Introduction
Sugarcane is a fleshy, tall perennial grass crop that grows fast infertile tropical soils (Sheridan, 2000). Physical and climatic factors such as temperature, soil, rainfall, and other factors largely affect its growth (Sheridan, 2000). The crop’s origin can be traced to South Asia and Southeast Asia, where it was first grown as early as the 7th Century (Galloway, 2005). In about the 18th Century, there was only one variety of sugarcane known as Saccharum officinarum, which was indigenous to the South Pacific, and was commonly known as Creole cane. After a detailed study of the crop, British planters introduced an improved cane variety known as “Bourbon” or “Otaheite” (Davis, 2006).
The Creole crop had a usual height of between four and eight feet and had stalks of varied thickness from one and a half to three inches (Galloway, 2005). These aspects of sugarcane were all dependent on the perfection of light and spongy deep soils supplied with sufficient rainfall and sunlight (Sheridan, 2000). From India, there were several varieties, such as Saccharum Barberi and Saccharum edule, that grew in different areas. The first variety, Saccharum officinarum, was a native crop of New Guinea (Sheridan, 2000).
The thick stalk of sugarcane stores sugar and sucrose in sap form. This was the main interest of the people who cultivated the crop (Galloway, 2005). Sugar is extracted from the sap by evaporating the liquid part of the sap. This method was used for the first time in India more than five thousand years ago; hence, India had its first sugar during that time (Galloway, 2005).
Sugarcane cultivation was introduced in the Americas by Christopher Columbus during his voyage. Later, the cultivation spread to countries in South America and the Caribbean, such as Jamaica, Barbados, Guadeloupe, the Dominican Republic, Belize, and Brazil.
In spite of its origin in Asia, South America embraced the cultivation of sugarcane so much that production in the region soon overtook that of South and South East Asia, and the activity spread to other countries of the world too (Williams 2006). Today, more than 200 countries in the world grow the crop, producing 1,324.6 million tons. Comparing production by country, Brazil leads followed by India with reference to 2005 rankings.
Sugarcane is used in the production of a variety of products and by-products such as sugar, molasses, rum, soda, and bagasse (Hutchinson, 1957).
Cultivation and harvesting of sugarcane
Unlike many crops, sugarcane is propagated from cuttings rather than from seeds (Raphael, 1983). Although few varieties still produce seeds, modern methods of stem cuttings have become the most common method of propagating the crop (Raphael, 1983). Each of the cuttings for propagation must contain at least one bud, and planting of the cuttings is done by hand (Raphael, 1983). The cuttings reproduce prolifically; hence, several harvests can be done on a set of cuttings planted just once. When the fully-grown sugarcane is cut, new ones sprout from the cut stems. These are called ratoons. Several harvests are obtained from one set of planted cuttings, and the magnitude of harvest dwindles as more and more harvesting is done (Raphael, 1983).
Harvesting of sugarcane is done manually in many countries but is mechanized in some. Harvesting by hand accounts for more than half of the world’s production of sugarcane, especially in developing countries (Raphael, 1983).
In situations where hand harvesting is practiced, some of the sugarcane plantations are set on fire so as to clear the dry leaves of sugarcane as well as scare away poisonous snakes that are commonly found in sugarcane fields. The fire, however, does not damage the water-rich stalks. In some countries, sugarcane is just harvested without subjecting the plantations to fire (Raphael, 1983). The process of harvesting is done by skilled men who use cane knives or machetes to clear the cane plantations by cutting each cane just above the ground level. It is estimated that a skilled harvester can cut 500 kg of sugarcane in one hour (Sachs and Collins, 1989).
When mechanical harvesting is done, a combined harvesting machine is used. The blades of the machine cut the sugarcane stalks at the base (Raphael, 1983). The machine then separates the canes from the leaves and piles them into a haul transporter to take transport them to the factory for processing (Raphael, 1983). These later stages are done manually and by use to tractors if the harvesting process is not mechanized.
Chain of processing for sugar production
Most sugar factories are usually located within close proximity to sugarcane plantations. At the processing factory or sugar mill, the sugarcane is washed and then chopped or shredded into fine pieces by revolving blades (Galloway, 2005). The fine pieces are mixed with water several times and crashed between rollers (Galloway, 2005). The resulting juice or sap contains between ten and fifteen percent sucrose, while the rest of their composition is usually fibrous solids that are identified by the name bagasse (Galloway, 2005). When the bagasse is burned, it produces energy, which surpasses the processing factory’s needs. Bagasse can also be burned to generate electricity to supply the neighboring areas (Sheridan, 2000).
The juice is then limed to adjust its pH to a neutral value of seven. This process arrests the decay of sucrose into glucose and fructose. In addition, it precipitates out some impurities (Sachs and Collins, 1989). The neutral mixture is then allowed to settle, and the clear juice is drawn into a multi-effect evaporator to make syrup containing about 60 percent sucrose (Sachs and Collins, 1989). The syrup is further concentrated in a vacuum until it is supersaturated. Upon supersaturation, the syrup is seeded with crystals of sugar, such that when the contents cool, sugar forms as crystals out of the syrup (Sachs and Collins, 1989). The contents are then centrifuged in order to separate sugar from the remaining liquid referred to as molasses.
Raw sugar is usually yellow or brown in color. However, if sugar is desired white, sulfur dioxide is bubbled through the cane juice just before it undergoes evaporation (Sachs and Collins, 1989). This process ensures that many color-forming substances or impurities in the juice are bleached to colorless ones. The resultant white sugar is referred to as mill-white sugar (Sachs and Collins, 1989).
Sugar refining
The brown or white sugar is usually impure and may have to undergo further processing to refine it. In sugar refining, the sugar is mixed with syrup and then centrifuged (Sachs and Collins, 1989). The efficacy of this process involves washing away the coating of raw sugar crystals. The remaining sugar is then dissolved to make syrup before being allowed to crystallize again (Sheridan, 2000).
Distribution of sugar
From the factory, sugar is usually packed into large bags and kept in depots to await access by wholesalers. Some sugar factories also package the sugar into smaller units to facilitate access by retailers, who then sell them to consumers. Consumers can also access sugar through the wholesale store, which offers both retail and wholesale services. Alternatively, some sugar factories may set up their own retail outlets to avoid hoarding of sugar in case there a looming shortage of sugar is foreseen.
Transportation of sugar from factories to wholesalers, retailers, or consumers is usually done by rail, water, road, or air depending on the bulk of the cargo, distance to be covered, and the urgency of need of sugar in given localities.
Consumption
Sugar is one of the commodities that have very diverse markets. Sugar is used in homemade beverages such as coffee, tea, cocoa, and so on. There is a wide range of beverages, and anyone who uses a particular beverage is likely to have a taste of sugar. Nonetheless, sugar is not just used in beverages; it is used in industries that manufacture ethanol, pastries, sweets, and chewing gums. Soda manufacturers also use sugar as one of their raw materials (Mars, 2000).
Sugar is, therefore, an all-time food item. If it is not taken as a beverage, it is taken in a sweet, toffee, chewing gum, or pastry. Cane ethanol, which is a by-product of sugar processing, is also used in large applications in the production of biofuel, which is an alternative to gasoline.
Labor issues in the field
In many countries of the world, particularly the developing nations, sugarcane production is too manual, and this exposes the participants to a lot of hard labor. The processes of tilling the land, harrowing, preparation of cuttings, and application of fertilizer are time demanding and labor-intensive (Hutchison, 1957). In addition, the sugarcane crop has to be given secondary care to enable it to flourish into a bumper crop (Hutchison, 1957). This exposes the staff involved to risks such as contact with fertilizers and harmful pesticides. There are many environmental concerns over the use of pesticides and fertile. Apart from being harmful to the users, in the long run, these chemicals also accumulate in the environment and, particularly in the soils, and cause havoc (Millennium Ecosystem Assessment, 2005). For instance, some of the pesticides used in sugarcane plantations contain heavy metals, which are harmful to aquatic organisms (Millennium Ecosystem Assessment, 2005). Harvesting and transportation of sugarcane too are tedious processes that need the intervention of machines.
In the factory, a lot of water is used for cleaning the machines and mixing the chemicals used in the production line. In addition, water is also used for cooling machine parts that constantly become hot (Carter, 2005). The bagasse and molasses produced in the factory too have to be cleaned and disposed of. All the chemicals used and the resultant effluents, therefore, ultimately end up in water bodies such as rivers, lakes, or streams (Millennium Ecosystem Assessment, 2005). Pollution of high magnitude results from such operations and causes high levels of chemical oxygen demand and biological oxygen demand of water. Toxic substances may as well cause harm to aquatic organisms such as fish (Millennium Ecosystem Assessment, 2005).
Atmospheric pollution during sugar processing can also not be gainsaid. Sugar factories usually have huge clouds of smoke billowing above them. This is not a good environmental characteristic of air in the purview of the health of humankind and other organisms. Noise pollution too results from sugar factories as they undertake their operations.
To the consumers, over-consumption of sugar increases the chances of diseases such as diabetes, anemia, arthritis, and allergies (Mars, 2000).
Conclusion
Sugar is a commodity whose production starts right from the farm when sugarcane cuttings are propagated. The processes of growing sugarcane and processing sugar are labor-intensive in most countries of the world. Processing is also a long process that requires a lot of attention. Consumption of sugar is almost ubiquitous, and this necessitates fast distribution. Many concerns are associated with the production of sugar, notably labor-intensive procedures and pollution as a result of processing. Over-consumption of sugar is also linked to various disorders in the health of human beings.
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