Sugar Cane Harvesting and Extraction

• Sugar is sucrose, a carbohydrate in every fruit and vegetable.
• Green plants produce sugar through photosynthesis.
• Sugar cane and sugar beet plants are used commercially for sugar production because of their high sucrose content.
• A cane plant stalk contains roughly 12-16% sucrose.

Sugar Cane Harvesting

• Sugar cane harvesting can be done manually or mechanically.
• Sugar cane fields were previously burned before mechanical harvesting.
• Green harvesting is a more effective method than burning.
• Total Soluble Solids (TSS) should exceed 16%.

Sugar Cane Juice Extraction

• Sugar cane must be crushed to extract the juice.
• The cane is usually shredded prior to crushing.
• Crushing breaks up hard nodes and flattens the stems.
• Hydraulic crushers can achieve juice extraction rates as high as 70%.

Filtration

• Non-sugars (bagasse) in juice causes discoloration and reduces sweetness.
• Filtration removes non-sugars, up to 60% with care.
• Juice can stand for hours to allow particulates to precipitate for filtration.
• Tanks should have fine mesh lids to filter particles.
• Meshes prevent insect infestation and contamination from animals and birds.
• After settling, juice is drawn without disturbing settled particulates.
• Juice is poured through cloth to filter fine particles.

Clarification

• Chemical clarification using modern cold lime sulphitation removes crystal-inhibiting impurities that can also discolor the final product.
• Lime reduces cane juice's natural acidity, which limits the formation of invert sugars.
• Juice batches are treated with milk of lime (CaO) and sulfur dioxide (SO2), then transferred to a boiling pan and quickly heated to 90°C or higher.
• Lime and heat create a heavy precipitant that flocculates and removes impurities.
• The juice is filtered and allowed to settle.
• The clear juice is decanted and transferred to boiling furnaces.

Boiling and Crystallization

• Boiling uses cascade-type furnaces in various configurations.
• Massecuite is removed at 84°Brix and about 112°C from the final boiling pan.
• Massecuite is placed in U-shaped vessels, slowly rotated, and cooled for up to 48 hours.
• Crystallization in motion is achieved through this technique.
• Rotation cools the massecuite evenly, aiding uniform crystal production.
• Seeding, which involves adding granulated massecuite from a crystallizer with already developed grains, can be implemented.
• Seeding helps promote uniform crystal growth.
• Massecuite is transferred to a centrifuge

Centrifuging

• Features a perforated inner drum inside a larger drum.
• Rapid rotation of perforated drum separates molasses from crystals.
• Water is sprayed to help remove molasses.
• Sugar crystals are transferred for drying after removal from centrifuge.
• Molasses is collected for re-boiling, crystallization, re-centrifugation to produce second, lower quality sugars or for biofuel/rum production.

Drying and Packaging

• Crystals can be dried in the sun, with solar driers, or with rotary/hopper driers that require fuel.
• The dried product is packed into bags or suitable containers for distribution.

Sugar Production Process Overview

• Harvesting → Crushing (Bagasse byproduct) → Filtration → Clarification → Boiling → Crystallization → Centrifuging (Molasses byproduct) → Drying & Packaging

Types of Sugars

• Non-crystalline sugar is a high-viscosity liquid from whole cane juice.
• Non-crystalline sugar varies from golden brown to dark brown, contains up to 50% sucrose, high levels (up to 20%) of invert sugars and up to 20% moisture with insoluble matter.
• Crystalline sugars are divided into non-centrifugal and centrifugal types.
• Non-centrifugal sugar is basic lump sugar where molasses and crystals are not separated.
• Centrifugal sugar is free-flowing granular sugar where the molasses and crystals are separated.

Non-Centrifugal Sugar (Lump Sugar)

• Concentrated cane juice product, produced in many countries for direct consumption.
• Varies from yellowish brown to dark brown and contains up to 80% sucrose, moisture, invert sugars, and insoluble matter.

Centrifugal Sugar

• Basic raw granular sugar separated from most of the molasses.
• Varies in color from golden yellow to brown and contains 94-98% sucrose.
• Juice undergoes simple clarification, boiled to a thick syrup, allowed to stand until sugar crystals are formed.
• Small crystals are separated in centrifuges and sun-dried.

Refined Sugar

• Raw sugar undergoes melting, clarification, and decolonization to produce refined sugar.
• Raw sugar is melted in a sugar melter.
• Clarification removes impurities and eliminates color.
• Refineries commonly use two types of clarification processes.

Melt Phospho-floatation

• Works by forming low-density aggregates of particles and bubbles, which float.

Melt Carbonation

• This carbonation process has two steps.
• The initial step involves the formation of a precipitate from calcium and CO2 and the second step conditions the precipitate.

Decolourization

• Color reduction will depend on the process type.
• Roughly 60-70% of the melt's input will be affected.
• Ion Exchange Resin (IER), Powdered Activated Carbon (PAC), and Granular Activated Carbon (GAC) are three decolorization processes.

Brown Sugar

• Also known as cane sugar/raw sugar.
• Its production doesn't involve a refining process.
• It's produced directly from sugarcane juice, boiled and left to cool and crystallize unlike white or refined sugar.
• Crystallization of brown sugar takes a long time, at times up to months.
• Major features are its brown color and strong taste are due to the presence of molasses.
• Refined sugar can be made into brown sugar with molasses.

Icing Sugar

• Also called confectioner's sugar or powdered sugar, granulated sugar ground into smooth powder.
• Corn starch is added to prevent clumping or caking.
• Used in baking and for making icings, confectionery, and whipped cream.

Jaggery

• Natural sweetener made by concentrating sugarcane juice or palm tree sap.
• It is a non-centrifugal sugar.
• Available in solid (lumped), liquid, and granular forms.

Jaggery Manufacturing

• Harvest sugar cane.
• Harvest matured sugarcane to achieve better quality and yield.
• Crush sugar canes via crushers to get sugar cane juice.
• Crushers were operated by bullocks and are now replaced by diesel engines.
• Juice filtration removes large impurities using cloth.
• Filtered juice is stored in a settling tank.
• Fresh sugarcane juice small impurities are removed during preheating.
• Different herbal and chemicals clarificants types are employed.
• Sugarcane juice is concentrated in a boiling pan by heating the clarified and preheated juice up to the jaggery's striking point temperature.
• To prepare solid jaggery, the clarified sugarcane juice is boiled between 116 to 120°C and filled in molds.
• For quality liquid jaggery, remove concentrate at 103-106°C.
• A temperature of 120°C yields quality granular jaggery.
• The concentrate or jaggery in the boiling pan cools in a large earthen container.
• Molding is done once the product is cool using various sizes and shapes.
• Jaggery can come in rectangular, cubic, bucket and trapezoidal shapes.
• Jaggery's packaging traditionally includes earthen pots, wooden boxes, and metal drums, but can include plastic and glass.
• LDPE pouches and composite containers are nowadays widely used.
• Jaggery storage problems is inverts of sugars and mineral salts, and being hygroscopic, leads to moisture absorption that causes jaggery to spoil.
• Edible coating, low temperature storage, PET film with 100 % nitrogen increases quality.
• Water is selectively frozen from sugarcane juice to form a concentrate.
• Juice's freezing point changes from -1.5 to -4.6°C for 20–40 minutes.
• Bagasse is recycled in composting after a 63% water removal.
• Concentrated juice is obtained at low temperature.
• Vegetative clarificants plus steam jacketed pans are used to concentrate juices.
• Improves the color of jaggery from dark brown to golden yellow.

Sugar Candy

• It is white to pale yellowish and has very sweet crystals.
• Sugarcane/palm sap is boiled to 108°C and the brix is raised to 67%.
• Concentrated syrup is allowed to crystallize slowly in metal crystallizers.
• Strings are tied crisscross to form crystals around them.
• The crystallizer is filled with syrup, covered, and buried in paddy husk up to the brim to allow undisturbed crystal formation.
• The crystallizers are kept for a month and crystals are formed on the strings.
• After a month, crystals and strings are taken out and washed via spraying water as they are centrifuged.
• Crystals are sun-dried, graded by size, and packed in polythene bags.
• It is believed to have curative value in reducing fever, curing sore throat, dry cough, eye conditions, and pregnancy complications.