Willie JJ wrote:The trouble is that it (grain whisky) has often been put in any old rubbish casks that are lying around just so it can get to 3 years old and can be chucked into a blend. I suspect that's why you get a lot of harshness in cheap young blends.
So true. As with any aged whisky, the quality of the wood into which the spirit is placed has a tremendous impact on what is finally racked off at the end of the maturation cycle.
Fairly 'neutral' barrels (i.e. well used ones that have not even been recharred) will impart relatively little in the way of additional flavour characteristics to the spirit they hold unless the ageing cycle is quite lengthy. On the other hand, good 1st-fill barrels will have a far greater influence on the contained whisky over the first three years of maturation.
It's also important to remember that such whisky can be produced from a variety of grains handled in different manners. Wheat and corn seem to be the most commonly used. But unmalted and malted barley also make their way into the grain whiskies utilized in many a blended Scotch.
For instance, Girvan's 'recipe' uses wheat and malt. North British goes for corn mixed with malted barley. And Cameronbridge uses, I believe, 'green' barley (unmalted).
So between differing sorts of grains utilized, variance of cask regimens and shorter or longer maturation periods, one can end up with whiskies exhibiting a very wide spectrum of flavour profiles.
Generally, though, sweetness and crispness do appear to be the most prevalent tastes one encounters from the contribution of the grain whiskies in a blended Scotch.