William HargisC127March 13, 2014Milk Separation and AnalysisObjective:This experiment uses natural product separation techniques and basic biochemical qualitative analytical tests to identify, separate and analyze the main components of milk. whole milk.Introduction:Milk is a natural biological product with a complex chemical composition1,2, it is a colloid composed of proteins, carbohydrates, fats, vitamins and minerals. Proteins found in milk are largely soluble in water due to the amine and carboxylic acid side chains, the amines are protonated and therefore positively charged at a pH close to that of 7.44 or pH human physiological 2. Amines remain unprotonated at high pH2. Carboxylic acids, however, are protonated at low pH and not protonated 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. Although the protein retains positively or negatively charged side chains, it is soluble in water2. Taking advantage of the isoelectric point by raising the pH until the protein charges balance results in a loss of solubility, causing protein precipitation2. The most abundant proteins in milk are water-soluble protein molecules called caseins. Caseins can be precipitated out of 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 around 4.6. Fat is also precipitated by this change in pH. The resulting solution is casein and fat precipitated into an aqueous solution called whey. Whey contains water-soluble proteins that do not precipitate...... middle of paper ...... cium tests confirmed the presence of phosphate and calcium, respectively, in liquid whey filtrate , this happened as expected, because metal ions are soluble in water. The positive Biuret protein test confirmed that the solid curd contains protein, which is normal since the curd should consist mainly of insoluble casein proteins. Fats added to water were found to be immiscible, indicating that the substance is a non-polar hydrophobic material, confirming that the fats are made of non-polar fat molecules. The results of these qualitative tests and observations strongly indicate successful separation of the natural product, whole milk. Conclusion: The separation was successful and produced separate steps consistent with predictions based on solubility properties. This was indicated by the qualitative tests and observations.