Quick background on me. I'm a pro brewer (side job) for a small place in Colorado. I also function as their QA manager/ microbiologist and have 2 degrees in it including my own home lab. It's safe to say I know a little that's going on here...but the nuances and separating it logically from the beer dogma I live by is proving difficult. If you guys could critique my proposed process, I'd much appreciate any advice. I really want to focus on a high quality spirit and a single day mash. All my vessels are direct fired with propane and keggle ~14 usable gallons in size. I'm going to be fairly wordy and order it well so you guys and gals can easily pick it apart. I'll leave an asterisk ** for specific questions I have.
1 - Grains
Mashbill
70% Whole Feed Corn (no fortifications)
20% US White Wheat Malt
10% US 2-row
I'm thinking of about 2.5 lbs of grain per gallon of water. Seems fairly thick but with my proposed shortened mash time, might run into some low extraction numbers. If this was a mash I could sparge, I'd get 1.080 easy with that grist....but it's not
21# Corn, 6#Wheat, 3# 2-row. 12 gallons of RO water (My local water is hard so I always build up from RO...it's the process control nazi in me). So 30 pounds of grain in 12 gallons. (** I've seen water to grist ratios all over the place, nothing standard like in brewing. My concern is if I'm getting too greedy and will just need more fluids. Current system is keggles to tops out around 14gal. What are the safe limits?). All grains including whole corn will be milled to my normal barley gap settings.
Strike water will be treated with 8g of CaSO4 and possibly acidified in the future with Phosphoric acid depending on mash pH level. Never had any difficulty hitting 5.2-5.5 at room tempture before but I have no idea what the buffering capacity of this much corn!
2 -Inital Strike
I plan on bringing strike/mash water to 200F (I'm at 7000' so this is pretty close to boiling anyway) then mashing in with the corn only. This should drop the temperature to below 180F. I love science so, it's enzyme time. At this point I'd add ~8ml of SEBStar HTL (@ 0.36ml/lb grain) and stir the hell out of it ~10 minutes. With that temp and the alpha-amylase action that corn doesn't stand a chance. (** Now my mash tun has removable insulation. It works VERY well. In a regular beer mash I'll only lose 2 degrees in 60 minutes once equilibrium is hit. BUT I'd really like this to be a single day grain to fermenter, so loss of heat that slow might be a bad thing. I was thinking of removing the insulation during this phase of the cereal mash. Thoughts??) If I could let the mash naturally lose temp until 145F while stirring every 30 minutes or so that would be great. 12 gallons of water+21 lbs grain + 30 lbs of stainless steel is a lot of thermal mass. I really have no idea how long it'll take to cool down, even in winter. Maybe 2-3 hours naked.
3 - Second Grain Addition
Once the mash temp hits 145, it's safe for the low temp enzymes and for the barley and wheat to be mashed in. While stirring grain in, ~11ml of SEBamyl GL (@ 0.36ml/lb grain). I chose 145F for this process to start at due to wanting max fermentability and protection for beta amylase. After a jolly good stirring, I was planning to button the mashtun up with the insulation and hold temps there for another hour or two with intermittent stirring. A pH check to make sure it's in the range of 5.2-5.5 would also be performed. Check for the presence of unconverted starches with iodine tincture. If no color change, it's time to remove the mash.
Now here's where I start to lose my mind. Remember I'm a microbiologist and vehemently try to keep contamination out of my ferments....
4 - IM COVERED IN BACTERIA
I'm not cool with just chucking this mash into a bucket and fermenting it. Sure the corn was pasteurized well but the barley and wheat have not been. Mash temp alone is not enough to pasteurize/sanitize a wort enough to prevent the growth of unwanted contamination...Clostridium, enteric bacteria, etc...they smell and taste awful...no way, it's there and ready to sprout wings. I thought of pre-acidifying the mash to ~ph 4.5 and trying to keep the oxygen away from it but my brain really REALLY wants to flash pasteurize the mash. BUT there's the issue of all that husk matter and polyphenol extraction at high temps, so it needs to be lautered (grain removed) somehow. I know, I know it sounds like I'm making beer. Another concern is that I will be fermenting low and slow (turbo yeast sounds awful, I'm avoiding it) and will not have the ability to distill the second the wort had finished fermenting. Lauter/transfer...I was thinking about taking a few fine mesh paint strainer bags, ladling the mash into them then squeezing out the wort goodness into a kettle. This is definitely going to take some time and I can't think of an elegant way to do it....maybe a clean mop bucket with compressor attachment? (** Ideas on the grain/wort separation?)
5 - Flash Pasteurization
So I've got a kettle full of squeezins. Time for an original gravity check. Will most likely be done with a refractometer. I'm hoping for 1.060-1.070. For the pasteurization, I'm just going to bring it to a boil, not a full timed one. I have heat exchanger capability so once this wort boils, I'll run it through the chiller and output into 2 sanitized buckets at 65F. This is what I want my pitching temperature to be. (** Any issues with actually boiling the wort? Other than denaturing the current enzyme load in a pseudo mash-out? I can't think of any but I've never done this before)
6 - Yeast
The yeast I was planning to use is US-05. I have lots of experience with it, it's inexpensive and ferments clean at 68F. I'll be pitching at 2x my normal beer rate of 1 million cells / ml / Degree Plato. I think that will sufficiently suppress a lot of ester formation and it most certainly will not stall at the proposed starting gravity. The dry yeast will be rehydrated per manufacture instructions but I probably won't use GoFerm. I normally have a 2:1 DAP/Fermentaid K mixture on hand for step feeding meads and ciders. I was contemplating adding a few grams of this but I've also read that excess DAP in solution then distillation can yield undesirable taste results. (** Thoughts on adding nutrient to this ferment?). I also have molecular oxygen that will be added post pitch at a rate of 1L per 5 gallons (basically bubbling in via carbstone 1 LPM for 1 min).
My fermentation chamber is capable of holding 10 gallons at 65F. Figuring the internal temperature of the bucket is slightly higher (I don't use a thermowell), I think 65F is a good spot. US-05 will chew through that sugar in 5 days. (** Thoughts on adding any exogenous enzymes at this point? For instance the Sebamyl GL or ground up Beano tablets as I killed off any leftovers during the kettle pasteurization step...just to be extra sure we're extra fermentable).
When terminal gravity is reached (hopefully 0.996! via hydrometer), fine with SuperKleer KC (chitosan/kieselsol). Cold crash and decant off sediment into boiler.
The plan is to run this 3-5 times until I have enough hooch to fill a 5 gal oak barrel for aging.
Ok that's it. Wow that was alot of typing. Please offer your guidance if you can. I'm eager to hear it. Hopefully my next big post on when it's time to distill isn't so lengthy.
For the TL;DR crowd:
1) Making Bourbon
2) No overnight mash, using enzymes
3) Scared of bacteria
4) Doesn't want to ferment on grain
5) Will do extra work if the result is better
get a head start on the bacteria by using a clean process and let the yeast do their job! It will denature the enzymes, however. They will normally keep working at fermentation temps. If you boil them, you won't have that benefit. Up to you..
On average 2-2.5#corn/gallon is a good ratio. Add any other grain based on any equation you like and add malt per PPG calculations. I DESTROY my corn.... just barely above what you would call flour.... to increase surface area and aid water penetration. Check your pH as needed. Aim for closer to 6 if you plan on liquid enzymes. 
(look up "dunder pit".... your concern for bacteria in all grain will be gone). The high temp of mashing in will eliminate many important unwanted customers that would later survive fermentation, especially since you will only be fermenting for a short time frame and you won't do a second fermentation. As far as removing the grain you can ferment right on the grain if you like and remove the grain later. There are many helpful posts here about it. I myself mash and ferment in a bag which allows me to easily remove 100# of grain from my tun. OK maybe "easily" isn't the word.... but you get the idea. I will occasionally get a lactobacillus infection if my ferment goes slower than anticipated but that just adds to the flavor. If you don't want this then I would warm your fermentation bucket to speed fermentation. If you do not want to ferment on the grain then mash in a bag and remove it immediately... easy peasy as FMH would say.
