In order to be quantitative about it, you’ll need to prepare like a scientist. If the pills are active, they may have as many as billions (i.e. 1×10^8) of bacteria to as few as a hundred. However, just dumping the contents into a growth medium (like milk) won’t tell you because the bacteria can grow very rapidly, and starting with a few or a lot will be all the same (lactobacilli can double every twenty minutes). One possibility is for you to make serial ten fold dilutions in a suitable growth medium or, if you can make or access them, use agar petri dishes.
1. For a home medium, you can try to dilute some milk so that it is not so turbid, and then boil it.
2. Thus, take 9 ml of your “boiled milk”, and mix the lactobacillus in 1 ml of water.
3. Add to the 9 ml to make 10 (this is 1:10).
4. Take 1 ml out and add to another 9 ml of “boiled milk” (1:100).
5. Repeat 6–7 times and include 9 ml of “boiled milk” that is untouched (your control). Ideally, these dilutions will be made into sterilized vessels.
6. Leave them out for several days at room temperature and assess daily for growth.
If this works (a big if), you should see growth in the most concentrated for sure, but also in most of your dilutions as well. Hopefully, your sterile technique will prevent growth in the control but will show you growth in your inoculated vessels. Good luck.