Everything on Glycogen, starches and fibres.
Both glycogen and starch are storage forms of glucose (glycogen in the body, and starch in plants) and both give energy for human use. The fibres also contain glucose, but their bonds cannot be broken by human digestive enzymes, so they give little, if any, energy.
When a person eats carbohydrate-rich foods, the body receives a valuable amount of glucose.
Phytic acid
A non nutrient component of plant seeds, also called phytate. Phytic acid occurs in the husks of grains, legumes, and seeds and is capable of binding minerals such as zinc, iron, calcium, magnesium, and copper in insoluble complexes in the intestine, which the body excretes unused.
A compound not classed as fibre but often found with it in foods is phytic acid. Because of this close association, researchers have been unable to determine whether it is the fibre, the phytic acid, or both, that binds with minerals, preventing their absorption. This binding presents a risk of mineral deficiency, but the risk is minimal when fibre intake is reasonable and mineral intake adequate.
Glycogen
Glycogen is found in limited meats and not in plants. So its not a significant food source of carbohydrate, but it does perform an important role in the body. The human body stores much of its glucose as glycogen. When the hormonal message "release energy" arrives at the storage sites in a liver or muscle cell, enzymes respond by attacking all the many branches of each glycogen simultaneously, making a surge of glucose available. It is manufactured and stored in the liver and muscles.
Starches
Plant cells store glucose as starches. These giant starch molecules are packed side by side in grains such as wheat or rice, in root crops and tubers such as yams and potatoes, and in legumes such as peas and beans. When you eat the plant, your body hydrolyses the starch to glucose and uses the glucose for its own energy purposes All starchy foods come from plants. Grains are the richest food source of starch, providing much of the food energy for people all over the world - rice in Asia, wheat in Canada, the United States, and Europe, corn in much of Central and South America, and millet, rye, barley, and oats elsewhere. Legumes and tubers are also important sources of starch.
Fibres
Fibres are the structural parts of plants and thus are found in all plant-derived foods such as vegetables, fruits, grains, and legumes. Fibres contribute little or no energy to the body. They are not digested by human digestive enzymes, although some are digested by GI tract bacteria.
Different fibres:
Cellulose
Cellulose is the primary constituent of plant cell walls and therefore occurs naturally in all vegetables, fruits, and legumes. Cellulose can also be extracted from wood pulp or cotton and added to foods as an anticaking, thickening, and texturizing agent during processing.
Hemicelluloses
The hemicelluloses are the main constituent of cereal fibres.
Pectin's
Commonly found in vegetables and fruits, especially citrus fruits and apples. Pectin's may be isolated and used by the food industry to thicken jelly, keep salad dressings from separating, and otherwise control texture and consistency. Pectin's can perform these functions because they readily form gels in water.
Gums and Mucilage's
When cut, a plant secretes gums from the site of the injury. Gums such as guar gum and gum Arabic are used as additives by the food industry to thicken processed foods. Mucilage's are similar to gums in structure and they include psyllium and carrageenan, which are added to foods as stabilizers.
Lignin
It's got a three-dimensional structure that gives it strength. Because of its toughness, few of the foods that people eat contain much lignin. It occurs in the woody parts of vegetables such as carrots and the small seeds of fruits such as strawberries.
Resistant Starches
A few starches are classified as fibres, known as resistant starches. These starches escape digestion and absorption in the small intestine. Starch may resist digestion for several reasons, including the individual's efficiency in digesting starches and the food's physical properties. It is common in whole legumes, raw potatoes, and unripe bananas.
Fibre Characteristics
Some fibres dissolve in water (soluble fibres), form gels (viscous), and are easily digested by bacteria in the colon (fermentable). Commonly found in legumes and fruits, these fibres are most often associated with protecting against heart disease and diabetes by lowering blood cholesterol and glucose levels, respectively.
Insoluble fibres
Other fibres do not dissolve in water, do not form gels (non viscous), and are less readily fermented. Found mostly in grains and vegetables, these fibres promote bowel movements and alleviate constipation. These generalizations between viscous and non viscous fibres are useful, but exceptions occur. Insoluble rice bran also lowers blood cholesterol, and the soluble fibre of the psyllium plant effectively promotes bowel movements. An example is strings of celery and the skins of corn kernels.
Just for interest
Glycogen in animal muscles rapidly hydrolyses after slaughter.
Normally, only liver cells can produce glucose from glycogen to be sent directly to the blood. Muscle cells can also produce glucose from glycogen, but must use it themselves. Muscle cells can restore the blood glucose level indirectly.
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