How to you recognize cold milk that has gone bad or is about to

milkspoilage

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?

Best Answer

Looks like FAO (Food and Agriculture Organization of the United Nations) publishes a formal testing handbook here.

One of the easier methods:

2.4.5.3. The Alcohol Test

The test is quick and simple. It is besed on instability of the proteins when the levels of acid and/or rennet are increased and acted upon by the alcohol. Also increased levels of albumen (colostrum milk) and salt concentrates (mastitis) results in a positive test.

Procedure:

The test is done by mixing equal amounts of milk and 68% of ethanol solution in a small bottle or test tube. (68 % Ethanol solution is prepared from 68 mls 96%(absolute) alcohol and 23 mls distilled water). If the tested milk is of good quality, there will be no coagulation, clotting or precipitation, but it is necessary to look for small lumps. The first clotting due to acid development can first be seen at 0.21-0.23% Lactic acid. For routine testing 2 mls milk is mixed with 2 mls 68% alcohol.

Simplified for home use:

This test is likely to be adaptable to household alcohol drinks such as vodka or similar beverages. For example the number of teaspoons of Vodka an ounce or two of milk can hold before it clots.

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