You're a bartender with a recipe you want to keep a secret, so you put black paper over the bottles so people can't see what they are.
Or you keep the ingredients somewhere the customers can't see, and mix it there.
Plus give it a one-off name, like "Freddie's Secret Likker" and copyright that.
If you want it to be a trade secret like Coca-Cola, you have some manufacturer make an ingredient just for you, and keep their identity secret. Also buy all their output and swear them to secrecy.