Refining and Processing Sugarcane

Sugarcane is a tropical grass that is cultivated in warm, moist climates. The canes grow from a little less than a year to close to three years before harvest, each cane growing to between 10 and 20 feet (3 and 6 m) high. Raw cane sugar contains 12 to 14 percent sucrose. Sugarcane is produced in the United States in Florida, Louisiana, Hawaii, and Texas. The production process occurs in two locations: at sugar mills and sugar refineries. The plants are harvested by cutting the cane off close to the ground with machines or, in some areas, by hand, using a machete. The leaves are stripped off the stalks, which are transported to a sugar mill. The refining process begins by crushing and shredding the stalks. The resulting material is passed through and pressed under a series of heavy rollers to extract the cane juice. The waste product left from this process is called bagasse and is most often used as fuel to run the mills; it is also processed into paper. The cane juice is clarified by adding milk of lime (made from limestone) and carbon dioxide. As the carbon dioxide creates bubbles, the lime forms calcium carbonate. These chalklike crystals bubble through the mixture, attracting the nonsugar matter such as wax, fats, and gums away from the juice. The calcium carbonate and other materials then settle to the bottom, leaving the clarified sugarcane juice. The juice is next concentrated by boiling in several stages under a vacuum, which allows the syrup to boil at a lower temperature to protect it from caramelizing. At this stage, it becomes a thick, brown syrup called massecuite. The syrup is crystallized by evaporating the last amount of water and is then passed into a centrifuge with a perforated basket at the center. After spinning and drying, the result is golden raw sugar; this is not the same as the product labeled raw sugar, which is sold commercially.