Foods High in Carbohydrates
Carbohydrates are the sugars, starches, and fibers found in foods. Plants are the primary source of carbohydrates, with the exception of milk, which contains a sugar called lactose. The muscles from animals can also contain some carbohydrate in the form of glycogen, but much of this is converted to a substance called lactic acid during slaughter. Most carbohydrates are stored in the seeds, roots, stems, and fruit of plants. Common food sources for carbohydrates include grains such as rice, wheat, rye, barley, and corn: legumes such as beans, peas.and lentils; fruits; and some vegetables, such as carrots, potatoes, and beets. Sugar cane and sugar beets provide table sugar, while honey is derived from the nectar of flowers.
Composition of Carbohydrates
The elements making up carbohydrates are carbon (C), hydrogen (H), and oxygen (0). The word “carbohydrate” can be broken down into “carbon” (C) and “hydrate” (H20). This leads to the basic chemical formula of carbohydrates, which is Cn(H20)n , where n stands for a number ranging from 2 into the thousands. Carbohydrates are found primarily in green plants, where they are synthesized through the process of photosynthesis. The chemical reaction of photosynthesis is written:
carbon dioxide water 4- sun energy
—> glucose + oxygen .
6 CO2 + H20 + sun energy —> C6H1206 + 602
The carbon, hydrogen, and oxygen atoms making up carbohydrates are arranged in a basic unit called a saccharide. Carbohydrates are classified into monosaccharides, disaccharides, oligosaccharides, and polysaccharides, depending on the type and number of saccharide units they contain.
- Monosaccharides (one saccharide)
- Disaccharides (two monosaccharides linked together)
- Oligosaccharides (“few”—three to ten—monosaccharides linked together; these are not as common in foods as either mono- or disaccharides)
- Polysaccharides (“many” monosaccharides linked together together in long chains; these include starch and fibers)