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Name:  N Alexander C.
Status: other
Age: 18
Location: N/A
Country: N/A
Date: 2000


Question:
Hi Recently I warmed up some milk in a saucer and then poured some vinegar in it. I filtered the fat out of it and shaped it into a ball. I let it sit for a couple of days and it turned into plastic.

Will you explain what reaction took place and why?


Replies:
N Alexander,

You precipitated the casein (a protein) out of the milk by effect of the acid (vinegar) and heat. Acids denature and coagulate proteins. The plastic-like substance you obtained was very likely rather sticky. In fact, in bygone days, a reaction such as you describe was a common and a popular means to produce an early form of glue -- now supplanted by good old Elmer's carpenter glue which is very different in composition and far superior to casein glue.

Regards,
ProfHoff



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