Sugar is a food widely used as a sweetener. People sprinkle sugar on such foods as grapefruit and cereal to improve their taste. Some people add it to coffee, tea, and other beverages. In addition, manufacturers include sugar in such foods as ice cream and soft drinks.
All green plants produce sugar. But most sugar that people use comes from sugar cane or sugar beets, which produce a sugar called sucrose. This sugar is the one that people keep in a sugar bowl. Other sources of sugar include cornstarch, milk, maple syrup, and honey. Cornstarch is an especially important source of sugar-rich syrups in the United States. The consumption of corn sweeteners in the United States is about equal to the consumption of sucrose.
Sugar belongs to the class of foods called carbohydrates. Carbohydrates provide energy for plants and animals. Sugar is refined (purified) before it is used for food. The refining process also removes vitamins and other nutrients that are necessary for growth and health. Thus, refined sugar serves only as a source of energy.
Eating large amounts of sugar may increase the risk of tooth decay and help cause a person to become overweight. To avoid these problems, many people use artificial sweeteners, such as aspartame and saccharin, instead of sugar (see Artificial sweetener).
Uses of sugar
In the food industry.
Most of the world’s sugar crop is used in food. Much of the sugar eaten by people in the United States is contained in processed (specially prepared) foods. For example, candy, canned fruit, jams, jellies, and soft drinks all include large amounts of sugar. Sugar is also added to many bakery products.
Manufacturers sell sugar in several forms. Most is sold in the form of white granules (small grains). Some sugar is ground into powdered sugar and used in cake frostings. Brown sugar, which is often used in baking, is a mixture of molasses-flavored syrup and sugar.
In other industries.
A small amount of the world’s sugar crop is used by nonfood industries to make various products. For example, sugar is used for mixing cement, tanning leather, and making plastics. Some medicines contain sugar to disguise their unpleasant taste.
Certain products obtained from the sugar-refining process are also made into nonfood items. For example, after sugar has been removed from sugar cane, a material called bagasse remains. Bagasse is burned as a source of energy or is made into paper or wallboard.
Kinds of sugar
There are two kinds of sugar, monosaccharides and disaccharides. In pure form, both are white crystals. Monosaccharides are the simplest carbohydrates. Common monosaccharides include glucose and fructose. Glucose is the most important carbohydrate in the blood. Fructose, also called levulose, is found in fruits and vegetables. Disaccharides are made up of two monosaccharides. For example, the disaccharide sucrose can be broken down by enzymes into glucose and fructose. Other common disaccharides include lactose and maltose. Lactose is found in milk and is used in making some medicines. Maltose, which is formed from starch, is used in the production of bread and baby food.
The sources of sugar
Sugar beets and sugar cane
are the world’s main sources of sugar. Sugar beets grow in temperate climates. Sucrose is stored in the plant’s fleshy root. Sugar cane is a tall grass plant that thrives in tropical and semitropical climates. It stores sucrose in its stalks. For more detailed information, see Sugar beet; Sugar cane.
Cornstarch and other starches
are made up of various sugars. Starches can be broken down to form individual sugars by mixing them with acid or enzymes (molecules that speed up chemical reactions). For example, the incomplete breakdown of cornstarch produces corn syrup, which consists chiefly of glucose and maltose. Corn syrup is used for flavoring such foods as candy and salad dressing. Solid corn sugar, which is also formed from cornstarch, is made up primarily of glucose. A liquid called high-fructose corn syrup is produced by converting some of the glucose in cornstarch to fructose. High-fructose corn syrup is used in place of sucrose in many baked goods and soft drinks. See Corn syrup; Cornstarch.
Honey
is the sweet liquid that bees make from the nectar they drink from flowers. Bees collect sucrose from the nectar and convert it into invert sugar, an equal mixture of fructose and glucose. Invert sugar is the primary ingredient of honey, which also contains small amounts of vitamins and other nutrients. See Honey.
Maple syrup
is the concentrated sap of certain maple trees. It consists chiefly of sucrose. But the syrup gets its maple taste from nonsucrose compounds that form during processing. People pour the syrup on pancakes, waffles, and other foods, and manufacturers use it to flavor certain candies. See Maple syrup.
Milk.
Lactose, also called milk sugar, is found in the milk of all mammals (milk-producing animals). It is obtained commercially from skimmed milk and whey, a liquid by-product of the cheese-making process.
Molasses
is a by-product of sugar-beet and sugar-cane refining processes. It contains 40 to 50 percent sugar. It is used chiefly in making alcoholic beverages, candy, and livestock feed. The word molasses also refers to the extracts of many sugar-bearing plants. For example, the syrup produced by the sweet sorghum plant is called molasses. See Sorghum (Sweet sorghums).
Sugar production
Making cane sugar.
Sugar cane stalks grow 7 to 15 feet (2 to 5 meters) high. When the cane is ready to harvest, the field is set on fire for a few minutes to burn off the plants’ dry leaves. The stalks do not burn because of their high moisture content and tough outer shell. The cane is then harvested and taken to a factory. There, the stalks are washed, shredded, and placed in a crushing machine or into vats of hot water that dissolve the sugar. Crushing machines burst the stalks, squeezing out the sugary liquid. Sprays of water dissolve more sugar from the stalks. The mixture of sugar and water, called cane juice, is then taken away for purifying.
Obtaining raw sugar. The cane juice, still diluted with water, is heated. Lime (calcium hydroxide) is added to the juice to settle out impurities, and carbon dioxide is used to remove the excess lime. Workers then put the clarified juice in huge evaporator tanks, where most of the water is evaporated and the juice becomes thick and syrupy. However, still more water must be removed from the syrup so that sugar crystals will form. To remove the excess water, the syrup is heated in large, dome-shaped vacuum pans. Sugar and sugar syrup scorch easily. But the vacuum lowers the boiling point of the syrup so that it will heat without scorching.
After large sugar crystals form in the thick syrup, workers put the mixture in a centrifuge. This machine spins at extremely high speeds and separates most of the syrup from the crystals. The remaining raw sugar contains 97 to 99 percent sucrose. Exporters ship sugar in this form from one country to another.
Refining cane sugar. To obtain pure white sugar for table use, the yellowish-brown raw sugar must go through several more steps. The film that gives raw sugar its yellow-brown color is rinsed off. Next, the sugar crystals are dissolved in water, and the solution is poured through filters until it becomes a clear, colorless liquid. The liquid is then evaporated until crystals form again. The crystals are again spun in the centrifuge, and sugar flows from the machine into drying drums. Heated air in the drums absorbs any remaining moisture.
Some of the syrup does not form crystals during evaporation and spinning. The process is repeated several times to form more of the white crystals. The remaining syrup is then used to make brown sugar.
Making beet sugar.
After sugar beets are dug out of the ground, they are shipped to a factory. There, they are washed and cut into thin slices called cossettes. The cossettes are placed in machines called diffusers to soak. The soaking removes the sugar from the slices. The cossettes are then dried and mixed with molasses to make cattle feed.
The solution obtained by soaking the cossettes is heated and treated with lime to settle out impurities. Carbon dioxide is added to remove the excess lime in the solution. The juice is then filtered to remove the impurities. The purified solution is called thin juice. The juice is evaporated to remove water and crystallize the sugar. From this point, the process for making sugar from sugar beets is the same as for sugar cane. However, in the United States and some other countries, beet-sugar processing is carried out in a single operation. Beet-sugar factories produce no raw sugar.
The sugar industry
About 200 million tons (180 million metric tons) of sugar are produced worldwide every year. Brazil and India lead the world in sugar production.
The United States produces more than 9 million tons (8 million metric tons) of sugar a year. Florida and Louisiana are major producers of cane sugar. The Red River Valley in Minnesota and North Dakota is the largest sugar-beet growing region in the United States.
History
Sugar from sugar cane.
Inhabitants of South Pacific islands grew sugar cane more than 8,000 years ago. The plants were also widely grown in ancient India. Sugar cane is specifically mentioned in records of an expedition by the Macedonian king Alexander the Great to what is now Pakistan in 326 B.C.
The cultivation and refining of sugar cane spread east from India to China about 100 B.C. but did not reach Europe until about A.D. 636. In the early 1400’s, Europeans planted sugar cane in northern Africa and on islands in the Atlantic Ocean. Portuguese settlers later planted sugar cane on the west coast of Africa and in Brazil. The Italian navigator Christopher Columbus brought sugar-cane cuttings to islands in the Caribbean Sea in 1493.
The first sugar mill in the Western Hemisphere was built in 1515 in what is now the Dominican Republic. Jesuit missionaries brought sugar cane to Louisiana in 1751. In 1791, the first sugar mill on the North American mainland was built in New Orleans by Antonio Mendez, a Louisiana planter.
Sugar from sugar beets.
The people of ancient Babylonia, Egypt, and Greece grew sugar beets. However, they were originally used as a leafy vegetable. In 1747, Andreas Sigismund Marggraf, a German chemist, found that sugar from the sugar beet was the same as that removed from sugar cane. In 1799, Franz Achard, a student of Marggraf’s, developed a practical method of removing sugar from sugar beets. Sugar mills then sprang up quickly in Europe and Russia. Beet sugar was first produced in the United States in 1838. E. H. Dyer, an American businessman, established the country’s first successful sugar-beet processing factory in Alvarado, California, near Oakland.
