What is food science??
• Definition: Food science is a systematic study of the nature of food materials and
the scientific principles underlying their modification, preservation, and spoilage.
• To understand food science, the basic concepts of physics, chemistry,
mathematics, and biology and their applications, i.e., biochemistry, microbiology,
and food technology, are necessary to prepare, package, store, and serve
wholesome, high quality products.
• Some important definitions:-
• 1) Food: food can be defined as any substance which nourishes the body
and is fit to eat. It may be solid or liquid.
• Food provides the body with materials for providing energy, growth and
maintenance, and regulating various process in the body. These materials of
which food is made up of are termed nutrients.
• Six nutrients are importance in nutrition. They are
• A) proteins
• B) carbohydrates
• C) fats
• D) vitamins
• E) minerals
• F) water.
• NUTRIENTS:- nutrients are the chemical substances present in food, which the
body needs to carry out its functions. Food is the source of all ntrients except
vitamin D. There are six major groups of nutrients namely, proteins carbohydrates,
fats, vitamins, minerals and water. Each group has several nutrients in it, and each
nutrient has specific function in the body.
• nutrition is the science of nourishing the body. It includes much more than just
consuming a balanced diet.
• NUTRITION: it is a combination of process by which the human body receives
and utilizes nutrients which are necessary for carrying out various functions and
for the growth and renewal of its components. Thus , nutrition refers to the various
processes in the body for making use of food. It includes eating the right kind and
amount of food, absorption of nutrients into the blood stream, use of individual
nutrients by the cells in the body, maintenance and growth of cells, tissues, and
organs, and elimination of wastes.
RELATION OF FOOD AND HEALTH
When the diet does not supply all nutrients in required amounts, it results in ill
health or malnutrition.
Malnutrition:- malnutrition ( mal means faulty) is an impairment of health resulting
from a deficiency, excess, or imbalance of nutrients in the diet. It includes both
undernutrition or deficiency and overnutrition or excessive consumption.
undernutrition:- it refers to a deficiency of calories and/ or one or more nutrients in
the diet. An undernourished person is underweight.
Overnutrition:- it refers to an excess of calories and/ or more nutrients in the diet.
An excessive intake of calories results in overweight which can lead to obesity. An
excessive intake of fat-soluble vitamins can cause hypervitaminosis or vitamin
• Diet:- a diet means the kinds and amounts of food and beverage consumed every
day. A diet may be a normal diet or it may be a modified diet which is used in the
treatment of a specific disease or condition.
• Kilocalories:- it is the unit for measuring the energy value of foods or the energy
needs of the body. It is the amount of heat required to raise the temperature of
1000 gm water by 1 degree C.
• 1 kcal= 4.184 kilojoules (kJ)
Food and its functions
• Each nutrient in food has specific functions to perform in the body. The physiological functions
performed by food are as follows.
• Providing energy:- the body needs energy to carry out voluntary and involuntary work.
involuntary work includes all process which are not under the control of our will such as
digestion, respiration, and circulation and go on continuously irrespective of whether we are
asleep or awake.
• Voluntary activities or activities which we wish to do such as walking, playing games, and
working require energy. The energy needed for these activities is supplied by oxidation of the
foods we eat mainly carbohydrates and fats.
• Body building or growth:- it is one of the most important functions of food. An infant grows
into a healthy adult by consuming the right kinds and amounts of food year after year.
Our body is made up of millions of cells and when growth takes place, new cells are added to the
existing cells and cells increase in size.
• Maintenance or repair:- in the adult body, worm out cells are continuously being
replaced by new ones. Proteins, minerals, and water are the main nutrients for
growth as well as maintenance of all cells and tissues in the body.
• Regulation of body processes:- food also regulates numerous activities in the
body such as the beating of the heart, maintenance of the body temperature,
clotting of blood, and excretion of wastes. Each of these processes is controlled
and carried out by specific nutrients, for example, vitamin K and calcium are
necessary for clotting of blood.
• Protective function:- nutrients keep body cells in a healthy condition toward off
infection. They help in building up the bodys resistance to disease and help the
body recover rapidly from any infection. These functions are performed by
vitamins and proteins.
• Health:- the world health organization defines health as a state of complete physical, mental,
and social well being, and not merely the absence of disease or infirmity.
Health is a positive state of complete well being and not just the absence of
disease. When we are tired or exhausted, we cannot concentrate on our work. To remain healthy a
balance between work and rest or recreation is necessary. This improves our work efficiency.
A person must look healthy, feel healthy, and have a balanced mind and a socially responsible
Adequate Nutrition:- adequate nutrition is one which meets in full all the nutritional needs in
good amount. These needs are set forth for infants, children, boys , girls, men and women.
Example:- 1-3 years children nutritional requirement is
Total energy ( calories) 1220, proteins 22g, calcium 0.4-0.5g, iron 20-25mg, thiamine 0.6mg,
riboflavin 0.7mg,nicotinic acid 8mg.
Optimum nutrition:- optimum nutrition as a revolution in health care. It means giving yourself
the best possible intake of nutrients to allow your body to be as healthy as it possible can.
Eat the right kind and the right amount of food.
Pack a home prepared school lunch
Eat nutritious snacks.
• Avoid eating spicy foods.
• Have plenty of rest and outdoor exercise.
• Eat your meals on time and in the company of your family.
• Proper nutrition is required for good health. Optimum nutrition results to good health that makes
a person productive.
• how can you tell if person is well nourished and healthy??
1. Clear eyes
2. Clean and smooth skin
3. Good body posture
4. Absence of any pain
5. Resistance to infection
• Classification of nutrients
• Nutrients are the essential constituents of food that are required by the body in suitable amounts.
There are approximately fifty nutrients which are placed in six categories, namely, proteins,
carbohydrates, fats, vitamins, minerals, and water.
• Based on their requirement in the body, nutrients are divided into two major groups- the
macronutrients and the micronutrients. Most of the weight of the food we eat is that of proteins,
carbohydrates, fats, and water. These are the macronutrients. Vitamins and minerals are required
in minute amounts and are also present in food I very small quantities. They are classified as
Proteins, Carbohydrates, Fats, water Vitamins, Minerals
• Both macronutrients and micronutrients are equally important for good health, and one cannot
enjoy good health without including all nutrients in the diet.
• The requirement for macronutrients is in grams, while the requirement for micronutrients is in
milligrams and micrograms.
DIGESTION, ABSORBTION, AND METABOLISM OF FOOD
• The food we eat needs to be broken down into simpler substances which the body can utilize.
This is accomplished by the process of digestion.
• Complex substances such as carbohydrates, proteins , fats are broken down into simpler forms
by the mechanical action of teeth and chemical action of various enzymes in the digestive
• Water, minerals and vitamins can be absorbed directly without undergoing any change. Glucose
needs no further breakdown and is immediately absorbed giving instant energy. Both digestion
and absorption take place in the digestive tract in the body.
• The liver and pancreas are not a part of the digestive tract, but provide vital secretions, namely,
bile and pancreatic juice respectively which aid in digestion of food.
• Digestive juices are also secreted by all parts of the digestive tract except the oesophagus,
rectum and anus.
• These juices contain chemical substances called enzymes, which act as catalyst in the
breakdown of nutrients.
• Digestion of food
• MOUTH:-the process of digestion begins in the mouth. Food is mechanically broken down by
the teeth by chewing and is moistened with saliva produced by the salivary glands in the mouth.
• Saliva contains an enzyme called salivary amylase or ptyalin which acts on cooked
carbohydrates and partially digests them into smaller units.
• if food remains in the mouth for sometime, carbohydrates are further broken down into maltose
by the action of salivary amylase giving food a sweetish taste.
• OESOPHAGUS:-food passes from the mouth into the stomach through a tube called the
oesophagus or food pipe. No digestion takes place in the oesophagus.
• STOMACH :- in the stomach the food is mixed with gastric juice. Gastric juice is composed of
hydrochloric acid, enzymes, and water. The stomach muscles muscles contract and churn the
food to a liquid consistency called chyme. Gastric juice has many important functions. The
acidic nature of gastric juice.
1) Destroys harmful bacteria which may be present in food
2) Activates enzyme pepsin
3) Swells proteins so that enzymes can easily act on them
4) Aids in the absorption of calcium and iron
• SMALL INTESTINE:- maximum digestion of proteins, carbohydrates, and fats takes place in
the small intestine. The small intestine includes the duodenum which is the first portion, the
jejunum, and the ileum.
• Bile which is produced by the liver and stored in the gall bladder is needed for digestion of fat.
Bile is highly alkaline and helps in neutralizing the acidic chyme so that other intestinal
enzymes can act.
• The small intestine secretes intestinal enzymes and the panaceas secretes pancreatic juice and
completes the digestion of proteins, carbohydrates, and fats into amino acids, monosaccharides,
and glycerol and fatty acids respectively.
• These simple substances are absorbed through the walls of the small intestine into the
• LARGE INTESTINE:- the large intestine includes caecum, colon, rectum, and anus. The food
which is not absorbed in the small intestine passes into the large intestine.
• water and digestive juices are reabsorbed in the large intestine giving the intestinal contents a
solid consistency. The unabsorbed material is called faeces, and it contains small amounts of
undigested food mainly fibre, bile salts, cholesterol, mucous, bacteria, and broken down cells. It
is excreted via the anus.