Big differences in grain absorption. Need help troubleshooting a bad brewday

[Dregsy]

I'm still pretty new to BIAB and have about 4 batches under my belt. I thought I was getting my procedure pretty dialed in and was hitting very consistent numbers with water levels and efficiency. However, I just brewed this recipe 1-Gallon Blonde Ale Recipe - BeerCraftr (scaled up to 3 gallons). My grain bill was:
6 lbs Abbey Malt, Weyermann
0.75 lbs Carabelge Malt, Weyermann

Mashed it at 148 f for 90 minutes, removed and gave the bag a good squeeze and was shocked to see the grain absorption at over twice what I had seen in previous brews, reducing my water levels by about a gallon. Additionally, after taking a gravity reading I was also down at about 1.035 instead of being at my predicted 1.045.

Any insight into what may have happened here? Was my mash too low temp for the grains I was using? Is grain absorption that different depending on the grains? I know it sounds like I just didn't get enough out of the grains after the mash but I squeezed the hell out of it same as my previous brews.

Any help is greatly appreciated.

 

[doug293cz]

Was the grain milled in the same mill and at the same gap setting as your previous batches?

The low SG reading indicates that the conversion process was probably incomplete. The first step in the conversion process is gelatinization of the starch. Gelatinization swells up the starch and surrounds the starch chains with water. Once the starch chains are surrounded by water, the amylase enzymes can get at the inter glucose bonds in the chain and break them. This puts the smaller starch molecules, and the sugar molecules into solution.

If a lot the starch is not completely solubilized, then the gelled starch can hold on to a lot of water (think cooked rice.) This could cause your grain absorption rate to be higher than normal.

In a 148°F mash, gelatinization and hydrolysis (the bond breaking) will be much slower than in higher temperature mashes, so more time will be needed to get (close to) full conversion of starch to sugar. 90 minutes may not have been enough with your particular malts and crush.

Brew on

 

[Dregsy]

Was the grain milled in the same mill and at the same gap setting as your previous batches?

The low SG reading indicates that the conversion process was probably incomplete. The first step in the conversion process is gelatinization of the starch. Gelatinization swells up the starch and surrounds the starch chains with water. Once the starch chains are surrounded by water, the amylase enzymes can get at the inter glucose bonds in the chain and break them. This puts the smaller starch molecules, and the sugar molecules into solution.

If a lot the starch is not completely solubilized, then the gelled starch can hold on to a lot of water (think cooked rice.) This could cause your grain absorption rate to be higher than normal.

In a 148°F mash, gelatinization and hydrolysis (the bond breaking) will be much slower than in higher temperature mashes, so more time will be needed to get (close to) full conversion of starch to sugar. 90 minutes may not have been enough with your particular malts and crush.

Brew on

The crush should have been consistent with all my other brews as I just get it done by my LHBS. I definitely think what your describing is what happened, the mash definitely looked different then normal after the 90 minutes. Additionally, I don't have the most confidence in my cheapy digital thermometer so it very well could've been even less than 148f. I'll have to look into ways to ensure the starches are converted for future brews.

Thanks for the in depth response, I really appreciate it.

 

[RM-MN]

The crush should have been consistent with all my other brews as I just get it done by my LHBS.

Never trust someone else to mill with consistency. If you want the grains milled the same, you need your own mill. An employee or even a customer may have changed the mill setting.

Additionally, I don't have the most confidence in my cheapy digital thermometer so it very well could've been even less than 148f.

Most cheap digital thermometers are pretty accurate but not all. They are pretty cheap so get a couple more to measure with. While it doesn't guarantee that the mash temp will be accurate, a temp reading in ice water and another at the boil temp will give you some level of confidence.

 

[madscientist451]

I have my own mill and run everything though twice to get a consistent fine crush for BIAB brews. Ask your LHBS to run your order through the mill twice, you should notice a difference.
My experience had been that dunk sparging also helps with BIAB efficiency and provides a predictable result. Others prefer to do a full volume BIAB mash, and doing a dunk sparge with a large amount of grain is kind of a hassle, so you'll have to see what works for you.
Checking your gravity before/after boiling is a good practice when you are trying to dial in your process.
So when you discovered you missed your numbers, what did you do?

 

[BrewnWKopperKat]

Original grain bill

• 2 lbs Belgian Pale 2-row Malt
• 4 oz Caramel/Crystal Malt

Actual grain bill

• 6 lbs Abbey Malt, Weyermann
• 0.75 lbs Carabelge Malt, Weyermann

Weyermann product information has a suggested usage amount (link, pdf).

Were you able to find a diastatic power value for Abbey Malt?

 

[Dregsy]

I have my own mill and run everything though twice to get a consistent fine crush for BIAB brews. Ask your LHBS to run your order through the mill twice, you should notice a difference.
My experience had been that dunk sparging also helps with BIAB efficiency and provides a predictable result. Others prefer to do a full volume BIAB mash, and doing a dunk sparge with a large amount of grain is kind of a hassle, so you'll have to see what works for you.
Checking your gravity before/after boiling is a good practice when you are trying to dial in your process.
So when you discovered you missed your numbers, what did you do?

I'm really not to concerned about the consistency of the milled grains from my LHBS. They make sure to ask if your doing BIAB and have specific settings for it and run it twice through the mill. Additionally, I order multiple recipes at once so the mill settings should be consistent at least between those batches and I've had good results with the other recipes ordered at the same time.
I've been doing the full volume BIAB mash and have avoided doing a sparge but it's something I might think about doing, although before this one my last two brews have been 79% efficiency on the nose which I'm pretty happy with.
I checked the gravity after the mash but all I have is a hydrometer and I always get frustrated with the amount of time I have to wait for it to cool down to get a more accurate reading. Is this unnecessary or is it fine to just measure the hot wort? by the time I saw it was quite low I was already near the boil, if I knew faster I probably would've let it continue mashing.
I need to get some DME on hand, I tried to just add some Belgian candi sugar I had laying around but ultimately didn't have enough and just accepted my low OG (1.042) in defeat.

 

[Dregsy]

Original grain bill

Actual grain bill


Weyermann product information has a suggested usage amount (link, pdf).

Were you able to find a diastatic power value for Abbey Malt?

Uhhhh no, don't know what that is haha. I'm a bit of a layman when it comes to that sort of stuff...

 

[BrewnWKopperKat]

I'm a bit of a layman when it comes to that sort of stuff...

This should get you started: Diastatic Power and Mashing your Beer

 

[doug293cz]

Original grain bill

Actual grain bill


Weyermann product information has a suggested usage amount (link, pdf).

Were you able to find a diastatic power value for Abbey Malt?

The Abbey malt looks to be a poor substitute for pale malt. The linked product information says it should only be used up to 50% of a grain bill, which hints that it may have low diastatic power (low amylase enzyme content.) So, your gain bill might not have had enough enzymes to convert all of the starch to sugar. The Abbey malt is also much darker than a pale malt, so using it instead of a pale malt will make a very different beer.

Brew on

 

[Dregsy]

The Abbey malt looks to be a poor substitute for pale malt. The linked product information says it should only be used up to 50% of a grain bill, which hints that it may have low diastatic power (low amylase enzyme content.) So, your gain bill might not have had enough enzymes to convert all of the starch to sugar. The Abbey malt is also much darker than a pale malt, so using it instead of a pale malt will make a very different beer.

Brew on

That is goood to know. I'll certainly be more careful with my grain bills going forward

 

[wilserbrewer]

Nice sleuthing Columbo Doug LOL.

OP should mention this to their LHBS so the don’t stack someone else’s grain bill w/ low enzyme malt.

 

[Birrofilo]

I need to get some DME on hand, I tried to just add some Belgian candi sugar I had laying around but ultimately didn't have enough and just accepted my low OG (1.042) in defeat.

You can add DME or candi sugar syrup during fermentation as well, there is no strict need to add it in the kettle, yeast will like it. You can add it also now. Just calculate how many points of density you are inserting so that you can evaluate better the revised original gravity.

I also suggest the good old iodine test would have helped seeing the problem, and maybe solving it by an extension of the mashing time.

 

[BrewnWKopperKat]

I also suggest the good old iodine test would have helped seeing the problem, and maybe solving it by an extension of the mashing time.

From what I read (see #6) at Weyermann's site, there's not enough diastatic power in their Abbey Malt to be "self-converting". I also saw recommendations for a maximum of 30% (Weyermann's site) or 50% (MoreBeer) for this malt in the grain bill.

 

[Birrofilo]

From what I read (see #6) at Weyermann's site, there's not enough diastatic power in their Abbey Malt to be "self-converting". I also saw recommendations for a maximum of 30% (Weyermann's site) or 50% (MoreBeer) for this malt in the grain bill.

You say this I presume because the maximum declared percentage in the grist is 50. But we don't know the diastatic power. The maximum suggested percentage is "style-dependent" along the leaflet (for certain grains there are two different suggested percentages depending on the style), so, who knows, maybe they suggest no more than 50% for those Belgian styles because more than that would be not suitable for the listed styles?

"Abbey malt" is a Weyermann trademark and I don't know how to relate it to a more common grain. Malt producers could be more transparent with the characteristics of their products.

It is entirely possible that the diastatic power is insufficient for self-conversion, sure! In any case with an adverse iodine test I would have made an attempt to extend the mash because diastatic power is not set in stone: for what I understand, enzymes do not get "consumed" in the process and, if they are kept well below the denaturation temperature, they go on and on and on, and if one extends the mash one might get better results and even arrive at full conversion. Or have a try at that.

 

[BrewnWKopperKat]

adverse iodine test

Do you have a link to instructions for an iodine test?

 

[Birrofilo]

Do you have a link to instructions for an iodine test?

You can search YouTube and you will find different "visual" clues. Barley and Hops certainly has a video or two.

I do this very simple procedure.

Get a white ceramic plate, small diameter like 10cm is OK, or larger.
Put a thin layer of wort into the plate, keeping it slightly inclined on one side. You will have a small "pond" of wort which is deep a few millimiters.
Put 1 or 2 drops of iodine tincture on the wort, and agitate the plate so that the iodine mixes with the wort.

Initially the iodine tincture will paint dark the spot where it fell and its immediate surroundings, but in a few seconds, IF there is no starch present, the iodine tincture will mix into the wort and will seem to disappear, the wort will regain its original colour because 1 or 2 drops of iodine tincture don't change its appearance.
If there is starch, the wort will remain tinted dark (blackish-purplish).

I have also seen a test with a test tube, you put some wort on it and then many drops of iodine tincture. If there is no starch the wort will become darker and if there is will get a purplish colour. I find this less practical.

You can also use a spoon full of wort and put one-two drops of iodine tinctures in it. Just put one or two drops, and not more, because otherwise you will have to evaluate what "kind of dark" that is.