By: Aamarpali Puri
Sugarcane (Saccharum) is a genus of between 6-37species (depending on taxonomic interpretation of tall grasses (family Poaceae, tribe Andropogoneae), native to warm temperate to tropical regions of the Old world. They have stout, jointed fibrous stalks 2-6m tall and sap rich in sugar. All the species interbreed, and give the major commercial cultivars hybrids. Given below is the scientific classification and some species of sugarcane plant.
Sugar cane is mainly composed of water, as well as a solid part, which is composed of fiber and soluble solids. The hard rind of the cane protects a softer fibrous center. The fibrous center serves as a reservoir for sugar as the cane ripens. Saccharose, fructose, glucose and other minor components such as: minerals, proteins, wax, fat and acids are among soluble solids present in sugarcane. The most important inorganic compounds within sugar cane juice are silica, potassium, sodium, lime, magnesium, iron, phosphorous, sodium acid and chlorine. The proportion of each component depends on the variety, soil type, agricultural management, age and weather factors etc. All of these factors may be altered during the growth process and makes it difficult to obtain a homogeneous product. Cane sugar, cane syrup, molasses, wax and alcohol are products of sugarcane.
Sugarcane cultivation requires a tropical or subtropical climate, with a minimum of 60cm (24in) of annual rain. Sugarcane is propagated from cuttings, rather than from seed. Once planted, a stand of cane can be harvested several times; after each harvest, the new stalks come up, called rations. Usually, each successive harvest gives a lesser yield, and eventually the declining yields justify replanting. Sugarcane is harvested either by hand or mechanically.
By careful selection and breeding, sugar cane has become one of the most efficient converters of solar energy into food carbohydrates and fiber. It is able to convert as much as 2% of incident solar energy into biomass. The largest producers of sugar cane are Brazil, India, and China. Brazil is a major grower of sugar cane where it is used to produce sugar as well as to provide the alcohol used in making gasohol and biodiesel fuels. In India the maximum yield of sugarcane is obtained in Coimbattore. It is the only place in India where seed formation takes place in sugarcane.
Brief details of the manufacture of sugar from sugarcane:
Usually the sugar is obtained from the cane at mills located near centers of production. Sugar cane is the source of sugar in all tropical and subtropical countries of the world. In a sugar mill, sugarcane is washed, chopped and then shredded by revolving knives. The shredded cane is then repeatedly mixed with water and crushed between rollers: the collected juices contain 10-15%sucrose, while the remaining fibrous solids, called bagasse, are burnt for fuel. Bagasse makes a sugar mill more than self-sufficient in energy; the surplus bagasse can be used for animal feed, in paper manufacture, or burnt to generate electricity for the local power grid.
- Extraction of juice
- Purification or defecation of the juice
- Evaporation of the juice to syrup point
- Concentration and crystallization of the syrup
- Curing or preparation of the crystals
After crystallization raw sugar is obtained, which is later refined in the sugar mills. The resulting white sugar is utilized for local consumption. The syrup is further concentrated under vacuum until it becomes supersaturated, and then seeded with crystalline sugar. Upon cooling, sugar crystallizes out of the syrup.
The clarified juice is then concentrated in a multiple-effect evaporator to make a syrup about 60 wt% in sucrose.
The second operation is the coagulation of the albumen, and the separation of it with other impurities from the juice, which holds them in suspension or solution. The moment the juice is expelled from the cells of the canes, chemical inversion commences, and the sooner it is stopped the better it is. So the cane juice is next mixed with lime to adjust its pH at 7. This arrests sucrose’ s decay into glucose and fructose, and precipitates out some impurities. The mixture then sits, allowing the lime and other suspended solids to settle out. The juice is extracted from canes by squeezing them between rollers. Canes vary very much in respect of the quality and also as to the quantity of the juice they contain. The quantity of the juice is the test to which recourse must be had in judging the efficiency of the extraction, while the quality is the main factor, which is taken into account with regard to the results of subsequent manufacture.
Sucrose: The white stuff commonly known as sugar, is sucrose, a molecule composed of 12 atoms of carbon, 22 atoms of hydrogen, and 11 atoms of oxygen (C11H22O11). Sugar crystal is an orderly arrangement of sucrose molecules. Sucrose is actually two simpler sugar molecules stuck together: fructose and glucose. It is carbohydrate and is found naturally in sugarcane and sugar beets in abundance. Sucrose is the main carrier of energy from one part of the plant to another, in all plant life. In this way it fulfills a role in the plant similar to that of glucose in the animal.
Medicinal value of sugar:
Refined sugar has been pulled out as something close to poison charged with diabetes, teeth decay, diabetes, cardiovascular diseases, yeast infections, hypoglycemia, obesity and hyperactivity etc but numerous scientific studies have time and again confirmed that consumption of sugar does not cause chronic diseases, such as obesity, diabetes, heart disease and hyperactivity, nor does it contribute to deficiency in the diet by displacing other more valuable nutrients. According to the American Dietetic Association (ADA) all foods have a place in a balance diet and having sugar in regular diet is okay, as long as one eats a healthful diet and balances the extra calories. Sucrose (sugar) is antidote, antiseptic, bactericide, cardio tonic, demulcent, diuretic, intoxicant, laxative, pectoral, piscicide, refrigerant and stomachic. It is folk remedy for arthritis, bedsores, boils, cancer, colds, cough, diarrhea, dysentery, eyes, fever, hiccups, inflammation, laryngitis, opacity, penis sores, skin sores, sore throat, spleen, tumors and wounds (Duke and Wain, 1981). It is used as a preservative for fruits and meats.
Sugarcane as foodstuff:
In most countries where sugarcane is cultivated, there are foodstuffs and popular dishes derived from it. On account of it’s standard crystal size, color and consistency sugar is considered best sweetener. It enhances flavor of bread. In jams, jellies it inhibits the growth of yeast and molds. It inhibits browning of canned fruits. Direct consumption of raw sugarcane cylinders or cubes, which are chewed to extract the juice and the bagasse, is spit out. Freshly extracted juice (garapa, guarab, guarapa or caldo de cana) by hand or electrically operated small mills, with a touch of lemon and ice, makes a delicious and very popular drink. Cane syrup contains lots of vitamins and minerals. It is laden with vital nutrients. It is free from harmful preservatives, flocculants, surfactants, bleaching agents and viscosity reducers. Molasses is used as a sweetener and also as syrup accompanying other foods, such as cheese. Rapadura, a candy made of flavored solid brown sugar in Brazil, which can be consumed in small hard blocks, or in pulverized from (flour), as an add-on to other desserts.