Almost everyone consumes milk or dairy products regularly. But have you ever been inquisitive about the constituents of milk? What is the chief element of which it is formed? Milk is formed of two proteins, namely casein and whey. 80% of it is casein while the remaining 20% is whey. Most people who want to build muscle or are on a diet intake casein protein powder.
It is mainly consumed in two different forms, namely, micellar casein and casein hydrolysate.
Micellar Casein:
The most natural form of casein protein available is micellar casein. Its chemical structure is in resemblance with the one found in milk. Casein is grouped in the form of tiny balls called micelles. These slow the process of absorption by clotting in the stomach.
Casein Hydrolysate:
This protein form is partially broken and is hydrolyzed protein, which can be absorbed quickly and is also easier to digest than others.
Properties of Casein
Casein is the most important protein in milk. Alongside, it is one of the quintessential ingredients of cheese. The properties of casein are as follows:
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It is an amorphous solid, which does not have any taste or odor. While the casein protein, which is produced commercially, has a yellowish color and a pleasing odor.
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The percentage of casein present in cow’s milk is 3%.
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Dry casein remains in good condition if it is well protected from rodents and other insects.
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While, damp casein, get a bad odor if kept for a long time. Along with this, it is more vulnerable to getting attacked by bacteria and molds.
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Casein is formed of several phosphoproteins, all of which have different molecular weights.
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It is a lyophilic colloid. It is related to gelatin and albumin.
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At pH 4.6, it has an isoelectric nature, having solubility in water of 0.01 percent.
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Casein has an amphoteric nature.
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For pH below 4.6, it forms salts that are moderately soluble—for example, casein chloride.
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For pH above 4.6, the formation of salts takes place with bases. Salts like sodium caseinate are soluble without any limit. While salts like calcium caseinate and other heavy metals are nearly insoluble.
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When slow coagulation takes place with the concentrated solutions, casein forms gels.
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When formaldehyde is mixed with casein, an insoluble compound is formed.
Manufacturing of Casein
Skim milk is mainly used for the manufacture of casein. The manufacturing of casein takes place through one of the three below-mentioned methods. These are as follows:
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Fermentation of milk sugar is done through the bacteria named Streptococcus lactose, which leads to the formation of lactic acid. This further leads to the natural sourcing of casein curdles after enough lactic acid is formed.
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It is formed by the addition of sulfuric acid or hydrochloric acid to precipitate acid casein.
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With rennet casein, the setting of warm skim milk is done with rennet extract till the time clotting of calcium para caseinate takes place. Following this, the clot is further cut into small parts allowing the whey to drain off.
In all the above-mentioned methods, after draining the whey, washing of curd is done with water. After this, it is dried in warm air, grounded, and packaged for sale.
Uses of Casein Protein
Casein protein in milk has various applications across several industries. The major uses include food preparation, the medical industry, cosmetics, and dietary supplements. The minor applications of this protein include shoe polishes and cleaners, dressing of leather, printing, and sizing of textile, soapmaking, and several others. In many cases, casein also serves as a binder, emulsifying agent, or colloid. The major uses of casein proteins are as follows:
Paper Coatings:
The art papers and books are coated with pigmented casein. This provides a suitable surface to create the half-tone illustrations. For this, acid casein having an alkaline solution is mixed with the water slurry. To increase the water resistance, lime or formaldehyde is also added. Further, the spread of the mixture takes place through a coating machine, and it is dried.
Glues:
Casein glue is used to form wood joints. These withstand the dampness just for some duration. However, the prepared casein glue is in a powdered form. Its composition takes place through lime, suitable sodium salts, acid casein, and lastly, a fungicide. Before using this glue, this powder is dissolved in water.
Not just this, there are several other uses which casein proteins serve. These mainly include paints, plastics, and human-made fibers.