3. Introduction
Food is substance consumed to provide nutritional support
for the body. It is usually of plant or animals origin, and
contains essential nutrients, such as carbohydrates, fats,
proteins, vitamins, and minerals.
The substance is ingested by an organism and assimilated
by the organism's cells to produce energy, maintain life, or
stimulate growth.
4. Foods can be classified in the following categories. each has its
own characteristics:
Cereals and starchy roots.
pulses, legumes, seeds and nuts.
Meat.
Milk and eggs.
Fats and oils.
6. The main cereals consumed by man are: wheat, rice ,grain , and
maize.
Cereals are a good source of carbohydrate (contains starch from
70-80 % of its weight).
Cereals are an important source of proteins in the poorer parts of
the world.
The grain contains 7-12% of its dry weight as protein.
7. Most cereal proteins are deficient in one or more amino acids
(wheat and sorghum protein are deficient in lysine and maize
protein deficient in tryptophan).
Cereals also are a good source of minerals and B group of
vitamins.
10. Starchy roots, e.g. cassava, yams and potatoes, are mainly
composed of starch.
They used in many parts of the world as a major source of
CHO instead of cereals.
Raw potatoes contains about 1-8% protein, and the new
potatoes contains ascorbic acid.
14. Many varieties of seeds are eaten in various parts of world.
The main nutrient ingredients of these are starch (60% of dry
weight) and a high content of protein (about 20% of dry
weight).
If eaten with a cereal food like bread, chapati, kisra, or
porridge (asida) or any other form of local cereal food, these
pulses supply the deficient amino acids of the cereal protein.
15. Ground nuts are pulses and have a high protein content (26%)
and high fat content (44%). And they are also very rich in iron
and niacin.
Sesame contain about 50% fat, 20% carbohydrates, 20%
protein.
Sesame has a good content of sulphur-containing amino acids,
and also is a rich source of calcium (1200 mg/100g).
16. Soya beans are rich in protein 38% CHO 20% fat
18% and already an ingredient of many food
preparations in the developed parts of the world.
17. Lupine (arabic: turmos or termis) is rich in
protein and phosphorus (545 mg/100g), and the
calcium content is (90 mg/100g).
It is common native practice to advise a person
who has sustained a fracture to eat lupine.
18. Beef, lamb, pork and poultry are the main meat products
consumed by the various people of the world to various extents
depending on availability, local culture and religious prohibitions.
The nutritional importance of meat lies:
- First in the rich protein content.
- Second the high quality of this protein:
I.e. containing all essential amino acids.. High biological
value protein.
21. Fish:
Fish, like meat, contains protein of high biological value.
Fish oils contain long-chain ω3-polyunsaturated fatty acids, mainly
eicosapentaenoic acid (20 c) and docosahexaenoic acid (22 c).
There is very little carbohydrate in fish and quite small amounts of
cholesterol.
It is not usually a good source of fat-soluble vitamins, particularly
those with antioxidant activity but whole body fish like sardines
provide vitamin D.
22. Human milk is the first food a baby gets. It provides all the
essential ingredients of a balanced diet except iron and vitamin C.
Up to the fourth month, babies may depend entirely on milk
without risk of nutritional deficient.
Cow’s milk is about 88% water and 3% protein.
The two main proteins are casein (comprises about 82% of the
total protein) and whey proteins which include lactalbumin and
lactoglobulin.
23. Milk carries B group vitamins, particularly riboflavin and
vitamin B12, and the fat soluble vitamins A and D.
• The energy content of milk varies mainly with its fat content.
• An approximately value is 270 kJ (65kcal)/100 ml.
• It is one of riches food of calcium.
• Cheese: the popular milk products, cheese is about ten times
the concentration of milk and provides a good storage form for
the protein, fat and calcium content of milk.
24. Comparison of human milk with milk from other sources:
Human cow goat ewe camel
Protein (casein) (g) 1.5 3.5 3.7 6.5 3.7
Fat (g) 4.5 3.5 4.8 6.9 4.2
CHO (lactatose) (g) 6.8 5.0 4.5 4.9 4.1
Iron (mg) 0.7 0.1 0.2 - -
Phosphorus (mg) 14 91 129 - -
Calcium (mg) 34 120 150 - -
25.
26. Eggs:
Eggs are good source high quality protein , calcium, vitamins A
and B12 and high cholesterol content of the yolk.
A medium size egg (60g) will provide the following:
27.
28. Ostrich egg (right), compared to chicken egg (lower left)
and quail eggs (upper left).
29. Fats & Oils:
The main sources of dietary fat are meats, dairy products, and
vegetable oils.
Some fats can occur in solid form when kept at low temperature
(saturated lipids).
Oils, however, do not solidify (composed unsaturated lipids).
Fats are a good source of energy .
30. Vegetables comprise any plant part, other than fruit which is
used as food.
They include roots and tubers such as potatoes, taroالقلقاس ,
carrots, and yams, lettuce الخس and cabbage ملفوف, Some
fungi (e.g.mushrooms) are also consumed as vegetables.
31. Green leafy vegetables have a very high water content and
are exceptionally low in energy while relatively high in
micronutrients.
Some vegetables are rich in micronutrients: potatoes are a
major source of vitamin C, carrots are exceptionally high in
β-carotene, and spinach is rich in folic acid and iron .
32.
33. Some fruit contain good supplies of calcium and
phosphorus, but is a poor source of iron.
This is because they are low in energy, fat and sodium and
make valuable contributions to the intakes of vitamin C,
carotenoids, folate and dietary fibre.
Numerous epidemiological studies have shown that people
who eat above average amounts of fruit and vegetables
have below average rates of heart disease and cancer.
34.
35. Cane sugar is a relatively new addition to the human
diet.
Sugar contains sucrose which gives about 4 kcal/g.
Syrup is also made of sugar.
36. • Tea and coffee is widely consumed beverages.
• The main ingredient of these drinks is caffeine.
• The usual dose in a tea cup is about 60 mg and in a coffee is 90
mg.
• Cola drinks may contain 50 – 200 mg of caffeine/ l.
• Alcohol containing drinks provide 7 kcal/g of alcohol.
• Alcoholic drinks can contain 3-5% beers, 10-15% in wines, 20-
25% in sherries and up 45-50% spirits.
38. Water:
The water content of a food item is obtained by means of
weighting the sample before and after drying by heat.
Some food may contain volatile substances and therefore
heating will not be suitable for estimating the moisture
content.
39. Energy values:
Energy values are obtained by two method:
• Directly, the energy content of a sample can be measured using a
bomb calorimeter .
• In this method, a measured amount of the food is burnt in
oxygen inside a heavy closed container.
• The heat generated is measured and converted into energy.
• Indirectly the energy content of foods is calculated from the
protein, fat and carbohydrates.
40. The proteins:
• Are usually calculated from the total nitrogen content of the
food item multiplied by a factor of 6.25/g of nitrogen.
41. The fat:
The fat content of food is obtained by extraction using different
methods.
Carbohydrate values:
Carbohydrate values include sugars and starches. This value is
calculated from results of direct analysis for sugars and starches.
44. Sukkar MY. Human Nutrition for Medical
Studies & Allied Health Sciences. London; 1985.
p.13-18.
Essentials of Human Nutrition (2002) Mann J. ;
p. 383-403.
