I’ve been doing a bit of reading around the forums, some books, and a little bit online, and I have come to realize how different mash temps can make a big impact on the beer. From what I understand (and please correct me if I am wrong) different mash temps coax out different enzymes that help convert the starches into fermentable sugars. This is where the different rests come into play (right?).
Why do some recipes say mash at 150f while others say 158f. How does time affect this? I would assume longer rests produce more fermentable sugars from that specific temp range? If this is the case, why wouldn’t all recipes utilize different rests? Will different or multiple rests produce different flavors overall? Will this affect how sweet the beer is overall at the end, or is that more up to the type of yeast you use and how far it will attenuate?
In my experience, if you mash anywhere from about 148 to 155 F for at least 40 minutes, you’re in pretty good shape and will make good beer that way. Below about the 147-148 F point, beta amylase is the dominant enzyme. Beta works more slowly but will do a good job of simplifying the sugars after sufficient time is applied, say 90 minutes or longer. Both alpha and beta work together quite well in the 148-155 F range previously quoted. Above some point around mid-150s, the beta enzyme begins to become denatured. However, this also takes time and the beta doesn’t all die at one time. Meanwhile the alpha goes chop-chop pretty fast at those same high temperatures, so you might not even notice a huge difference until you get up into the 160s F, where beta is denatured much more rapidly. In that case, your wort will be less fermentable by most beer yeasts. Saison yeast might be the one exception where it continues to munch on almost all sugars no matter what the mash temperature.
Since any schmuck can make great beer in the range anywhere from about 148-155 F, I find that mash TIME is a far more interesting variable worth playing with. My own experiments have found thatm at least on a homebrewing scale, 30 minutes still results in a full efficiency beer, but with full attenuation/fermentability occurring only roughly 50% of the time. The other 50% you will end up with a fuller beer with lower alcohol. Below 30 minutes, you are virtually guaranteed a very full bodied beer. From 40 minutes and above (again, on a homebrewing scale, not commercial), you won’t be able to notice any difference in attenuation/fermentability unless perhaps you are using >50% Munich malt as your base malt. Dark Munich especially contains far less enzymes so you’ll want to mash for at least 60-75 minutes when using a ton of Munich. But any other base malt I’ve found is perfectly capable of getting the job done in just 40 minutes.
You are on the right track, but there are specific enzymes that are active in a certain range that are denatured (become inactive) at higher temperatures. The beta amylase works at lower temperatures starting around 131F and denatures over about 156F, whereas the alpha amylase works best in the 152-162F range. The key for any style of beer is hitting the sweet spot for the style of beer you are brewing, along with the yeast being used, and then controlling the fermentation temperature. Next to sanitation, temperature control is key to a good result - that means temp control at all stages of the process. Read John Palmer’s How To Brew and other texts for more detail on this. It is important to grasp this at least somewhat in order to improve your brewing. Best of luck, and keep asking questions. There are some really smart guys here who can answer just about anything beer-related.
Edit - and Dave is one of those guys and a faster typer than me!
I just noticed I should have clarified, where I said “From 40 minutes and above (again, on a homebrewing scale, not commercial), you won’t be able to notice any difference in attenuation/fermentability”. That’s not exactly true unless you’re only mashing for the standard 40-90 minutes that most homebrewers employ. However, if you mash for a really long time like 90-120 minutes or even more like overnight or something like that in any broad range of temperature from 130s to 160s, you will indeed notice an increase in fermentability as well. No matter whether it’s the alpha or beta amylase or other enzymes available, they’ll continue to chomp away at the sugars and simplify them more and more until they are all denatured or until the temperature falls to someplace they don’t want to act much anymore, or until all the sugars are tiny size molecules, whichever comes first. In any case, if you want a super dry beer, you have two options: either mash for a really long time, or use saison yeast. Either one will work. If you want to maximize fermentability but only want to mash for about 60-90 minutes, then a mash temp in the mid 140s is probably best to maximize the beta’s time in their favorite zone without denaturing them too much.
While I do think temp does play a role, but it is relatively minor compared to pH and/or yeast. However, temp is the easiest one to change. I’ve never found “big” changes were made by temperature. Slight change to FG maybe a little thickness but that’s about it. I’ve mashed beers at 160F with 10% crystal and chico chewed it down just fine.
I don’t feel that a 151F mash is noticeably different than 150F, or that 155F is noticeably different than 156F, in terms of body or FG. But I do feel that in a given grist and using a given strain, a sub-150F mash is noticeably lighter in body and lower in FG, and that a mash above 156F gives a noticeably fuller body and higher FG. The middle range between 151F and 156F (given same grist and strain) has only very subtle differences in terms of body or FG IMO.
Thanks for the replies everyone. You are all helping me understand this better. So apart from the fermentability/ body of the beer, alpha and beta amalayse don’t really change much else about the beer? No flavor differences between the two?
If someone were to do a longer rest at beta temps (like 60-90 min) then mash at alpha temps for like 30-40, it seems like you would get the best of both worlds right? Might not be long enough for the beta to denature, and a good amount of time for some of the alpha to come out? Or is that middle ground dmtaylor was talking about do essentially the same thing as the different rests?
I didn’t realize that the body and fermentability of a beer can change at different mash temps… I figured all OG are equal and it depends on the yeast you are using.
You just hit on the reason some brewers (especially lager brewers) like to step mash a beer - to have the best of both temp ranges. Alpha works best at 154-162°F, while beta works best between 131-150°F. So if I mash a helles for 45 minutes at 145F and 45 minutes at 160F, I’ve created a beer that will both attenuate well with a nice drinkability (from the beta rest), and also have some nice body and foam stability (from the alpha rest).
Edit - Step mashing is still fairly common in Belgium as well.
Jury’s still out if you ask me. More experiments are needed. Personally I’d rather save the time and extra dorking around for something that we most likely can’t probably taste the difference anyway, just split the difference, mash in the 150s for 45 or 90 minutes as you prefer, and call it good.
Another thing I wonder about… if beta amylase doesn’t all die right away at 154 F or so, doesn’t it make more sense to do a reverse “step” mash (actually more of a “smooth” mash) starting at that point, not insulating, and allowing the temperature to fall to the mid 140s by the end of the mash? Anyway, that’s what I do almost all the time, without thinking too hard about it and without worrying, and with very good results IMHO. Way less effort for probably very similar results.
But, you know, many people just can’t help but play with their food. Insulated mash tuns… bah… humbug.
Denaturing is a little bit more than simply becoming inactive. An egg will harden and turn white under heat. This is the egg denaturing. Same thing happens with the enzymes in your grist (though they don’t turn white like an egg does). Once they become denatured, they can’t convert starches into sugars any more.
I agree that the jury’s out, too. I’ve been experimenting with step mashing (again) for about a year now. The one difference I’m absolutely convinced of is the benefit of better foam from the alpha rest @ 160-162F. It’s an easily noticeable difference IMO. Flavor wise, I don’t find a single infused lager to be inferior in any way (if mashed right).
Sub 160 it’s not as pronounced, but 160-162F for 45 mins and the foam has been thicker and more persistent than the single mashed lagers for me every time.
Edit - Though adding ~ 2.5% flaked barley does seem to approximate that in a single infused beer IMO.
+1 on the 160-162* at the end of the mash for better foam. I run a direct fire RIMS system and at the end of my selected mash schedule I run it up to those temps for at least 20 mins. I’ve noticed a improvement in foam and foam stability. Higher mash temps I use for beer with more body[ 156* for Porters etc.] and lower for more fermentable [dry] beers[ 149* for Saisons etc.]. Using longer mash times for the lower temps[90 mins]. To the OP, hope this helps, and no the mash out temp is around 168*, so these temps for foam are lower. Some use a mashout and others don’t, I just collect the Wort after the 160-162* into the BK while adding heat to raise temp while collecting.
Yep. The main purpose of a mash out is to denature the enzymes and ‘lock in’ the mash profile. So that would denature the alpha that contributes to the good foam.
I haven’t really noticed any trouble with foam although I have to say that my mashout never quite hits 168 F, but only goes to about the low 160s, so I’ve probably been enjoying the benefits all along completely by accident!
It never ceases to amaze me just how much malt mixed with warm water then allowed to ferment loves to turn itself into the most perfect beer even without a whole lot of help from expert brewmasters.
