Well since we really want to test the null hypothesis how about this: Bile will not color olive oil or non-olive oil oil green.
and another one:
bile salts in the presence of Liver Flush ingredients will not coagulate the oil into lumps or sludge.
For a control group I will place the ingredients for a Liver Flush into a balloon and not add any bile salts. Thus effects seen can be attributed to the presence of bile salts.