The methods that I know to test cold milk is to either boil it and look for the break, taste it (yuk!), or hope it smells bad enough to know it's bad.
Is there an easy and scientific way to know whether milk is still good? and for how much longer it's likely to stay good?
The expiry date alone is not a good indicator since it assumes some conditions about the storage temperature and we've all seen good milk past expiry and bad milk before expiry.
I'm also curious about the particular moment beyond which we consider milk 'goes bad'. Can one tell how far away it is from the current seemingly healthy condition of milk?