Milk analysis? investigate the proteins

In summary, the milk sample is neutralized before the addition of formalin in Formol titration for protein analysis because proteins are too weak to be titrated directly with alkali. Adding formalin causes the proteins to react with -NH2 groups and form methylene-amino (-N=CH2) groups, making the carboxyl group available for titration. If the milk sample is not neutralized first, the proteins in milk will react with NaOH and produce a higher volume of base used, leading to an inaccurate protein content value. The neutralization step ensures that the subsequent titration accurately reflects the protein content of the milk sample.
  • #1
CuriousSam
5
0
For protein analysis, why is milk sample neutralised before the addition of formalin in Formol titration?

could we say that...

The proteins are too weak to be titrated directly with alkali,if formalin is added, it reacts with the -NH2 groups to form the methylene-amino(-N=CH2) group and the carboxyl group is then available for titration.

HOOC.CHR.NH2 + HCHO ----> HOOC.CHR.N=CH2 +H2O

HOOC.CHR.NH2(neutral) HCHO(formalin) HOOC.CHR.N=CH2(acidic)

Also , the proteins(which are acidic) in milk will react with NaOH will produce a higher amount
of volume used which would made higher protein content value thus giving an inaccurate
result.

Thank you very much and please help
 
Last edited:
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  • #2
I thought that a known amount of base was added to the neutralized protein and the excess base titrated after addition of formalin. Do I have the wrong method?
 
  • #3
The procedure is this
1) Add 0.5ml of 0.5% phenophthalein indictator and 0.4ml of neutral saturated potassium
oxalate.
2) Mix , allow to stand for a few minute and neutralise with 0.1M NaOH.
3) Add, 2ml formalin , allow to stand for a few minutes and titrate with the new acidity
produce with the 0.1N NaOH to the same pink colour(a ml) .Then carry out a blank titration
by replacing the milk sample with 10ml of water (b ml) .The protein content of the milk is
1.7 (a-b)%. The question is , why must the milk sample is neutralised 1st?? is this base on the answers
i have derided in the 1st post or is it something else. pls enlighten me.
 
Last edited:
  • #4
CuriousSam said:
The procedure is this
1) Add 0.5ml of 0.5% phenophthalein indictator and 0.4ml of neutral saturated potassium
oxalate.
2) Mix , allow to stand for a few minute and neutralise with 0.1M NaOH.
3) Add, 2ml formalin , allow to stand for a few minutes and titrate with the new acidity
produce with the 0.1N NaOH to the same pink colour(a ml) .Then carry out a blank titration
by replacing the milk sample with 10ml of water (b ml) .The protein content of the milk is
1.7 (a-b)%.


The question is , why must the milk sample is neutralised 1st?? is this base on the answers
i have derided in the 1st post or is it something else. pls enlighten me.


What do you think you were neutralizing after you added the potassium oxalate? Would the amount of NaOH required be the same regardless of your sample? After you add the formalin, you have generated more acid. What does this new acidity correspond to? Would the acidity neutralized after you added the oxalate interfere with this measurement?
 

FAQ: Milk analysis? investigate the proteins

What are the main proteins found in milk?

The main proteins found in milk are casein and whey. Casein makes up about 80% of the protein content in cow's milk, while whey makes up the remaining 20%. Other proteins found in milk include lactalbumin, lactoglobulin, and immunoglobulins.

Why is it important to analyze the proteins in milk?

Analyzing the proteins in milk can provide valuable information about the quality and nutritional value of the milk. It can also help identify any potential issues or abnormalities, such as contamination or changes in protein composition due to processing methods.

How is milk protein analysis performed?

Milk protein analysis is typically performed using methods such as electrophoresis, chromatography, and spectroscopy. These techniques allow for the separation, identification, and quantification of different protein components in milk.

What factors can affect the protein composition of milk?

The protein composition of milk can be affected by various factors such as the animal's breed, diet, health, and lactation stage. Processing methods, storage conditions, and environmental factors can also impact the protein content and composition of milk.

What are the potential applications of milk protein analysis?

Milk protein analysis has a wide range of applications, including quality control in dairy products, nutritional evaluation of milk, detection of adulteration or contamination, and research on the effects of different processing methods on milk proteins. It can also be used to develop new dairy products with specific protein profiles to meet consumer demands.

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