Transcript Lecture 13. Biochemical principles of nutrition

Biochemical
principles of
nutrition
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Nutrition may be defined as the science of
food and its relationship to health. It is concerned
primarily with the part played by nutrients in body
growth, development and maintenance. The word
nutrient or "food factor" is used for specific dietary
constituents such as proteins, vitamins and
minerals. Dietetics is the practical application of
the principles of nutrition; it includes the planning
of meals for the well and the sick. Good nutrition
means "maintaining a nutritional status that
enables us to grow well and enjoy good health".
In various historical times structure of nutrition
and character of a nutrition changed depending on
 development of industrial forces of a society,
 climate-geographical conditions,
 direction of economic activity and so on.
The character of nutrition of the population was
formed gradually depending on an economic and
cultural level of development of the country, in view of
national customs and features.
Through centuries, food has been recognized as
important for human beings in health and disease.
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Good nutrition is a basic component of health. The
relation of nutrition to health may be seen from the following
view points:
Growth and development: Good nutrition is essential for the
attainment of normal growth and development. Not only
physical growth and development, but also the intellectual
development, learning and behaviour are affected by
malnutrition.
Specific deficiency: Malnutrition is directly responsible for
certain specific nutritional deficiency diseases. Good nutrition
therefore
is essential for the prevention of specific
nutritional deficiency diseases and promotion of health.
Resistance to infection: Infection, in turn, may aggravate
malnutrition by affecting the food intake, absorption and
metabolism.
Mortality and morbidity: The indirect effects of malnutrition
on the community are even more striking - a high general
death rate, high infant mortality rate, high sickness rate and
a lower Expectation of life.
'You are what you eat',
some people say.
If you eat rubbishy food,
you can't really expect to
grow up strong and
healthy.
But if you eat goodquality food, you've a
good chance of doing so.
That's just commonsense
really.
Main rules of healthy nutritional
Eating fruits, vegetables, and grain products that contain
fiber may help prevent heart disease
Limiting the amount of saturated fat and cholesterol in
your diet may reduce your risk of heart disease
Limiting the amount of total fat you eat may help reduce
your risk for cancer
Eating fiber-containing grain products, fruits, and
vegetables may help prevent cancer
Eating fruits and vegetables that are "low in fat" and
"good sources" of dietary fiber, vitamin A, or vitamin C may
help prevent cancer
Nutrition as a science can be regarded as the
study of six main categories of food components
protein
fat
carbohydrate
minerals
vitamins
water
Water
Water is necessary to make up the loss caused by
its excretion in breath, sweat, urine, faces, and also
to renew all the various fluids and solid organs of the
body.
It is estimated that about 2 liters of water enters
the body daily as such or as a part of cooked food,
beverages etc. Out of which 1.37 - 1.81 liters is
excreted daily in urine, sweat etc.
Some important uses of water are:
 - As a solvent for transportation of nutrients in the
body.
 - It helps regulating body temperature through
evaporation from lungs and skin.
 - As an aid in removing wastes of metabolism in the
urine.
 - As an aid in functions like osmosis.
Diseases, that is direct or mediate
related with a nutrition
1. Alimentary disease,
illness caused by
deficiency or
surplus of
components of
nutrition.
The
secondary
illnesses of insufficiency
or excessive nutrition,
which is developed as
complication
on
a
background
of
wearisome
illnesses
(surgical,
infectious,
oncology and others.)
2.
3. Disease of
multifactor nature
that very much
frequently
develops on a
background of
genetic
predilection, for
example,
atherosclerosis,
gout, idiopathic
hypertension, etc.
4. Disease, which
are transferred by a
nutritional way
(some infections
diseases and
intestinal worms,
alimentary
poisonings).
5. Alimentary
intolerance atypical reaction to
nutrition, for
example alimentary
allergy,
idiosyncrasy.
Function of nutrition
Provision of energy
Body building and repair
Maintenance and regulation of
tissue functions
CLASSIFICATION OF FOODS
1.Classification by predominant functions:
Energy-giving foods. These constitute fats and
carbohydrates. They are also called protein sparer. Proteins
also produce energy to some extent. Cereals, roots and tubers,
dried fruits, sugars and fats belong to this group. They supply
heat and energy to the body.
Body building foods. These are foods rich in proteins,
mineral salts and water. Milk, meat, fish, pulses, oilseeds and
nuts fall in this category.
Protective foods. These constitute inorganic salts, vitamins
and minerals. They include proteins and water. Milk, eggs,
liver, green leafy vegetables and fruits are included in this
group. They build our bones, teeth, muscles, soft tissues, blood
and other body fluids. They provide material for repair in the
body as wear and tear goes on constant.
2. Classification by origin:
• Foods of animal origin
• Foods of vegetable origin
3. Classification by chemical
composition:
• Proteins
4. Classification by nutritive value:
• Fats
•Cereals and millets
• Carbohydrates
•Pulses (legumes)
• Vitamins
•Vegetables
• Minerals
•Nuts and oilseeds
•Fruits
•Animal foods
•Fats and oils
•Sugar and jaggery
•Condiments and spices
•Miscellaneous foods
Balanced diet is one, which will meet a person's
caloric need and contain all nutrients, particularly
proteins, and vitamins. In addition, the food should
satisfy the taste and desire of a person and should
have enough roughage to promote the peristalsis.
Balanced diet should have 50-60 % carbohydrates
30-35 % fats and 10-15 % proteins with necessary
vitamins and minerals. A balanced diet must
contain foods from the above three groups.
Importance of the main components
of food in nutrition of the man
Nutrients are organic and inorganic
complexes contained in food. There are about
50 different nutrients which are normally
supplied through the foods we eat. Each
nutrient has specific functions in the body.
Most natural foods contain more than one
nutrient. These may be divided into :
(i) Macronutrients: These are proteins, fats and
carbohydrates which are
often
called
"proximate principles" because they form the
main bulk of food.
(ii) Micronutrients : These are vitamins and
minerals. They are called micronutrients
because they are required in small amounts
which may vary from a fraction of a milligram
to several grams.
PROTEINS
The word "protein" means that which is of first importance.
Indeed they are of the greatest importance in human nutrition.
Proteins are composed of carbon, hydrogen, oxygen, nitrogen
and sulphur in varying amounts. Some proteins also contain
phosphorus and iron and occasionally other elements. Proteins
differ from carbohydrate and fat in the respect that they
contain nitrogen. Proteins are made up of simpler substances,
called amino acids. These are the building blocks of protein
Some 22 amino acids are stated to be needed by the human
body, out of which eight are called "essential".
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Proteins are needed by the body:
For growth and development: They furnish the building
material, i.e. the amino acids from which the body proteins
are synthesized.
For repair of body tissues and their maintenance: It has
been shown that the body proteins are constantly being
broken down; they have to be replaced for which fresh
protein intake is required.
For synthesis of antibodies, enzymes and hormones:
Antibodies, enzymes and hormones contain protein. The body
requires protein to produce them.
Proteins can also furnish energy to the body, but generally
the body depends for its energy on carbohydrates and fats
rather than proteins.
Sources of protein
Animal sources:
Plant sources:
Protein requirements
Doctors recommended 1,0 g. protein/kg body
weight for an adult.
Daily allowances recommended by experts of
the World Health Organization (Geneva, 1976)
is 37 g of protein per day for the standard man
with mass of body 65 kg for professions of
average hardness (II group) and 29 g of protein
for the standard woman with body mass 55 kg.
Effects of protein deficiency:
The effects of protein deficiency may summarized as below.
During pregnancy:
 Still birth,
 low birth weight,
 anemia
Infancy and early childhood:
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Marasmus,
kwashiorkor,
mental retardation,
stunted growth and development
Effects of protein deficiency:
Adults:
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Loss of weight,
underweight,
poor musculature,
anemia,
increased susceptibility to infection,
frequent loose stools,
general lethargy,
incapacity to sustained work,
delay in wound healing,
cirrhosis of liver,
oedema,
ascitis, etc.
Fats are composed chemically of carbon, hydrogen and
oxygen, only in different proportion than they are contained
in carbohydrates. There is less of oxygen in fats than in
carbohydrates. Fats are a form of concentrated food and like
carbohydrates, they are used as body fuels for the
production of heat and energy. As fats are not soluble in
water, the process of digestion changes the fat into an
emulsion form for their absorption into the body. Liquid fats
and those which melt at body temperature are somewhat
better digested than those which are much harder.
Fats serve the following functions:
• Dietary fat is a concentrated source of energy. One
gram of fat supplies 9 calories of energy.
• Fats are carriers of fat-soluble vitamins, e.g., vitamins
A, D, E and K.
• Dietary fat supplies "essential fatty acids". Linoleic
acid, one of the essential fatty acids, prevents scaly skin
formation.
• The fat layer below the skin plays an important role in
maintaining our body temperature.
• Fats provide support for many organs in the body
such as heart, kidney, intestine etc.
• Foods containing fats are tasty.
Animal sources:
These are ghee, butter, fat of
meat, fish oils, etc.
Vegetable sources: These are various
vegetable oils such as groundnut,
gingely, mustard, cottonseed,
safflower (kardi) and coconut oil.
CARBOHYDRATES
Chemically carbohydrates are
composed of carbon, hydrogen and
oxygen as the name implies.
Polysaccharides are various starches
which are converted into two
molecules saccharides i.e. cane sugar,
beet sugar, milk sugar and malt sugar.
These on further, glucose and
digestion change into single molecule
monosaccharides fructose.
Foods that are high in
carbohydrates: Breads,
pastas, beans, potatoes, bran,
rice and cereals.
The original source of all starches and sugars is green
plants. When plants have excessive sugar and they need
to store it, as reserve supply of food, plant body is
capable of changing its sugar into starch. Carbohydrates
are abundantly present in food. All carbohydrates have
to be changed into glucose and fructose before they can
be absorbed into the body.
1 gm of carbohydrates yields 4.1 calories of heat.
The daily requirement of carbohydrates varies from
50 to 60% of total energy intake.
The carbohydrates are chief sources of energy. In the
active muscles, the glucose is oxidized for the
production of energy and warmth. Glucose which cannot
be used immediately, is converted into glycogen and
stored in the liver and muscles or converted into fat and
stored under the skin.
There are three main sources of carbohydrate:
Starches:
These are present in cereals
(rice, wheat); roots and
tubers (potatoes).
Sugars:
(a) Monosaccharides: glucose, fructose,
galactose.
(b) Disaccharides: Sucrose, lactose, maltose.
(c) Cellulose: This is the tough fibrous lining
found in vegetables, fruits, cereal, etc.
It is hard to digest and has no nutritive value.
However, cellulose acts as "roughage" and
prevents constipation.
VITAMINS
These are complex organic substances contained
in food and are very essential for the normal
growth and nutrition of animals. In fact, they are
vital accessory food factors required for the
maintenance of optimum, health. They are present
in various foods in minute quantities and diet
devoid of vitamins, if taken for some period, gives
rise to certain diseases known as deficiency
diseases and may ultimately even cause death.
They do not supply energy but are simply
protective foods.
vitamins
Water-soluble
Vitamins
Fat -soluble
Vitamins
Thiamine (B1)
A (retinol)
Riboflavin (B2)
Niacin (B3)
Pyridoxine (B6)
Pantothenic acid
Cobalamin (B12)
Ascorbic acid
Folic acid
E (tocopherol)
D (calciferol)
K (menadione)
Nutritional Diseases:
1. Protein Calorie Malnutrition (PCM).
(i) Kwashiorkor. It results from consumption of very low
protein in diets of low biological values, yet providing just
enough energy to satisfy the needs of the child. This
condition is usually seen in children between the age group
of 1-4 years. This symptom is characterized by pitting
oedema, anemia, retarded growth, loss of appetite,
diarrhoea, scanty hair growth...
(ii) Marasmus. It is a clinical condition of protein energy
malnutrition, primarily due to total deprivation of the
requisite calories required by the body. It usually occurs in
the age group of 1/2 to 5 years. This syndrome is
characterized by failure to gain weight, wasting of muscles
and of subcutaneous fat. The child feels good appetite but
is irritable.
(iii) Marasmic-Kwashiorkor. Patients suffering from
Marasmic-Kwashiorkor show clinical symptoms of both
Marasmus and Kwashiorkor.
2. Protein Deficiency in Adults.
Protein deficiency in adults is also quite prevalent
in poverty areas.
Protein deficiency will result in adults having
 reduced weight,
 reduced subcutaneous fat,
 anaemia,
 greater susceptibility to infection,
 frequent loose motions,
 general lethargy,
 delay in healing of wounds
 oedema.
3. Mineral Deficiencies
(i) Deficiency of iodine in water
and feed leads to goitre.
(iii) Calcium deficient diets lead to
rickets and osteomalacia.
(iv) Iron deficiency diets lead to
anaemia,
(v) There are other important
minerals like copper,
(ii) Lack of flourine ( < 0.5 ppm) selenium etc. Usually their
requirements are so little that
in water leads to caries.
deficiency conditions do not
occur.
4. Vitamins Deficiencies
(i) Lack of vitamin A results
in xerophthalmia, Bitot's
spots, night blindness
and keratomalacia.
(ii) B Complex: Deficiency of
Thiamine leads to beri beri.
Niacin deficiency results in
pellagra.
Riboflavin
deficiency
symptoms
are
angular
stomatitis, cheilosis, scrotal
dermatitis and
corneal
vascularisation.
Other B Complex deficiencies also result in glossitis,
cheilosis and angular stomatitis
(iii) Vitamin C deficiency leads to scurvy, spongy bleeding
gums, haemorrhages in skin and other haemorrhages,
(iv) Vitamin D deficiency result in rickets and osteomalacia.
(v) Vitamin K deficiency leads to hypoprothrombinaemia,
which further leads to haemorrhages.
5. Problems of Overnutrition (eating too much)
Proteins/fats/carbohydrates
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Cardiovascular disease (Leading cause of death in
the western world); a primary cause is thought to be
ingestion of saturated fat and trans fat
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Some cancers
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Diabetes mellitus
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Insulin resistance
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Obesity The main features of obesity are overweight
and fatness. It is mostly caused by overeating and
intake of abundance of calories
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Metabolic syndrome
Vitamins
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Vitamin poisoning
(i) Hypervitaminosis A is at times caused by excess of vitamin A
therapy. The manifestation are headache, nausea, vomiting,
irritability and anorexia. Carotenaemia is also caused due to
excessive consumption of carrots which is characterised by
yellow skin with normal conjunctiva
(ii) The toxic manifestations of hypervitaminosis D are anorexia,
nausea, vomiting, thirst, polyuria and drowsiness. Calcium
and phosphorus levels in serum and urine are raised. Calcium
may be deposited in many tissues also
(iii) Fluorosis occurs if fluorine is available > 1,5 mg in water. It
is characterised by (a) dental fluorosis, i.e., mottled enamel of
teeth and (b) skeletal fluorosis i.e., dense bone formation,
severe spondylitis and even calcifications of ligaments of spine
and tendinous inflamation of other muscles in severe cases.
Food allergies
Some people have allergies or sensitivities to foods which
are not problematic to most people. This occurs when a
person's immune system mistakes a certain food protein for
a harmful foreign agent and attacks it. About 2% of adults
and 8% of children have a food allergy.
Commonly food allergens are gluten, corn, shellfish
(mollusks), peanuts, and soy. Most patients present with
diarrhea after ingesting certain foodstuffs, skin symptoms
(rashes), bloating, vomiting and regurgitation. The digestive
complaints usually develop within half an hour of ingesting
the allergen.
Rarely, the food allergy chelce can lead to anaphylactic
shock: hypotension (low blood pressure) and loss of
consciousness. This is a medical emergency. An allergen
associated with this type of reaction is peanut, although
latex products can induce similar reactions.
The hygienic characteristics of some
food-stuff and their sanitary
examination
Wheat
It is the most important of all cereals and is extensively
used all over the world. It contains 60-70 % starch, 8-12 %
gluten and 15 % water. The seeds have an outer envelope called
pericarp, which is very hard. It is composed mainly of cellulose
and mineral matter and forms about 13 % of the grain. A
middle layer called endosperm or kernel consists chiefly of
starch. It forms 85 % of the grain. The germ or embryo forms
about 1.5 % of the entire grain. It is rich in protein and fat.
Flour is prepared by grinding up wheat.
Rice
In fact, it forms the staple article of diet for half the
population of the world. In composition, it is poorest in
proteins, fats and mineral matter, out of all the cereals and
has no cellulose contents or roughage. Its chief constituent is
starch, which is in a very digestible form. It is digested within
3-4 hours. Being rich in starch it is eaten with nitrogenous
and fatty substances, like pulses, fish, ghee etc., to supply the
deficiency in proteins and fats. The bulkiness of rice eaters'
diet gives rise to two important consequences:
(i) it tends to prevent the absorption from the intestines of the proteins and
vitamins contained in other foods eaten with it, as dais or pulses
(ii) it is apt to cause distension of the stomach and bowels with
fermentation of their contents, thus result in indigestion and bowel
complaints.
The outer layer or pericarp contains vitamin B1 and its complete
removal may give rise to beri-beri in rice eating population. Rice does not
contain vitamins A, C and D.
Barley. It is very nutritious and is characterized by its
richness in mineral salts and fat but is poor in gluten, so it
is unsuited for making bread.
Maize. It is as nutritious as wheat, and richer in fats than all
cereals except oats. It contains 10 % proteins, 65 %
carbohydrates, 5 % fats, 1-2 % salts and 14 % water.
Maize is poor in certain amino acids—such as
tryptophane. It is deficient in vitamins, the anti-scorbic
and anti-pellagra factors being absent and an exclusive use
of maize may cause pellagra.
Oats or Jao. These are highly nutritious. They are deficient in
vitamins A and D and gluten. Oats are used as oatmeal
porridge and should be eaten with plenty of milk.
Pulses
Soya Bean
These are mostly legumes and are richer in
nitrogenous substances that other vegetable foods.
Pulses include peas, beans, and lentils. Owing to
their richness in proteins, they are called "poor
man's meat". Compared to meat, pulses are deficient
in fat. Pulses also contain a good deal of
carbohydrates If their fresh state they contain
vitamins A, B, and C, but when dried they lose
vitamin C.
It is the richest form of vegetable proteins but with low fat
content, a large amount of mineral matter and almost
complete absence of starch. Iron content of soya beans
varies from 7-30 mg. per 100 gms. The protein is of good
quality and easily digestible. It contains large quantities of
vitamin B1 but no vitamin C and D. A milk from soya bean
is prepared to resemble more or less the composition of
cow's milk. It contains absolutely no cholesterol. The high
fibre content of soya milk helps relieve constipation, while
high mineral protein and vitamin (especially B complex)
levels provide "ideal" nutrition.
Roots and Tubers.
They exist chiefly in the form of starch which is about 80 % proteins and
fats being practically absent. They contain some mineral matters which are
mainly salts of potash. The common form of tubers are carrots, potatoes,
beet-root, radish, onions, arrow-root, sago and tapioca.
Potatoes are rich in carbohydrates and contain starch 22 %,
protein 2 % and a trace of fat (0.16 %). They are a good source of
vitamins B and C and contain iron and phosphorus; that is why
they are universally used as wholesome and palatable dietary
articles having much nutritive value.
Green Vegetables.
They have little nutritive value, but form an important article of
diet on account of the presence of vitamins and mineral salts of
sodium, calcium and chlorine, which they contain. In composition
they consist of 90 % water, 2 % nitrogenous substance or proteins,
4 % starch and ½ % fats.
They contain large amount of alkaline salts which act as "buffers" and maintain the
alkalinity of the blood. They supply vitamins A, B1, B2 and C and give relish to the
food, so their inclusion is essential in an ideal dietary. Green vegetables are rich in
cellulose, so add bulk and are of value in curing chronic constipation. So far as possible,
they should be eaten raw as salad.
Fruits
Fruits contain a large amount of sugar, vegetable
acids and salts. These are protective foods. According to
their nutritive value fruits have been divided into food
fruits and flavouring fruits.
Food fruits are those which afford nutriment, and
include bananas, dates, figs, grapes, mangoes etc. Their
nutritive value depends on the presence of
carbohydrates, which exist in the form of sugar and
commonly known as levulose or fruit sugar. Certain
fruits such as lemons and oranges are rich in potassium
salts, lime and magnesia and contain vitamin C.
The fruits are valuable because:
They have cooling effect and quench thirst.
They contain important mineral salts of potash
combined with vegetable salts.
They have anti-scorbutic properties being the
richest sources of vitamin C and for this reason
they are included in children's dietary. They
prevent scurvy.
They prevent constipation.
Nuts.
They differ from
fruits as they have
higher calorific and
nutritive value, being
rich in proteins and fats.
The common nuts are
almonds, cocoa nuts,
ground nuts, walnuts etc.
They are rich in vitamin
B but contain very little
vitamin A and no
vitamin C.
Meat
It consists of muscle-fibres held together by connective tissues.
The fibres of meat contain muscle plasma or muscle-juice. It
contains 1 to 2 % salts which are chiefly chlorides and phosphates
of potash. The proteins of meat which are present to the tune of
about 17 to 20 % are myosin, muscle-albumen and haemoglobin.
Fat (10 to 20 %) is often embedded in the connective tissues of
meat.
• Inspection of Meat. Anti-mortem inspection of animals should be
done, wherever possible and the animals should be rejected, if they
appear to be ill. The carcase should be inspected after slaughtering
whole and also part by part and subsequently organ by organ.
Mediastinal and bronchial lymphatic glands should be examined
for evidence of tuberculosis. If the animal has suffered from
jaundice, the flesh will have a yellow tinge.
• Characteristics of Good Meat. The muscle fibres are of deep red
colour and marbelled with fat. The reaction should be acidic. It
should be firm, elastic to touch. It should have little or no odour as
diseased meat emits odour of putrefaction or sickly smell. The fat
should be firm and of whitish or yellowish grey colour. Lymphatic
glands should be free from all diseases. Any diseased condition, i.e.,
cysts of tapeworms etc., should not be present.
Unsound Meat.
It is that meat which has begun to putrefy.
1. It becomes soft, moist, pale and often has greenish colour.
2. The reaction becomes alkaline
3. Оdour of putrefaction may commence in the deeper part of
the meat especially near the bones and so the odour may not
be apparent from the outer surface. Therefore, in case of
suspected meat, it is advisable to push an iron skewer deep
into the meat; pull it out and smell it.
4. The smell should be sweet and agreeable.
5. The juice should be reddish and acidic, since alkalinity is an
indication of decomposition.
6. Putrified meat is extremely dangerous, as poisonous
substances get developed, which introduce sudden and fatal
illnesses due to ptomaine poisoning.
Diseased Meat
The flesh of animals killed by accident, lightning or those
who happen to be suffering from diseases like anthrax, rabies,
glanders, general tuberculosis etc., should be condemned. The
diseased meat should be condemned and prevented from
sending into the market.
The chief diseases of animals are:
(1)Tuberculosis.
(2)Cysticercus.
(3)Trichinella Spiralis.
(4)Actinomycosis or Ray Fungus.
(5)Distomum Hepaticum of Liver Flukes.
Fish
It is easily digested and is assimiable. It has a high
nutritive value, though not so stimulating as meat, but
generally it is less rich in fats and contains more
calcium than ordinary meat. It has all the vitamins
except vitamin C. Fish liver is a rich source of
vitamins A and D. Sea fish is a rich source of iodine.
There are two kinds of fish: Lean fish. It consists of
small fibres and contains fat below 2 %. It is easily
digested. Fat fish. It consists of medium or large fibres
with fat content of 2.5% or more. It is somewhat
difficult to digest.
Characteristics of Good Fish A fish should have bright pink gills, firm
glistening scales and prominent lustrous eyes. It should have a bright and
glistening skin with a covering of clear slippery mucous. It should be free
from any disagreeable odour. When held flat on hand by head, the tail should
not droop. It should not feel soft or leave an impression or depressed mark
when pressed by a finger. Its skin should be intact and scales should not be
easily detachable. If not eviscerated a sound dead fish sinks in water.
A decaying fish has dull grey sunken eyes, grey muddy gills,
the scales become detached and have a characteristic
putrefying smell. It may cause ptomaine poisoning. It floats in
water with belly up, A putrefying fish shows dark blood or
dark tarry liquid on cutting and its body becomes flaccid. A
large tapeworm called Dibothriocephaluslatus is conveyed to
man by eating insufficiently cooked fish. Fish poisoning may
occur due to toxins produced by Cl. botulinus. Its
decomposition may give rise to ptomaine poisoning. It may be
found that some persons possess idiosyncracies especially to
muscles, which are said to cause poisoning by mytilo toxin.
The chief symptoms produced are dyspepsia, urticaria,
swelling of tongue, numbness of limbs, weak irregular pulse
etc.
Tinned Meat and Fish.
They are commonly used. It is very essential to
see that meat and fish in tins are wholesome,
not old and putrefied. The tins should be
carefully examined before consumption in the
following ways:
On Inspection. There should be no indentations, holes, soldering defects or
signs of gross ill usage. It should not be rusty. It should have concave ends and
not be bulging or blowing out indicating putrefaction and formation of
hydrogen gas in acidic medium. A collapsed tin signifies too much vacuum. All
leaking and non-airtight tins should be discarded.
On Palpation. If putrefaction has set in and gas has formed it gives a springy
feel with a sense of resistance. It so happens particularly, when air has entered
into the tin through a leaking hole and the vacuum is lost.
On Percussion. If the note is tympanitic, it indicates unsound tin due to
formation of gas, while a dull note indicates a sound tin.
On Shaking. A sound tin will produce no sound, but if the contents are
putrefied and are partially liquid then a loose sloppy sound will be detected.
Eggs
A egg's weighs approximately 56.70 gms and consists of 10
% outer covering or shell, 60 % white, and 30 % yolk. It
is a food containing all the proximate principles of food,
except carbohydrates necessary for the growth and
development of the body. It is a protective food containing
first-class proteins with all the essential amino acids and
have the highest nutritive value among dietary proteins.
In view of the presence of sulphur in the white of egg, they
are considered as acid forming foods and resemble meat
in this respect.
It consists of an outer shell with its interior white and
yolk. The shell consists of carbonate of lime, the white is
made up wholly of proteins, the chief being egg albumen
and the yolk contains less proteins and a large amount of
fat. Besides, it contains lecithin, vitalin and the organic
compounds of phosphorus, lime, and iron. It is rich in
calcium salts, anti- neuritic and anit-rachatic vitamins.
Yolk of egg is a valubale food for anaemic patients, since it contains iron
which is very easily digested and assimilated in the body. Since the fat
present in the yolk of eggs is in emulsified form, just like milk, it is easily
digested and is almost completely absorbed in the intestines; only 3 % of
residue is left.
Freshness of eggs can be tested
(1) by holding them in the hand in front of a candle in the dark. Fresh ones
being more transparent in the centre and stale ones are transparent at
their extremities. This process of testing the eggs is known as Candling.
(2) By putting them in 10 % salt solution; fresh eggs will sink, whereas
stale ones will float.
Milk
It is a food material of special importance. It is
almost complete, an ideal food and contains most
of the proximate principles of a well balanced
diet required for human body. It is thus the
nearest approach to perfect food. It forms the
only diet of children to the age of a year or so. It
is the best source of calcium in diet both on
account of quality and the valuable assimilable
form in which it exists. It provides proteins of
high biological value to the body.
Milk contains the following proximate principles:
1. Proteins: 3,5% of total weight, consisting of 3 %
Caseinogen, 0,4 % Lact albumen, and 0,1% Lactoglobulin. Milk proteins are of high biological value.
Cow's milk is rich in casein, and human milk in
Lactalbumi
2. Carbohydrates: The carbohydrate in all milks is
lactose or milk sugar (4 to 5%). Human milk
contains more lactose than cow's milk
3. Fats: 3,5 to 4 % in the form of glycerides in emulsified form. Milk fat
is a good source of vitamins A and D When milk is allowed to stand for
sometime, fat rises to the surface as cream. Chemically milk fat consists of
myristin, olein, palmitin and stearin.
4. Vitamins: It contains all the vitamins except vitamin E. In summer,
cows, if fed on grass, produce milk containing large amount of vitamins B,
C and D. But in winter, amount of vitamins A and D in milk is much
reduced.
5. Mineral Salts: Phosphates and chlorides of calcium, potassium and
sodium. It is poor in iron.
Average specific gravity of cow's milk is 1.032. Lactometer is used to
determine the specific gravity.
Solids other than fat are estimated by evaporation to complete dryness,
a known weight of milk and then weighing total solids and subtracting
therefrom the fat previously determined from percentage of solids, which
gives percentage of solids other than fat.
Milk-borne diseases.
The important milk-borne diseases are:
1. Directly from the milch animal:
• Tuberculosis,
• Brucellosis
• Streptocobbsl infection
• Malta fever
• Anthrax
2. Inderectly from the human handler or environment
• Typhoid and paratyphoid fevers;
• Cholera,
• Dysentery,
• Diphtheria,
• Viral hepatitis
Methods of Preservation of Milk
These are as follows:
(1) Boiling is ancient method of rendering the milk safe for human
consumption.
(2) Pasteurisation. According to WHO, pasteurisation may be
defined as the heating of milk to such temperatures and for such
periods of time, as are required to destroy any pathogenic
organisms that may be present, while causing minimal changes in
the composition, flavour and nutritive value of milk.
There are various methods of pasteurisation of milk. Some of
them are as follows:
Holder or Vat Method. In this method milk is heated and kept at
63 to 66°C for 30 minutes and then quickly cooled to below 5 °C.
High Temperature and Short Time method: milk is heated rapidly
to a temperature of 72 °C and then quickly cooled to below 5 °C.
Ultra High Temperature method: The temperature of milk is raised
to 125 to 150 °C for a few seconds only and then rapidly cooled
Difference b|w pasteurization and boiling
Pasteurization
1.Temperature
(a) 63 0C-65 0C
(b) 72 0C – 800C
2. Both iodine and Vit. C
decreased by 20 %
3.Lactose is not caramelized
or chared.
4. Pathogenic organisms are
killed and iactia acid forming
bacilli.
5.Taste, appearance and food
value not charged.
6. Souring delayed.
Boiling
1.Temperature
100 0C
2. Iodine and Vit. C totally
lost.
3. Lactose is completely
caramelized.
4. All organisms are
destroyed
5. Taste, appearance and food
value affected.
6. Souring may be prevented.
3. Sterilisation. This is done by raising the temperature to
100°C and then by maintaining it for 15 minutes in closed
sterilised vessels. It kills all micro-organisms and their spores.
The disadvantages is that vitamin C and B are destroyed to
one-half and one-third respectively of their original content.
The biological value of proteins is said to be slightly reduced.
It is unsuitable for feeding infants.
4. Drying or Desiccation The milk prepared from this
powder is of uniform composition, free from all dangerous
organisms and easily digested by infants, as the curd formed
in their stomach is more flocculent and finely divided than
that of the fresh cow's milk. The vitamin content of dried milk
is variable. Vitamin C is reduced considerably. So when it is
given to infants, orange juice or any other vitaminised
preparation should be added to it.
Cream. It is prepared by allowing the milk to stand for a
considerable time in the cold so that butter fat may rise to the top
and then removing the top layer. The fat or cream may be
separated from milk mechanically through a centrifuge machine
known as a separator or it may be obtained by churning the
curdled milk. Cream may contain about 50 % fat. Besides milk fat,
cream contains proteins and lactose also.
Butter: It is the most nutritious and easily digestible form of all
fats. Good butter should neither be rancid nor have an unpleasant
odour. Specific gravity of butter fat varies from 0.911 to 0.913. Its
melting point is 35.8°C.
Its average composition should be:
Water 12 - 15 %
Fat
80 - 90 %
Caseinogen
1-3%
Lactose
1%
Ash
2-3%
Salt and Vitamins -q.s.
Cheese.
It is a very concentrated protein
food and methods of making it
vary considerably at different
places. It is prepared by
coagulating caseinogen of whole
milk or skimmed milk with
rennet. Cheeses differ by high
content of protein (20-25 %), fat
(25-30 %) and what is also
important
–
calcium
and
phosphor.
Depending on quality the food-stuff can be divided
on such groups:
1. Products of high quality - the products which may be used without
restrictions.
2. Non-standard. The products, which have the certain deviations from
requirements of state standards or specifications, but it does not interfere
to their realization (for example, chicken eggs of mass less 40g etc.).
3. Conditionally suitable. It is products, which can be used after
additional processing.
4. Substitutes (ersatz). The products with reduced value as natural
substitutes, for example, barley and acorn coffee. They are allowed to
realization, provided that the consumer would be informed, what kind
product is offered to him.
5. Food Adulteration It is products, in which premeditatedly qualitative
structure are changed to hide the certain disadvantages or sings of decay.
Such products are forbidden to realize to the population.
6. Low-quality. The products concern to those, which are not suitable to
nutrition in any way, that is, which have the expressed signs of decay
(rotting, etc.).
Some of the common practices in different country include
Rice and wheat: There are mixed with stone chips and gravel to incrase the
bulk.
 Flour: Wheat flour is mixed with soap stone powder and cheaper flours
such as maize flour;
Milk: Removal of fat and addition of water, starch and skimmed milk, milk
powder etc. are the common types of milk adulteration
Butter is adulterated with other animal fats in Western countries and in
India by other vegetable oils.
Miscellaneous : Tea leaves are adulterated with old tea leaves, leather and
saw dust. Coffee is adulterated with chicory. Honey is adulterated with sugar
or jaggery and boiled with empty beehives. Papaya seeds are mixed with
pepper. Powdered condiments and spices often contain an assortment of
innumerable substances including horse dung and brick powder.
Some forms of adulteration may not be very dangerous e.g., addition of
water to milk, cheap edible oils to expensive ones, cheap flours to expensive
ones etc. However, they may considerably reduce the nutritive value,
contaminate the food (e.g. water to milk) and add toxins to the food (e.g.,
kesari dal flour to other flour and adulteration of edible oils with argemone
oil and white mineral-oil, use of non-permitted colours in sweets and cordials,
and that of lead chromate for spices etc.
Fortification and Enrichment
Addition of one or more dietary essentials to some foods in
amounts which make the total content greater than that found in that
particular food in its natural state is known as Fortification. It also
includes addition of one or more dietary essentials which original food
does not contain in its natural state. Enrichment means addition of
dietary essentials to a food to restore the total content of the former.
Some of the examples of fortification and enrichment are as follows:
Addition of Vit. A and D to milk,
 addition of potassium iodate to common salt for endemic goitre
areas,
addition of iron and calcium to common salt is being considered by
the Government of India,
addition of synthetic aminoacids foods e.g., lysine to wheat flour etc.
Supplementary Foods
A number of cheap supplementary foods are being formulated,
which can provide nutrients at low cost, as a supplement to the
usual diet.
Food Additives
Food additives are non-nutritious substances which are
added intentionally to food, generally, in small quantities to
improve its appearance, flavour, texture or storages properties.
Food additives are generally used as food colours,
antimicrobials, anti-oxidants and as stabilising, bleaching and
maturing agents. Their use for a number of techinical processes
such as the maintenance of the nutritive quality of food,
enhancement of keeping quality, making food attractive to the
consumers and providing essential aids to food processing, is
well recognised. However, their abuse is creating serious public
health problems, because they are sometimes used to deceive the
consumer by disguising the faulty handling and processing
techniques. Several food additives are under controversy about
their safety; and some are dangerous to health, which are quite
often used in spite of not being permitted by law.
BASES OF TREATMENT - PROPHYLACTIC
NUTRITION
Treatment-prophylactic nutrition – is a special
nutrition for workers of harmful enterprises. The base
of this nutrition is rational nutrition, which is structured
according to metabolism of harmful substances in the
human organism and curative action of some nutrients,
which protect human organism from negative influence
of chemical compounds and physical factors.
Treatment-prophylactic nutrition is an obligate
component of protective health-proving measures,
directed on limitation of negative action of
harmful factors on production on the organism.
Treatment-prophylactic treatment is directed on:
elimination of possibility of harmful substances
penetration into internal medium of the organism from the
digestive tract, meaning their binding in stomach and
intestines;
quickening of excretion of harmful substances from the
human organism;
increasing of general resistance of the organism towards
harmful factors;
protection of certain, most damageable systems of the
organism from harmful action of toxic substances;
quickening or on the opposite slowing down toxic
substances metabolism in the organism (aiming to stop
their income into internal medium).
In Ukraine there are 3 kinds of treatmentprophylactic nutrition on harmful enterprises:
 Treatment-prophylactic ratios.
 Milk.
 Synthetic vitamin drugs.
Introduction of treatment-prophylactic nutrition as a
rule follows after theoretical and medical-biological
investigations directed on determination of mechanism of
action of certain harmful substances and their combinations
on the organism.
Complex interrelations between components of the
mixture are determined during studying of complex action of
several toxic substances; as if they enter the organism
together character of their toxic action may change
(synergism or antagonism). After detoxic action of different
nutritive products and substances is studied. It is proved
that many nutrients have a considerable detoxicating action.
Thus, pectin substances are able to bind heavy metals and
radionuclide in digestive tract, preventing their absorption
and entering internal medium of the organism. Sulfur
containing amine acids methyonin, cystin, magnesium salts
promote excretion of some toxic substances from the
organism. Vitamins raise protective capabilities of the
organism.
In case of constant poisonings with chemical
substances their multiple influences on the
organism is often performed, presented by damage
of central and peripheral nervous system, internal
organs (liver, kidneys, respiratory organs) and blood
producing organs (anemia often develops). General
result of the influence of all chemical substances on
the organism is disordering of functional condition
of liver, which leads to its inflammation (hepatitis),
and after to cirrhosis.
Following principles are followed during
organization of treatment-prophylactic nutrition:
1. As a usual result of influence of all chemical
substances on the organism is disordering of liver
function, so in treatment-prophylactic nutrition a
considerable attention should be paid to nutrients
and substances which increase functional condition
of liver and limit consumption of substances and
products which overload its work. Products, which
increase functional condition of liver, are: milk, sourmilk products, cheese and cottage-cheese. Wide
usage of milk products in treatment-prophylactic
nutrition is explained by considerable contents of
sulfur containing amine acids (methyonin, cystin),
which protect liver from fat infiltration.
2. Quantity of fats should be limited as they speed up
absorption of many chemical substances, most of
which are fat-soluble substances.
3.
Treatment-prophylactic nutrition should be
provided by a necessary quantity of fruit and
vegetables, which are the source of many watersoluble vitamins, carotene, microelements, pectin
substances and fiber.
4. Treatment-prophylactic nutrition should have an
alkali orientation. Disorder of acid-base balance of
the organism to acidosis side leads to increasing
of harmful substances income into blood, for
example, lead, and moving to alkalosis side
promotes accumulation of many toxic substances
in the organism. Milk, milk products, fruit and
vegetables possess alkaline properties.
5. Consumption of salt should be limited, since it
promotes water retention in the organism.
6. Treatment-prophylactic nutrition should
provided based on general rational nutrition.
be
VEGETARIANISM
Vegetarianism is the practice of not consuming the
flesh of any animal, with or without also eschewing other
animal derivatives, such as dairy products or eggs. Some
vegetarians choose to also refrain from wearing clothing
which has involved the death of animals, such as leather, silk
and fur. Veganism, sometimes called "strict vegetarianism",
excludes all animal products from diet and attire, whether or
not their production has involved the actual death of an
animal (dairy, eggs, honey, wool, silk and down feathers).
Vegetarians have varied motivations including religious,
cultural, financial, ethical, environmental, and health
concerns.
There are many different practices of vegetarianism. The
following table summarizes the practices of various different
types of vegetarian diet:
Foods allowed in the main vegetarian diets
Diet Name
Meat (includes fish)
Eggs
Dairy
Lacto-ovo
vegetarianism
No
Yes
Yes
Lacto
vegetarianism
No
No
Yes
Ovo vegetarianism
No
Yes
No
Veganism
No
No
No
Other dietary practices commonly associated with
vegetarianism
 Fruitarianism is a diet of only fruit, nuts, seeds, and other plant
matter that can be gathered without harming the plant.
 Macrobiotic diet is a diet of mostly whole grains and beans,
though it allows the consumption of fish.
 Natural hygiene in its classic form recommends a diet principally
of raw vegan foods.
 Raw veganism is a diet of fresh fruit, nuts, seeds, and vegetables.
 Freeganism — argues that all commodities produced under
capitalism, not only those from animal sources, contribute to
exploitation and avoid buying anything, including food. Freegans thus
focus on acquiring foods and other commodities by means other than
purchasing, including dumpster diving, foraging for wild plants, and
gardening with intent to cause as little violence and ecological
destruction as possible through their consumption. While many
freegans are vegans or vegetarians, others will eat animal products
recovered from dumpsters that would otherwise go to waste on the
belief that doing this does not encourage further animal exploitation.
Vegetarian diets appeal to people for various reasons. For some
people, religious and philosophical teachings prompt adherence to a
vegetarian regimen. Other people seek health benefits.
There is much to be said for most of us making our food
choices in the direction of vegetarian principles, eating less meat and
eggs and substituting foods of vegetable origin. Such choices will
reduce the amount of fats, particularly the saturated ones, and
increase the amount of fiber consumed. Although such choices will
reduce the amount of protein we eat, most of us consume more protein
than we need.
At the same time, a poorly planned vegetarian diet can put
you at risk for disorders such as vitamin B12 deficiency iron-deficiency
anemia, growth retardation (in persons who have not yet achieved
their full adult growth), and osteoporosis.
Careful planning is the key to such a diet. Because many of the
nutrients a human body needs are found most readily in animal
products, finding substitutes requires effort.
There are various degrees of food restrictions in vegetarian diets.
 Total vegetarians, known as vegans, restrict their foods to those of
plant origin only.
 Fruitarians further restrict their foods to only raw or dried fruits
and nuts, honey, and olive oil.
Lacto-vegetarians eat foods of plant origin plus milk and other
dairy products.
Lacto-ovovegetarians eat plant foods, milk and other dairy
products, and eggs.
Obviously, the question of the nutritional adequacy of a
particular vegetarian regimen depends on the extent of food
restrictions. Also, children and teenagers, pregnant and lactating
women, and people recovering from a serious illness or injury who are
vegetarians need to take precautions to ensure that all of their body's
needs are met. Such people should follow a vegetarian regimen only
with the careful supervision of an experienced, registered dietitian.
Protein is of some concern when planning a strict vegetarian
diet. Protein found in foods of plant origin tends to have only small
amounts of one or more essential amino acids. Protein from animal
sources contains essential amino acids in an optimal proportion.
•
Grains and cereals with ingredients including wheat, com, oats, and
rice provide some essential amino acids, while legumes such as peas,
peanuts, and dry beans provide others. When, during the course of
a day, you combine a grain with a legume, or cornmeal with beans,
you have a more nearly complete set of essential amino acids.
• Another important nutrient in the vegetarian diet is vitamin B12.
Vegetarians who consume milk or eggs will get enough of this
vitamin. Those who do not can eat foods artificially enriched with
vitamin B12. Some commercial foods made from soybeans and other
plant proteins are fortified with vitamin B12.
• Vegetarians who eat eggs and dairy products also usually receive
enough calcium and riboflavin, but the vegan has to devise special
dietary strategies. Many foods of plant origin contain calcium, but
they may not be as easily used by the body because of the presence
of fiber and oxalic acid in the foods. Oxalic acid and fiber may
interfere with the body's ability to use the calcium present in the
foods. Thus, if you are a strict vegetarian, you may need calcium
supplements.
•
Vitamin D, iron, and zinc are other nutritional elements
needing special attention in the vegetarian diet. Most of us
obtain vitamin D through fortified milk and exposure of our
skin to sunlight. If you do not drink milk, you must rely on
sunlight or on a vitamin supplement. However, children and
pregnant and lactating women who are vegetarians should
not rely solely on sunlight but should take a supplement.
• The high fiber content of most vegetarian diets tends to
impair the absorption of iron and zinc. Good sources of iron
include enriched cereals and grains, legumes, dates, prunes,
raisins, and leafy green vegetables. You can enhance
absorption of the iron in vegetables by including citrus fruit
or juice or other foods high in vitamin C with meals :hat
contain plant sources of iron. Vitamin C helps increase the
iron absorption from plant roods. Good sources of zinc
include legumes and nuts.