well quite by chance, ive been experimenting with blueberry flavour im in the uk btw so they are quite scarce, so, anyway, I was sat in my neighbours, the other month, who just happened to have an empty bowl full of pistachio nut shells, I had been experimenting with blueberry flavour as an f pack kinda flavour, but the dryness detracted from the overall effect, as, there was no natural sweetness, so, kinda experimentally I added 3 halves of pistachio nut shells per gallon as my neighbour gave me a bowl full of them, so in experimental fashion I added 6 blue berries and 3 halves of pistachio nut shells per gallon, to a random red coloured fruit wine, I had made, which tbh was a bit naff and then let it steep, well a few months later, it now is worth drinking, the nut shells seem to impart either slow fermenting or unfermentable sugars, which add a natural sweetness to coincide with the blueberry`s natural flavour, replacing its natural sweetness, overall at this moment in time, it seems to have worked well, although I am sloshed from drinking a very enjoyable drink, I would rank this a 9 on 10 and quite well balanced as a blueberry kinda wine flavoured drink, which at this moment in time has retained a natural sweetness and a woody taste from the nut shells, which has gradually improved over several months of steeping and aging. I deem this worthy of further experimentation, as the over all effect is very noteworthy.