Purdue iGEM Page through the registry : 
Links to Outside Sources that may be useful
IBE Student Chapter Wiki, 
A general overview of milk and how factors affect its lifespan and production, .
Go through Purdue Libraries  to get to the research databases. I prefer Web of Science.
Wiley Protocols in Molecular Biology. Link will only work on Purdue Recognized Computers. 
University of Guelph Overview of Milk: .
Literature Articles that may be of use
Investigations into the activity of enzymes produced by spoilage-causing bacteria: a possible basis for improved shelf-life estimation: Braun et al. Food Microbiology. v.16 Pgs. 531-540. 1999.
Microbial and biochemical spoilage of foods: An overview. intVeld, JHJH. International Journal of Food Microbiology. v.33 Pgs. 1-18. 1996.