For those interested this link explains a bit about the off flavours in wines & beers .
http://www.researchgate.net/publication/223068827_Off-Flavours_Detection_in_Alcoholic_Beverages_by_Electronic_Nose_Coupled_to_GC If you hoping to make blackberry wine or compote commercially like we were, with fruit off your small holding its worth reading the whole article .
The gist of it is :-
The presence of an unexpected off-flavour in
alcoholised beverages such as beer or wine is always an economi-
cal problem. Indeed, one of the main marketing and commercial
rules is that alcoholic beverages, and particularly wines have to
be free of defect. The diagnosis of off-flavour may involve detec-
tion of presence of one or several compounds normally absent in
beer or wine such as 2,4,6 TCA which is causes the cork defect
or 1-octen-3ol which brings mushroom odour.
We lost two 50 gallon barrels to the musty mushroom off flavour despite using a sulphite solution as a sterilizing pre wash