by Brendan » Sun Jun 02, 2013 2:38 pm
Emzy,
This may not be a very definitive answer...but you are really talking specific boiling points of pure compounds measured in lab conditions...you probably wont see this.
You have a wash of many compounds mixed in together, and they will not perfectly boil at those lab measured temperatures...not to mention that you cannot guarantee your thermometer used at home to that level of accuracy...
The best answer I can probably give you here, is that you need to learn by smell and taste and learn how to dial your senses in, so that you will know with a quick whiff whether it's any good or not :handgestures-thumbupleft:
Foreshots have acetone components which you will smell immediately without any indecision...Heads contain ethyl acetate, which many recognise as a sweet kind of smell with a very harsh bite in the taste...Your hearts will be very clean and only carry a mild but pleasant smell of the base of your wash used (ie. Corn, wheat, tomato paste)...and the tails are recognised by a really nasty, oily smell which i think some people refer to as a wet cardboard or wet dog smell...alot of the stronger flavour compounds from your wash come through here, which is why people tend to add back some of the really early tails into whiskies to add a bit of that character in (which require more ageing to smooth out)...
Hope that helps...unless you're running a commercial distillery, where every wash is identical day in day out, I don't think you can predict your output just by the vapour temperature alone (except maybe on a very effective VM rig).