CHEM 1406 Casein Report Sheet

Chem 1406 Isolation of Casein Report Sheet
Name Melanie Black-Van Wright
Date 11/10/14
Partner if applicable

Part I:
Observations of formation of casein precipitate
The milk began to curd. As the curd increases the milk appeared more clear at times.

Mass of casein
1.65 g
Part II:
Test tube
Observation of CuSO4 biuret Test
Test Results (+ or -)
Casein
Solution turned violet
+
Egg white solution turned violet
+
Water solution turned blue
-
Sugar solution turned blue
-
Postlab Questions
1. Whas is the theoretical yield of casein based on the table of Milk Composition Analysis?
3.3 %
2. What is your percent yield? 3.2g/3.9g x 100= 82%
3. Why might your percent yield be lower than expected?
More fat has a decrease in protein which would cause a lower percent yield.
4. Why might your percent yield be higher than expected? Less fat causes an increase in protein, thus giving a higher percent yield.
5. In the precipitation of casein, why is it important that the temperature be maintained at 40°C?
To allow and encourage , for example with the milk casein to form and appear.