Carbohydrates
| [ • Nutrition • Healthy Eating • Miracle Diets? • Handling Food • Food Trouble• Food Facts • Food
Fun! • Discussion • Archive • |
|
[ Role of Carbohydrates | How are Carbohydrates Made? | Grass for your Meal | Empty Calories | Artificial Sweeteners | How Sweet is your Sugar? | Carbohydrates and your Waistline | Carbohydrate Loading | Simple and Complex Carbohydrates | Food Sources of Carbohydrates ]
Sugars and starches are important carbohydrates that we take in often. Carbohydrates provide a great part of the energy in our diets. Foods rich in carbohydrates, including potatoes, bread, and maize, are usually the most abundant and cheapest when compared with foods high in protein and fat content. Carbohydrates are burned during body processes to produce energy, giving out carbon dioxide and water. Starches are found mainly in grains, legumes, and tubers, and sugars are found in plants and fruits. Sugars are the smallest units of carbohydrates, and when they join together, they form starch.
The main role of carbohydrates in our diet is to produce energy. Each gram of carbohydrates provides us with about four calories. Carbohydrates also act as a food store. Our bodies also store carbohydrates in insoluble forms as glycogen or starch. This is because these two carbohydrates are compact. Carbohydrates are also combined with nitrogen to form non-essential amino acids.
In plants, carbohydrates make up part of the cellulose, giving plants strength and structure.
Plants can make their own food because they have chlorophyll in their green leaves. They make food in a process known as photosynthesis. The process of photosynthesis is essential for all living things in the world, and plants are the only food-producers, while the other animals either feed on plants or feed on other animals.
For the process of photosynthesis, carbon dioxide and sunlight have to be present. Also, the plant must have water. Only then can the plant photosynthesize and produce glucose and oxygen from carbon dioxide, water and sunlight. The equation of photosynthesis is as follows:
|
 |
The glucose produced is then stored in the leaves as starch.
When you see cows roaming about in the fields, grazing the grass, have you ever wondered why humans do not eat grass? Partly, it is because it does not taste nice; but more importantly, we are unable to get any nutrients from grass. Our digestive system does not have the ability to break down the cellulose of grass and, even if we eat grass, the grass will come out undigested. Herbivores, such as sheep, cows and rabbits, have special bacteria in their bodies that do the trick. The bacteria breaks down the cellulose of the plant cells. Thus, they are able to receive nourishment from the grass.
If you really want to live on grass, try cooking the grass before eating. Cooking breaks down the plant cellulose. But you may find that you do not like the taste after all.
Empty Calories refer to food that provides you with nothing other than calories. For example, soft drinks contain only sugar, and you can't get many nutrients from it. Hence, we say that soft drinks are loaded with empty calories. There are many other foods rich in calories, but at the same time contain many other nutrients required by the body. An example would be a potato, which is not only high in carbohydrates, but also contains proteins, vitamins and minerals.
Are you trying to cut down on sweet stuff, watching your weight carefully? Don’t you miss the sweet taste of sugar? Fortunately, there are several substitutes that can be used to provide the desired sweet taste. One of them is saccharin and the other is aspartame. They contain almost no calories and can be found commonly in soft drinks. Although saccharin is 500 times as sweet as sugar, it leaves a bitter taste in your mouth after a while.
| Here, we compare
the sweetness of some sugars with sucrose: Sucrose = 100% |
 |
|
|
Carbohydrates and your Waistline
Can starchy foods such as bread, rice, potatoes, and spaghetti make you fat? Yes! Carbohydrates will still be converted into fats if they are unused. But carbohydrates contain less calories than fats, and are filling and satisfying. You can fill yourself with a bowl of rice and will feel full, rather than having a high-calorie candy and still feeling hungry. So, eat more carbohydrates and less fats.
You may want to run faster at the coming cross-country race. Try carbo-loading. It will help you. By changing the amount you exercise and eating extra carbohydrates for several days before your event, your muscles store up extra glycogen. This extra fuel supply will keep your muscles going longer, and you will have better performance.
Simple and Complex Carbohydrates
Simple Carbohydrates
In simple sugars, each chemical unit or molecule contains just a single ring of atoms. Glucose, the sugar found in blood, and fructose, a sugar in fruits, are simple sugars. Both contain six carbon atoms in each molecule. Simple sugars are referred to as monosaccharides. (Mono means "one", and saccharide comes from the Latin word for sugar.) Two simple molecules join together to form a disaccharide. (Di means "two".) A polysaccharide is made up of more than two saccharides, and can contain as many as a few hundred saccharides. (Poly means "many".) In all simple sugars, the carbon, hydrogen, and oxygen are always in a 1:2:1 ratio. This means that for every unit of carbon and oxygen, there will be two units of hydrogen. Each glucose molecule has 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms.
Monosaccharides
Three, four, five and six...
Some monosaccharides have another name that tells us how many carbon atoms, hydrogen atoms and oxygen atoms they contain. For example, glucose is also called hexose (hex means 6) because each glucose molecule has 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms. Here are the names of the monosaccharides:770-7017
| Name | Scientific Name | Chemical Composition |
| Glucose | (Hexose) | C6H12O6 |
| Xylose | (Pentose) | C5H10O5 |
| Erythrose | (Tetrose) | C4H8O4 |
| Glyceraldehyde | (Triose) | C3H6O3 |
Glucose Glucose, one of the simple sugars, is the body’s most important energy source. This sugar is just mildly sweet, about 70 percent as sweet as table sugar. Because it is found in the blood, it is also known as blood sugar. When you hear dextrose, it is also glucose, but sold commercially. It has a molecular formula of C6H12O6. and is also known as grape sugar.
Fructose Fruit-ose? Fructose is found in fruits, as well as vegetables. It is very sweet and is commonly known as fruit sugar.
Did you know… Honey is very, very sweet because it contains both glucose and fructose.
Mannose Mannose can be found in apples, oranges, peaches, manna, and yeast.
Disaccharides
Some disaccharides include sucrose, lactose and maltose.
Sucrose The white crystals of sweetness Mom uses in her cooking or table sugar is actually sucrose. Sucrose is made up of two saccharides: one glucose and one fructose. Sucrose is very sweet, and it comes from sugar cane and sugar beets.
Lactose Lactose is the sugar found in milk. It is not very sweet and is made up of glucose and galactose, another sugar. Many people develop lactose-intolerance in adulthood.
Maltose Maltose, or malt sugar, can be found n cereals and legumes (peas, beans). It is formed when beer is brewed and is made up of two glucose units.
Complex Carbohydrates
Complex carbohydrates are long chains of sugar units. Different complex carbohydrates exist because the sugar units join differently to form different complex carbohydrates.
Starch Starch is made up of thousands of glucose units. It is in this form that plants store energy. Starch is broken down by our digestive system into glucose, which can be used for energy.
Glycogen While plants store starch, animals store glycogen. Sometimes called animal starch, it is also made up of long chains of glucose units. Our bodies convert glucose into glycogen in the liver and muscles,and glycogen can change back into glucose when needed.
The carbohydrates containing the most nutrients are the complex carbohydrates, such as:
Sugars and simple carbohydrates are found in fruits and vegetables.
Food made from sources of carbohydrates:
This page has been authored for participation in
the 1997 Thinkquest Competition.
|
|
