Sugarcane Manufacture
Table Sugar is one of the staple foods that is found in many of our dining tables. It is also used for baking, beer and winemaking, in medicines and many other manufacturing processes. I have lived in sugarcane producing areas and have witnessed first-hand the process of growing, harvesting and processing of sugarcane into table sugar.
At maturity (about seven months since planting), sugarcane is harvested by a mechanical harvester by cutting it into about 30 cm long pieces which are then transported to the sugarcane mill. At the mill, the cane is weighed and later cleaned by flooding the carrier with warm water or by spreading it on mixing conveyors that pass through strong water jets and combing drums. The canes are then shredded. After this, the juice extraction process starts, which involves breaking the cane stalks with two or three heavily grooved crusher rollers to extract a large part of the juice. The extracted juice has impurities and to remove them, lime is added into the juice and then heated. Lime helps in neutralizing the extracted juice, which is often acidic (Panda, 2011). The final clarified juice is made up of about 85 per cent of water. Heating, on the other hand, coagulates the albumin and some fats, waxes and gums. The sugarcane leftovers are used as fuel in the furnaces of the sugarcane mills.
The water from the juice is later evaporated through vacuum evaporation to form a syrup. This is followed by crystallization. The syrup is evaporated in a single-stage vacuum pan and passed through a UV light sterilizer. Evaporation happens until the syrup is saturated with sugar. At this point, small grains of sugar known as seeds are added to the pan. Seed helps with the formation of sugar crystals. Additional syrup is added to the mixture and evaporated so that the original sugar crystals that were made can grow into bigger sizes. This growing of crystals continues until the pan is full. This dense mixture known as massecuite is later discharged into large containers called crystallizers. The mixture is stirred slowly and cooled for crystallization to continue. Molasses is later separated from the raw sugar through a process known as centrifugaling
Centrifugaling involves putting the massecuite into high-speed revolving machines known as centrifugal. A centrifugal machine is made of a cylindrical basket suspended on a spindle, with perforated sides lined with wire cloth, inside with metals sheets containing many perforations (Chen, 1993). The sugar crystals are retained at the baskets as they revolve at high speeds while the molasses goes through the lining( due to the exerted force at the centrifugal). The molasses are put in large storage tanks while the sugar is sent into the granulator for drying.
Drying involves tumbling the damp sugar crystals through heated air in a granulator. Once dry, the sugar crystals are sorted bt sizes through vibrating screens and later put in storage bags. Sugar is then packed ready for sale in the stores. It can also be packaged in bulk or in liquid to be used in industries. Molasses, on the other hand, can be used as livestock feed, in alcohol production in factories. It can also be used to make yeast, organic chemicals and rum.
At the grocery stores, sugar comes in different types as follows; Granulated sugar has all the molasses removed, giving it the white colour. This type is often used for baking and other home-based uses. Brown sugar is has some molasses retained, the more the molasses, the darker the sugar. This sugar is often used in the industries, especially the beverage-making factories. Golden sugar is a less-processed form of granulated sugar. Much of the the naturally occurring molasses is retained and used as the regular table sugar. Powdered or confectioner’s sugar is often light, and in a fluffy form which is produced after the granulated sugar is further ground. Cornstarch is added to prevent clumping. Raw sugar, on the other hand, has large crystals because there minimal filtering and a large amount of molasses is retained (Board, 2012).
References
Board, N. (2012). Manufacture of Food & Beverages (2nd Edn.). NIIR PROJECT CONSULTANCY SERVICES.
Chen, J. C., & Chou, C. C. (1993). Cane Sugar Handbook: A Manual for Cane Sugar Manufacturers and Their Chemists. John Wiley & Sons.
Panda, H. (2011). The Complete Book on Sugarcane Processing and By-Products of Molasses (with Analysis of Sugar, Syrup and Molasses). ASIA PACIFIC BUSINESS PRESS.