Mathcarver,

I've never heard of anyone using 'grape juice' to create a fishing scent.

That being said, it's not the first use of the grape 'smell' I've seen. There was an old plastic worm brand that made a purple worm that smelled like grape, and I caught lots of bass with it. Can't think of the name, though...(Jelly Worm, maybe?).

If you decide you want to try to 'replicate' this concoction, it won't be hard to do. Remember what you are trying to do with it, i.e; cover or mask any unpleasant odors that may be on your baits. Most commercially available 'scents' have very strong smells....this is because scents dissipate quickly in water, and usually the 'coverage area' is small and the 'coating' is thin (very few lures allow the liquid to 'soak in' or somehow fill a chamber that controls it's release).

This means that to get reasonable results, you'll want the grape juice to be as concentrated as possible, and use only enough mineral oil to get a decent consistency of the mix (how 'thick' you want the concoction is a matter of preference).

You can concentrate the grape juice by heating it and allowing the water to evaporate until you get the concentration you like.

Scents, or more properly 'scent masks' were very popular with the main stream bass fishermen when I was a part of that...I still use a 'scent' on all of my subsurface flies and lures to this day, primarily to cover any bad odors that may be on the materials.

Buddy