BIAB/Full Volume Mash and wort fermentablity

[BroStefan]

I made the switch to BIAB from batch sparging about 10 batches ago and am very happy overall but I have observed something that I’m trying to figure out.

It seems that my beers are ending up with less body then before. These are established recipes that I know well. The only difference is that I have moved from a cooler batch sparge at 1.33 qt/lbs to a full volume BIAB. I mash at the same temp and have good control of mash temperature in both set-up, using the same RIMS controller on both. My total mash/sparge times are roughly equal to my BIAB mash times.

My hypothesis is that the thinner mash is resulting in a more fermentable wort..

I’m going to test this out on my next brew day. I’ll do my brown porter – near clone of Fuller’s Porter – but mash at 155 not the usual 152. But it will be a week or more until I can get the time, so I’d appreciate some wisdom from the forum. Does my analysis make sense to you all?

 

[TexasWine]

My hypothesis is that the thinner mash is resulting in a more fermentable wort..

Easy enough to check. What's your final gravity been with BIAB compared to previous batches?

If everything else is the same except mash thickness, then you might be on to something.

 

[McKnuckle]

I Googled this topic and came up with a few references, including this quote:

"A thin mash increases the proportion of maltose, which will lead to greater attenuation (and a thinner body)."

The author* implies that mash temperature alone is not the only factor influencing the relative proportions of maltose (fermentable) vs. dextrin (not fermentable) in the mash. As a mash gets thinner, the degree to which maltose is liberated increases - regardless of mash temp. Obviously there's a curve for this, and it's probably not linear or super predictable without tedious experimentation. But I find that the concept still makes sense and helps one understand what's going on.

*http://byo.com/hops/item/1135-maximizing-mouthfeel-tips-from-the-pros

 

[shaneshepherd]

Not 100% sure this is relevant to your scenario, but I have noticed that it seems like when I have a large grain bill and there isn't much room in my 10gal pot for space between my grain in the mash water, that my efficiency can drop significantly. I've wanted to test my theory out by using a larger pot for big grain bills...haven't made the financial leap to purchase the larger pot though.

 

[RM-MN]

Not 100% sure this is relevant to your scenario, but I have noticed that it seems like when I have a large grain bill and there isn't much room in my 10gal pot for space between my grain in the mash water, that my efficiency can drop significantly. I've wanted to test my theory out by using a larger pot for big grain bills...haven't made the financial leap to purchase the larger pot though.

Just make a smaller batch in the pot you have. There isn't any law that says that a batch of beer has to be 5 gallons or 10 gallons. Try 3 1/2 gallons sometime.

 

[1MadScientist]

I made the switch to BIAB from batch sparging about 10 batches ago and am very happy overall but I have observed something that I’m trying to figure out.

It seems that my beers are ending up with less body then before. These are established recipes that I know well. The only difference is that I have moved from a cooler batch sparge at 1.33 qt/lbs to a full volume BIAB. I mash at the same temp and have good control of mash temperature in both set-up, using the same RIMS controller on both. My total mash/sparge times are roughly equal to my BIAB mash times.

What is your full volume BIAB mash time? Doesn't your batch sparging grain spend any extra time during the sparge, start to finish?

MS

 

[madscientist451]

If you are happy with the flavor and your ABV/malt/roastiness combination of your porter, I think I'd try to add some unfermentables to your grain bill before I changed the mash temp. You can try a touch of unmalted barley or oatmeal for additional body. Some say to add dextrin malts, but for me that caused digestion problems and gas.
I'd only try changing one thing at a time so you can really focus on what you are trying to change/achiueve.

 

[Iseneye]

I have only ever done full volume BIAB so don't notice the difference but I recall reading the following thread:

https://www.homebrewtalk.com/f163/b...ofiles-cybi-other-thoughts-221817/index2.html

where AJF said that he mashed thick to retain good body. Other posters said that it wasn't true but maybe there is something to it.

One thing I have noticed with BIAB is that I need to add more acid than spargers to reach mash pH (measured). Perhaps the higher pH is making it taste thinner if you're not testing. Do you have an accurate pH meter and adjusting your mash if necessary?

 

[BroStefan]

Easy enough to check. What's your final gravity been with BIAB compared to previous batches?

If everything else is the same except mash thickness, then you might be on to something.

Duh... hadn't thought of that. they are consistently 2-3 grav pt lower.

 

[BroStefan]

Not 100% sure this is relevant to your scenario, but I have noticed that it seems like when I have a large grain bill and there isn't much room in my 10gal pot for space between my grain in the mash water, that my efficiency can drop significantly. I've wanted to test my theory out by using a larger pot for big grain bills...haven't made the financial leap to purchase the larger pot though.

It is not an efficiency issue, at least not mainly. My BIAB system consistently gets 80%-83% extract efficiency, very similar to my batch sparge system.

 

[BroStefan]

What is your full volume BIAB mash time? Doesn't your batch sparging grain spend any extra time during the sparge, start to finish?

MS

My BIAB mash time is typically 60 minutes, where as in the batch sparge i'd mash for ~50 min, drain, add sparge water and let it sit for ~ 10 minutes. I monitor the mash with a refractometer to dial in the time batch by batch. High gravity mashes take a little longer.

 

[helibrewer]

I made the switch to BIAB from batch sparging about 10 batches ago and am very happy overall but I have observed something that I’m trying to figure out.

It seems that my beers are ending up with less body then before. These are established recipes that I know well. The only difference is that I have moved from a cooler batch sparge at 1.33 qt/lbs to a full volume BIAB. I mash at the same temp and have good control of mash temperature in both set-up, using the same RIMS controller on both. My total mash/sparge times are roughly equal to my BIAB mash times.

My hypothesis is that the thinner mash is resulting in a more fermentable wort..

I’m going to test this out on my next brew day. I’ll do my brown porter – near clone of Fuller’s Porter – but mash at 155 not the usual 152. But it will be a week or more until I can get the time, so I’d appreciate some wisdom from the forum. Does my analysis make sense to you all?

Makes sense. I've heard it said that the exact same recipe will taste different on every system so the change in your process will probably require you to re-dial in your recipes.

 

[BroStefan]

If you are happy with the flavor and your ABV/malt/roastiness combination of your porter, I think I'd try to add some unfermentables to your grain bill before I changed the mash temp. You can try a touch of unmalted barley or oatmeal for additional body. Some say to add dextrin malts, but for me that caused digestion problems and gas.
I'd only try changing one thing at a time so you can really focus on what you are trying to change/achiueve.

The oatmeal might be a nice addition to the recipe in it's own right!

The flavor is about right, just too dry and much too easy to over carbonate.

 

[1MadScientist]

My BAIB mash time is typically 60 minutes, where as in the batch sparge i'd mash for ~50 min, drain, add sparge water and let it sit for ~ 10 minutes. I monitor the mash with a refractometer to dial in the time batch by batch. High gravity mashes take a little longer.

You could easily pick up those 3 points by mashing for 90 mins. and do a mash-out.

 

[BroStefan]

Thanks all for your thoughts.

I'll post the results of my trial at a higher mash temperature.

 

[TexasWine]

Thanks all for your thoughts.

I'll post the results of my trail at a higher mash temperature.

I'll be curious to see what you find. My FGs are usually lower than predicted as well, with attenuation being very high for any yeast I use. However, I've never noticed suboptimal flavor from finishing lower.

 

[RM-MN]

I have a guess at what is going on but it is only a guess, don't take this as proven.

When you mash in a conventional mash tun, you need the grains to be crushed, but not as fine as in BIAB. With this coarser crush it takes more time to get the grains wetted through and for conversion to happen. Since it takes more time, the grain particles spend more time in the heated water and this denatures some of the beta amylase before it can act on the starches.

With the fine milling in BIAB, the enzymes can work together at the same time on nearly all the starches so the beta amylase gets its part done quicker, before it has a chance to get denatured. That makes for a more fermentable wort.

Any thoughts on this guess?

 

[BroStefan]

I have a guess at what is going on but it is only a guess, don't take this as proven.

When you mash in a conventional mash tun, you need the grains to be crushed, but not as fine as in BIAB. With this coarser crush it takes more time to get the grains wetted through and for conversion to happen. Since it takes more time, the grain particles spend more time in the heated water and this denatures some of the beta amylase before it can act on the starches.

With the fine milling in BIAB, the enzymes can work together at the same time on nearly all the starches so the beta amylase gets its part done quicker, before it has a chance to get denatured. That makes for a more fermentable wort.

Any thoughts on this guess?

That does make sense.

There are so many interacting variables in brewing. I'll try the mash hotter plan first and see what happens. Next I'll watch the mash gravity and move to mash out as soon as I get the points I need.

Now I just need to find the time to brew!

 

[RM-MN]

That does make sense.

There are so many interacting variables in brewing. I'll try the mash hotter plan first and see what happens. Next I'll watch the mash gravity and move to mash out as soon as I get the points I need.

Now I just need to find the time to brew!

Today I intend to brew again and fit in a different variable. Two days ago I brewed a simple blonde ale with Briess Brewers malt, Gambrinus honey malt, and flaked rice which I mashed for 10 minutes. This new brew will follow the same recipe but the mash will only be for 5 minutes. It could turn out to be a dumper, but it's only 2 1/2 gallons so I'm willing to risk that. I'll try to hit the exact amount of water and the same mash temp, 154.

 

[1MadScientist]

There are so many interacting variables in brewing. I'll try the mash hotter plan first and see what happens. Next I'll watch the mash gravity and move to mash out as soon as I get the points I need.

Now I just need to find the time to brew!

Good for you Brother! With your refractometer, do both. A 90 mins. mash is recommended for BIAB on the BIABrewer.info website.

MS

 

[madscientist451]

I have a guess at what is going on but it is only a guess, don't take this as proven.

When you mash in a conventional mash tun, you need the grains to be crushed, but not as fine as in BIAB. With this coarser crush it takes more time to get the grains wetted through and for conversion to happen. Since it takes more time, the grain particles spend more time in the heated water and this denatures some of the beta amylase before it can act on the starches.

With the fine milling in BIAB, the enzymes can work together at the same time on nearly all the starches so the beta amylase gets its part done quicker, before it has a chance to get denatured. That makes for a more fermentable wort.

Any thoughts on this guess?

My understanding of the denaturing of alpha and beta amylase enzymes was that it was strictly temperature dependent. RM-MN's post is interesting because it brings in the time element (duh, why didn't I think of that before?)
and the variable of the grain crush.
However after googling around a bit on this, I'm still finding that below certain temperatures, denaturing of enzymes doesn't occur no matter how long the enzyme is exposed. The time element comes into play when denaturing temperatures are reached.
Its interesting that the more you look into certain things, you find that there's more to understand.
Here's a good explainer of enzymes and brewing:

https://jrhb.org/docs/Enzymes-2010-05.pdf

and two quotes from the article:

Beta Amylase works best at 140-149F and rapidly denatures at
temperatures 158F or above.

Alpha Amylase works best at temperatures between 161F-167F and denatures
rapidly at temperatures above 176F.

 

[RM-MN]

My understanding of the denaturing of alpha and beta amylase enzymes was that it was strictly temperature dependent. RM-MN's post is interesting because it brings in the time element (duh, why didn't I think of that before?)
and the variable of the grain crush.
However after googling around a bit on this, I'm still finding that below certain temperatures, denaturing of enzymes doesn't occur no matter how long the enzyme is exposed. The time element comes into play when denaturing temperatures are reached.
Its interesting that the more you look into certain things, you find that there's more to understand.
Here's a good explainer of enzymes and brewing:

https://jrhb.org/docs/Enzymes-2010-05.pdf

and two quotes from the article:

Beta Amylase works best at 140-149F and rapidly denatures at
temperatures 158F or above.

Alpha Amylase works best at temperatures between 161F-167F and denatures
rapidly at temperatures above 176F.

That's it in a nutshell, beta amylase rapidly denatures at temperatures at 158 or above. I'm sure that is true. However, it denatures at temperatures lower than 158 but at a slower rate. How rapidly it denatures hasn't been defined nor have I seen a graph of how long it takes to denature at lower temperatures. If the alpha amylase has broken down all the starches it can and the beta amylase survives long enough to break down all it can or at least a majority of what it can before it breaks down, we'll get a more fermentable wort. How can we design an experiment that shows how long beta amylase works at various temperatures or how can we change the mash time to limit it.

Good for you Brother! With your refractometer, do both. A 90 mins. mash is recommended for BIAB on the BIABrewer.info website.

I've seen this on that site. I'm getting the same amount of conversion in 20 minutes as I was at 60 minutes so why do they on the BIABrewer.info website recommend a 90 minute mash?

 

[BroStefan]

Today I intend to brew again and fit in a different variable. Two days ago I brewed a simple blonde ale with Briess Brewers malt, Gambrinus honey malt, and flaked rice which I mashed for 10 minutes. This new brew will follow the same recipe but the mash will only be for 5 minutes. It could turn out to be a dumper, but it's only 2 1/2 gallons so I'm willing to risk that. I'll try to hit the exact amount of water and the same mash temp, 154.

10 Minutes??? Really? I've been thinking of shortening my mash times, but that is extreme! What kind of mash extract efficiency to you get?

 

[RM-MN]

10 Minutes??? Really? I've been thinking of shortening my mash times, but that is extreme! What kind of mash extract efficiency to you get?

85%, same as when I was mashing for 60. It looks like my experiment with a 5 minute mash was less, perhaps all the way down to 84%.

 

[BroStefan]

85%, same as when I was mashing for 60. It looks like my experiment with a 5 minute mash was less, perhaps all the way down to 84%.

Cool!

I'm trying that!

 

[RM-MN]

Cool!

I'm trying that!

Try a 30 minute mash first and see how that comes out. I know that with my grain milling that a 20 minute mash works but I'm still in the testing phase for the shorter mashes and they may not turn out at all.

 

[HerkimerBrewer]

I had noticed the same thing on my last batch...seemed a bit thin, so on this batch, with the same receipe, I mashed higher. We shall taste the results in a couple weeks

 

[Magnus314]

My experience with BIAB is that my FG was much lower with a fine crush and the same 60 minute mash times that I used to use in my 3V system.

Many others and I have speculated that we get those results because BIAB allows a finer crush because there's no risk of a stuck sparge, and that finer crush wets through faster and releases it's starches - to be converted by the enzymes- faster as well.

Makes sense to me, and I've experimented with shorter mash times as the "solution" to high attenuation on beers I don't want dry.

I've done about a dozen batches with mash times from 20 - 30 minutes and I get the same efficiency I got from 60 minutes, but not over-attenuated FG's.

That makes me think the starches are being extracted more quickly, and the 60+ minutes is just letting the beta enzymes go to town too long.

I can't vouch for the science, I don't brew in a lab setting, but the theory seems to work, and the change fixed the problem, so I'll believe it

I haven't tested shorter times like 10 mins. because I just can't seem to get everything together that fast without rushing and screwing something up!

 

[lazarwolf]

Yes, your hypothesis seems correct
Any time something water soluble (hydroscopic) is coming into a water based solution, the lower the density of the solution, the "easier" it is for it to come into the water based solution.

 

[doug293cz]

The smaller particles also speed up the diffusion of water into the grain particles, and the soluble starches and sugars out of the grain particles. So, higher concentration gradients (due to lower sugar concentration in the wort) and shorter diffusion distances both speed up a rate limiting part of the mash process.

Brew on

 

[slcalex]

I just wanted to chime in as well. I've been doing BIAB partial mash usually with about 8lbs grain and 2lbs DME.

I get my grain double milled and mash 150-151 for 60 minutes. I've noticed consistent low FG, 1.008-1.007. I have yet to try higher mash temps.

I am not doing full volume BIAB, and usually sparge with 1.5 gallons. So maybe this lends to the theory of finer crush plus long mash equals greater fermentability??

Edit: Also I use US-05 exclusively and am consistently getting around 85% attenuation. No oxygenation other than a vigorous transfer from kettle to fermenter.

 

[BroStefan]

Just getting caught up reading posts after a few days. Thanks to all who have chimed in.

I hope to brew on Monday and will try the shorter mash time at my "standard" temp. that seems to be the consensus.

I'll keep you all posted.

 

[bobbrews]

The grist/water ratio factor influences the performance of the mash. A thinner mash of >2 quarts of water per pound of grain dilutes the relative concentration of the enzymes, slowing the conversion, but ultimately leads to a more fermentable mash because the enzymes are not inhibited by a high concentration of sugars. A stiff mash of <1.25 quarts of water per pound is better for protein breakdown, and results in a faster overall starch conversion, but the resultant sugars are less fermentable and will result in a sweeter, maltier beer.

As always, time changes everything; it is the final factor in the mash. Starch conversion may be complete in only 30 minutes, so that during the remainder of a 60 minute mash, the brewer is working the mash conditions to produce the desired profile of wort sugars. Depending on the mash pH, water ratio and temperature, the time required to complete the mash can vary from under 30 minutes to over 90. At a higher temperature, a stiffer mash and a higher pH, the alpha amylase is favored and starch conversion will be complete in 30 minutes or less. Longer times at these conditions will allow the beta amylase time to breakdown more of the longer sugars into shorter ones, resulting in a more fermentable wort, but these alpha-favoring conditions are deactivating the beta; such a mash is self-limiting.

A compromise of all factors yields the standard mash conditions for most homebrewers: a mash ratio of about 1.5 quarts of water per pound grain, pH of 5.3, temperature of 150-155 F and a time of about one hour. These conditions yield a wort with a nice maltiness and good fermentability


Tip: If brewing via Partial Mash, and making a dry style like an IPA, then it would be best to mash the grain you have in the mid to upper 140s. The low mash temp. gives you some control and will offset the standard 153-154 F temp. that the extract manufacturer probably mashed at.

 

[RM-MN]

The grist/water ratio factor influences the performance of the mash. A thinner mash of >2 quarts of water per pound of grain dilutes the relative concentration of the enzymes, slowing the conversion, but ultimately leads to a more fermentable mash because the enzymes are not inhibited by a high concentration of sugars. A stiff mash of <1.25 quarts of water per pound is better for protein breakdown, and results in a faster overall starch conversion, but the resultant sugars are less fermentable and will result in a sweeter, maltier beer.

As always, time changes everything; it is the final factor in the mash. Starch conversion may be complete in only 30 minutes, so that during the remainder of a 60 minute mash, the brewer is working the mash conditions to produce the desired profile of wort sugars. Depending on the mash pH, water ratio and temperature, the time required to complete the mash can vary from under 30 minutes to over 90. At a higher temperature, a stiffer mash and a higher pH, the alpha amylase is favored and starch conversion will be complete in 30 minutes or less. Longer times at these conditions will allow the beta amylase time to breakdown more of the longer sugars into shorter ones, resulting in a more fermentable wort, but these alpha-favoring conditions are deactivating the beta; such a mash is self-limiting.

A compromise of all factors yields the standard mash conditions for most homebrewers: a mash ratio of about 1.5 quarts of water per pound grain, pH of 5.3, temperature of 150-155 F and a time of about one hour. These conditions yield a wort with a nice maltiness and good fermentability


Tip: If brewing via Partial Mash, and making a dry style like an IPA, then it would be best to mash the grain you have in the mid to upper 140s. The low mash temp. gives you some control and will offset the standard 153-154 F temp. that the extract manufacturer probably mashed at.

I love the part about the thinner mash slowing the conversion. Using iodine as an indicator (I know, it's flawed) the change from starch to sugar in my fine milled grain and thin mash is complete in about 3 minutes. If the thin mash is slowing conversion, why shouldn't I be mashing thicker and shorter, like maybe 1 minute instead of 1 hour?

I just made a beer using the 1.5 qts/lb and mashed it for 30 minutes at 156F. That should make a very malty beer. Update in about 3 weeks.

 

[doug293cz]

I love the part about the thinner mash slowing the conversion. Using iodine as an indicator (I know, it's flawed) the change from starch to sugar in my fine milled grain and thin mash is complete in about 3 minutes. If the thin mash is slowing conversion, why shouldn't I be mashing thicker and shorter, like maybe 1 minute instead of 1 hour?

I just made a beer using the 1.5 qts/lb and mashed it for 30 minutes at 156F. That should make a very malty beer. Update in about 3 weeks.

Braukaiser has shown that the part about thinner mashes resulting in more fermentable wort is not necessarily true (http://braukaiser.com/wiki/index.ph...ncy_in_single_infusion_mashing#Mash_thickness.) The assertion about conversion being slower in thinner mashes is questionable as well. The author ignores all variables other than enzyme concentration in the analysis, with no consideration for things like increased molecular mobility in more dilute solutions, higher sugar concentration gradients at the particle surfaces (quicker diffusion of soluble species out of the grain), and who knows what else.

Brew on

 

[BroStefan]

I brewed my Brown Porter on Monday. I know this is not the best way but I decided to change two variables. I mashed at 154 (not at 152 as usual) and I closely monitored the SG of the mash and as soon as it hit my target (1.048) I fired it up to 168 F, held for 5 minutes and then pulled the grain. From dough in to grain out was 35 minutes.

FYI - I have a direct fired RIMS system so my temp control is tight.

Pitched WLP 013 London Ale from a 1.5L starter at 3 pm Monday. By 5 am Tuesday there was very active fermentation. By Thursday things had slowed down and I took a SG reading

Beersmith estimated a FG of 1.016. We are now at 1.018. It will loss a few more points I should think.

The mouth feel is just right there and the malt profile is good.

I think I've have it figured out. Shorter times and higher mash temp may have over corrected a little but I'm much closer to where I want this beer to be. I'll fine tone these variables from this point.

Thanks for the comments and insights.

 

[Psylocide]

I brewed my Brown Porter on Monday. I know this is not the best way but I decided to change two variables. I mashed at 154 (not at 152 as usual) and I closely monitored the SG of the mash and as soon as it hit my target (1.048) I fired it up to 168 F, held for 5 minutes and then pulled the grain. From dough in to grain out was 35 minutes.

FYI - I have a direct fired RIMS system so my temp control is tight.

Pitched WLP 013 London Ale from a 1.5L starter at 3 pm Monday. By 5 am Tuesday there was very active fermentation. By Thursday things had slowed down and I took a SG reading

Beersmith estimated a FG of 1.016. We are now at 1.018. It will loss a few more points I should think.

The mouth feel is just right there and the malt profile is good.

I think I've have it figured out. Shorter times and higher mash temp may have over corrected a little but I'm much closer to where I want this beer to be. I'll fine tone these variables from this point.

Thanks for the comments and insights.

Wanted to chime in on this quickly (though late), even mashing for 30 mins, I am getting over 80% attenuation with mash thickness of 1.33 and sparging to volume.

I think the fine crush has to be at least somewhat to "blame." I recently (Sunday) mashed at 3° higher than I thought was needed in my recipe purely to account for the higher attenuation rates I've been experiencing.

Very interested to see how it works out for me... if I can nail down this variable, I'll be well on my way to consistent brews.

 

[BroStefan]

Wanted to chime in on this quickly (though late), even mashing for 30 mins, I am getting over 80% attenuation with mash thickness of 1.33 and sparging to volume.

I think the fine crush has to be at least somewhat to "blame." I recently (Sunday) mashed at 3° higher than I thought was needed in my recipe purely to account for the higher attenuation rates I've been experiencing.

Very interested to see how it works out for me... if I can nail down this variable, I'll be well on my way to consistent brews.

Your results are consistent with mine. Since my last post the Brown Porter is on tap back to what it was when I made it on my 3V batch spurge system.

I also have done a Helles using the same method. I mashed 2 deg F higher and pulled the grain at 45 minutes - as soon as my (full volume) mash hit the target SG. It is fermenting now by the wort seemed to be what I wanted.

 

[JohnSand]

Thank you all for contributing to this thread. My BIAB also over attenuates. I didn't really think much about it, but recently I have had comments like "light" or even "thin". I'm probably brewing today, I will shorten the mash at a higher temp.

 

[Psylocide]

Thank you all for contributing to this thread. My BIAB also over attenuates. I didn't really think much about it, but recently I have had comments like "light" or even "thin". I'm probably brewing today, I will shorten the mash at a higher temp.

Do shorten your mash length if you want to, but I don't think it has much (if anything) to do with this.

I'm pretty comfortable attributing this to the grain crush unless someone can prove me wrong. I'd be interested to learn what someone doing BIAB with a "traditional" crush has to say on the issue.

I would say, mash for however long you want (as long as you get conversion), but mash at a higher temp.

What does your crush look like?