Recently I wanted to trial using raw wheat rather than malted in my bourbon. Thus far I've been happy with malted for my product, however I wanted to learn what the impact to the flavor profile is using raw grains.
I'm cooking the corn for an hour with high temp alpha amylase.
Adding the roller milled raw wheat at 185 for another hour. (man the motor doesn't like that stuff.)
- (note: When I was reading up on the process for raw wheat, I've read different info on the best temp for this step... both higher and lower have been suggested, though lower was generally from an amateur source, that when I traced the source, had some other info that was incorrect, so i view that dubiously. Any opinions?)
Bringing the temp to 153 for powdered alpha amylase since the corn temps were high enough to denature high temp alpha with a 1/2 hour hold, then I take it down to 146 and add bioglucanase for another hour.
SG reads 1.068 which is in the range I'd expect, so it seemed to convert ok. I use a transfer method with lots of splash, so I don't believe oxygenation is the issue, I'm maintaining consistent temps in the fermentation room, yet as I'm trialing using raw wheat, I've suddenly begun to have stuck ferments at 1.04. I did work to break the stick with another pitch and with agitation with partial success (1 fermentor weakly kicked off again, another didnt), but ultimately chose to toss the batches as I didn't feel I could learn meaningful flavor profile information in a situation where the yeast had gotten badly stressed.
Is there anything specific I'm doing wrong that might lead to stuck ferments? Is raw grain more prone to this? It does occur to me that I was using the same yeast pitch as I used for malted. Does raw require more? I also checked for any changes in water treatments with the water department on the chance that might be the problem. Validated chorine rather than chloramine. They did note they had slightly upped chlorine recently so the 2nd batch gave the water a boil and an overnights rest before use, but nothing changed. PH was in the same ranges over time that has consistently worked with malted. Starting water is generally at 7.4 with low iron but moderate calcium.
Just to be clear, does your mash consist of un-malted corn + un-malted wheat + Alpha + Beta? No malted grain?
I am not an enzyme expert but I have been experimenting with them for years. Maybe reasonably pure alpha and beta are not the best at breaking down wheat starch to fermentable sugars. Malted wheat has its own specific enzymes.
Also high start gravity does not necessarily mean high fermentable sugars, the high final gravity could mean non-fermentables caused by incorrect enzymes.
I will follow to see what others have to say.
Usually a Beta-Glucanase is recommended for a high rye or wheat mashes. It should make your mash less gluey as well if your agitator was the motor that you mention was strained, not your mill. It needs to be added around 140F though. Glucoamylase is supposed to break down more types of starch chains than Beta or Alpha. I also use a little yeast nutrient when using non-malted grains.
Reply:18 hours ago, PeteB said:
Reply:18 hours ago, PeteB said:
Reply:17 hours ago, adamOVD said:
Reply:43 minutes ago, JonDistiller said:
Trouble shooting a ferment is like trouble shooting and engine or anything else. Start gathering data eliminating possibilities step by step. Is the problem with the conversion or the ferment? Do an iodine conversion test so you have a better idea. Is your grain gelling? Do a longer or hotter cook to see what happens, or do a mini sample without enzyme to see if it thickens up. Is your ferment healthy? What's the gravity, ph and temp of your ferment each day? Does it start slow? What does it taste like? Will it start again if you repitch? When I was brewing I'd even do yeast cell counts and viability tests to get ahead of any problems before they happened.
Mashing schedules are really up to you and your equipment/ mash bill. You'll probably get more helpful tips if you can isolate the actual problem. Good news is there are really only a handful of things that can go wrong.
Reply:4 hours ago, JailBreak said:
Reply:2 hours ago, adamOVD said:
Consider mashing in all your raw grain with your base grain - corn or rye.
Reply:On 11/3/2020 at 7:44 PM, Silk City Distillers said:
Yes, not only better yields, but far easier workflows.
In almost every case for us, getting good conversion and yield with high % of raw grain required far higher temperatures and longer holds than the literature would indicate.
Higher temperatures than usually recommended gives us better yields. Strike temperature 90 - 92 Celsius works works well for me with un-malted oats, rye and barley
This is the paper I see most often cited when talking about raw grain processing and ethanol yield.
Only caution is that the comparison is against high temperature pressure cooking. It's a pretty massive temperature difference being compared to here, and most of us don't pressure cook.
Appreciate the advice @Silk City Distillersand @PeteB. I'll go for that on my next batch, once the missing enzyme gets delivered. BTW Silk, I just wanted to say thanks for some advice you gave another distiller a while ago about the proofing process, which was very helpful to me.
Reply:On 11/5/2020 at 11:23 PM, Silk City Distillers said:
Every time I come across a pressure vessel cooker, I wonder about being able to cut hold times dramatically by cooking above boiling. Time is money. Never enough time.
A 1000 gallon pressure cooker sounds kinda terrifying. One of my neighbors gets deliveries in the alley behind our distillery where the still is, and when the driver's air brakes go off it already makes me jump every time. I guess it's not really any scarier than a 1000 gallon still though, and all the benefits mentioned sound pretty great, plus i suppose you could even sterilize your mash if that was important to you.
It sounds like your enzymes aren't being used to their maximum potential. Wheat gel temp is in the 160F range, you shouldn't need to cook it to death to get good conversion. Our enzyme supplier (also a large distillery) suggests not cooking above a grain's required gel temp for both flavor and efficiency reasons. I can see a lot of dough balls / clumping happening if you add your wheat to a 185 degree mash. I would aim to not denature your Alpha enzymes (or get a more robust one), and pitch the wheat down in the 160-170F range. we do that with our raw wheat and get a full conversion.
Reply:On 11/11/2020 at 5:48 AM, PeteB said:
Reply:23 hours ago, SlickFloss said:
Reply:On 11/17/2020 at 9:35 AM, kleclerc77 said:
Non milled grain !?!. that sounds very interesting , no floury mess to deal with?. Where would one look for such info?