Elementary of Food and Nutrition

Introduction to food and Nutrition

Food is the substance, which nourishes the body. Only those substances, which when eaten or drunk are absorbed by the body, produce energy facilitate growth, repair tissues and regulates the processes of foods. The components of food, which perform these functions, are called nutrients and the study of various nutrients, their function, food sources and their utilization by the human body and their effects on human well-being are called nutrition.

Food provides six types of nutrients- Proteins, carbohydrates, fats, vitamins, minerals and water. In addition, the body also requires a continuous supply of oxygen. There are over 40 essential elements which are supplied by the food we eat.

The word health refers to the condition of the body. Good health indicates not only freedom from the disease but physical, mental and emotional fitness as well, according to the WORLD HEALTH ORGANIZATION (WHO).

Carbohydrates, protein, and lipids are the major constituents of food. Besides these, foods contain small amount chemical constituents like vitamins, minerals, pigments, flavoring present in small or large quantities. These constituents provide structure, color, flavor, texture and nutritive value. Thus, the study of these components will give gastronomists, bird view knowledge of properties and their importance in food.

Carbohydrates

Carbohydrates are widely distributed in nature in the form of sugars, starches, cellulose and other complex substances. Carbohydrates mean the hydrate of carbon, which contains, carbon, hydrogen and oxygen can be represented by the formula C_x(H₂O)_y ; where the value of x and y may be range from 3 to 100'_s. There are much more carbohydrates which may fit into this formula.

Carbohydrates are primarily produced during photosynthesis. They are organic compounds formed from carbon dioxide and water through the sun's radiations in photosynthesis plant cell.

Carbohydrates are easily digested and provide 4 cals/gm energy and promote the utilization of fat and reduce wastage of protein.

Protein

The word protein is derived from the Greek word "proteins" which means M "principle" or "prime" Proteins are the principal components of all living cells and are important practically in all aspects of cell structure and functions. They are molecules of great size, complexity, and diversity. Proteins are present in all living plants and animals tissues.

Proteins, like fats and carbohydrates, contain carbon, hydrogen, and oxygen. In addition, they contain about six percent nitrogen, which distinguishes the proteins from carbohydrates and fats.

Proteins are more complex and larger molecules than carbohydrates and fats. Some protein contains Sulphur, phosphorus, iron or other minerals also.

Fats and Oil

Oils and fats are composed of the element carbon, hydrogen, and oxygen. They are similar in their composition but physically, fats are solid at normal temperature (18-25) degree Celsius, whereas oil is liquid. Fats are built up by linking together a number of individual fatty acid with glycerol.

Role in Cooking

The role of different types of fats and oils in cookery is largely based on their composition and properties. Thus liquid fats or oils with a high smoke point (170 – 180) degree Celsius is used for deep – fat frying purpose and like new, solid fats like butter and margarine are used as shortening and tenderizing agents in foods.

Fats are used in food preparation.

• As a medium of cooking
• As a shortening (curbing) in biscuits, pastry, and cakes
• To add richness and flavor as well as the seasoning of vegetables and salads.

Vitamin

UNTIL the beginning of this century, it was thought that a diet containing proteins, carbohydrates, fats, minerals, and water was adequate to maintain life. But research conducted in the early part of this century proved some vital factor was missing from the diet. This vital factor was given the name vitamin. Later it was found that there was more than one factor involved.

A plant pigment (red – orange in a color called carotene) is converted into vitamin A in the body. Therefore, food which contains carotene is indirect sources of vitamin A. such foods include dark green leafy vegetables, such as coriander, drumstick, radish leaves and Spinach. Orange_ yellow vegetables fruits, such as carrot, pumpkin, papaya, and mango are also the rich source of the vitamin. Be sure to include one of these in the daily diet. Severe deficiency of vitamin A leads to growth failure, skins changes, infection of their eye and even loss of vision.

Types of Vitamin

Vitamins are generally categorized into two major types according to their solubility.

1. Fat soluble vitamins
2. Water soluble vitamins

Minerals

It is known that human body requires 14 different elements for health and growth. Those elements are present in appreciable amounts (0.5 percent or more) the other elements like iron , iodine, manganese, copper, zinc, cobalt, and fluorine are found in traces.

Types and Source of Minerals

• Calcium and Phosphorous

The minerals are needed in comparatively large amounts to help in normal growth and development of bones and teeth a human being. Breast-milk supplies these in sufficient amount for the first six months.

The best source of calcium is milk. Babies receive an excellent supply of calcium from their mother's milk. The milk of cows, buffaloes and goats are rich in calcium, so are milk products, sesame seeds, millet, dark green leafy vegetables and eggs.

Deficiency of calcium may lead to poor bone and teeth formation. Cruel deficiency may cause rickets in children and osteomalacia in adults.

• Iron

Iron is needed for the formation of hemoglobin (the red pigment in the blood)

which is required for 3 months of birth, and found to be insufficient in the infants fed only milk.

Iron deficiency in low hemoglobin in the blood which leads to anemia. The severity of anemia causes tiredness, fainting, breathlessness and pale looking. Eggs, fresh meat, liver, lentils and green leafy vegetables are the excellent sources of iron.

Water

Water accounts for about 55 to 68 percent of our total adult body weight. The percentage of water tends to decrease, as we grow older. Thus infants and children have a much higher amount of body water than adults. Fat persons have less water than thin persons. Water is an essential nutrient and is good for oxygen. Deprivation water even for a few days can lead to death. Water helps in the transportation of the products of digestion to the appropriate organs. For example, blood which contains 90 percent water, carries carbon dioxide to the lungs, nutrient to the cell, and waste nitrogenous materials (urea, uric, acid etc) and slats to the kidneys. Urine, which contains 97 percent water, has all the waste materials dissolved in it and the body is thus able to excrete soluble waste products of metabolism.

Effects of Heat on Nutrients

Protein

When the protein is headed, it shrinks and overheating causes determination which further destroys the texture of the stuff. This effect can be seen while roasting and grilling different meat items. Moderately cooked proteins can easily digest, for example, moderately cooked eggs are more easily digested than hard boiled eggs and well-done steaks.

Carbohydrate

When the carbohydrate is cooked, the starch granules should swell and burst then only the carbohydrate digested easily this process is called gelatinization of starch. Carbohydrates are considerably lost during cooking.

Fat

The nutritive value of fat does not have any effect on heat. Fats get rancid when heated, more than 180 degree Celsius.

Minerals

There is a possibility of the minerals being lost during cooking thus diminishing the amount. This is possible only in case of minerals like sodium and iodine. Minerals like calcium and iron do not have any effect on cooking.

Vitamins

1. Vitamins A and D withstand cooking temperatures and are not lost during cooking.
2. Vitamins B₁ (Thiamin) is lost by high temperature and by the use of bicarbonate of soda. It is soluble in water and can be lost during cooking.
3. Vitamin B₂ (riboflavin) is not destroyed easily by heat but bright sunlight can break down.
4. Vitamin C (Ascorbic acid) is soluble in water and can be destroyed is unstable and therefore easily destroyed in alkaline conditions .bicarbonate of soda destroys vitamin C content. So, green vegetables are not advisable to be cooked in bicarbonate soda.

References:

Joshi, Basant Prasad et.al., Fundamentals of Hotel Management-XII, Sukunda Pustak Bhandar, Kathmandu

Bhandari, Saroj Sing et.al., Principle of Hotel Management-XII, Asmita Publication, Kathmandu

Oli, Gopal Singh et.al., Hotel Management Principle and practices-XII, Buddha Prakashan, Kathmandu