How to get high attenuated all grain ferments

[Iulistoi]

Hi everyone,
I did a lot of all grain mashes for whiskey, vodka or homemade beer. Every time I tried different techniques on malting and mashing and allways there are some sugars that remain unfermented after fermentation is completed. The FG is between 1.010 to 1.040. This means a lot of wasted yeald if we talk about vodka or whiskey but for beer is another story.

The rice is the only grain that ferments dry, perhaps because of high amylose content, so less 1-6 glycosidic bonds. All others, corn, barley, rie, wheat, malted or not, ferment with lots of residual sugars.

I know that I can use glucoamylase but I feel that I cheat. I want to go straight, all natural, without additives.

So, how do you do to ferment all grain mashes to under 1.000 FG ? I tried everything, from different tehniques in malting, soaking malt very long to release more free limit dextrinase, mashing between 60-62.5 degrees celsius, long saccharification rests, short rest for preserving enzimes during fermentation. None of them worked.

A few times it worked and I achieve under 1.000 FG but I think it was the infection who dragged the density so low. It is known that some bacterias and wild yeasts have the ability to ferment some dextrins.

There is nothing to do with beta-amylase rest. It is useless to say that no matter how long and how low you keep that rest interval of 60-65 degrees C. There are allways dextrins from amylopectin that can't be broken neither by alfa nor beta amylase.

The rescue can come from limit dextrinase, this enzyme found in malted grains, usually in bound form. But how to manage the process to maximise it's potential?

[Demy]

Hi, it seems that at the mashing level you have already done everything. I would like to recommend a different type of yeast that is able to break down sugars that common yeasts do not ferment. My only experience with "particular" yeasts was with "angel yeast", there are several threads here on the forum, it is a complex of yeast and fungi. I also try to keep the process as natural as possible.

[Windy City]

What are you mashing and what is your process?
Have you been controlling your PH?
The only times I couldn't finish dry is in the beginning when I was not buffering my PH or when I had a fermenter that was infected with butro so bad that I had to throw it away.

[8Ball]

+1 to earlier questions on mashing process & pH.

Also, are you correcting your reading for the presence of alcohol?

Original RI (°Bx): 1.073 17.72
Final RI (°Bx): 1.031 7.80
Wort correction factor: 1.040
(Default: 1.040)
Original Gravity: 1.0699 (17.04°P)
Estimated Final Gravity: 1.0109 (2.78°P)
Alcohol by Volume: 7.6% (6.2% ABW)

In the example above, an all malt mash that I fermented finished at an indicated refractometer reading of 1.031. After correction, it worked out to 1.011, which is about as low as I’ve ever seen my malts finish.

When I stripped it all out, I collected 2 gallons @ 28% abv from a 7 gallon boiler charge. (2/7)*28= 8.0%, which is right inline with my mash OG & corrected FG: (1.073-1.011)*131=8.122 % abv

So, if you say you are getting 1.010 to 1.040 AND those FG’s are not corrected, then my guess is that your ferments are finished or are very close to finished. Adjusting pH and temperature along with yeast selection might improve the situation a bit more.

[jonnys_spirit]

When you mash try to do a starch test with iodine to confirm that all starches are converted.

Cheers,
jonny

[Iulistoi]

Depending on what I use, just malted or malted + unmalted grains, I do different mashing schemes. I test the pH with pH strips and it is not accurate bit is somewhere between 5 and 6.

For exemple, for cornmeal, using 1:4 malt to grain and 1:3 grist to water, I add a small amount of malt when heating the mash. When it reaches the gelatinisation temperature, it starts to liquefy a bit and becames more easily to stirr with pedal. Then I rise to boiling. When comming down the temp, I do another short rest at 72 degrees with another small amount of malt for alfa, and then go to 60-63 degrees, add the rest of the malt and rest for 1.5 hours for beta amylase and limit dextrinase rest adjusting the temp between 60 to 63 degrees. I never do iodine test. I calculate the conversion by finding out the density, then brix and then grames of sugar per liter of wort. If it gives what I expected from initial calculation on starch content of the grains, it's ok. Otherwise iodine just tells if you have unconverted starch but tells nothing about the sugar profile of the mash.

The presence of alcohol drags the apparent density lower, so the real density is higher. But this doesnt matter in our discussion. The point is, you have to get the final density below 1.000 to be satisfactorily and have good yield.

Yeast would be an option if I find one who can ferment dextrins. But I am sure there are secrets that big distilleries dont tell us and those secrets are in malting/mashing procedures. They cant afford to lose such big yields. I calculated, between 1/5 to 1/3 of sugars from starch hydrolysis within a regular mashing ARE NOT FERMENTABLE! Imagine what a waste!

[Twisted Brick]

I tried everything, from different tehniques in malting, soaking malt very long to release more free limit dextrinase, mashing between 60-62.5 degrees celsius, long saccharification rests, short rest for preserving enzimes during fermentation. None of them worked.

Where does your grain come from? What is your malting process? Because you achieve 1.00 FG only occasionally, it might be your source grain.

[zapata]

Your mashing seems solid. Getting a pH meter and adjusting to idea for each step may help (or not, I'm not sure, it seems to help with exogenous enzymes).

Yeast that can eat dextrins has been mentioned, there are several diastaticus strains available. But there are other yeast aspects to consider. A naturally mashed wash will be high in maltose and yeast strains vary in their ability to digest it. You have more options here than just the diastaticus strains, and you can go the way of some scotch distilleries and mix distillers strains for high fermentability and brewing strains for flavor. Yeast prep may matter too, yeast that has been cultured on simple sugars will not digest maltose well. A source of this problem I recently discovered is malt extract. Apparently a lot of malt extracts are prepared with exogenous enzymes resulting in low maltose content. As a result, yeast starters made with malt extract do not perform as well on naturally mashes. Using all grain wort for starters can make a difference.

Overall I think yeast strain matters the most, and high attenuation seems to be the focus of most of the whiskey industry. What strain/s have you been using?

Finally, something I haven't tried yet but intend to is to intentionally pre-stress yeast. I seriously doubt it is commercially practiced. I posted a cool study in the recent "is sodium bad" thread. In the study they fermented 2 batches of wine, one for control and one with yeast that had been stressed with salt. The salt stressed batch finished a full 3% abv stronger. Of course it was with wine yeast and in must, but it is a huge difference and the basic metabolism and stressors are the same. I think it's worth a shot.

[Iulistoi]

Twisted brick, the grains used for malting are from a local market sold as food for birds. I usualy use wheat but I tried barley too and the result was the same. I tried different sources of grains for malting but the result was the same.

I start by puting the grains into a permeable bag and put the bag in a bucket. I wash the grains very well and let them soak for 24 hours. After that I let them breath by hanging the bag somewhere to drain the water. In the morning and evening I soak the grains a bit just for washing and keeping them moist. I stop the malting process when the acrospire is between half and full length of the grain, not anymore. I used it fresh or dried. Fresh, it can be turned into a paste by grinding with a meat grinder but have the drawback I have no time to wait, because the fresh malted, grinded malt spoils quickly.

Sometimes I think to intentionaly let the malt to spoil a bit and put a part of it with the yeast, thus intentionally infecting the mash. I tried a few times. Once it worked very well and the fermentation was very dry but another time I used too much infected malt and It stuck at the middle of fermentation and the smell was terrible. So, infecting intentionally is risky. Plus, you can loose at the yield is too much bacteria ferment sugar into lactic acid. The smell could be foul as well.

Rice is the only one that ferments dry everytime.

I will focus more at adjjsting the right pH in favour for limit dextrinase enzyme. You, Zapata, say very interesting things. I didnt know the technique with stressed yeast. Seems very interesting.

[Iulistoi]

I forgot to mention, I usualy use bakers yeast. I know it is not the best choice because it gives yeasty smell but I distill it at high purity 94-95% with packed column and doesnt matter. The smell doesnt come off to that purity.

When I made whisky I used special yeast and I distilled twice with pot still. I tried different yeasts time along and even distillers yeast doesnt ferment to dry. Once I used glucoamylase and I had best yield, 12 liters pure alcohol from 30 kg wheat flour

[Triplequad]

Boy does this sound familiar. As a bio engineer, I knew I could just crush this endeavor. I was doing my method development but for the life of me , I could rarely break 1.030 .
I'm not going to guide you as I'm still a novice, but there are some giants on this forum that will help once you get away from what you know. Because my friend, I could teach a post doc fractional distillation and I just knew I wasn't the problem as my process was sound. I was spinning my wheels running down rabbit holes... performing GC and LCMS analysis looking for hydrocarbons and what not.
Well I was the problem. So I went back to sugar washes and followed some advice until I could make those yeasies do what I wanted, then moved to grains.
I will offer this, cross reference every step, particularly what comes from YouTube. Keep an eye on ph and temp, pay attention to nutrition and everything around the pitch. Good luck .

[PoppaW]

I’m glad to see what I thought was my problem seems to happen a lot. My all grain usually finished closer to 1.010 to 1.005. I had some dryer but it’s not the norm. I am happy for now but will keep working my ferments to get it lower. I would prefer 1.000 to 1.005 to be my FG. I use a temp corrected online program for checking temp to hydrometer reading. A little more accurate.

[Iulistoi]

Hi, I have good knews!

Right now I have a cornmeal+wheatmalt mash fermenting. It's 4th day of fermenting and the SG is 1.002 from 1.063 and it's still working! So, is possible that next days the density to drop under 1.000. This sounds very good. I am very happy! )

What I did different? I don't know. What I did everytime. Maybe the fact that I was more careful to not heat the mash over 62.5 degrees celsius to not kill limit dextrinase. And maybe that I let the malt soaked in water more at the end of malting, thus releasing more free, active form of limit dextrinase. Or may be just the source of the grain as Twisted Brick remarked and the ratio of amylose/amylopectin, quality of wheat or both.

Anyway, I will repeat the same process with other grains to see if the result is the same.

[Twisted Brick]

Twisted brick, the grains used for malting are from a local market sold as food for birds. I usualy use wheat but I tried barley too and the result was the same. I tried different sources of grains for malting but the result was the same.

I start by puting the grains into a permeable bag and put the bag in a bucket. I wash the grains very well and let them soak for 24 hours. After that I let them breath by hanging the bag somewhere to drain the water. In the morning and evening I soak the grains a bit just for washing and keeping them moist. I stop the malting process when the acrospire is between half and full length of the grain, not anymore. I used it fresh or dried. Fresh, it can be turned into a paste by grinding with a meat grinder but have the drawback I have no time to wait, because the fresh malted, grinded malt spoils quickly.

Although your malting process can be improved somewhat, I do not think your low yield is a product of anything you are doing. I will dare say that you are looking to achieve results akin to commercial malt with grain that is not optimized for malting. That you realize the same disappointing results with barley is not surprising.

Regarding your malting process, I would change a few steps. I would follow a 12hr steep followed with an 8hr airing, done twice. I would also look to conduct these steps at a constant temperature, ideally 60F - 68F. I would also stop rinsing the grains during malting as this has proved detrimental to the chemical balance of the grain to complete malting. Many home-malters perform this step to overcome bacterial growth (and associated odors) when keeping the malting grain at the proper colder temperature achieves this.

The objective in the steep is to achieve 42% hydration of the grain. The airing portion is to allow needed oxygen for the process. I tested different time lengths of each, and although I don't have a centrifuge, measured 1lb batches of malting grain until I had achieved 42% (by weight) and have had very satisfactory results with the 12hr/8hr interval.

I know you are more concerned with starch yield in your malt, but know that proper drying/kilning has a direct effect on the quality of the enzymes produced.

Lastly, I would discontinue any souring or infecting of the malting grain. If you are looking for a beneficial lactobacillus infection this can be achieved later on following fermentation.

Here are several papers you might find helpful. The second one outlines optimization tests for wheat, but I have used the same controls for rye with success.

Barley β-Glucans and Their Degradation During Malting and Brewing

Effect of Malting Procedure on Alpha Amylase and Protease Activities

Brewing Beer the Hard Way


Achieving the numbers you just listed with corn is promising. If you can source food-grade grains your malting exploits should produce better results.

[Iulistoi]

I read your lectures, very informative! Sometimes I do a rest at 45 degrees for beta-glucanase, for that reason, to decrease apparent viscosity. On the other hand, an optimal moisture shoud be 42% and about temperatures I feel a bit unfamiliar because all my life I used Celsius scale as well as metric system of units. But I dont know how can I control the temperature within malting room. It is known that grains produce heat during germination. If you turn the wheat malt you can break the acrospire witch I think is bad. This is why I preffer to shortly soak the bag with grains in the bucket with water. When water drains, fresh air with oxigen is dragged and penetrates throgh the grains.

Another reason I dont like malting floors is that it requires lots of space. The bucket is more practical and convenient. The germination is always uniform.

I will try your recipe of malting with shorter steeping time (12 hours instead of 24) and no washing during airing. But I'm afraid it will spoil with many bacterias and molds.

I dont dry the malt. I grind it wet with meat grinder and let the rootlets there. It gives the final product a grassy / hay flavour but doesnt bother me, I even enjoy the taste.

[8Ball]

I dont dry the malt. I grind it wet with meat grinder and let the rootlets there. It gives the final product a grassy / hay flavour but doesnt bother me, I even enjoy the taste.

I noticed that “grassy taste” in my Irish style new make whisky from home malted & unmalted toasted barley and a little corn. Now, about a year later, that “grassy” (I call it green) taste has faded away, replaced by a dry biscuit like flavor. A good sipper stash for the price of a couple sacks of feed store grain.

[Iulistoi]

I have new news about my mash. It dropped the density to 0.999 and this is a good sign that things go well. I will repeat the same process with another batch.

But as you said, the source of the grains and malt are important and the mashing temperatures as well. I think we shoud focus on preserving the limit dextrinase enzyme as much as possible. Now I used bakers yeast, so nothing special about fermentability of the yeast.

Keep in mind that 62.5 degrees celsius is the upper limit over limit dextrinase enzyme denaturates. So I think that temperature shoud not be exceded. The pH of 5.1 to 5.5 is most favorable for limit dextrinase. The bound form of limit dextrinase is not active but it can become active during fermentation due to dropping in pH.

The taste of the mash is almost dry. Doesnt seems that have residual sugars. Comparing with sugar wash that ferments realy dry, the densimeter dips a little higher but is acceptable. Very low gravity could be reached with glucoamylase.

[Stibnut]

Yeast that can eat dextrins has been mentioned, there are several diastaticus strains available. But there are other yeast aspects to consider. A naturally mashed wash will be high in maltose and yeast strains vary in their ability to digest it. You have more options here than just the diastaticus strains, and you can go the way of some scotch distilleries and mix distillers strains for high fermentability and brewing strains for flavor. Yeast prep may matter too, yeast that has been cultured on simple sugars will not digest maltose well. A source of this problem I recently discovered is malt extract. Apparently a lot of malt extracts are prepared with exogenous enzymes resulting in low maltose content. As a result, yeast starters made with malt extract do not perform as well on naturally mashes. Using all grain wort for starters can make a difference

I'll chime in on diastaticus yeast with an experiment and a yeast recommendation.

I bought a few packets of a diastaticus strain, Belle Saison by Lallemand. To find out how good it is at fermenting dextrins, I made up a wash with straight maltodextrin, almost entirely unfermentable by those lazy yeast that don't bother to make their own amylase and expect to just be given all their food in chains of no more than three glucose units.

I brought the SG all the way up to 1.095 by dissolving 456 g maltodextrin in a little 1/2 gallon jug. It took forever to get all that maltodextrin into solution but I did finally pull it off with some heating and a buttload of stirring. I also added just over 2 g of Fermaid K and 30 mL of a nutrient solution I keep in the fridge. This solution contains ammonium, calcium, magnesium, and zinc chlorides along with a buffer made from citric acid and potassium citrate. The OG was measured after nutrient addition, and I took some readings at irregular intervals after that. Ultimately I let it sit for two months but almost all of the fermentation was done by day 21.

Here's how the SG changed over time:

Days SG
0 1.095
2 1.059
4 1.035
8 1.016
16 1.008
21 1.004
41 1.000
61 1.000

This strain really impressed me. If anything, I suspect the ABV may have caused issues before the lack of sugar did. I'd strongly recommend it to anyone who wants to try the diastaticus route.

[Iulistoi]

Yeast that can eat dextrins has been mentioned, there are several diastaticus strains available. But there are other yeast aspects to consider. A naturally mashed wash will be high in maltose and yeast strains vary in their ability to digest it. You have more options here than just the diastaticus strains, and you can go the way of some scotch distilleries and mix distillers strains for high fermentability and brewing strains for flavor. Yeast prep may matter too, yeast that has been cultured on simple sugars will not digest maltose well. A source of this problem I recently discovered is malt extract. Apparently a lot of malt extracts are prepared with exogenous enzymes resulting in low maltose content. As a result, yeast starters made with malt extract do not perform as well on naturally mashes. Using all grain wort for starters can make a difference

I'll chime in on diastaticus yeast with an experiment and a yeast recommendation.

I bought a few packets of a diastaticus strain, Belle Saison by Lallemand. To find out how good it is at fermenting dextrins, I made up a wash with straight maltodextrin, almost entirely unfermentable by those lazy yeast that don't bother to make their own amylase and expect to just be given all their food in chains of no more than three glucose units.

I brought the SG all the way up to 1.095 by dissolving 456 g maltodextrin in a little 1/2 gallon jug. It took forever to get all that maltodextrin into solution but I did finally pull it off with some heating and a buttload of stirring. I also added just over 2 g of Fermaid K and 30 mL of a nutrient solution I keep in the fridge. This solution contains ammonium, calcium, magnesium, and zinc chlorides along with a buffer made from citric acid and potassium citrate. The OG was measured after nutrient addition, and I took some readings at irregular intervals after that. Ultimately I let it sit for two months but almost all of the fermentation was done by day 21.

Here's how the SG changed over time:

Days SG
0 1.095
2 1.059
4 1.035
8 1.016
16 1.008
21 1.004
41 1.000
61 1.000

This strain really impressed me. If anything, I suspect the ABV may have caused issues before the lack of sugar did. I'd strongly recommend it to anyone who wants to try the diastaticus route.

Very good fermentability for maltodextrin but too many days for accomplishment. Anyways, I hope that only a few oligodextrins in grain mash will not take so much time to go below 1.000 SG.

[zapata]

Those results show a 60 point drop in 4 days. No normal wash has 60 points worth of dextrins.

[brewer24]

The point is, you have to get the final density below 1.000 to be satisfactorily and have good yield.

This seems to be a strangely absolute statement. If you get joy out of pursuing a max number, have at it I suppose, but it's not required at all to make a tasty drink.