PH of Wash during Distillation?

MikeAggie

I have been distilling for about 3 years now, and it's been fun learning along the way. I have the PH during fermentation under control, were I can fix my stuck ferments when necessary or maintain a happy yeast environment, but does PH of the wash carry over flavor issues during distillation?

I always just tossed it in and started boiling when my wash was ready. Should I bring my PH to neutral prior to distillation?

I know vinegar cleaning runs still come over acidic. Could this be a factor in flavor or carryover of esters?

grim

Higher total acidity will favor esterification in the still, this includes the required carboxylic (aka fatty) acids which are the precursors for the Fischer Esterification reaction, but also mineral acids which may also catalyze the reaction.

In addition to the esters, you also have the factor of volatile acids coming through in the distillate.

In both of these situations, completely neutralizing the acids with something like baking soda will lock up the fatty acids and slow the esterification reactions, as well lock up some of the volatile acids from coming through in the distillate.

More correctly - the esterification process is an equilibrium reaction, with the reactions taking place, and the reversals taking place, simultaneously. It's not a reaction that runs to completion. By increasing the acidity, you change the equilibrium point. Adding sulfuric acid to the wash to increase acidity will increase esters by moving the equilibrium point. Or, by using LeChatelier's Principal, and increasing the amount of ethanol in the wash (For example, adding backset, dunder or fermented wash (which all contain fatty acids) to the low wines in a spirit run, which will also increase the esters by moving the equilibrium point.

Long times under reflux in the still will also favor esterification.

Also worth noting, these are not selective reactions that favor either good or bad fatty acids and esters, it applies to them all. Increasing esterification in a wash that has high acetic acid will give you a run of nail polish remover.

MikeAggie

So for a neutral like a vodka run, neutralizing wash should help, but for a rum run, it can change flavor profile by preventing esters from carrying over?

grim

@MikeAggie - Yep

(everyone stop reading here, what lies beyond is not a recommendation) Sodium Hydroxide should work equally as well to shift the equilibrium point to favor fewer esters, this would be added at distillation, and would require no waiting time.

Kapea

It would also aid in clearing out the hair and other gook clogging the drain pipes that you pour your dunder down. :D