Study of coaguable and non-coaguable milk proteins
Answers
The coagulated and non-coagulated milk proteins are : Casein (Coagulated ),B-lacto globulins ,a-lactalbumin(Non coagulated ).
Explanation:
Coagulation
- It is the process of precipitating the colloid b y adding suitable electrolyte .
- It is actually a process involving destruction of colloid .
- We know, that colloids are charged ,due to which they are somehow stable ,but if any factor removes the charge ,it causes precipitation.
The charges can be removed by or precipitation can occur by following methods :
- Boiling
- By neutralizing the charge of colloid by adding other colloid with different charge .
- By adding electrolyte .
Milk : It is also a colloid and we can precipitate by above discussed methods .
The proteins present in Milk are :
- Casein
- B-lacto globulins
- a-lactalbumin
Casein: It is the main protein present in the milk.
Some antibodies called immunoglobulin present in milk are also proteins.
Casein can be coagulated by acid, rennet and heating. It is a coaguable protein.
The b-lactoglubind and a-lacto albumins : milk proteins are non-coagulating proteins as they can be coagulated only by heating.
Investigatory Project on Coagulable And Non-Coagulable Milk Proteins
Introduction:
Milk is considered an ideal food as it contains most of the constituents of our diet. It is a rich source of proteins and fats. It also contains calcium and phosphorous in sufficient quantity. Therefore, milk is considered to be an important diet for the growing children, and pregnant and lactating women. The milk of buffalo, cow and goat are commonly used for human consumption. Milk is slightly heavier than water (specific gravity = 1.035) and has a slightly acidic pH (pH =6.7).
Coagulation is the process of precipitating the colloid by adding suitable electrolyte. It is actually a process involving destruction of colloid. We know, that colloids are charged, due to which they are somehow stable, but if any factor removes the charge, it causes precipitation.
The charges can be removed by or precipitation can occur by following methods:
1. Boiling
2. By neutralizing the charge of colloid by adding other colloid with different charge.
3. By adding electrolyte.
Milk: It is also a colloid and we can precipitate by above discussed methods.
The proteins present in milk are:
Casein: It is the main protein present in the milk. It represents about 80% protein nitrogen of the milk and is a coagulable protein. Casein can be coagulated by acid, rennet and heating.
B-lactoglobulins and a-lactalbumin: They are the non-coagulating proteins. They can be coagulated only by heating.
Immunoglobulin: It is one of some antibodies present in milk.
Materials required:
Cow/Buffalo milk
Test tubes
Rennin tablets
Millon’s reagent
Beaker
Burner
Procedure:
Take about 20ml of milk in a beaker.
Grind a rennin tablet and add it to the milk.
Warm the milk. The milk will coagulate.
Filter the coagulated (solidified) milk. The liquid filtrate is whey.
Take a small amount of whey in separate test tubes and test it for the presence of protein by using Millon’s reagent.
Observation:
Whey gives positive test for protein, indicating the presence of non-coagulable proteins in whey.
Conclusion:
Cow and buffalo milks contains both coagulable and non-coagulable proteins.
References:
Comprehensive Laboratory Manual in Biology
Meritnation
Wikipedia