Just curious: why use shampoo bottles when old Ketchup bottles are made for the purpose (i.e., safe plastic) and have a nice squeeze feature? One other bonus, minimal cleanup: I made BBQ sauce last night after reading the first post in this thread, and used up the Ketchup in one bottle. I just poured the finished BBQ sauce back into the Ketchup "bottle" (it is a plastic squeeze bottle) when I was finished, without even bothering to rinse it out, other than to clean the lid of any old crud.
As for sterility, does any of that matter for something that is refrigerated? While refrigeration won't stop spoilage, I always thought it stopped growth of bacteria that create toxins.