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Principles of Food Science
Principles of Food Science
and Nutrition
and Nutrition
Dr. Nahlaa Khalifa
PROTEIN PART I
Protein
Tofu
Nuts
Beans
Meat
What is the Nitrogen Cycle?
What is the Nitrogen Cycle?
 The nitrogen cycle represents one of the most important
nutrient cycles found in terrestrial ecosystems. Nitrogen is
used by living organisms to produce a number of
complex organic molecules like amino acids, proteins, and
nucleic acids.
 Despite its abundance in the atmosphere, nitrogen is often
the most limiting nutrient for plant growth.
 This problem occurs because most plants can only take up
nitrogen in two solid forms: ammonium ion (NH4+ ) and
the ion nitrate (NO3- ).
 Ammonium is used less by plants for uptake because in
large concentrations it is extremely toxic.
Why is Nitrogen Needed?
Why is Nitrogen Needed?
 All life requires nitrogen.
 In a never ending nitrogen cycle Plants use the
nitrogen take up the nitrates to form their own
amino acids and convert them to proteins. Animals
eat the plants and use the amino acid for tissues
Human eat animals and plants for their amino acids
and rearrange the nitrogen to make the pattern of
amino acids required . Finally everybody dies,
organic molecules are degraded by microorganisms
, nitrogen goes back into the soil to be used by
nitrogen fixed bacteria , and the cycle start again.
The Nitrogen Cycle
The Nitrogen Cycle
 Nitrogen is the most
abundant element in the
atmosphere, but most
organisms cannot use it in
that form.
 Rhizobium bacteria in soil ,
cyanobacteria in in fresh
water, and blue  green algea
in sea water have the ability to
utilize inorganic nitrogen and
fix it into organic ammonia.
The Nitrogen Cycle
The Nitrogen Cycle
 Certain plants, like legumes e.g. soybean rely on a special
type of bacteria to help them obtain the nitrogen they
need.
 These plants cannot use nitrogen gases in the atmosphere
nor can they use the nitrogen compounds in the soil.
 Nitrogen-fixing bacteria can find a home and moisture in
root nodules (little bumps on the roots of plants).
 A symbiotic relationship is formed , in which the bacteria
provide nitrogen , in exchange for sugars and other
nutrients from the plant. This accounts for the high
nitrogen content in legumes such as soya beans and
beans
The Nitrogen Cycle
The Nitrogen Cycle
Agricultural practices take advantage of this
phenomenon farmers rotate legume crops with corn
and wheat to provide added nitrogen to the soil
Whereas plant structure is primarily carbohydrate ,
the structure of humans and animals is built on
protein .
Deamination is the removal of the amino (nitrogen)
from the amino acid  thus creating urea. The
remaining deaminated carbon compound can be
used to form carbohydrate or fat to produce energy
at the rate of 4 kcal/g
.
The Nitrogen Cycle
The Nitrogen Cycle
Protein in muscles and body tissues is in constant
turnover.
Tissue protein is degraded and nitrogen excreted
in the urine and new protein is required daily to
maintain the body in steady state.
 An energy deficit or an inadequate protein intake
may force the body to use amino acids as fuel
creating a negative nitrogen balance .
 Protein eaten in excess of need is degraded and
stored as body fat.
The Nitrogen Balance
The Nitrogen Balance
1.Zero Nitrogen Balance
2.Positive nitrogen balance.
3.Negative nitrogen balance
Zero Nitrogen Balance
Zero Nitrogen Balance
Nitrogen intake equals nitrogen excreted or
Protein made = protein broken down
Anabolism = catabolism
Most adults are in zero nitrogen balance
Positive nitrogen balance
Positive nitrogen balance
 exists when nitrogen intake exceeds amount
excreted or Making more protein than
breaking down
 Anabolism > catabolism
 It occur in
a. Pregnancy
b. Growth periods Infants and children
c. Building muscle Athletes
d. Rebuilding tissue after trauma/illness
Negative nitrogen balance
Negative nitrogen balance
 Exists when more nitrogen is lost than taken in. or
Breaking down more protein than you are making
 Catabolism > anabolism
 It occur in
a. Fever
b. Injury
c. Surgery
d. Burns
e. Starvation
f. Immobilization
Protein Part-1 sources function clasification
Proteins:
Proteins:
The Basis of Body Structure
The Basis of Body Structure
 Protein =Proteins are the most structurally
sophisticated molecules known, and all are polymers
constructed from the same set of 20 amino acids.
Polymers of amino acids are called polypeptides
 Proteins form key parts of the bodys main structural
componentsmuscles and bonesand of blood,
enzymes, cell membranes, and some hormones
Elementary Composition of
Elementary Composition of
Proteins
Proteins
Chemical composition:
primarily carbon, hydrogen, oxygen
Additional difference: contain a fairly
constant amount of nitrogen found in
amino groups (17%)
many also contain sulfur, phosphorus and
iron
structure is typically complex, having high
molecular weight
Amino acids
Amino acids
Amino acids are organic molecules possessing
both carboxyl groups and amino
Types of amino acids :
1. Essential amino acids
2. Nonessential amino acids
3. Conditionally Essential amino acids
COOH

2
NH
1.Essential Amino Acids
1.Essential Amino Acids
 There are 9 amino acids in total
1. Valine
2. Lycin
3. Methionine
4. Phenylalanine
5. Threonine
6. Tryptophan
7. Isoleucine
8. Leucine
9. Histidin (required for children)
1.Essential Amino Acids
1.Essential Amino Acids
 Called essential because;
i. You must get them from your diet
ii. They are essential for life & growth
iii. The body is NOT able to produce these
nine Amino acids.
 Found in animal protein food
sources*except Soy proteins
2. Non - Essential Amino Acids
2. Non - Essential Amino Acids
 Are the 13 amino acids that can synthesized by
the body in adequate amount and they are as
follow :
7.Alanine
8.Arginine
9.Asparagine
10.Aspartic acid
11.Cysteine
12.Cystine
13.Glutamic acid
1.Glutamin
2. Glycine
3.Hydroxyproline
4.Proline
5.Serine
6.Tyrosine
3. Conditionally Essential Amino Acids
3. Conditionally Essential Amino Acids
Sometimes non-essential amino acids
become essential under special
circumstances e.g. the body use essential
amino acids phenylalanine to make tyrosine
(non-essential). If the diet fail to supply
enough phenylalanine or if the body can not
make conversion for some reasons
(inherited disease phenyleketonuria)
Complete and
Complete and
Incomplete Proteins
Incomplete Proteins
Biological value :
 Is the term describes how well a particular
protein food approximate the amount and
combination of essential amino acids in the body.
Types of protein:
 There are tow types of protein
1. Complete protein
2. Incomplete protein
Complete and
Complete and
Incomplete Proteins
Incomplete Proteins
 Complete proteins or higher quality proteins come
from foods containing all of the essential amino acids
in the quantity and correct ratio to maintain nitrogen
balance and allow for tissue growth and repair.
Sources are; Meat, fish, poultry, eggs, milk, cheese, and
soy
 Incomplete proteins or lower quality proteins lack ore
or more of the essential amino acid. Incomplete protein
diets will eventually lead to protein
malnutrition. Sources are ; Plants, including legumes,
grains, and nuts
Complete and
Complete and
Incomplete Proteins
Incomplete Proteins
 Generally speaking , animal sources of protein
such as meat, fish, poultry and dairy product
contain complete proteins of high biological
value. Incomplete yet good sources of protein
food that are lacking one or more of the essential
amino acids include plant sources ; whole grains,
legumes , nuts and seeds .
Complementary Proteins
Complementary Proteins
Occurs when a combination of sources of
incomplete / low quality proteins are eaten
in the same day to make a complete protein
Examples: corn and beans, rice and beans,
rice and lentils , bread and peanut butter,
bread and split pea soup, bread and cheese,
bread and baked beans, macaroni and
cheese, cereal and milk tortillas and beans
Complementary Proteins
Complementary Proteins
Combining incomplete protein foods
over the course of the day can give the
body all of the essential amino acids
needed for adequate protein status .
Therefore , vegetarians can receive
adequate protein without eating meat
if food choices are made wisely
Complementary Proteins
Complementary Proteins
Complementary Proteins
Complementary Proteins

More Related Content

Protein Part-1 sources function clasification

  • 1. Principles of Food Science Principles of Food Science and Nutrition and Nutrition Dr. Nahlaa Khalifa PROTEIN PART I
  • 3. What is the Nitrogen Cycle? What is the Nitrogen Cycle? The nitrogen cycle represents one of the most important nutrient cycles found in terrestrial ecosystems. Nitrogen is used by living organisms to produce a number of complex organic molecules like amino acids, proteins, and nucleic acids. Despite its abundance in the atmosphere, nitrogen is often the most limiting nutrient for plant growth. This problem occurs because most plants can only take up nitrogen in two solid forms: ammonium ion (NH4+ ) and the ion nitrate (NO3- ). Ammonium is used less by plants for uptake because in large concentrations it is extremely toxic.
  • 4. Why is Nitrogen Needed? Why is Nitrogen Needed? All life requires nitrogen. In a never ending nitrogen cycle Plants use the nitrogen take up the nitrates to form their own amino acids and convert them to proteins. Animals eat the plants and use the amino acid for tissues Human eat animals and plants for their amino acids and rearrange the nitrogen to make the pattern of amino acids required . Finally everybody dies, organic molecules are degraded by microorganisms , nitrogen goes back into the soil to be used by nitrogen fixed bacteria , and the cycle start again.
  • 5. The Nitrogen Cycle The Nitrogen Cycle Nitrogen is the most abundant element in the atmosphere, but most organisms cannot use it in that form. Rhizobium bacteria in soil , cyanobacteria in in fresh water, and blue green algea in sea water have the ability to utilize inorganic nitrogen and fix it into organic ammonia.
  • 6. The Nitrogen Cycle The Nitrogen Cycle Certain plants, like legumes e.g. soybean rely on a special type of bacteria to help them obtain the nitrogen they need. These plants cannot use nitrogen gases in the atmosphere nor can they use the nitrogen compounds in the soil. Nitrogen-fixing bacteria can find a home and moisture in root nodules (little bumps on the roots of plants). A symbiotic relationship is formed , in which the bacteria provide nitrogen , in exchange for sugars and other nutrients from the plant. This accounts for the high nitrogen content in legumes such as soya beans and beans
  • 7. The Nitrogen Cycle The Nitrogen Cycle Agricultural practices take advantage of this phenomenon farmers rotate legume crops with corn and wheat to provide added nitrogen to the soil Whereas plant structure is primarily carbohydrate , the structure of humans and animals is built on protein . Deamination is the removal of the amino (nitrogen) from the amino acid thus creating urea. The remaining deaminated carbon compound can be used to form carbohydrate or fat to produce energy at the rate of 4 kcal/g .
  • 8. The Nitrogen Cycle The Nitrogen Cycle Protein in muscles and body tissues is in constant turnover. Tissue protein is degraded and nitrogen excreted in the urine and new protein is required daily to maintain the body in steady state. An energy deficit or an inadequate protein intake may force the body to use amino acids as fuel creating a negative nitrogen balance . Protein eaten in excess of need is degraded and stored as body fat.
  • 9. The Nitrogen Balance The Nitrogen Balance 1.Zero Nitrogen Balance 2.Positive nitrogen balance. 3.Negative nitrogen balance
  • 10. Zero Nitrogen Balance Zero Nitrogen Balance Nitrogen intake equals nitrogen excreted or Protein made = protein broken down Anabolism = catabolism Most adults are in zero nitrogen balance
  • 11. Positive nitrogen balance Positive nitrogen balance exists when nitrogen intake exceeds amount excreted or Making more protein than breaking down Anabolism > catabolism It occur in a. Pregnancy b. Growth periods Infants and children c. Building muscle Athletes d. Rebuilding tissue after trauma/illness
  • 12. Negative nitrogen balance Negative nitrogen balance Exists when more nitrogen is lost than taken in. or Breaking down more protein than you are making Catabolism > anabolism It occur in a. Fever b. Injury c. Surgery d. Burns e. Starvation f. Immobilization
  • 14. Proteins: Proteins: The Basis of Body Structure The Basis of Body Structure Protein =Proteins are the most structurally sophisticated molecules known, and all are polymers constructed from the same set of 20 amino acids. Polymers of amino acids are called polypeptides Proteins form key parts of the bodys main structural componentsmuscles and bonesand of blood, enzymes, cell membranes, and some hormones
  • 15. Elementary Composition of Elementary Composition of Proteins Proteins Chemical composition: primarily carbon, hydrogen, oxygen Additional difference: contain a fairly constant amount of nitrogen found in amino groups (17%) many also contain sulfur, phosphorus and iron structure is typically complex, having high molecular weight
  • 16. Amino acids Amino acids Amino acids are organic molecules possessing both carboxyl groups and amino Types of amino acids : 1. Essential amino acids 2. Nonessential amino acids 3. Conditionally Essential amino acids COOH 2 NH
  • 17. 1.Essential Amino Acids 1.Essential Amino Acids There are 9 amino acids in total 1. Valine 2. Lycin 3. Methionine 4. Phenylalanine 5. Threonine 6. Tryptophan 7. Isoleucine 8. Leucine 9. Histidin (required for children)
  • 18. 1.Essential Amino Acids 1.Essential Amino Acids Called essential because; i. You must get them from your diet ii. They are essential for life & growth iii. The body is NOT able to produce these nine Amino acids. Found in animal protein food sources*except Soy proteins
  • 19. 2. Non - Essential Amino Acids 2. Non - Essential Amino Acids Are the 13 amino acids that can synthesized by the body in adequate amount and they are as follow : 7.Alanine 8.Arginine 9.Asparagine 10.Aspartic acid 11.Cysteine 12.Cystine 13.Glutamic acid 1.Glutamin 2. Glycine 3.Hydroxyproline 4.Proline 5.Serine 6.Tyrosine
  • 20. 3. Conditionally Essential Amino Acids 3. Conditionally Essential Amino Acids Sometimes non-essential amino acids become essential under special circumstances e.g. the body use essential amino acids phenylalanine to make tyrosine (non-essential). If the diet fail to supply enough phenylalanine or if the body can not make conversion for some reasons (inherited disease phenyleketonuria)
  • 21. Complete and Complete and Incomplete Proteins Incomplete Proteins Biological value : Is the term describes how well a particular protein food approximate the amount and combination of essential amino acids in the body. Types of protein: There are tow types of protein 1. Complete protein 2. Incomplete protein
  • 22. Complete and Complete and Incomplete Proteins Incomplete Proteins Complete proteins or higher quality proteins come from foods containing all of the essential amino acids in the quantity and correct ratio to maintain nitrogen balance and allow for tissue growth and repair. Sources are; Meat, fish, poultry, eggs, milk, cheese, and soy Incomplete proteins or lower quality proteins lack ore or more of the essential amino acid. Incomplete protein diets will eventually lead to protein malnutrition. Sources are ; Plants, including legumes, grains, and nuts
  • 23. Complete and Complete and Incomplete Proteins Incomplete Proteins Generally speaking , animal sources of protein such as meat, fish, poultry and dairy product contain complete proteins of high biological value. Incomplete yet good sources of protein food that are lacking one or more of the essential amino acids include plant sources ; whole grains, legumes , nuts and seeds .
  • 24. Complementary Proteins Complementary Proteins Occurs when a combination of sources of incomplete / low quality proteins are eaten in the same day to make a complete protein Examples: corn and beans, rice and beans, rice and lentils , bread and peanut butter, bread and split pea soup, bread and cheese, bread and baked beans, macaroni and cheese, cereal and milk tortillas and beans
  • 25. Complementary Proteins Complementary Proteins Combining incomplete protein foods over the course of the day can give the body all of the essential amino acids needed for adequate protein status . Therefore , vegetarians can receive adequate protein without eating meat if food choices are made wisely

Editor's Notes

  • #14: Protein = a compound made of amino acids that contains carbon, hydrogen, oxygen, and nitrogen Proteins form key parts of the bodys main structural componentsmuscles and bonesand of blood, enzymes, cell membranes, and some hormones