Carbohydrates powerpoint presentation ppt
- 1. CARBOHYDRATES Carbohydrates are organic compounds made up of Carbon, Hydrogen and Oxygen. Carbohydrates are synthesized by the process of Photosynthesis. Recommended Daily Allowance in India (RDA)- In a balanced diet 55-60 % kcal should come from CHO out of which 10% should be simple (glucose) CHO and rest should be complex (starch etc) CHO.
- 2. Classification of Carbohydrates- They are classified on the basis of the number of sugar units or saccharide units present in their structures. Carbohydrates Monosaccharides Disaccharides Oligosaccharides Polysaccharides • Glucose • Fructose • Galactose • Sucrose • Maltose • Lactose • Raffinose • Stachyose • Starch • Dextrin • Pectin • Cellulose • Gums • Agar etc. • Glycogen
- 3. Monosaccharides- They are the simplest form of CHO found in nature. • Glucose- It is the most important of all mono’s, as it is the primary CHO used by the body. It is the sugar which is necessary for all the body systems. It is absorbed in the blood stream (after CHO are digested). Also known as Dextrose. • Fructose- It is the fruit sugar found in honey and fruits. It is converted to glucose in the human body & used as a source of energy. • Galactose- It is found in combination with glucose in the disaccharide lactose in milk. It gets converted to glucose in the human body.
- 4. Disaccharides - When 2 monosaccharides combine with the removal of a molecule of water disaccharides are formed. • Sucrose- Called as table sugar. It is made from sugarcane, beetroot. And is also found in some fruits & vegetables. Glucose + Fructose → Sucrose • Lactose- It is the least sweet of all sugars and is present in milk. It gets easily fermented to lactic acid in the preparation of curds, cheese. Glucose + Galactose → Lactose • Maltose- It is formed when whole grains are sprouted and in the commercial preparation of malt from starch. In the body maltose is formed during the digestion of starch. Glucose + Glucose → Maltose Oligosaccharides - They are composed of 3-10 monosaccharide units linked with each other. Not commonly found in foods but are formed during breakdown of starch into simpler sugars, e.g. raffinose, stachyose, and are present in pulses.
- 5. Polysaccharides- They are complex CHO formed by linkages of 100 – 2000 glucose units in a chain or branch form. • Starch- Roots, tubers, cereals, pulses, sago etc. are the main sources of starch which is present in abundance. • Dextrin- It is formed because of the breakdown of starch by enzymes during digestion or by the action of dry heat on starch during toasting of bread or roasting of chapati etc. • Glycogen- This is animal starch. CHO are stored in the animal body as a reserve source of energy. 1/3rd of the glycogen is stored in the liver and 2/3rd is stored in muscles. • Pectin- They are indigestible CHO found in fruits. They easily absorb water and form gels. Found in Guava, Apple, Wood Apple, Papaya. • Cellulose- It cannot be digested by the human digestive system. They help in increasing the bulk of the intestinal content thus aiding the function of excretion. Hemicellulose- Same as cellulose. Sources are peels of fruits, leafy vegetables, whole grains etc.
- 6. Food Sources - 1. Plant Sources: • Cereals, Grains- Rice, Wheat, Corn, Bajra etc contain large amount of starch. They also contain some proteins, minerals & vitamins. Whole grains and sprouts also contain iron, B complex vitamins and some fibre. • Vegetables- Roots, tubers, starchy legumes, beans, peas, potatoes, yam contain a large amount of CHO. Vegetables also supply iron, fibre. • Fruits- They contain the simpler forms of CHO - mono & disac. Dry fruits contain large amounts of CHO. Fruits also contain cellulose & pectin. Nuts contain about 10-20% CHO and are also a rich source of proteins & fats. • Sweets- table sugar and different form of sugar, honey etc only supply calories hence referred to as empty calories. Jaggery & molasses contain some minerals in addition to calories. 2. Animal Sources: • Other than milk, that is, lactose present in milk, there is no other animal source of CHO. Glycogen stored in the animal liver degrades rapidly hence only a small amount may be found in meat, fish & poultry.
- 7. Functions in Human Body- 1. Energy- The main function of CHO is to give energy. Carbohydrates are the cheapest source of energy. (1 gm of CHO gives 4 kcals) 2. Protein sparing action- They spare proteins so that proteins can be used for the repair of wear and tear of tissues and build new tissues. If there is an insufficient amount of CHO in the diet the body is forced to break down proteins to release energy instead of doing there main functions of body’s growth & maintenance. 3. Regulation of fat metabolism- Adequate amount of CHO in the diet prevents excessive breakdown of fat in the body. If CHO are restricted or in deficit in the diet, it leads to more use of fat resulting in accumulation of ketones in the body called as ketosis. 4. Role in gastro-intestinal system- Lactose encourages the growth of favourable intestinal bacteria. It has laxative property and enhances the absorption of calcium. 5. The cellulose helps in eliminating the faeces from the body. 6. Glucose is the only form of energy used by the central nervous system, that is, the brain and the spinal cord. When blood glucose levels fall the brain does not receive energy and it can lead to convulsions.
- 8. Importance of fibre in the diet- Dietary fibres are indigestible part of food. They do not provide energy but perform many important functions. They are of 2 types: 1. Soluble fibres prevent several illnesses. It gives satiety (feeling of bulkiness), lowers cholesterol, blood pressure levels & prevents constipation. They prolong stomach emptying times. Food sources are nuts, flax seeds, oat, oat bran, fruits like orange, carrot, apples etc. 2. Insoluble fibres move the bulk through intestines, control & balance the ph (acidity) in intestines. It promotes regular bowel movements, prevents constipation. It also helps to prevent colon cancer by keeping an optimal ph in the intestine to prevent microorganisms from producing cancerous subs. Food sources are vegetables like green vegetables like beans, green leafy vegetables, fruit skin, seeds, nuts etc.
- 9. Deficiency of CHO - The daily diet should not contain less than 100 gm of CHO. Deficiency of CHO is generally not seen. If it all there is deficiency of CHO it results in utilization of fat for energy resulting in ketosis. Deficiency of CHO (energy) and Protein together leads to malnutrition. It is of 2 types- Marasmus & Kwashiorkor. Marasmus is CHO deficiency. Symptoms- 1. Emaciation & shrivelled skin 2. Dull and dry hair 3. Enlarged eyes & face 4. Loss of body weight 5. Marasmic child is characterized by its thin, lean and skinny appearance.
- 10. Excess of CHO - 1. Excess of CHO especially sugar can lead to dental caries or tooth decay. 2. Causes obesity because more calories are ingested than expended. 3. Can result in malnutrition due to deprivation of food items from the 5 food groups. 4. It irritates the gastro intestinal mucosa thus affecting digestion. 5. Affects the appetite. 6. Increases the blood triglyceride levels leading to heart diseases. 7. Excessive fibre leads to gas formation.
- 11. Effect of heat on Carbohydrates - 1. Dextrinization- It is a process in which on application of dry heat the starch granules break down into dextrin which gives a brown colour to the product, a sweet taste, specific aroma & makes the product easy to digest. e.g- toasted bread, bhakri, chapati 2. Gelatinization- It is a process by which on the application of wet heat or when starch is heated in water it absorbs water and the starch granules swell up and make it thick and translucent. e.g- outer covering of Momo’s, modak, rice, white sauce, custard etc. 3. Caramelization- When sugar is heated at a temperature around 163°-170° C it turns brown which is called as caramelization e.g- chikki, tilgul, caramel sauce 4. Crystallization- When concentrated sugar solution is heated and then cooled gradually it imparts an unpleasant texture. e.G – sugar coated groundnuts, Rawa besan wadi