Now, I'm not about wether these tests are actually usefull or not but rather I just to see if someone can confirm or deny my hypotesis about why this happened.

Coca cola has a pH of 2.7, so what happened is that after exposing the strip to acid the antibodies changed conformation and and made the coloidal gold particles to precipitate turning making the test look like it was positive.

I ask mostly because I can't find any usefull information about what these strips are actually made of. I just find broad strokes about their fundamentals, but I can't find anything about what exactly precipitates to give a red colour and how precipitates exactly and I don't have any strips to simply test the hypothesis, so maybe heresomeone can tell me wether I'm wrong or right.