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Anish | chemistry | January 5, 2014

Quantity of Casein in MilkCHEMISTRY PROJECT


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When we hear the name of casein it subjects to

the family of phosphoprotiens.

These proteins mainly make up 80% of the

animal milk(cow) and 20% to 45% of the

proteins in human milk. Casein has a wide

variety of uses.

Let me first brief you about the composition of

casein.

Composition of casein

Casein contains a fairly high number of

proline(an amino acid) residues, which do not

interact. There are also no disulfide bridges. As a result, it hasrelatively littletertiary structure.It is relativelyhydrophobic,

making it poorly soluble in water. It is found in milk asasuspensionof particles called "casein micelles" which show only

limited resemblance with surfactant-typemicellaein a sense that

thehydrophilicparts reside at the surface and they are spherical.

However, in sharp contrast to surfactant micelles, the interior of a

casein micelle is highly hydrated. The caseins in the micelles areheld together bycalciumionsand hydrophobic interactions.

Several models account for the special conformation of casein in

the micelles. Several models account for the special conformation

of casein in the micelles.[4]

One of them proposes the micellar
http://en.wikipedia.org/wiki/Tertiary_structurehttp://en.wikipedia.org/wiki/Hydrophobichttp://en.wikipedia.org/wiki/Suspension_(chemistry)http://en.wikipedia.org/wiki/Suspension_(chemistry)http://en.wikipedia.org/wiki/Suspension_(chemistry)http://en.wikipedia.org/wiki/Micellehttp://en.wikipedia.org/wiki/Micellehttp://en.wikipedia.org/wiki/Hydrophilichttp://en.wikipedia.org/wiki/Hydrophilichttp://en.wikipedia.org/wiki/Hydrophilichttp://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Ionshttp://en.wikipedia.org/wiki/Ionshttp://en.wikipedia.org/wiki/Ionshttp://en.wikipedia.org/wiki/Casein#cite_note-4http://en.wikipedia.org/wiki/Casein#cite_note-4http://en.wikipedia.org/wiki/Casein#cite_note-4http://en.wikipedia.org/wiki/Casein#cite_note-4http://en.wikipedia.org/wiki/Ionshttp://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Hydrophilichttp://en.wikipedia.org/wiki/Micellehttp://en.wikipedia.org/wiki/Suspension_(chemistry)http://en.wikipedia.org/wiki/Hydrophobichttp://en.wikipedia.org/wiki/Tertiary_structure


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nucleus is formed by several submicelles, the periphery consisting

of microvellosities of -casein.[5][6]

Anothermodelsuggests the

nucleus is formed by casein-interlinked fibrils.[7]Finally, the most

recent model[8]

proposes a double link among the caseins for

gelling to take place. All three models consider micelles as

colloidal particles formed by casein aggregates wrapped up in

soluble -casein molecules. The isoelectric point(the particular pH

where the element carries no elsctric charge) of casein is 4.6. Since

pH of milk is 6.6, casein has a negative charge in milk.

Uses of casein:

Casein is used in the production of the following:

1.Paint

2.Glue

3.Cheesemaking

4.Plastics and fiber

5.Protein supplements

6.Medical and dental uses

PAINT: Casein paint is a fast-drying water-soluble medium used

by artists. Casein paint has been used since ancient Egyptian times

as a form of tempera(a long lasting painting, painted to make it last

for years to come) paint, and was widely used by commercialillustrators as the material of choice until the late 1960s.

GLUE: Casein-based glues were popular for woodworking,

including for aircraft, as late as thede Havilland

Mosquito.[14]

Casein glue is also used intransformermanufacturing
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(specifically transformer board) due to its oil

permeability.[15]

While largely replaced by synthetic resins, casein-

based glues still have a use in certain niche applications, such as

laminating fireproof doors and the labeling of bottles.

Cheese Making:

Cheese consists of proteins and fat frommilk,usually the milkofcows,buffalo,goats,orsheep.It is produced bycoagulationof casein.

Typically, the milk is acidified and then coagulated by the addition ofrennet,containing aproteolyticenzyme,typically obtained from the stomachs

ofcalves.The solids are separated and pressed into final form.[19]

Unlike many proteins, casein is not coagulated by heat. During the process

of clotting, milk-clottingproteasesact on the soluble portion of thecaseins,-casein,thus originating an unstablemicellarstate that results in

clot formation. When coagulated withchymosin,casein is sometimescalledparacasein.Chymosin is an aspartic protease that

specificallyhydrolyzesthe peptide bond in Phe105-Met106 of -casein, andis considered to be the most efficient protease for the cheese-making

industry (Rao et al., 1998). British terminology, on the other hand, uses the

term caseinogen for the uncoagulated protein and casein for the

coagulatedprotein.As it exists in milk, it is asaltofcalcium.

Plastics and fiberSome of the earliest plastics were based on casein. In

particular,galalithwas well known for use inbuttons.Fiber can be

made from extruded casein.Lanital,a fabric made from casein fiber

(known asAralacin the United States), was particularly popular in
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Italy during the 1930s. Recent innovations such asQMilchare

offering a more refined use of the fiber for modern fabrics.

Protein supplements[edit]

An attractive property of the casein molecule is its ability to form a gel or

clot in the stomach, which makes it very efficient in nutrient supply. The clot

is able to provide a sustained slow release of amino acids into the bloodstream, sometimes lasting for several hours.[20]

Medical and dental uses[edit]

Casein-derived compounds are used intooth remineralizationproducts to

stabilizeamorphous calcium phosphate(ACP) and release the ACP ontotooth surfaces, where it can facilitate remineralization

Casein preparation in an old etching operation in Mllheim.
http://en.wikipedia.org/w/index.php?title=QMilch&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=QMilch&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=QMilch&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Casein&action=edit&section=8http://en.wikipedia.org/wiki/Casein#cite_note-20http://en.wikipedia.org/wiki/Casein#cite_note-20http://en.wikipedia.org/wiki/Casein#cite_note-20http://en.wikipedia.org/w/index.php?title=Casein&action=edit&section=9http://en.wikipedia.org/wiki/Remineralisation_of_teethhttp://en.wikipedia.org/wiki/Remineralisation_of_teethhttp://en.wikipedia.org/wiki/Remineralisation_of_teethhttp://en.wikipedia.org/wiki/Amorphous_calcium_phosphatehttp://en.wikipedia.org/wiki/Amorphous_calcium_phosphatehttp://en.wikipedia.org/wiki/Amorphous_calcium_phosphatehttp://en.wikipedia.org/wiki/File:Caseinaufbereitung.jpghttp://en.wikipedia.org/wiki/File:Caseinaufbereitung.jpghttp://en.wikipedia.org/wiki/File:Caseinaufbereitung.jpghttp://en.wikipedia.org/wiki/File:Caseinaufbereitung.jpghttp://en.wikipedia.org/wiki/Amorphous_calcium_phosphatehttp://en.wikipedia.org/wiki/Remineralisation_of_teethhttp://en.wikipedia.org/w/index.php?title=Casein&action=edit&section=9http://en.wikipedia.org/wiki/Casein#cite_note-20http://en.wikipedia.org/w/index.php?title=Casein&action=edit&section=8http://en.wikipedia.org/w/index.php?title=QMilch&action=edit&redlink=1


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Milk is a complete diet as it contains in its Minerals, Vitamins Proteins,

Carbohydrates, Fats And Water. Average composition of milk from

different sources is given below:

Source Water Mineral Protei Fats Carbohydra

of milk (%) s (%) ns(%) (%) tes (%)

Cow 87.1 0.7 3.4 3.9 4.9

Human 87.4 0.2 1.4 4.0 4.9

Goat 87.0 0.7 3.3 4.2 4.8

Sheep 82.6 0.9 5.5 6.5 4.5

Caesin is a major protein constituent in milk & is a mixed phosphor-

protein. Casein has isoelectric pH of about 4.7 and can be easilyseparated around this isoelectric pH. It readily dissolves in dilute acids

and alkalies. Casein is present in milk as calcium caseinate in the form

of micelles. These micelles have negative charge and on adding acid to

milk the negative charges are neutralized.

Ca2+-Caesinate +

2CH3COOH(aq)^Caesin+(CH3COO)2Ca

AIM

To study the quantity of Casein in different samples of milk.


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REQUIREMENTS

> Beakers (250 ml)

> Filter-paper

> Glass rod

> Weight box

> Filtration flask

> Buchner funnel

> Test tubes

> Porcelain dish

> Different samples of milk

> 1 % acetic acid solution

> Ammonium sulphate solution

Theory


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Natural milk is an opaque white fluidSecreted by the mammary glands

ofFemale mammal . The main constituents of natural milk are Protein,

Carbohydrate, Mineral Vitamins,Fats and Water and is a complete

balanced diet . Fresh milk is sweetish in taste. However , when it is kept

for long time at a temperature of 5 degree it become sour because of

bacteria present in air . These bacteria convert lactose of milk into lactic

acid which is sour in taste. In acidiccondition casein of milk starts

separating out as a precipitate. When the acidity in milk is sufficient

and temperature is around 36 degree, it forms semi-solid mass, called

curd.

PROCEDURE

1. A clean dry beaker has been taken, followed by putting 20 ml of cows

milk into it and adding 20 ml of saturated ammonium sulphate solution

slowly and with stirring. Fat along with Caesin was precipitate out.

2. The solution was filtered and transferred the precipitates in another

beaker. Added about 30 ml of water to the precipitate. Only Caesin

dissolves in water forming milky solution leaving fat undissolved.

3. The milky solution was heated to about 40oC and add 1% acetic acid

solution drop-wise, when casein got precipitated.

1. 4. Filtered the precipitate, washed with water and the precipitate was

allowed to dry.

2. 5. Weighed the dry solid mass in a previously weighed watch glass.

3. 6. The experiment was repeated with other samples of milk.

OBSERVATIONS


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CONCLUSION

Different samples of milk contain different percentage of Caesin.

Structure of Casein Is a phosphoprotein, which has phosphate groups

attached to some of the amino acid side chains. Mostly

these amino acid are serine and threonine.

casein is a mixture of at least three similar proteins,which differ primarily in molecular weight and

amount of phosphorus they contain (number of

phosphate groups).

Casein is made up of the main 3 types of proteins are

-casein, -casein, and -casein.

All casein proteins have different hydrophobic and

hydrophilic regions along the protein chain.

-Caseins are the major casein proteins. Its containing

8-10 phosphate groups,

- casein contains about 5 phosphate residues,

- casein it is more hydrophobic than -caseins and -

casein

Because -caseins and -caseins are highly

phosphorylated, they are very sensitive to the


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concentration of calcium salts, that is, they will

precipitate with excess Ca2+ ions

miccle under microscope

asein can be precipitated byrennin

Renin enzyme :

Found in calves and gout

Is hydrolysis enzyme (peptidase) so cleave

the peptide bond between amino acid

Mechanism:


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1.Enzyme attack the k- casein and breaking

the peptide bond and release small part of

peptide bond

2.This destroy cause left k-casein the and

B casein which protect the casein from ppt

and ppt it as Para kappa casein

3.Unlike kappa the Para kappa casein cannotprevent the casein from ppt in the present of

calcium ion

4.If calcium removed from milk the renin

cannot form ppt to milk

When the pH level decreases the milk forms

Curdsor whey.

Curdsare a dairy product obtained by ppt of

milk with renin or an acidic substance and

then draining off the liquid portion.


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Wheyor milk serumis the liquid remaining

after milkhas been coagulation and remove

curds
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The curds are the solid white at the bottom,

they whey is on the bottom

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