The Case of Casein
By Candy Tan and Elizabeth Ching
Introduction and Purpose
Most Canadians drink or used to drink milk. It’s delicious with cereal, cookies, or just on its own. However we don’t just drink milk for its taste – most people drink milk for its nutritional benefits. With so many different types of milk to choose from, though, how do we know which milk is the best? With the help of chemistry, we have found a way to separate the main protein of milk, casein, from the rest, therefore revealing which type of milk has the most protein! We will be testing 1% chocolate milk, 2% original milk, and 3.25% homogeneous milk to see which yields the most casein. Hypothesis
3.25% homogeneous milk will have the most casein protein, followed by 2% original milk, and 1% chocolate milk. Materials and Methods
* 100 mL of Neilson’s 1% chocolate cow’s milk
* 100 mL of Neilson’s 2% original cow’s milk
* 100 mL of Neilson’s 3.25% homogeneous cow’s milk
* (2) 1000 mL beaker
* (6) 300 mL beakers
* Stirring rod
* 500 mL of water
* (3) Coffee filters
* Hot plate
* Paper towel
* 60 mL of vinegar
* Crucible tongs
Steps 1-8 were completed three times with each of the three different types of milk. 1. We poured 500 mL of water into a 1000 mL beaker and placed the beaker onto a hot plate. 2. After about a minute, we poured 100 mL of milk into a 500 mL beaker, with a label stating which type of milk it was, and placed that into the 1000 mL beaker with crucible tongs.
3. When a layer of film appeared on the top of the milk, we took picked it off with a stirring rod. We continued to heat the milk and remove the film until there was no more film to be removed. This film was fat. 4. Then, we added 20 mL of vinegar into the milk and stirred let it sit for 30 as the casein precipitated from the rest of the milk. 5. With crucible tongs, we took the 500 mL beaker containing the milk...
Bibliography: 1. "Chem2O06 - 1997/98 - Experiment 11." McMaster University | Department of Chemistry. 1998. Web. 09 May 2011.
2. McGuigan, Brendan. "What Is Casein?" WiseGEEK: Clear Answers for Common Questions. 14 Apr. 2011. Web. 09 May 2011. <http://www.wisegeek.com/what-is-casein.htm>.
3. "Casein Micelle Structure." Food Science | University of Guelph. Web. 09 May 2011. <http://www.foodscience.uoguelph.ca/deicon/casein.html>.
4. Southward, C. "Casein Products." Web. 9 May 2011. <http://nzic.org.nz/ChemProcesses/dairy/3E.pdf>.
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