Estimation of protein in milk__

 The Kjeldahl method was developed in 1883 by a brewer called Johann Kjeldahl.
 
*Principle :-
 A food is digested with a strong acid so that it releases nitrogen which can be determined by a suitable titration technique. The amount of protein present is then calculated from the nitrogen concentration of the food.
 Milk naturally contains a number of key nutrients, including protein, which is beneficial to humans regardless of their age.
 Proteins are  that play a crucial role in nutritional growth and development.
 A food is digested with a strong acid so that it releases nitrogen which can be determined by a suitable titration technique. The amount of protein present is then calculated from the nitrogen concentration of the food. The same basic approach is still used today, although a number of improvements have been made to speed up the process and to obtain more accurate measurements. It is usually considered to be the standard method of determining protein concentration. Because the Kjeldahl method does not measure the protein content directly a conversion factor (F) is needed to convert the measured nitrogen concentration to a protein concentration. 
 The Kjeldahl method is widely used internationally and is still the standard method for comparison against all other methods. 
 Total Kjeldahl Nitrogen (TKN) Analysis is the standard method for determining protein in milk. Find out how one dairy factory automated the titration portion of their analysis and improved accuracy and saved time.

*Protocol:-
conveniently be divided into three steps:+ 
1)Digestion 
2) Distillation 
3)Titration

1. Digestion
In the initial digestion stage, a mixture of potassium sulfate, copper sulfate, and sulfuric acid are added to a digestion flask containing a pre-weighed, pre-heated (38°±1°C) sample of milk.
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 The digestion solution is heated and kept at a rolling boil for approximately 1.5 to 2 hours.  
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After cooling, purified water is added to the digest.
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 The digest is then transferred to a distillation flask, where sodium hydroxide is added to neutralize the solution and ultimately convert ammonium sulfate to ammonia gas.
                   
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2. Distillation
In the distillation stage, the solution is again heated until all of the ammonia gas is liberated and captured in a boric acid solution.
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3. Titration
The analysis stage first involves the titration of a blank sample, containing only digested reagents, followed by the titration of the sample-containing distillate with a standard sulfuric or hydrochloric acid solution.
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