Health and Nutrition
posted by tia .
Define carbohydrates, chemical make up and basic functions of sugars and starches in the body.
Carbohydrates and Sugars
Carbohydrates are one of three basic macronutrients needed to sustain life (the other two are proteins and fats). They are found in a wide range of foods that bring a variety of other important nutrients to the diet, such as vitamins and minerals, phytochemicals, antioxidants, and dietary fiber. Fruits, vegetables, grain foods, and many dairy products naturally contain carbohydrates in varying amounts, including sugars, which are a type of carbohydrate that can add taste appeal to a nutritious diet.
Carbohydrates encompass a broad range of sugars, starches, and fiber. The basic building block of a carbohydrate is a simple union of carbon, hydrogen, and oxygen. The chemical definition of a carbohydrate is any compound containing these three elements and having twice as many hydrogen atoms as oxygen and carbon.
Sugars in Foods
When people hear the word “sugar” they often think of the familiar sweetener in the sugar bowl. That sugar is sucrose and is the most familiar form of sugar to home bakers. But there are many types of sugars, which scientists classify according to their chemical structure. Sugars occur naturally in a wide variety of fruits, vegetables, and dairy foods. They can also be produced commercially and added to foods to heighten sweetness and for the many technical functions they perform, including: contributing to foods’ structure and texture, sweetening and flavor enhancement, controlling crystallization, providing a medium for the growth of yeast in baked goods, and preventing spoilage. The sweetening ability of sugar can promote the consumption of nutrient-rich foods that might not be otherwise. Some examples are a sprinkle of sugar added to oatmeal or adding sugar to cranberries in the juice-making process.
Sugars come in several forms, most containing approximately four calories per gram. Simple sugars are called monosaccharides, made up of single sugar molecules. Examples of these are glucose, fructose, and galactose. When two simple sugars are joined together by a chemical bond they are called disaccharides, the most common of which is sucrose or table sugar. Table sugar is made up of equal amounts of the simple sugars glucose and fructose, which are joined together by chemical bonds. Starches and fiber are made up of many simple sugars joined together chemically. Any carbohydrate that is made up of more than two simple sugars is referred to as a polysaccharide. Some common sugars found in foods are:
◦Corn Syrup: Made from corn and usually 100% glucose. According to the Food and Drug Administration (FDA), “corn syrup” can be used to describe numerous corn-derived products.
◦Fructose: A simple sugar found in fruits, honey, and root vegetables. It is used as a caloric sweetener, added to foods and beverages in the form of crystalline fructose (made from corn starch), and it makes up about half the sugar in sucrose or high fructose corn syrup (see below). Fructose does not elicit a glycemic response so it sometimes has been used as a sweetener for foods intended for people with diabetes. However, because of concern about the effect of excessive use on blood lipids, the Academy of Nutrition and Dietetics does not recommend fructose as a sweetening agent for people with diabetes.
◦Galactose: A simple sugar found in milk and dairy foods. Galactose and glucose form the disaccharide lactose.
◦Glucose: The main source of energy for the body and the only used by brain cells. Glucose is produced when carbohydrates are digested or metabolized. Glucose is sometimes referred to as dextrose. Starch is comprised of long chains of glucose. Glucose make up exactly half of the sugar in sucrose and nearly half of the sugar in high fructose corn syrup.
◦High Fructose Corn Syrup: A mixture of glucose and fructose produced from corn. The most common form of high fructose corn syrup (HFCS) has 55 percent fructose and 45 percent glucose.
◦Lactose: The sugar found naturally in milk, it is a disaccharide composed of one galactose unit and one glucose unit; sometimes called milk sugar.
◦Maltose: A disaccharide composed of two glucose units. It is found in molasses and is used in fermentation.
◦Sucrose: A disaccharide or double sugar made of equal parts of glucose and fructose. Known as table or white sugar, sucrose is found naturally in fruits and vegetables. Appearing most abundantly in sugar cane and sugar beets, sucrose comes from these foods for commercial use.
food in sight website
A carbohydrate is an organic compound that consists only of carbon, hydrogen, and oxygen
source - wiki
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