"Hi boxholland,
Quote:A mash intended for distillation only undergoes a primary fermentation. Grain mash fermentations are typically 72-80 hours long, and then they are distilled. In fact, a secondary fermentation would be very deleterious to the ester profile of the mash and would ruin the finished whiskey.
Yep ... I read that as well. He also goes on to say:
Quote:When the fermentable sugars have been exhausted, the yeast metabolism changes and begins breaking down unfermentable sugars and other organic compounds and consumes them. This involves the secretion of very different enzymes such as permease that enable the consumption of unfermentable sugars (dextrins and polysaccharides). This altered chemistry results in the formation of a family of esters, which have come to be called the "dreaded esters" by the author. The dreaded esters have very nearly the same boiling point as the alcohol/water azeotrope (i.e. 78.15oC (172.67oF)), and are almost impossible to separate out by distillation. Therefore, they pervade into the finished whiskey and ruin its flavour.
Now I know some of the bourbon guys want to get their wash in their stills within several days ... that's fine. But I have found things in Smiley's book that are questionable, so I take them with a serious grain of salt. The quoute I added is one of them, which is one of the following paragraphs that you refer to.
First, he states that the yeast ferment (""break down"") unfermentable sugars. Enough said there.
Second, he mentions consumption of (again ""unfermentable"") polysaccharides. The best I can figure is that he's confusing this with the
release of polysaccharides (the mannoproteins) during maturation ... I believe the wine guys know all about these. The only polysaccharide that I'm aware of that is transported into the cell is maltose (a disaccharide).
Then there is the self-coined phrase ""dreaded esters"" which appears only a few times his book and nowhere else (other than a few forum posts). Since these never identified esters have ""nearly the same boiling point as the alcohol/water azeotrope"" I assumed he must be referring to ethyl acetate (via acetic acid) ... which is usually associated with hyperosmotic stress (high gravity), not fermentations that go beyond 80 hours. Honestly, in all of the studies I've read, I've have yet to come across one that concludes that shorter fermentation times will reduce the amount of acetic acid produced by a yeast.
Finally, the permease thing has me a bit confused as I thought it was an amino acid transport and remained in the cell ... not secreted into the substrate. But that's the extent of what I've read. Also, the ""secretion"" thing is confusing as even invertase remains within the cell wall and the rest I thought were all intracellular. Again, I'm out of my comfort zone here ... so if someone knows this stuff I'd love to learn more.
In any case, it was never clear to me if Smiley was just sampling his wares when he wrote those few paragraphs or if I'm just missing something.
I've tried to find scientific evidence (rather that anecdotal statements) for his assertions but I'm still searching.
Regards,
--JB"
