Controlling Attenuation Through Mash Times

Learning new things everyday and I'm glad I found this thread. Just wanted to clarify a few things for my understanding...

I've only recently started AG brewing with 4-5 under my belt but I've not been extremely happy with the results. I have some kinks to work out in my mashing process, specifically related to controlling temps.

A friend of mine just recently introduced me to the concept of drier/sweeter brews based on target mashing temps, but based on what I'm reading here mash times also play into this as well. So if I understand it correctly higher temps and shorter mash times equate to more un-fermentable sugars and therefore a sweeter tasting beer (less attenuation if I'm using the lingo correctly), where lower temperatures and longer mash times equate to more fermentable sugars and therefore a drier tasting beer (more attenuation?).

Is this just an advanced technique? I assume someone like myself should focus on hitting the proper temps before worrying about extending/decreasing mash time.

Lower attenuation also sounds like a potentially bad thing if you're not careful. Couldn't you end up with a bad batch that fails to ferment at all?

I'm curious how this plays into recipes and processes for brewing stronger IPAs. As I understand it stronger hop bills require higher grain bills to balance bitter flavors with maltier ones. Should these beers be brewed at shorter length and higher temps as well?

Jablestein said:

........... So if I understand it correctly higher temps and shorter mash times equate to more un-fermentable sugars and therefore a sweeter tasting beer (less attenuation if I'm using the lingo correctly), where lower temperatures and longer mash times equate to more fermentable sugars and therefore a drier tasting beer (more attenuation?).

Is this just an advanced technique? I assume someone like myself should focus on hitting the proper temps before worrying about extending/decreasing mash time.
................

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Sweetness is mostly dependent on the grain bill, not the mashing regime. The mashing regime affects the body. A hotter, short mash will result in a beer with more BODY. Sweetness in a beer is largely from the grains themselves. During the kilning process the maillard reaction is occurring. This results in a darkening of the malt and also produces unfermentable compounds that taste sweet. Generally the darker the malt the more sweetness it provides - roasting is something else altogether. Body and sweetness often do go hand in hand (and body contributes to perceived sweetness), but it is possible to brew a rich, full bodied, high FG beer, that is not sweet at all.

Balance is complicated. There is the BU:GU guidelines for beer styles (bittering unit/gravity unit ratio). This is very simplified though but is still a good starting off point. It gets more complicated.

Bitter and sweet need to be balanced - these are perceived on your tongue by the taste buds. Body perception is much more complex, and also helps to offset bitterness (but not like sweet does). The higher the FG, the better it will offset the bitterness, but you can achieve a similar bitterness offset in a beer with a lower FG by including some ingredients that provide sweetness.

And then there are some funky Belgian yeasts out there that I would swear make some kind of compound that tastes sweet. I know there are certain proteins that taste sweet, and of course more simpler natural products like stevia. I like the White labs Saison II yeast. It is a monster and will chew through anything. I routinely have beers around a FG of 1.005 with this yeast, yet they taste quite sweet - even in a grain bill that is almost all pils malt with just a little wheat added to it. There is some byproduct of fermentation that is responsible for this. I use a similar grain bill for my Kolsch, which tastes and feels nothing like my saison

After reading this whole thread I noticed one factor that's missing and that's how well your malt is milled. If you mill the malt to where the endosperm is in 4 pieces and the hulls are left whole you will likely not stick your mash and is good for home brewing. HOWEVER, you will need longer mash times to convert these large pieces of starch to sugars. Since Budweiser was mentioned, they use a three roller system and the endosperm is like talcum powder. They also must use rakes in the lautertuns to keep the "vorlauf", or recirculation, going. This allows shorter mash times which helps save money since you can do more brews per day. So basically, the finer the mill the quicker the mash but for a homebrewer it's much safer to be a bit coarse and just use longer mash times.

Now as far as Budweiser forcing sterile air through the hot wort after the boil causing oxidation well that's not exactly what happens. What they do is they have a tank that's full of tubes. The wort raises up to the height of the tubes and starts running down the sides of the tubes. This unit is called the stripper. The hot air blowing up the tubes "strips" out the DMS etc. It does not however, oxidate the wort. You would think it would but since it's sliding down the sides of the tube it doesn't pick up oxygen but only gives up the volatils.

tootal said:

So basically, the finer the mill the quicker the mash but for a homebrewer it's much safer to be a bit coarse and just use longer mash times.

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Is this statement about efficiency or about attenuation?

tootal said:

Now as far as Budweiser forcing sterile air through the hot wort after the boil causing oxidation well that's not exactly what happens. What they do is they have a tank that's full of tubes. The wort raises up to the height of the tubes and starts running down the sides of the tubes. This unit is called the stripper. The hot air blowing up the tubes "strips" out the DMS etc. It does not however, oxidate the wort. You would think it would but since it's sliding down the sides of the tube it doesn't pick up oxygen but only gives up the volatils.

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The brewing nerd in me wants to know a lot more about this process.

I googled for "budweiser stripper" but couldn't quite find what I was looking for.

Efficiency.

As far as the "stripper", only Anheuser Busch and Kirin uses it. When AB started making Kirin beer in LA the Japanese came over to taste it and see the process. They liked it better than theirs. During the process they saw the stripper so AB had one made for them so Kirin uses it in Japan now too.
We use to use a Drop Receiver too. It splashed the wort in a large tank that drained quickly and had sterile CO2 flowing through it to get even more of the volatiles out but the cost and loss of CO2 made it too expensive for Inbev to continue to use.

TheZymurgist said:

Many people do see an increase in efficiency (sugar extraction) with higher sparge volumes, so this would cause an increase in your OG, but not because of the boil volumes.

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I know this is an old post, but this is what I immediately noticed during my last brew. I did a pretty thick mash (about 1 qt/lb) but sparged with enough to get 7 gallons for a 90 minute boil. My OG ended up being 1.060 when I was targeting 1.053. Hopefully the 150*F 60 minute mash means it will dry out a bit more.

Sorry to bring this thread back to life, but I figured it would be better to post here than to start a new thread.

I am wondering just how low of a FG you can get by mashing low and long. So for instance a 2 hour mash at 145*F for an imperial IPA or something like that. Could you get a beer with an OG of 1.080 down to 1.010 without using sugar and only using "normal" yeasts?

Another idea I had was to actually start off mashing higher and then drop the temperature. This comes from the fact that the alpha amylase will digest the bigger proteins into sugar which the beta amylase will then convert to fermentable sugars. So my idea would be to do a 30-60 minute rest at 156*F, then drop the temperature down to 145*F for 1-2 hours. If the enzymes cannot survive the higher temperature, could you just add some 6-row since it is rich in enzymes to kick start the beta conversion again?

I am only on my 7th all-grain, but there is so much interesting information and so many tactics that I doubt I will ever learn it all.

Good questions. I unfortunately don't have answers because I also wonder the same things. I think picking a particular yeast strain would make the conversation more useful as there are some yeast strains that will take 1.080 down to 1.010 and some that will not.

I like you idea about dropping the temperature. It doesn't get discussed much. I even asked about a few posts earlier in this thread and got no reply. I like the 6-row idea. ALso perhaps splitting the mash into 2 smaller mashes and then combining to let the beta finish off.

Some thoughts on wort fermentability:
You need an accurate thermometer and accurate ph meter.
Thin mash for fermentability. What can your system handle?
Mash ph that favors beta
malster information. You probably don't get a copy of the malsters grain data when you buy grain at lhbs. All grain is different.
yeast nutrients and aeration technique. general yeast health when added to the wort. Amount of yeast pitched.
accurate fermentation temperature controls. Using techniques like rising temperature and ferementing at higher temps.

There was a podcast or something by Mitch Steele? some guy that worked at Budweiser and Sierra Nevada. He talks about getting IPAs fermented down low.


You also need to understand Why you want to get that low. And also how it effects things like mouthfeel and flavor and possibly exposing flaws in your beer as well.

grathan said:

Good questions. I unfortunately don't have answers because I also wonder the same things. I think picking a particular yeast strain would make the conversation more useful as there are some yeast strains that will take 1.080 down to 1.010 and some that will not.

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I was thinking WLP007 or WLP090 might do the trick, but mashing would be important to get the correct amount of fermentables into the wort.

This is something I am thinking about while I wait for my fermenters to open up again (4 more weeks! not sure how I am going to make it!). I have some "fresh"* hops that I want to use to finish an imperial IPA.

*vacuum sealed and frozen 1 day after harvest. 6 oz of Mosaic and Cascade

gometz said:

..........
Another idea I had was to actually start off mashing higher and then drop the temperature. This comes from the fact that the alpha amylase will digest the bigger proteins into sugar which the beta amylase will then convert to fermentable sugars. So my idea would be to do a 30-60 minute rest at 156*F, then drop the temperature down to 145*F for 1-2 hours. If the enzymes cannot survive the higher temperature, could you just add some 6-row since it is rich in enzymes to kick start the beta conversion again?

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The temperature drop doesn't work. Once you heat up above where beta-amylase is happy it denatures. For most proteins, this is the end of the road and cooling back down does not restore activity, that would be like making a hard boiled egg back into an un-boiled egg.

If you want a low FG, then mashing cooler and longer will do that. If you want a low FG, but don't want it too thin tasting there are a couple of things you can do. Split the mash and mash most of it at 145-147, and have another small portion that you mash high. Combine the two at the boil stage. You also could just hold back some of the malt and add it toward the end of the mash - this is tricky as it could result in starch haze. If you don't care about that, then it is a good technique to use. If you want it thin, then you can add some crushed up beano, typically to cooled wort. The enzymes in beano will break down the last of the dextrins that the amylases cannot attack.

I wonder if starting at 152* instead of 156* would allow much more of the beta to survive? Any information on denaturing amounts at specific temperatures?

I got a pump for my system and now have a direct fire RIMS setup. I did a step mash with a 30 minute rest at 133. It took 15 minutes to step up to 151 which is when I then started the clock for a 60 minute sach rest. Total mash time was 105 minutes.

My efficiency was through the roof at 93%! My mash efficiency is typically VERY consistent at about 80% prior to the new RIMS process. Grain bill was about 94% 2-row, 5% honey malt, and 1% flaked barley.

This beer was supposed to be a Blonde ale but I overshot my OG beyond what I was anticipating. OG was 1.057 after a 60 minute boil. Pitched an estimated 250B cells of WLP090 via multi-step starter. Gravity was 1.020 after 2 days, 1.010 after 5 days, and 1.008 after 8 days. The crazy thing is that it's still going! It's slowed down noticeably but it's still emitting CO2 and doing the yeast blob rise thing.

I ferment in a temperature controlled chamber. First two days were at 65-66F. Then let free rise to 68F. After I took the reading at 1.010, I let free rise to 69-70F. Temp has dropped to about 68F as active fermentation is for the most part done.

So far, it's attenuated 86%. I usually get about 80% attenuation with my process for this style. I was initially planning on cold crashing by now but I'm letting this thing ride as I want a drier beer. The sample I took tonight still had a noticeable sweet malt flavor which surprised me. It may be the honey malt. I think that it will drop another point or two over the next few days.

Any update on this, d_striker?

brewmcq said:

Any update on this, d_striker?

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I finally pulled the plug on fermentation after gravity hit 1.007. Beer tastes dry up front with a slight malt finish.

I just want to say thanks for this thread. This has really shed a lot of light on an area where my brewing knowledge was pretty scant.

Thanks to BierMuncher and all other contributors. Even those asking questions have helped a lot because it brings forth the wisdom being shared here. nestar:nestar:nestar:

d_striker said:

I got a pump for my system and now have a direct fire RIMS setup. I did a step mash with a 30 minute rest at 133. It took 15 minutes to step up to 151 which is when I then started the clock for a 60 minute sach rest. Total mash time was 105 minutes.

My efficiency was through the roof at 93%! My mash efficiency is typically VERY consistent at about 80% prior to the new RIMS process.

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I was getting very high efficiencies on my new RIMS at first as well but I had bad issues with tannin extraction. I made a number of changes, each one improved the beers and eventually eliminated the tannin off-flavor.

1.) Reduced volume of sparge water (with smaller beers I add fresh water to the boil to hit my volumes now) and monitor runoff every minute with a refractometer
2.) Slowed down the speed of the recirculation. You will find this makes controlling the temp more difficult but I believe it was one of my biggest contributors to tannins.
3.) Use RO water from local grocer. I have three 7 gallon water containers I will up for about 30 cents/gallon.

My efficiency is no longer ~ 90%, it has dropped to about 80 to 85, but the beer tastes so much better. I am sure I could still tweak it to get higher efficiencies without tannins, but grain is cheap and my time isn't.

Did you mess with sparge ph at all?

grathan said:

Did you mess with sparge ph at all?

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I personally acidify my sparge water with lactic acid. I do not have any problems with tannin extraction whatsoever.

joety said:

I was getting very high efficiencies on my new RIMS at first as well but I had bad issues with tannin extraction. I made a number of changes, each one improved the beers and eventually eliminated the tannin off-flavor.

1.) Reduced volume of sparge water (with smaller beers I add fresh water to the boil to hit my volumes now) and monitor runoff every minute with a refractometer
2.) Slowed down the speed of the recirculation. You will find this makes controlling the temp more difficult but I believe it was one of my biggest contributors to tannins.
3.) Use RO water from local grocer. I have three 7 gallon water containers I will up for about 30 cents/gallon.

My efficiency is no longer ~ 90%, it has dropped to about 80 to 85, but the beer tastes so much better. I am sure I could still tweak it to get higher efficiencies without tannins, but grain is cheap and my time isn't.

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My sparge process is still the same as it has been for years. Nothing has changed in that regard.

d_striker said:

My sparge process is still the same as it has been for years. Nothing has changed in that regard.

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Understood, I was just inquiring as the RIMS process is so efficient in extracting sugars that is it much easier to oversparge creating ph issue and tannin extraction.

d_striker said:

I personally acidify my sparge water with lactic acid. I do not have any problems with tannin extraction whatsoever.

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That is an interesting concept. I might have to give that a whirl. I hate to cutoff my sparge early and miss my gravities.

pjj2ba said:

The mashing regime affects the body. A hotter, short mash will result in a beer with more BODY.

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Appreciate this thread greatly and looking for some clarification. We have been fighting pretty much just the opposite problem for a few of our beers and wind up over attenuating beers we want to retain body. We recirc with a RIMS for good temp control and keep bumping up the temp trying to correct the outcome. Last batch was an hour mash at 155 and still finished 6-7 points low and thin. I now believe it is a function of our process. After the one hour mash we are typically draining over an hour for first runnings and then doing a batch sparge for 20 minutes with another hour drain for the second. This long time sitting at cooler temps must be breaking down the non-fermentables.

If we raise the primary mash temp to 170 prior to vorlauf will that "lock in" the ratio of fermentables/nonfermentables? Thanks

markklug said:

Appreciate this thread greatly and looking for some clarification. We have been fighting pretty much just the opposite problem for a few of our beers and wind up over attenuating beers we want to retain body. We recirc with a RIMS for good temp control and keep bumping up the temp trying to correct the outcome. Last batch was an hour mash at 155 and still finished 6-7 points low and thin. I now believe it is a function of our process. After the one hour mash we are typically draining over an hour for first runnings and then doing a batch sparge for 20 minutes with another hour drain for the second. This long time sitting at cooler temps must be breaking down the non-fermentables.

If we raise the primary mash temp to 170 prior to vorlauf will that "lock in" the ratio of fermentables/nonfermentables? Thanks

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If you like everything else in your process, then I'd do a mash out. My batch sparging takes about 30 min total (drain, sparge, sparge - pump assisted). Yours seems quite long. Typically favoring alpha amylase results in more dextrins (and a higher FG) as it's attack on starch is more random producing a range of sizes of dextrins. It will though attack the ends of chains like beta-amylase does and can produce glucose, maltose and maltotriose (as opposed to only maltose for beta-amylase). So given enough time it will keep working on the dextrins making them smaller and smaller until there is nothing left to act on but limit dextrins (short chains with branches that the amylases cannot cut). I like to remind people that just because one might get a negative iodine starch test, that does not mean that enyzme activity has stopped.

I have a pretty good setup for infusion mashing (not a RIMS or HERMS system by any stretch), and two batches ago, I made an Ordinary Bitter. Even though I used a thermowell (might be the problem), my temps read extremely high on the HLT (going to get a heat shield now) and our mash hit 106. I couldn't figure out what was wrong, but then felt the thermowell...HOT. So, I heated up and added more water, but it wouldn't raise the temp that much. Finally, I pulled some of the wort off, heated it up to mash temp and dumped it back in.

Finally, we got the mash to 154 and I let it sit for 60 minutes and then fly sparged with water at 180 (to bring mash to 170).

Prior to brewing I made a starter with 1318 yeast that I had yeast banked with the frozen yeast bank method in an article on HBT. This was first time, and it took about two days to get to high krausen...way longer than a smack pack and starter.

With all the mashing issues I had, I figured I'd have very little if any fermentables. I was pretty pissed actually...the brew day (for many reasons) was quite the disaster. However, the yeast took off like a rocket and I finished (after week and a few days in primary) at 1.009. BeerSmith suggested 1.008 for that style, so I almost crapped my pants. Hahaha.

The last beer I made (Friday) was a Pumpkin Brown Ale. Mashed at perfect temps...used a secondary digital thermometer. However, I used BeerSmith and mashed out with the right amount of water at appropriate temp, but my mash raised to 180. Not sure what happened there, but I only let it sit a few minutes, vorlaufed almost immediately and sparged quickly. Hit my target, pre-boil volume perfectly.

It, again, is fermenting like mad. The gurgling has been non-stop since yesterday afternoon...before that, it was about every 15 seconds, and then BOOM....jumped quickly and hasn't stopped.

grathan said:

Good questions. I unfortunately don't have answers because I also wonder the same things. I think picking a particular yeast strain would make the conversation more useful as there are some yeast strains that will take 1.080 down to 1.010 and some that will not.

I like you idea about dropping the temperature. It doesn't get discussed much. I even asked about a few posts earlier in this thread and got no reply. I like the 6-row idea. ALso perhaps splitting the mash into 2 smaller mashes and then combining to let the beta finish off.

Some thoughts on wort fermentability:
You need an accurate thermometer and accurate ph meter.
Thin mash for fermentability. What can your system handle?
Mash ph that favors beta
malster information. You probably don't get a copy of the malsters grain data when you buy grain at lhbs. All grain is different.
yeast nutrients and aeration technique. general yeast health when added to the wort. Amount of yeast pitched.
accurate fermentation temperature controls. Using techniques like rising temperature and ferementing at higher temps.

There was a podcast or something by Mitch Steele? some guy that worked at Budweiser and Sierra Nevada. He talks about getting IPAs fermented down low.


You also need to understand Why you want to get that low. And also how it effects things like mouthfeel and flavor and possibly exposing flaws in your beer as well.

Click to expand...

How much does the maltster and the grain affect the attenuation and does that affect how the grain responds to the mash temp? I had been hitting my OG or slightly overshooting it and coming out just slightly under the projected FG for a couple years, mashing at 152 to 154 BIAB but the brewers malt I got was from Briess. The latest is pale malt from Rahr and mash temp doesn't seem to make much difference but I'm always overattenuating. For example, a pale ale with an OG of 1.056, mashed at 152 was predicted to end at 1.011 but finally quit at 1.004, quite a bit drier than I was wishing for. Raising the mash temp hasn't seemed to help either.

RM-MN said:

How much does the maltster and the grain affect the attenuation and does that affect how the grain responds to the mash temp? I had been hitting my OG or slightly overshooting it and coming out just slightly under the projected FG for a couple years, mashing at 152 to 154 BIAB but the brewers malt I got was from Briess. The latest is pale malt from Rahr and mash temp doesn't seem to make much difference but I'm always overattenuating. For example, a pale ale with an OG of 1.056, mashed at 152 was predicted to end at 1.011 but finally quit at 1.004, quite a bit drier than I was wishing for. Raising the mash temp hasn't seemed to help either.

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In my experience, the mash times have even more impact on the attenuation levels. If I want to finish a mid 50's beer above 1.010, I need to begin sparging at around the 45 minute mark. This is a mash that would have rested at 154-156. For a rich ESB I've gone as high as 160.

BierMuncher said:

In my experience, the mash times have even more impact on the attenuation levels. If I want to finish a mid 50's beer above 1.010, I need to begin sparging at around the 45 minute mark. This is a mash that would have rested at 154-156. For a rich ESB I've gone as high as 160.

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I've been mashing for only 30 minutes and am getting that attenuation using Rahr malt whereas before I was doing the same process with a fine grind and BIAB using Briess malt, mashing for 60 and getting a higher FG. That's why I was wondering about the difference in who malted the grain. Using the same process and a shorter mash time should get a higher FG, not lower.

Allow me to further support the premise of this thread.

I have been focused on beers that should be very dry. Very attenuated.

I always do a 90 minute mash with these beers.
I have even mashed as low as 144.
Raised to mashout temps for the batch sparge.

I can achieve nice body through the use of adjuncts high in beta glucans.

Conversely, I mash very high for beers that will be earmarked for wild or bacterial fermentation.
As high as 160.

Still using an extended mash time, of course.

jdoiv said:

Yes, this works as well and is the way many of the larger breweries do it. The problem for homebrewers is that most use coolers for MLTs and would have to use infusions to raise the temp. This can be a bit tricky and more difficult than a single infusion mash where you simply change the time needed.

I have a SS MLT that is direct fired and have done several step mashes recently and have been getting better than rated attenuation lately. Luckily none have gone too dry yet.

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I use a cooler mash tun and had to adjust my mash temp up the other day. I pulled about 2 gallons of wort off the mash, heated to 210, then put back into mash. This raised my mash temp in the cooler by 4-6 degrees. I didn't think about it at the time, but didn't I essentially do a step mash?

I think you actually did something closer to a decoction mash. With a true decoction, you would pull a certain amount of the mash (grains and wort) from the main mash, boil it separately for a bit and then add it back to the mash to step up to the next temperature.

Frymn1969 said:

I use a cooler mash tun and had to adjust my mash temp up the other day. I pulled about 2 gallons of wort off the mash, heated to 210, then put back into mash. This raised my mash temp in the cooler by 4-6 degrees. I didn't think about it at the time, but didn't I essentially do a step mash?

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This is basically a turbid mash used by lambic producers in Belgium. I believe they repeat the process a number of times, as one might in a decoction.
They push a wicker strainer down into the mash to collect only liquid.

The aeration done by one of the big brewers is a falling-film stripper--it's not just bubbling air into hot wort, it's a fairly gentle action--the wort falls down a tube surface in a film as the air blows past it flowing upward. As I understand it, it's to remove DMS. They do use a lot of corn and/or rice in the mash. I've read that hot-side aeration should be avoided, in general.

I read your post with interest. I brew mostly hoppy ambers bordering on IPA's. I am pretty happy with the beers but some leave a bit of molasses aftertaste and the FG is often about 1012. This idea might be just what I need to perfect the process. By coincidence I brewed a Robust Porter yesterday and used an 80 minute mash rest. I did the same Porter once before and had a stuck sparge, which seemed like an unfolding disaster at the time but was one of my all-time best brews. The stuck sparge took about 30 minutes to resolve (with panic accompaniment). I used a longer, cooler mash rest this time instead of repeating the stuck-sparge method to re-create the brew.

markklug said:

Appreciate this thread greatly and looking for some clarification. We have been fighting pretty much just the opposite problem for a few of our beers and wind up over attenuating beers we want to retain body. We recirc with a RIMS for good temp control and keep bumping up the temp trying to correct the outcome. Last batch was an hour mash at 155 and still finished 6-7 points low and thin. I now believe it is a function of our process. After the one hour mash we are typically draining over an hour for first runnings and then doing a batch sparge for 20 minutes with another hour drain for the second. This long time sitting at cooler temps must be breaking down the non-fermentables.

If we raise the primary mash temp to 170 prior to vorlauf will that "lock in" the ratio of fermentables/nonfermentables? Thanks

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Holy cow - why an hour long first running drain? I can see a slower drain on the sparge, but even an hour for that seems unnecessarily long. I would think a mashout would help with your problem - I've been pondering doing this in our RIMS but it seems of the people that do run into scorching wort issues, it's those that are raising temp in their RIMS as opposed to maintaining temp.


I'm wondering in reality how many brewers are "controlling [increasing] attenuation through [longer] mash times" because a longer mash in their case = more temperature loss. For those that claim their coolers only lose 0-1 degree still through the duration of the mash, I'm wondering if this is true everywhere in the mash.

So I have done a little research on mashing and the science behind it. From what I have read you really are not doing that much more in leaving your mash in the TUN for an extended period of time. The first 20 min of your mash is where all the magic happens. This is where the enzymes convert 80% of the starches to sugar. Then the conversion rate drops off drastically from there on. Anything after 60 minutes in the tun is not doing much more conversion to sugars at that point. Given you will see a little change and you will probably get the same results I do with your longer mash times but, I’m just saying there is an easier way to do it.
This is done by controlling the temp of the mash. The largest of the 3 factors in what starches are broken down into sugars during your mash is the temp. The other two factors being the PH level and the quantity of water which, are negligible in comparison unless you have really soft or hard water.
If you keep your temp at the lower end of the mash temp range (around 148-151) you will be able to break down some of the more complex starches into fermentable glucose which give you higher attenuation and a dry finish. Now if you move the mash temp the the higher end of the range (154-158) you will not break down the long chain starches and will give that malty finish and give you a lower attenuation percentage. This can all been done in the 60 min mash without waiting that extra time.
If you want to get into the weeds about mash temp and schedules check out John Palmers “How to Brew” and look into the chapter on mashing. He goes full nerd on it and give a better explanation than I

Actually "How to Brew" says that low mash temp makes a less fermentable wort.

As for your comment on shorter mash times. What's your opinion on having unconverted starch in your beer?

grathan said:

Actually "How to Brew" says that low mash temp makes a less fermentable wort.

As for your comment on shorter mash times. What's your opinion on having unconverted starch in your beer?

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Aparently John Palmer missed that error because a low mash temperature does make a more fermentable wort.

Unconverted starch means you had a poor quality crush or bad temperature control. If you haven't converted all of it in 60 minutes its because the grains didn't get wet through or your temperature was wrong.

I've been using Beer Smith and hitting the target strike water (about 164 degrees depending on grain temp) and the mash temp of about 150 deg for 75 minutes. My ferments with Safale 04, safale 05 or Nottingham seem to go well but the FG is often in the 1018 range (starting from 1046 to about 1056). My current session IPA fermented at 68F for a couple of days and is flocculated. The gravity is 1020. It tastes great but WTF? I just roused the carboy and am raising the temp in the fermentation closet. Any other ideas? Longer mash? Cooler mash?

I've read that lower mash temps take longer to convert than higher mash temps and a temp of about 153 was best for a highly fermentable wort because it favors both Alpha and Beta enzymes. If you go lower than 153 maybe you should mash longer since Beta takes longer? I also read starch fully gelanitizes at 149 so going lower than that may not convert all the starch and its possible to have a less fermentable wort.

Personally I like a two step mash (hockhurtz) in each enzymes optimum range and adjust those times according to what kind of fermentability I'm looking for.