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Components of Food
Components of Food
The main components of food are carbohydrates, fats, proteins, vitamins and minerals, these are called nutrients in addition to this, dietary fibres and water are also essential for maintaining the life processes in the human body.
Carbohydrates are the compounds made up carbon, hydrogen and oxygen. Photosynthesis consist of two phase (i) light phase and (ii) dark phase
During the light phase sunlight is absorbed by the photosynthetic pigment present in the green part of the plant, for formation of energy which is used during dark phase for the reduction of carbon dioxide for the formation of carbohydrates.
Carbohydrates are the main and cheapest source of energy for human body there for carbohydrates are called energy giving food,
There are three types of carbohydrates:
i) Sugars: Glucose, fructose, sucrose (cane sugar or sugar), jaggery etc.
ii) Starch: Rice, what, potatoes, maize etc.
iii) Cellulose: Roughage
Sugars: Sugars are the simple carbohydrates and are sweet in taste. These are water soluble main sources of sugar in our food are glucose, can sugar, milk, fruits such as banana, apple, grapes etc. Table sugar is mostly obtained from sugar cane and sugar beet. Refined sugar is a pure carbohydrate. It does not contain any minerals and vitamins.
Starch: Starch is a complex carbohydrate. Starch is tasteless, odourless, white powder. Starch is insoluble in water. Starch molecule contain large number (200 - 1000) of simple sugar (glucose molecules). Major sources of starch in our food are wheat, rice, maize and potatoes.
Cellulose: Cellulose is a complex carbohydrate. Cellulose is tasteless white powder. A molecule of cellulose is made up of large number (100 - 3000) of glucose molecule. Cellulose is present in plants cell wall, wood, cotton etc.
Digestion of carbohydrates: During the process of digestion, starch and sugars get hydrolysed to form glucose. Glucose is then absorbed by blood and transported to various part the body. During respiration, a part of glucose gets oxidized to carbon dioxide (CO2) and water (H2O) and energy is released.
Proper source of fats in our diet include meat, fish, eggs, and nuts.
i) Fats on digestion produce more energy then carbohydrates,
ii) Oils and fats are greasy in nature
iii) Human body stores excess energy in the form of fat.
iv) This stored fat is used by body for producing energy as and when required. That is why fat is considered as energy banned in our body
v) Fat deposit in our body provides cushion to the body organs and protect them from injury. Too much fat deposition in our body leads to obesity.
vi) Animals like whale, camel, polar bear, store fat in their bodies for future use, during winter, the polar bear sleeps for months. During its long sleep it uses the fat sotred in hte body to meat its energy requirements.
vii) Fat gives flavour and taste to our food.
viii) Fats are essential for absorption of vitamins A, D, E and K in the body.
Proteins are complex organic compounds containing carbon, hydrogen, oxygen and nitrogen.
i) A protein molecule is made up as large number of smaller molecules called amino acids.
ii) Proteins are body building food.
iii) Proteins are obtained from both plants and animals, plants contains some proteins but ground nuts, beans, cereals are the best sources of vegetable proteins.
iv) Animal protein contain sufficient quantity of essential amino acids.
v) Proteins helps in – digestion, body growth, tissues repair and catalysing certain biochemical process.
i) Vitamins are essential for growth and maintenance of body.
ii) Vitamins do not provide energy but they help in proper utilization of other nutrients such as carbohydrates and fats.
iii) Our body can synthesize only two vitamins, Vitamin-D and K, therefore, other vitamins should be present in our diet.
iv) The vitamin-B complex is a mixture of several water soluble vitamins. The important vitamins of this group are vitamin-B, B2, B4, B6, B9 and B12.
v) Vitamin-C is destroyed by heat during cooking. Therefore, they should be present in our diet in the form of fruits and half cooked vegetables.
Classification of Vitamins
Vitamin are classified on the basis of their solubility:
i) Water soluble vitamins: Vitamin-B and C
ii) Fat/Oil soluble vitamins : Vitamin-A, D, E and K. Vitamin-A, D, E and K are stored in the body fat
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