A.V.N. SR. SEC.

SCHOOL
Sector-19, Faridabad

Chemistry Investigatory project

Analysis on Presence of Proteins
in Different Food Items

SUBMITTED TO SUBMITTED BY
Mr. GS Kukreja Srishti Goel
CLASS 12 B
 CERTIFICATE

This is to certify that SRISHTI GOEL, a

student of class XII B has successfully
completed the research analysis project
on the topic “Analysis of Food Stuff for
the presence of Proteins” under the
guidance of Mr. GS KUKREJA (Subject
teacher).

This project is absolutely genuine and does

not indulge in plagiarism of any kind.

The references taken in making this

project has been declared in bibliography.

(Subject Teacher) (Principal)

Mr. GS KUKREJA Ms. SUNITA
KHULLAR
 ACKNOWLEDGEMENT

“Success is the progressive realization of a

worthy goal,” says our respected Principal, I wish
my deep gratitude to my Principal Ms. SUNITA
KHULLAR & respected teachers Mr. GS KUKREJA,
whose eloquent guidance and valuable
suggestions have been indispensable in bringing
out this assigned project successfully. It is
through there practical knowledge, there
suggestion and help offered by them from time
to time that brought great confidence in taking
up this work and synchronizing my efforts in
accomplishment of the project work.
 INDEX

1:- What are Proteins?

2:- What are Amino Acids?

3:- Structures of Proteins.

3.1:-Primary Structure.
3.2:- Secondary
Structure.
3.3 :- Tertiary Structure.
3.4 :- Quaternary Structure.

4:-Types of Amino Acids.

4.1 :-Essential Amino Acids

4.2 :-Semi Essential
Amino Acids 4.3:-Non
Essential Amino Acids
5:– Diseases caused by deficiency
of Proteins.

5.1 :- Marasmus
5.2 :- Kwashiorkor
5.3 :
- Deficiencies of Protein C and
Protein S
5.4 :- Cachexia

6:- Tests for Proteins.

7:-Sources of Proteins.

7.1 :-Seafood
7.2 :-White-Meat
Poultry 7.3:-Milk,
Cheese & Yogurt 7.4:-
Egg
7.5 :-Beans
7.6 :-Pork Tenderloin
 PROTEINS
1-What are protiens?
Proteins large biomolecules, or macromolecules,
consisting of one or more long chains of amino
acidresidues. Proteins perform a vast array of
functions within organisms, including catalysing
metabolic reactions,
DNA replication, responding to stimuli, and
transporting molecules from one location to another.
Proteins differ from one another primarily in their
sequence of amino acids, which is dictated by the
nucleotide sequence of their genes, and which
usually results in protein folding into a specific
three-dimensional structure that determines its
activity.

A linear chain of amino acid residues is

called a polypeptide. A protein contains at least one
long polypeptide. Short polypeptides, containing less
than 20–
30 residues, are rarely considered to be proteins and
are commonly called peptides, or sometimes
oligopeptides. The individual amino acid residues
are bonded together by peptide bonds and
adjacent amino acid residues. The sequence of
amino acid residues in a protein is defined by the
sequence of a gene, which is encoded in the
genetic code. In general, the genetic code specifies 20
standard amino acids; however, in certain organisms
the genetic code can include selenocysteine and
—in certain archaea—pyrrolysine. Shortly after or
even during synthesis, the residues in a protein are
often chemically modified by post-translational
modification, which alters the physical and chemical
properties, folding, stability, activity, and ultimately,
the function of the proteins. Sometimes proteins have
non-peptide groups attached, which can be called
prosthetic groups or cofactors. Proteins can also
work together to achieve a particular
function, and they often associate to form stable
protein complexes.

Once formed, proteins only exist for a certain period

of time and are then degraded and recycled by the
cell's machinery through the process of protein
turnover. A protein's lifespan is measured in terms of
its half-life and covers a wide range. They can exist
for minutes or years with an average lifespan of 1–2
days in mammalian cells. Abnormal and or misfolded
proteins are degraded more rapidly either due to
being targeted for destruction or due to being
unstable.

Like other biological macromolecules

such as polysaccharides and nucleic acids, proteins
are essential parts of organisms and participate in
virtually every process within cells. Many
proteins are enzymes that catalyse
biochemical reactions and are
vital to metabolism. Proteins also have structural or
mechanical functions, such as actin and myosin in
muscle and the proteins in the cytoskeleton, which
form a system of scaffolding that maintains cell
shape. Other proteins are important in cell signaling,
immune responses, cell adhesion, and the cell cycle.
In animals, proteins are needed in the diet to
provide the essential amino acids that cannot be
synthesized. Digestion breaks the proteins down for
use in the metabolism.

2 -What are amino amino acids?

Amino acids are biologically important
organic compounds containing amine (-NH2) and
carboxyl (- COOH) functional groups, along with a
side-chain (R group) specific to each amino acid.[ The
key elements of an amino acid are carbon, hydrogen,
oxygen, and nitrogen, though other elements are
found in the side-chains of certain amino acids. About
500 amino acids are known (though only
20 appear in the genetic code) and can be classified
in many ways. They can be classified according to the
core structural functional groups' locations as
alpha- (α-),
beta- (β-), gamma- (γ-) or delta- (δ-) amino acids;
other categories relate to polarity, pH level, and side-
chain group type (aliphatic, acyclic, aromatic,
containing hydroxyl or sulfur, etc.). In the form of
proteins, amino acids comprise the second-largest
component (water is the largest) of human muscles,
cells and other tissues. Outside proteins, amino acids
perform critical roles in processes such as
neurotransmitter transport and biosynthesis.

3 – STRUCTURE OF PROTIENS
Most proteins fold into unique 3-dimensional
structures. The shape into which a protein naturally
folds is known as its native conformation. Although
many proteins can fold unassisted, simply through
the chemical properties of their amino acids, others
require the aid of
molecular chaperones to fold into their native
states. Biochemists often refer to four distinct
aspects of a protein's structure:
3.1 :-Primary structure:- The amino acid
sequence. A protein is a polyamide.

3.2 :- Secondary structure :- Regularly repeating

local structures stabilized by hydrogen bonds. The
most common examples are the α-helix, β-sheet
and turns.
Because secondary structures are local, many
regions of
 different secondary structure can be present in the
same protein molecule.

3.3 :- Tertiary structure :- The overall shape of a

single protein molecule; the spatial relationship of
the secondary structures to one another. Tertiary
structure is generally stabilized by nonlocal
interactions, most commonly the formation of a
hydrophobic core, but also through salt bridges,
hydrogen bonds, disulfide bonds, and even
posttranslational modifications. The term "tertiary
structure" is often used as synonymous with the
term fold. The tertiary structure is what controls the
basic function of the protein.
3.4 :- Quaternary structure:- The structure
formed by several protein molecules (polypeptide
chains), usually called protein subunits in this
context, which function as a single protein
complex.

Proteins are not entirely rigid molecules. In addition to

these levels of structure, proteins may shift between
several related structures while they perform their
functions. In the context of these functional
rearrangements, these tertiary or quaternary
structures are usually referred to as "conformations",
and transitions between them are called
conformational changes. Such changes are often
induced by the binding of
a substrate molecule to an enzyme's active site, or the
physical region of the protein that participates in
chemical catalysis. In solution proteins also undergo
variation in structure through thermal vibration and
the collision with other molecules.
Proteins can be informally divided into three main
classes, which correlate with typical tertiary
structures: globular proteins, fibrous proteins, and
membrane proteins. Almost all globular proteins are
soluble and many are enzymes.
Fibrous proteins are often structural, such as
collagen, the major component of connective tissue,
or keratin, the protein component of hair and nails.
Membrane proteins often serve as receptors or
provide channels for polar or charged molecules to
pass through the cell membrane.
A special case of intramolecular hydrogen bonds
within proteins, poorly shielded from water attack
and hence promoting their own dehydration, are
called dehydrons.
4 – Types of amino acids
Amino acids are organic compounds which contain
at least one amino group (-NH2) and a carboxy (-
COOH) group. In the human genome, 20 amino acids
are created to build proteins and therefore termed
proteinogen. Besides this,
there are approximately 250 amino acids which do
not form proteins. These are used to form sugar for
example.
The 20 proteinogen amino acids are also called
standard amino acids, which can be divided into three
groups: essential, semi-essential and non-essential.
4.1 :- ESSENTIAL AMINO ACIDS:- Eight amino
acids are essential for humans, as the body cannot
produce them by themselves, and they have to be
supplied externally. These are: isoleucine,
leucine,
lysine, methionine, phenylalanine, threonine,
tryptophan and valine.

4.2 :- SEMI ESSENTIAL AMINO ACIDS:-Arginine

and
histidine form the group of so-called semi-essential
amino acids. They have to be consumed in the diet
under certain circumstances.

4.3 :- NON ESSENTIAL AMINO ACIDS:- The ten

non-essential amino acids are able to be produced in
the body. The following amino acids fall into this
category: alanine, asparagine, aspartic acid,
cysteine, glutamine, glutamic acid, glycine,
proline, serin and tyrosine.
It should be noted that the grouping ‘essential’ and
‘non- essential’ does not mean that one group more
important is that the other. This is because the
division of the two does not assess whether the body
has sufficient supply of
the amino acids in question at its disposal. The
protein requirement can differ greatly from person to
person. The amount of semi-essential and non-
essential amino acids produced by the body itself
depends on many different factors, such as age,
mental and/or physical stress or distress situations.
These determine the various amino acid levels
required to stay fit and healthy.
5 – Diseases caused by deficiency of proteins
5.1 :- Marasmus

Marasmus is a disease caused by a severe deficiency

of protein and calories that affect infants and very
young children, often resulting in weight loss and
dehydration. Marasmus can develop into starvation
and cause fatality caused by a lack of essential
nutrients. People with marasmus appear bony with
little muscle tissue, according to Food4Africa.
5.2 :- Kwashiorkor

Kwashiorkor is a disease caused by a severe deficiency

of protein in diets that contain calories mostly from
carbohydrates such as yams, rice and bananas. It
usually affects older children. People with kwashiorkor
appear puffy in the abdomen area from retention of
fluid, according to the University of Maryland Medical
Center. Common symptoms of both marasmus and
kwashiorkor
include fatigue, irritability, diarrhea, stunted growth
and impairment of cognition and mental health.
5.3 :- Deficiencies of Protein C and Protein
S

Deficiencies of protein C and protein S are inherited

conditions that cause abnormal blood clotting,
according to Medline Plus. Deficiency of protein C
occurs in about 1 out of 300 people. Deficiency of
protein S affects 1 in 20,000 people. Symptoms for
these deficiencies include redness, pain, tenderness
or swelling in the affected area. People with these
protein deficiencies need to be careful about activities
that increase risk of blood clots, such as prolonged
sitting, bed rest, and long-time travel in cars and
airplanes. Research by A. Hooda published in the
"Annals of Indian Academy of Neurology" in 2009
discovered that protein S deficiency causes ischemic
stroke.
5.4 :- Cachexia

Cachexia is a condition that involves protein

deficiency, depletion of skeletal muscle and an
increased rate of protein degradation, according to
research by D.P. Kotler published in the "Annals of
Internal Medicine" in 2000.
Cachexia causes weight loss and mortality and is
associated with cancer, AIDS, chronic kidney failure,
heat disease, chronic obstructive pulmonary disease
and
rheumatoid arthritis, according to J.E. Morley in the
"American Journal of Clinical Nutrition." Patients with
malignant cancer of the stomach, colon, liver, billiary
tract and pancreas experience under nutrition from
reduced intake of protein, calories and
micronutrients, and have fatigue and a negative
nitrogen balance as a result of loss of muscle mass
from cachexia, according to J. Ockenga in "Alimentary
Pharmacology and Therapeutics" in 2005.

6:-Tests for Proteins in food items :

The presence of Proteins in food stuffs can be

detected by performing following tests :
- Xanthoprotein test
- Biuret test
- Million’s test
- Ninhydrin test

7:-Sources of Proteins.
7.1 :-Seafood
Seafood is an excellent source of protein because it's
usually low in fat. Fish such as salmon is a little higher
in fat, but it is the heart-healthy kind: it has omega-3
fatty acids.
 7.2 :-White-Meat Poultry
Stick to the white meat of poultry for excellent, lean
protein. Dark meat is a little higher in fat. The skin is
loaded with saturated fat, so remove skin before
cooking.

7.3 :-Milk, Cheese, and Yogurt

Not only are dairy foods like milk, cheese, and yogurt
excellent sources of protein, but they also contain
valuable calcium, and many are fortified with vitamin
D.
Choose skim or low-fat dairy to keep bones
and teeth strong and help prevent osteoporosis.

7.4 :-Eggs
Eggs are one of the least expensive forms of protein.
The American Heart Association says normal healthy
adults can safely enjoy an egg a day.

7.5 :-Beans
One-half cup of beans contains as much protein as
an ounce of broiled steak. Plus, these nutritious
nuggets are loaded with fiber to keep you feeling full
for hours.

7.6 :-Pork Tenderloin

This great and versatile white meat is 31% leaner than
it was 20 years ago.
 EXPERIMENT

AIM:-
To analyze the presence of proteins in a sample of
Soybeans, Egg white, Nuts, Bread.

APPARATUS REQUIRED:-
❖ Test tubes
❖ Test tube stand

CHEMICALS REQUIRED:-
❖ Reagents as required for testing and
analysis of proteins for various test.
❖ A sample of taken food in crushed with water.

PROCEDURE:-
Biuret Test :
✓ Take 2ml meshed sample of taken food in a test
tube.
✓ Add few drops of sodium hydroxide solution.
Add very dilute solution of copper sulphate drop--wise.
✓ Note the observation. The appearance of violet

colour confirms the presence of proteins.

Xanthoprotein Test :
✓ Take 2ml meshed sample of taken food in a test
tube.
✓ Add few drops of 2ml of conc. Nitric acid. Shake
for some time and keep aside.
 ✓ Note the observation. The appearance of deep
yellow colour confirms the presence of proteins.
Ninhydrin’s Test:-
✓ Take 2ml meshed sample of taken food in a test

tube.
✓Add 2 few drops of Ninhydrin Solution and
boil the content.
✓ Note the observation. The appearance of intense
blue
colour confirms the presence of proteins.
Millon’s Test:-
✓ Take 2ml meshed sample of taken food in a test
tube.
✓Add 2 drops of Millon’s Reagent and boil
the content.
✓Note the observation. The white ppt changes
to
brick red on boiling.
OBSERVATIONS:

Sn. Test Soyabea Egg Bread Nuts Inference

performed n white
1. Buiret Test Violet Violet Violet Violet Protein
colour colour colour colour Present
2. Xanthoprote Yellow Yellow Yellow Yellow Protein
in ppt ppt ppt ppt Present
test
3. Ninhydr Intens Intens Intens Intens Protei
in Test e blue e blue e blue e blue n
colour colour colour colour Prese
nt
4. Million’s Brick red Brick Brick Brick Protein
Test ppt red ppt red red Present
ppt ppt
 BIBILIOGRAPHY

✓ NCERT Text book on Chemistry

✓ Together with Lab Manual Chemistry - Class – XII

✓ Arya Publications on Chemistry laboratory Manual

✓ Dictionary of Science

✓ www.Wikipedia.com
✓ www.google.com
✓ www.scribd.com
✓ www.amrita.olabs.edu.in