Separation And Analysis Of Milk Essay

1384 Words3 Pages

William Hargis
C127
March 13, 2014
Separation and Analysis of Milk
Objective:
This experiment employs techniques of natural product separation and basic biochemical qualitative analytical tests in order to identify, separate, and analyze the major components of whole milk.

Introduction:
Milk is a natural biological product with a complex chemical makeup1,2, it is a colloid consisting of proteins, carbohydrates, fat, vitamins, and minerals. The proteins found in milk are largely water-soluble due to amine and carboxylic acid side chains, amine’s are protonated, and thus positively charged, at a pH near that of 7.44 or human physiological pH2. Amine’s remain unprotonated at high pH2. Carboxylic acids, however, are protonated at low pH and unprotonated at higher pH, such as physiological pH2. Carboxylic acids retain a negative charge in their unprotonated state, at physiological pH carboxylic acids are negatively charged side chains. While the protein retains positively or negatively charged side chains it is water-soluble2. Taking advantage of the isoelectric point by raising the pH to the point that the protein’s charges are balanced results in a loss of solubility, causing the precipitation of the proteins2. The most abundant proteins in milk are water-soluble protein molecules referred to as caseins, the caseins may be precipitated out of the milk by reaching their respective isoelectric point via a change in pH via the addition of an acid, this experiment used acetic acid to lower the pH to approximately 4.6. Butterfat is also precipitated by this change in pH. The resulting solution is precipitated casein and butterfat within a watery solution referred to as whey, the whey contains water soluble proteins that do not precipit...

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...cium tests confirmed the presence of phosphate and calcium, respectively, within the liquid whey filtrate, this was as expected, as the metal ions are water-soluble. The positive Biuret’s Protein Test confirmed that the solid curds contains proteins, this is as expected as the curds should consist primarily of insoluble casein proteins. The butterfats when added to water were found to be non-miscible, indicating that the substance is a non-polar hydrophobic material, this confirms that the butterfats consist of the non-polar fat molecules. The outcomes of these qualitative tests and observations strongly indicates a successful separation of the natural product, whole milk.
Conclusion:
The separation was successful and produced separated stages consistent with prediction based upon solubility properties. This was indicated by the qualitative tests and observations.

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