Author Topic: Mash rests, their functions, and when to use them.  (Read 3177 times)

Offline Westley

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Mash rests, their functions, and when to use them.
« on: July 14, 2017, 05:42:43 AM »
Hi all, I've been looking around for information on mash rest temperatures. I've come to find that a beta rest makes for a more fermentable dryer beer, and an Alpha rest makes for a less fermentable sweeter beer. I've been seeing things like "protein rest", "diacetyle rest", etc. What are all the various mash rests, and when do you know to use a specific rest, or combination of mash rests. Please break down this information for me.

Offline kramerog

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Re: Mash rests, their functions, and when to use them.
« Reply #1 on: July 14, 2017, 06:43:57 AM »
Check out howtobrew.com or better yet buy the latest edition of the book for a detailed explanation of the mash rests.  Most people do single infusion for most of their batches.  Single infusion means that hot water and malt is added to achieve a temperature (typically 149-158F) between the alpha and beta rests so as to do both simultaneously. The diacetyl rest is not a mash rest but a lager fermentation rest.

Offline dmtaylor

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Re: Mash rests, their functions, and when to use them.
« Reply #2 on: July 14, 2017, 07:21:35 AM »
This is an advanced topic.  Opinions as well as "facts" are all over the place on the usefulness of the different rests or lack thereof.  I second the motion to review howtobrew.com.  In all honesty, you can make fantastic beer without knowing anything about this topic.

Others may beg to differ, and may provide you with more information, and I'm cool with that.
« Last Edit: July 14, 2017, 07:25:06 AM by dmtaylor »
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Re: Mash rests, their functions, and when to use them.
« Reply #3 on: July 14, 2017, 07:42:02 AM »
A bit of a misconception there.  A diacetyl rest is not a mash rest.  It's a post fermentation tehcnique to make the yeast more active in order to remove diacetyl from the fermented beer.  It's usually mot necessary.
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Offline BrodyR

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Re: Mash rests, their functions, and when to use them.
« Reply #4 on: July 14, 2017, 10:57:34 AM »
Hi all, I've been looking around for information on mash rest temperatures. I've come to find that a beta rest makes for a more fermentable dryer beer, and an Alpha rest makes for a less fermentable sweeter beer. I've been seeing things like "protein rest", "diacetyle rest", etc. What are all the various mash rests, and when do you know to use a specific rest, or combination of mash rests. Please break down this information for me.

The current go-to for german lager brewing is simple.

Rest 1 around 30m at 145f then 30m at 160f then 10m mash out at 170f.

You don't want to rest in the 'protein rest' ranges. I do this mash as well as single infusions regularly. In my experience it provides a bit more body and improved head retention compared to a single. I also get increased efficiency (not that it matters at our price scale). If you can get your hands on Kunze - Technology, Brewing, & Malting Section 3.2 goes into the science behind the rests.

Offline erockrph

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Re: Mash rests, their functions, and when to use them.
« Reply #5 on: July 14, 2017, 04:12:26 PM »
A single rest at 153F will span both alpha and beta ranges and  will be sufficient for 95+% of your brewing. That said, the best way to know what a particular rest will do is to try it for yourself. It's not going to ruin a beer.

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Re: Mash rests, their functions, and when to use them.
« Reply #6 on: July 14, 2017, 04:56:06 PM »
A single rest at 153F will span both alpha and beta ranges and  will be sufficient for 95+% of your brewing. That said, the best way to know what a particular rest will do is to try it for yourself. It's not going to ruin a beer.

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I have to disagree here. β will be largely inactive at 153 °F. If you are going to choose a single infusion rest temperature, I'd say you are better served choosing a lower temperature.

In the end, single infusion mashing is a very useful compromise, especially given the fact that some people cannot direct fire step mash. Set aside esoteric flavor discussions and the "better or worse" argument between step mashing and single infusion. The true beauty of the step mash is how it gives complete control of the wort composition to the brewer.

One of the greatest overviews I have seen came from an article of Brauwelt that detailed a multi step mash. It talked about ideal β rest temperatures and times, particularly the half life of β amylase at those temperatures:

144 °F (20 minutes gives ~ 46% of β amylase activity)

147 °F for (10 minutes gives ~25% additional of β amylase activity while 10 more minutes here gives ~10% additional β amylase activity)

153 °F (20 minutes. By the time you enter this rest there is no residual β amylase activity, although the ramp from 147 °F to 153 °F will likely net an additional 5% β amylase activity)

162 °F (30 minute α amylase rest. This promotes full body)

171 °F (10 minute mashout promotes glycoproteins and other foam positive substances)

A nice compromise would be 144 °F for 18-20 minutes, 147 °F for 8-10 minutes, Step through 153 °F on the way to 162 °F where you rest for 30 minutes then mashout for 10 minutes at 171 °F.

For a single infusion, a temperature between 147-150 °F may be ideal.



« Last Edit: July 14, 2017, 04:58:37 PM by Big Monk »

Offline Westley

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Re: Mash rests, their functions, and when to use them.
« Reply #7 on: July 14, 2017, 05:27:35 PM »
Thank you for the information guys.

Offline coolman26

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Re: Mash rests, their functions, and when to use them.
« Reply #8 on: July 16, 2017, 05:42:15 AM »
For what it is worth, when I single infuse, I rest at 149. I tried to do multiple infusion steps when I brewed last week. I'm going to knock the dust off the HERMS today. I've seen the pics of amazing foam that I'm not getting. That is why these batches are stepped. My steps were 147 for 30, 161 for 30, and 171 for 10. Not sure if that is the best temps, but that is what they got. I feel the gradual rise w the HERMS will be beneficial.


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Offline Westley

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Re: Mash rests, their functions, and when to use them.
« Reply #9 on: July 16, 2017, 10:14:05 AM »
For what it is worth, when I single infuse, I rest at 149. I tried to do multiple infusion steps when I brewed last week. I'm going to knock the dust off the HERMS today. I've seen the pics of amazing foam that I'm not getting. That is why these batches are stepped. My steps were 147 for 30, 161 for 30, and 171 for 10. Not sure if that is the best temps, but that is what they got. I feel the gradual rise w the HERMS will be beneficial.


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Keep me updated with your results. I'm curious how it turns out. My last mash I tried 148 degree for 30 minutes, stepped to 158 degrees for 60 minutes. It will be kegged in about a week, so I'll see how it goes.

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Offline denny

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Re: Mash rests, their functions, and when to use them.
« Reply #11 on: July 16, 2017, 03:52:10 PM »
http://howtobrew.com/book/section-3/the-methods-of-mashing/multi-rest-mashing


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One of the big takeaways in the chapter you reference is this..."If you use less well-modified malts, such as German Pils malt, a multi-rest mash will produce maltier tasting beers although they need a protein rest to fully realize their potential".  There just aren't that many less modified malts around, and certainly not domestic malts.  And keep in mind that what you quoted is a very old edition of the book.  Its even harder to find less well modified malts now.
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Offline BrewBama

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Re: Mash rests, their functions, and when to use them.
« Reply #12 on: July 16, 2017, 04:43:47 PM »
I simply provided a link to a resource. It's up to the reader to determine accuracy or usefulness. Pragmatism: an approach that assesses the truth of meaning of theories or beliefs in terms of the success of their practical application. 

Here's another: http://braukaiser.com/wiki/index.php?title=Infusion_Mashing


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Big Monk

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Mash rests, their functions, and when to use them.
« Reply #13 on: July 16, 2017, 05:20:49 PM »
This is the best mashing schedule "canvas" I've seen. It's from the pages of Brauwelt and can be manipulated in many ways to yield optimal results:


Offline hopfenundmalz

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Re: Mash rests, their functions, and when to use them.
« Reply #14 on: July 16, 2017, 06:14:24 PM »
A single rest at 153F will span both alpha and beta ranges and  will be sufficient for 95+% of your brewing. That said, the best way to know what a particular rest will do is to try it for yourself. It's not going to ruin a beer.

Sent from my XT1650 using Tapatalk

I have to disagree here. β will be largely inactive at 153 °F. If you are going to choose a single infusion rest temperature, I'd say you are better served choosing a lower temperature.

In the end, single infusion mashing is a very useful compromise, especially given the fact that some people cannot direct fire step mash. Set aside esoteric flavor discussions and the "better or worse" argument between step mashing and single infusion. The true beauty of the step mash is how it gives complete control of the wort composition to the brewer.

One of the greatest overviews I have seen came from an article of Brauwelt that detailed a multi step mash. It talked about ideal β rest temperatures and times, particularly the half life of β amylase at those temperatures:

144 °F (20 minutes gives ~ 46% of β amylase activity)

147 °F for (10 minutes gives ~25% additional of β amylase activity while 10 more minutes here gives ~10% additional β amylase activity)

153 °F (20 minutes. By the time you enter this rest there is no residual β amylase activity, although the ramp from 147 °F to 153 °F will likely net an additional 5% β amylase activity)

162 °F (30 minute α amylase rest. This promotes full body)

171 °F (10 minute mashout promotes glycoproteins and other foam positive substances)

A nice compromise would be 144 °F for 18-20 minutes, 147 °F for 8-10 minutes, Step through 153 °F on the way to 162 °F where you rest for 30 minutes then mashout for 10 minutes at 171 °F.

For a single infusion, a temperature between 147-150 °F may be ideal.

IIRC both Greg Doss (when he was at Wyeast) and Kai both reported maximum fermentabily for single infusion mashes at 153F using Pils Malt. That is what I remember, haven't looked at those in some time. Greg presented at an NHC, so you might find that on the NHC page.

Your thoughts? I have have had good results on certain beers using a single at 153F. US 2-row is so "hot" in DP that big breweries say the mash is pretty much converted when they are done mashing in 200 bbls. For some malts I see where a step mash is they way to go, for US malts, not so much.
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