The milk test is not scientific method. A probiotic that reacts to milk has no chance of getting past the stomach acid so would not deliver them where they are needed.
Here are a few more reasons why this test/method does not work:-
1. Room temperature is not gut/intestine temperature.
2. Digestive enzymes alter activity within the body.
3. Milk is not the best test of chyme (Food in the stomach that is partly digested and mixed with stomach acids is called chyme) or of in vivo gut environments
4. Many people are looking for the milk to turn into custard, which is not the purpose of Probiotics.
5. You cannot compare different species or mixes - i.e. if there are a lot of lactose digesters lactobacilli) in the mix, they will thicken the milk, BUT if there are little or no lactose digesters, then nothing will happen to the milk even though you have very high quality bacteria there (B. bifidum, etc).
6. You cannot tell the bacterial count or CFU (colony forming units) OR how many dead vs alive units by whether it curdles or thickens milk. You can have very few but strongly lactic acid forming colonies and a not good product despite the curdled milk - OR a mix of many good bacteria that collectively do not thicken milk well, but are very good activity wise.
Our probiotic supplements have been manufactured specifically to protect the bacterial cultures and maintain the quality of the supplement. The milk test is absolutely irrelevant to the effectiveness of these supplements.