Working with corn, confused, high FG

[triplet]

Hello all,

I am having real trouble with corn based mashes. I need help please. I am no stranger to brewing beer, like most users here, I also home brew. I have a pretty killer all electric 1/2bbl brew house at home, and luckily, I also work part-time as a brewer on on a 7bbl system. I understand my mashes, temperatures and yeast management/health. I am stuck. On my 100% malt mash/washes, I hit 7-8% perfect, with no problems. Corn however...

Recipe:
60% Cracked corn (I have tried two different brands, Family Farm (walmart) and O.H. Kruse (feed house) (9lbs)
30% Double milled Rye (4.8lbs)
10% Double milled 6 row (1.8lbs)
Total: 15lbs of grain for a 5 gallon batch

Using techniques from here, I use 1.5 gallons of previous corn backset and 5.0 gallons of carbon filtered water. I heat this water up to boiling, and add this amount (6.5 gallons) to the corn into an insulated cooler. The corn will sit for a minimum of 3 hours, stirring every 45 minutes or so (unless over night) and does not get below 170. I stir an drop temp, once at 150ish I add my grains and stir. I usually then mash for a minimum of 2 hours around 145-147. I always hit a great OG. My last OG was 1.070 (high 80s% efficiency). I was shooting for 1.060, so this was a little high, the recipe was calculated for 75% efficiency, I hit over by double milling the grain I believe. I split the mash into two buckets, let it cool over night and pitch yeast in the AM. I even ferment these mashes a tad hot, close to 75.

The catch.

All my washes stop between 1.020 and 1.030. I have used bakers yeast, US05, Nottingham, Fresh White Labs 001 pitches from the brewery. I have tried White Labs yeast nutrient, "bombs" using Vit B and a multivitamin with DAP and amylase. No avail. The batch at 1.070 stopped at 1.032. I do not understand. This is only approx. 57% attenuation. I know 001/US05 very well as a yeast. Mashing low (145) without amylase I can always hit close to 88-90% attenuation on beers. Its leaving 3-4% of wash on the table and frustrating. I should be hitting 1.010 minimum, if not close to 1.000.

What I am missing? Am I using a poor corn product? Am I somehow producing a high amount of non-fermentable? I thought the O.H. Kruse cracked corn was going to be the ticket as it is double the price of the walmart brand. However, I was hitting 1.020 with walmart brand. Thoughts?

[rad14701]

You're using quite a thick mash at 3 pounds per gallon... That will raise the osmotic stress on the yeast cells and perhaps once the alcohol content gets to a specific point the colony succumbs prematurely... Or pH issues... Also, when the yeast colony is stressed it becomes more intolerant of low or fluctuating temperatures... Or . . . .

[triplet]

You're using quite a thick mash at 3 pounds per gallon... That will raise the osmotic stress on the yeast cells and perhaps once the alcohol content gets to a specific point the colony succumbs prematurely... Or pH issues... Also, when the yeast colony is stressed it becomes more intolerant of low or fluctuating temperatures... Or . . . .

A thick mash should not affect fermentation, correct? I do ferment on grain. However, I always thought that thin/thick mash affected flavor and efficiency, not attenuation?

** I should say, the first couple times I tried this, I did not add the entire amount of water. I did about a 1.5qt/lb mash for the corn/grain and it didn't change the FG.

[skow69]

I used to have a similar problem. Try using DADY and ferment at 80 - 85f. I use 2 tbls in 5 gallons and always get to 1.010 or below in 3 to 4 days.

Actually, I'm surprised you're not getting higher OGs. I run 2lb/gal and get 1.060 - 1.065 consistently.

[triplet]

I used to have a similar problem. Try using DADY and ferment at 80 - 85f. I use 2 tbls in 5 gallons and always get to 1.010 or below in 3 to 4 days.

Actually, I'm surprised you're not getting higher OGs. I run 2lb/gal and get 1.060 - 1.065 consistently.

I will try DADY and just ordered it, but I am not conveinced. I am concerned that I have already tried so many yeasts. I should be getting much higher than high 50s % attenuation with any of those yeasts. I just ordered a MW101, so I will check my pH too. Once I nail my efficiently I think I can move to 2lb/gal, so I am not over concerned about that. Something is going on and I am so confused.

[White_Lightning_Rod]

How are you determining that your mash is finished fermenting? My last AG with corn I used Us-05 after 3 or 4 days the cap fell and all bubbling stopped and it seemed to have stopped at 1.032, I chalked it up as inexperience on my part since it was only my second corn AG mash and racked 10 gallons off the top and stripped it a week after it started fermenting. Life came up and instead of stripping the second 10 gallons the next day it was another week before I got to squeeze the grain and strip it. After squeezing the grain I checked the gravity and it had dropped from 1.032 to 1.010 this change happened with absolutely zero visible fermentation activity, no bubbles no cap nothing. Maybe you are just rushing it a little.

[rad14701]

75F is not "hot"... For most yeasts just below that is where they start getting sluggish... How about the pH...???

[woodshed]

PH is what I am thinking.

[White_Lightning_Rod]

PH is what I am thinking.

Yea from what research on AG Ive done 1.5 gallons of backset in a 6.5 gallon total is a little much. I would say Woodshed and Rad are probably right, you are a little on the acidic side.

[corene1]

I would agree on PH also . I have had that happen in my AG mashes when using backset. I typically have to adjust with Gypsum or calcium carbonate to get my fermentations to finish as far as yeasts go I use plain old bakers yeast at 8o degrees and just had an AG mash go from 1.064 to .0998 in 10 days, though I have never tried any of the beer specific yeasts.

[triplet]

Thanks for all the info guys. The pH meter just showed up today, so some testing is in order. I will keep this thread updated in case anybody else has similar issues.

[culvercreek]

I had the same thing happen to me on a SF recipe and it was the PH. Once I got that adjusted it took back off like a rocket.

[triplet]

I had the same thing happen to me on a SF recipe and it was the PH. Once I got that adjusted it took back off like a rocket.

All y'all was correct. Wash pH was 3.15. Will adjust and recheck.

Thank you all, cheers

[islandgreen1971]

Did you aerate the mash?

[BoomTown]

A trick I use to tell when a mash seems to go quiet is it stalled? or just quitely churning away.

I take a plastic water bottle, fill it about half full, the squeeze the air out of it and put the cap on tightly. If the yeast are still working, in a couple of hours the bottle will inflate, if it's really stalled, or finished, the bottle will stay all crumbled up.

I typically ferment on the grains, and when I draw off the beer into a separate bucket to allow it to clear, it sometimes seems to 'restart' in the new bucket before it clears. I attribute that to the beer getting aerated while I squeeze the grains, and the yeasts giving it a last go. Typically, the SG I separate at is 1.002 to 1.0005, and I've seen that drop to .999 after a few days, if the yeasts restart.

[engunear]

I've had a lot of difficulty with rye and am only slowly mastering it. I've had rye recipes start fermenting spontaneously after an overnight 165C mash. Looking at my diary the other day I noticed I lost 9 batches in a row with rye, though some of those were them wash burning on the boiler due to the ferment sticking.

When the ferment finishes is it really sour? When you distill do you get high lactic acid in the tails? Fermenting on the grain with rye can cause the lactic acid bacteria to take over and push the ph too low for yeasties. Then the ferment will stop. A solution to this is to up the amount of yeast by pitching with yeast that has been bred up in a healthy starter culture. Use liquid malt in the starter to keep the flavor consistent.

Is it malted rye? Is the wash slimy at the end? Rye has a high amount of dextrins. So it may help to add malted rye aiming for a mash temperature of 170 where the alpha amylase is most active then letting it drop before adding the barley. There are also rye recipes where you cook the rye to 180 or so with the corn to break them both up and reduce the lacto. Then cool and add the barley aiming for 160-165 mash temperature. But if you have rye and are mashing at 145 you are outside the window for alpha amylase so it might be dextrins.

There is a great book called "Debugging: The 9 Indispensable Rules for Finding Even the Most Elusive Software and Hardware Problems" - two of the rules are "Divide and conquer" and "Change one thing at a time". I'd suggest try the same recipe with the rye replaced with corn. That will cut the lacto load and the dextrins but keep your sugar levels the same. Then see what happens. If that works it shows your OG is fine for your yeast choice.

Let us know how you get on!

[BoomTown]

I work with nearly the identical Grain/water recipe, except for the backwash, and OG's run about 1.060 most of the time. I stopped using backwash when my mashes too started stalling out. What I do now is use the trub from the previous mash as about 1/2 gallon of the new mix, instead of yeasting. Haven't had many problems since,

I was fermenting on the grains, but with the recent addition of a SS Mash Tun that has a false bottom and a ball valve under the screen, let it cool to about 100F, and just drain off the mash, (usually SG is right at 1.060) and add in the leavings from the last Mash. I also usually add back into the once used grains 5 gallons of water, and bring the temperature back up slowly to about 160, hold that for about 2 hours, and drain off the 2nd mash too. SG off the 2nd batch usually runs about 1.025, so I toss in 4 lb bag of white sugar, and call that a wash, (also OG of 1.060 after adding the sugar). I've been running both separately, to see if I can detect a difference in the taste, but haven't had either on oak long enough to detect a measurable difference yet.

Good luck.

[triplet]

Ok so to answer all the above...

(1). I did a batch of the very first recipe with no backset. I hit 1.058, but once again, stalled out at 1.018. I have aerated. Used a stone even too. I tried using DADY. No dice.

(2). I decided to go simple and just do what engunear stated and replace the rye with corn. So I did 9lb corn and 3lb wheat (and another batch used 6 row). Both batches ended up at 1.018-1.020. The pH on the last batch ended at 3.8, which isn't terrible. I am still so confused. I have tried Bakers and DADY. I do not plan to add any sugar to any of these batches, I want grain only.

[triplet]

When the ferment finishes is it really sour? When you distill do you get high lactic acid in the tails? Fermenting on the grain with rye can cause the lactic acid bacteria to take over and push the ph too low for yeasties. Then the ferment will stop. A solution to this is to up the amount of yeast by pitching with yeast that has been bred up in a healthy starter culture. Use liquid malt in the starter to keep the flavor consistent.

Is it malted rye? Is the wash slimy at the end? Rye has a high amount of dextrins. So it may help to add malted rye aiming for a mash temperature of 170 where the alpha amylase is most active then letting it drop before adding the barley. There are also rye recipes where you cook the rye to 180 or so with the corn to break them both up and reduce the lacto. Then cool and add the barley aiming for 160-165 mash temperature. But if you have rye and are mashing at 145 you are outside the window for alpha amylase so it might be dextrins.

There is a great book called "Debugging: The 9 Indispensable Rules for Finding Even the Most Elusive Software and Hardware Problems" - two of the rules are "Divide and conquer" and "Change one thing at a time". I'd suggest try the same recipe with the rye replaced with corn. That will cut the lacto load and the dextrins but keep your sugar levels the same. Then see what happens. If that works it shows your OG is fine for your yeast choice.

Let us know how you get on!

I did try all that above. The rye is the same homebrewer rye I use and get grain conversion and finished products. I decided to ditch the rye all together and still having the problems.

I didn't run the batches, I toss them. Ingredients are cheap, if I am not hitting about 6% I dump them.

[BoomTown]

Now you got me wondering if your mashes are actually 'stalling'. It could be that the action has just quieted down and you aren't seeing the bubbles. Mashing isn't simple and the 'best practice' isn't always obvious. Suggest Try the following:

1) Using Dawn dishwashing soap, sponge out your fermentor, to assure that the action that occurs there is from your intended source of yeast, and that it's got very little or no competition. Be sure to rinse the fermentor very clean afterwards.

2) Add a tablespoon/5 gallons of Baking Soda to your mash, and wait for that action to finish, before you pitch your yeast. That ought to raise your pH a tad.

3) In a mason jar, fill it half way with some of your mash and add your yeast. Cap it tightly and shake it very hard for a few seconds, then loosen the lid and sit aside for a few minutes. Allow that to ballon up to fill the jar, then add this (yeast bomb) to your mash. That allows the yeast to get a head start at gobbling up the sugars in the same world they will be in after you add the whole to your mash. After tossing your yeast, wrap the fermentor in an old coat, or blanket or sleeping bag. That should keep the temperature stable, not that that is your problem, but it is a good practice.

4) Do not touch it again till 6 days have passed. Then dip out about 4 oz off the top, and put it into a 12 oz clear plastic water bottle and squeeze out the extra air and seal the bottle tight. It should look like a crumpled up bottle with dirty water in it, and it might even taste a little citric acid.

5) Sit the bottle in a warm place, and watch it for 4 or 5 hours. If it inflates itself, that will be yeast still active, making CO2. Let it set a couple more days, then do that again. If it stays the same, then take your OG reading, it is done.

In my stalls, I discovered was that I was adding in my Barley Malt at a too high a temperature, I got conversion of the higher sugars, but killed off the Beta Enzymes that should have been active in the lower temperature ranges, so I had a lot of un usable sugars. I now add Alpha enzymes at about 160F, and Beta enzymes at 130F. Mine have consistently stabilized at FG of 1.001 to .0999.

Don't give up. What ever it is that is causing this problem for you, it is a simple thing, and once you unravel this mystery, it'll be much easier.

[engunear]

Checking Bryan Davis's corn whiskey recipe, there are two differences:

1) He uses 1:5 parts malt barley to adjuncts, where your recipe is 1 to 9. So maybe you don't have enough amylase?
2) He mashes at 152-155 where you are at 145-147. So maybe your alpha amylase is not getting enough of a chance?

... and maybe its the combination of these differences?

BTW, how do you distill off grain? Just curious about what people are doing that works.

[Yodaspike]

Hi all
Hope you greate
I have a simmilar issue, but...
So corn wash, 25kg cracked, 10kg sugar about 120lt total water used, only took sg a day after fermentation started, at around 11%abv potential.
Been 12 days, but from 6th day it slowed, took as fg 4 days ago, and was sitting at 1.04ish, so left it as there was still plenty bubbles coming up in the mash, now 4days later same thing, bubling but no drop in reading, checked all i can think of, even raised the ph a bit to 4.4, so not sure if the yeast is making sugar and alchohol at the same time or whats going on, mash does have a bit of a sweet taste still. Any ideas? All corn etc sitting at the bottom and the clean liquid on top

[SW_Shiner]

Hi all
Hope you greate
I have a simmilar issue, but...
So corn wash, 25kg cracked, 10kg sugar about 120lt total water used, only took sg a day after fermentation started, at around 11%abv potential.
Been 12 days, but from 6th day it slowed, took as fg 4 days ago, and was sitting at 1.04ish, so left it as there was still plenty bubbles coming up in the mash, now 4days later same thing, bubling but no drop in reading, checked all i can think of, even raised the ph a bit to 4.4, so not sure if the yeast is making sugar and alchohol at the same time or whats going on, mash does have a bit of a sweet taste still. Any ideas? All corn etc sitting at the bottom and the clean liquid on top

Is your hydrometer reading correctly? 10kg of sugar and 120L of water only give me an potential abv of 4.9%

[Yodaspike]

So took a sample added some hunny and visible fermenting started, so decided to run it, either way seems like might be getting about 6lt @ 55abv, so probably low yield, will see if i try it again next time, will probably do thing it bit different