This is a total theory with no studying done by me yet. In either case, this is what Iíve noticed:
For some reason, Grapes seem to test rather high consistently. Iíve tested conventional grapes at 18 brix. However, this was a sharp reading. Other grapes off the same vine would be lower like 15 or 16. So that was cause for concern but thatís not my point. My point is that Iím starting to think grapes will produce an overload of sugars even if the minerals are not there to complex with. Most other fruits will stop creating the sugars sooner if no minerals are present. Or should I say grown on poor soil.
Conclusion, yes grapes will naturally be a little higher that other fruits by default, but Iím thinking that they will still create ďsimpleĒ sugars even when grown in bad soil. Perhaps why they make a good fermenting fruit?
So this could be an answer to the question but again, this is only my theory.