In the second separation of this experiment, the Erlenmeyer flask with the first filtrate was put into a beaker so the filtrate was in the beaker. The beaker was then heated on a hotplate until near boiling. After the whey protein had precipitated, a vacuum filter was used to filter out the whey. These proteins were then air-dried. A qualitative test was done to indicate that the sample extracted was the protein whey. Again, a small test tube was used and 2 mL of protein test solution was put in the tube.
Five drops of 10% NaOH and 2 drops of 0. 5% CuSO4 were added to this tube. If a purple color showed, it would indicate there was protein in the test tube. In the third separation of this experiment, the hood in the lab was used. The curds were placed in a 100 ml beaker and extracted using 30 mL of ethyl acetate. The curds were crushed with a stirring rod. This extraction was then gravity filtered through a funnel fitted with the filter paper. A rubber policeman was used to scrape the beaker to get as much casein as possible.
This casein was then put aside in the hood safely. Boiling chips were put into an Erlenmeyer flask along with the filtrate collected. This flask was then put inside of the large beaker that was put to heat in the first separation of this experiment creating a hot water bath. This was done to evaporate the ethyl acetate. The flask was stirred using a stirring rod constantly. After the ethyl acetate had evaporated, the flask with the filtrate was put into an ice water bath for ten minutes. Then the color of the residue was recorded.
Qualitative tests were conducted to indicate the presence of phosphates, calcium, carbohydrates, and lactose. The Fehling’s test was done to show the presence of carbohydrates. Two small test tubes were used and 5 mL of Fehling’s reagent was added to it. Five drops of 1% glucose was added to one test tube, the control. This tube was then boiled and if a brown-red precipitate was formed, it would indicate that there was a carbohydrate present. The other tube had 5 mL of the Fehling’s reagent put in it and five drops of the filtrate after the ethyl acetate was gone and the filtrate had been cooled.
If this created a brown-red precipitate, it would indicate that there was a carbohydrate present. A test for calcium was done where a small test tube was obtained and 1 mL of the Ca2+ solution was added to it. One milliliter of 0. 1 Mammonium oxalate was added. This was the control for this test. If a white precipitate formed for the filtrate, it would indicate the presence of calcium. Another test tube was obtained and 1 mL of 0. 1 M ammonium oxalate was added. Then, one milliliter of the filtrate sample was added to it. A test for the presence of phosphate was conducted.
For the control, two milliliters of 6 M HNO3 was put into a large test tube. Then, 2 mL of the phosphate test solution was added to this tube and then 2 mL of 0. 5 M ammonium molybdate solution was also added. This was stirred and heated for 5 minutes and then left to cool for ten minutes. If a yellow precipitate formed, it would mean there was phosphate in the filtrate. Another large test tube was obtained and 2 mL of 6 M. HNO3, 2 mL of 0. 5 M ammonium molybdate solution, and 2 mL of the filtrate was added to this test tube.
Another test done was the one for lactose and lactase. Two test tubes were obtained and 0. 5 mL of distilled water was added to both tubes. A spatula tip of lactose was put on each. A lactase tablet was crushed using a mortar and pestle and a spatula tip of the lactase tablet was put into one tube. A glucose urinalysis strip was put into both tubes and the color shown was compared to chart on the bottle of the strips. Another urinalysis strip was put into the filtrate. The urinalysis strip without the lactase was the control.
If the strip turned green-brown, it would indicate that glucose was present in the filtrate meaning lactase and lactose was in the filtrate. A disposable pipette was used to add a small amount of the residue to water and if the water stayed above the residue it would mean that fat remained in the liquid left. A final test was done for the presence of protein in the filtrate. If the results were purple that would mean there was protein left in the filtrate. A small test tube was used and 2 mL of the filtrate was put in the tube.
Five drops of 10% NaOH and 2 drops of 0. 5% CuSO4 were added to this tube. Results: For the Fehling’s test for carbohydrates, the control was a royal blue colored liquid with a brick red precipitate at the bottom. The test on the filtrate formed was royal blue with a precipitate at the top. For the lactose and lactase test, the control urinalysis strip with no lactase turned a light blue color. The urinalysis strip with the crushed lactase tablet turned a light green color. The urinalysis strip with the filtrate turned a brown-green color.
For the test for calcium, the control test tube with ammonium oxalate and Ca2+ solution contained a white precipitate with white liquid at the top. The test tube with the filtrate and ammonium oxalate contained a white precipitate at the top. For the test for phosphate, the control did not form a precipitate because the lab material was contaminated a yellow precipitate. For the test for phosphate that involved the filtrate, a yellow precipitate formed. For the both the whey and casein test, the test tubes turned a light purple color indicating there was protein in both. They were proteins