Curdling Milk

CCA! Volume 5

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Curdling Milk

Milk protein is cleaved by rennin and forms curds. Larger curds form when calcium ions are added to the solution.


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5.2 MB, 80 seconds

File: MOVIES/KJBIOCHEM/CURDMILK.MOV

Voiceover
Milk is poured into three petri dishes. Rennin, a protease, is added to two of the samples to curdle the milk. Calcium chloride is added to one of the samples.

Later, each petri dish is examined for extent of curdling. The first sample did not contain any rennin, and did not curdle. In the second dish, the rennin specifically cleaved a hydrophilic portion of the milk protein. This allowed a more hydrophobic portion of the protein to associate much closer, forming curds. The third sample, containing added calcium ions, has much larger curds since calcium ions form cross-links between the hydrophobic portions of the milk proteins.

Design, Text, and Demonstration:
	Kristin Johnson	University of Wisconsin - Madison, Madison, WI 53706

Video production, editing, and voice:
	Jerrold J. Jacobsen	University of Wisconsin - Madison, Madison, WI 53706
	Greg Minix	University of Wisconsin - Madison, College of Engineering, Madison, WI 53706
	Michael Killips	University of Wisconsin - Madison, School of Nursing, Madison, WI 53706