I would do it via an attribute (just add a custom one), so it will be shown in the additional information tab along with the default fields like weight and size.
If you need anything beyond what you can do with attributes, I'm afraid you are looking at custom work. You can add a custom field in the same meta box, where you can fill in the contents of the bottle and have it stored in postmeta. That way you can output it virtually everywhere on the product page.
But as I said, attributes are probably your best bet in this case.