Crystallisation equipment in a mill

Crystallisation is an important step in the sugarcane manufacturing process. At the crystallisation stage, the syrup is seeded with crystals.

Crystallisation 

Crystallisation is an important step in the journey towards the final saleable sugar product. To start this process, the juice-syrup produced in the last step is seeded with tiny sugar crystals and boiled in a vacuum. It’s this seeding process that allows the sugar crystals to develop into a richly saturated massecuite syrup. 

At this stage of the cane sugar manufacturing process, the flavour, colour and aroma of molasses begins to form. 

Industrial centrifuges (left), a worker in a factory (right)

Industrial centrifuges are used for the sugar crystals and syrup separation (left), and the crystals may be checked manually (right) and graded.

Separating the crystals  

The massecuite syrup is spun at 1,050 rpm for two minutes to separate the crystals from the liquid. The separated syrup still contains a lot of sugar, so it’s spun a varying number of times. Different amounts of spinning help to produce the different sugars with their signature colours, such as demerara sugar.

The first and second spins produce dark and light muscovado sugar. The third and fourth spins produce demerara and golden granulated sugars, with the lighter sugars being shipped for white sugar refining. 

The sugar drying, sieving and bagging process 

Once the sugar crystals are separated, they are passed through drum rotating driers before cooling. Hot air is blown into the drier to remove moisture from the sugar crystals.  

Three men chatting by industrial machinery in an industrial setting

Crystalline sugar passes through horizontal drum rotating driers before being packed.

The sugar crystals are then passed over a vibrating screen and through a rare earth magnet as part of a sieving process to remove foreign particles before being packed into bags. With that important step complete, raw sugar is loaded into lorries for delivery to the port terminal for shipment to markets across the world. 

Worker with hard hat in a factory setting assessing bags of product

Bags of crystalline sugar are stored ahead of being transported.

Ragus sources sugarcane responsibly and manufactures pure sugar crystalline and syrup ingredients in bulk for food and beverage brands. To learn more about our products, please contact our Customer Services Team, or continue browsing SUGARTALK and follow Ragus on LinkedIn.  

Ben Eastick

A board member and co-leader of the business, Ben is responsible for our marketing strategy and its execution by the agency team he leads and is the guardian of our corporate brand vision. He also manages key customers and distributors.

In 2005, he took on the role of globally sourcing our ‘speciality sugars’. With his background in laboratory product testing and following three decades of supplier visits, his expertise means we get high quality, consistent and reliable raw materials from ethical sources.

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