Sugarcane is an economically important crop globally, as it is the primary source of table sugar. Sugarcane Extract from sugarcane accounts for over 75% of the world’s sugar production. Understanding the process of rooting sugar from sugarcane is crucial to meeting global demands.
The birth of sugar from sugarcane involves multiple way harvesting and preparing the sugarcane, rooting the juice, clarifying and filtering the juice, concentrating the juice through evaporation, shaping the sugar, and separating and purifying the sugar chargers. This post will give an overview of each step.
Sugarcane is a tall, perennial grass that typically matures in 12-16 months, at which time it contains a high concentration of sucrose in its stalks. Ideal harvest time is determined by factors like sucrose content, fiber levels, and stalk growth.
Harvesting methods involve either manual cutting of the stalks near ground level or mechanized cutting of stalks followed by residue removal through controlled burning. Cut stalks are neatly stacked and transported for processing.
Preparation of Sugarcane for Extraction
At the mill, sugarcane stalks are thoroughly washed and cleaned to remove any residual soil and debris. Additional chopping may occur to cut the stalks into manageable lengths if needed.
Mechanical shredder mills equipped with revolving knives are then used to crush the washed stalks into small fibers to expose the sugar-containing parenchyma tissues.
Sugarcane Juice Extraction from Sugarcane
A series of heavy-duty crushers are used to press and grind the sugarcane fibers. Rollers crush the fibers and squeeze out the juice while grinders and shredders break down any remaining solids. This results in the extraction of up to 50% of the stalk’s weight in juice.
The extracted cane juice contains 10-15% sucrose as well as other sugars, minerals, proteins, and plant fibers. The design of the mill maximizes juice extraction while minimizing the amount of solids extracted.
Juice Clarification and Filtration
The freshly extracted cane juice contains impurities that can disrupt the crystallization process. Treatment steps are used to remove suspended solids, colloids, and other non-sugars. Methods include heating, liming, flocculation, decantation, and skimming off solids.
The clarified juice then undergoes filtration through press filters of bone char, cloth, or other media. This removes fine particles and helps decolorize the juice.
Evaporation and Concentration
Clarified juice is evaporated in a series of vessels to remove excess water and concentrate the sucrose. This involves multiple stages of boiling under vacuum conditions to lower the boiling point and prevent caramelization.
Concentration continues until a supersaturated sugar syrup results, reaching 65-85% dissolved sucrose. Further water removal will cause crystallization in the evaporators.
Crystallization and Separation
The concentrated syrup is transferred to crystallizers where careful cooling and agitation induces nucleation and crystallization of sucrose. Temperature, rate of cooling, and residence time are controlled to produce the desired size and number of crystals.
The resulting sugar crystal and syrup mixture is spun in a centrifuge to separate the crystals from the mother liquor which contains impurities and uncrystallized sucrose.
Refining and Purification
The separated raw sugar crystals undergo additional steps of remelting, recrystallization, decolorization, filtration, and drying to remove any remaining impurities and produce pure white sugar.
Multiple recrystallization steps are performed to increase purity. Bleaching agents are sometimes used to remove any residual color. The refined sugar crystals are then dried to a low moisture content.
How do they extract sugar from sugarcane?
The key steps in extracting sugar from Sugarcane Extraction are:
1. Harvesting - Sugarcane is manually or mechanically cut at the base of the stalks when the plants reach maturity.
2. Milling - The sugarcane stalks are washed, chopped and milled between heavy rollers to extract the sugar-rich juice.
3. Clarifying/Filtering - The cane juice is heated and treated with lime to coagulate impurities which are filtered out.
4. Evaporating - The clarified juice is concentrated by boiling off water under vacuum conditions.
5. Crystallizing - The concentrated syrup is cooled and agitated to induce sucrose crystal formation.
6. Centrifuging - The sugar crystal and syrup mixture is spun in a centrifuge to separate the crystals.
7. Refining - The raw sugar undergoes multiple recrystallization and filtration steps to increase purity.
How much sugar can be extracted from sugarcane?
On average, every 100 kg of harvested sugarcane stalks will yield approximately:
- 50 kg of extracted cane juice
- 8 to 15 kg of sucrose sugar
- 65 to 85% purity after single crystallization
The actual sugar extraction efficiency depends on the sucrose content of the particular sugarcane variety and growth conditions. Modern extraction in a well-equipped mill can recover over 90% of the sucrose present in the cane.
With optimal crystallization, up to 12-13% of the original sugarcane weight is extracted as raw sugar. Further refining and recrystallization can increase purity to over 99.9% sucrose content.
What is used to separate sugar from sugarcane?
There are several key steps involved in separating sugar crystals from the sugarcane plant:
- Milling: Heavy rollers crush sugarcane stalks to press out the sugar-containing juice.
- Clarification: Heat and lime are used to coagulate impurities in the extracted juice.
- Filtration: The clarified juice is filtered through media like bone char or cloth.
- Crystallization: Concentrated syrup is cooled and agitated to induce sucrose crystal formation.
- Centrifugation: A centrifuge spins the sugar crystal and syrup mixture, forcing the denser crystals to separate from the liquid.
- Recrystallization: Raw sugar is re-dissolved, re-crystallized and filtered repeatedly to increase purity.
So mechanical, chemical, and physical separation techniques are all utilized to extract and purify the sucrose crystals from sugarcane.
How do you separate sugar crystals from sugarcane?
There are several steps involved in separating sugar crystals from Sugarcane Extract:
1. Crush the harvested sugarcane stalks using heavy rollers to extract the sugar-rich juice.
2. Clarify the extracted juice using heat and lime to remove impurities.
3. Filter the clarified juice through media like bone char or cloth to remove fine particles.
4. Concentrate the filtered juice by evaporating water to form a supersaturated sugar syrup.
5. Cool and agitate the syrup to induce crystallization of the sucrose.
6. Spin the mixture in a centrifuge which forces the denser sugar crystals to separate from the liquid mother liquor.
7. Rinse the separated raw sugar crystals with water to remove residual syrup.
8. Recrystallize the raw sugar by dissolving, reforming crystals and filtering to increase purity.
So a combination of mechanical, chemical, and physical separation processes are used to extract and isolate the sucrose crystals from the original sugarcane plant.
What is the best way to separate sugar?
The most effective method for separating sugar on an industrial scale is via centrifugation. The steps include:
- Crystallizing the sucrose by cooling and agitating a concentrated sugar syrup. This forms many small sugar crystals with syrup residue.
- Loading the crystal/syrup mixture into a large centrifuge basket.
- Spinning the basket at high rotational speeds up to 1200-1600 rpm.
- The centrifugal force causes the denser sugar crystals to move outward through the syrup to the basket wall.
- The liquid syrup remains behind and flows out through screened openings.
- The accumulated sugar crystals are washed with water to remove residual syrup.
Centrifugation allows rapid, continuous separation of large quantities of sugar crystals compared to other techniques. It takes advantage of the density difference between the crystalline and liquid phases. This mechanized separation method is efficient and cost-effective.
How do you remove sugar crystals?
Here are some common methods for removing sugar crystals:
- Dissolving in a liquid solvent like water, then decanting or filtering to recover the crystals. The water can be evaporated off.
- Gentle mechanical separation by sifting, scraping or brushing off loose crystals. Vibration may help dislodge adhered crystals.
- Using temperature differentials - heating may melt crystals for easy pouring off, while cooling may make them brittle for removal.
- Centrifugation spin forces denser crystals to separate from surrounding liquid and collect on container walls.
- Magnetic separation if the crystals contain iron impurities that respond to magnetic fields.
- Vacuum aspiration uses suction to draw crystals away from a surface.
- Sonification uses high-frequency sound waves to dislodge crystal buildup.
The best method depends on the type of crystals, their location, what they are adhered to, and desired recovery purity. A combination of techniques may be required.
In summary, extracting sugar from sugarcane is a multi-step process involving harvesting, milling, clarifying, crystallizing, centrifuging and refining procedures. Careful control is needed at each stage to maximize sucrose recovery and purity. Sugarcane’s high natural sugar content makes it an ideal industrial source for meeting global sugar demand.
As one of the world’s major crops, sugarcane production and sugar refining processes are important to overall food supplies and economies. Further research continues to improve sugar yields and sustainability practices for sugarcane agriculture. With rising populations and sweetener needs, sugarcane will remain an invaluable global commodity into the foreseeable future.
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