Question about mash temperatures

[bernardsmith]

Is there a downside to slowly heating my grains in water so that they reach the mash temperature rather than adding the grains when the water is about 10 degrees F above this temperature? If there is no significant down side does the time needed to mash the grains drop or do I still want to mash them for about 60 minutes after they have reached the optimum mash temperature? Thanks... And a happy - and safe -Thanksgiving holiday to all.

 

[RmikeVT]

I don't do this, but it sounds like you are more or less step mashing. If I were you I would do some research on step mashes. I think they typically start around 110* and there are different temperatures that you do "rests". Although, with the modified malts we use today, step mashes are not necessary and could possibly even mess with your malt profile, decreasing head retention by break up to many proteins or drying out the beer too much.

The great thing about brewing is you can blaze your own path and develop you own unique methods. I am sure with some tweaking you can figure out what is best for you.

 

[kombat]

I guess that would be fine if you were aiming for a very dry beer and your target mash temperature was low anyway (like 145-149° F), but if your target mash temperature is, say, 156° and you want a beer with more body and some unfermentable sweetness, the risk is that those beta amylase enzymes will chew through all those sugars and convert them to fermentable sugars before you reach your target mash temperature where the alpha amylase enzymes will wake up. By the time you get there, there might not be any sugars left for the alpha amylase enzymes to convert to longer-chain, unfermentable sugars. You'll end up with a dry beer, whether you intended to or not.

 

[bernardsmith]

Thanks Kombat. I guess I thought that these enzymes (alpha and beta) produced (different?) sugars from the starch at different temperatures so if you mashed at a high temperature you would not get at the sugars that the beta amylase would modify and if you mashed at a low temperature you would not get the sugars that the alpha amylase would modify. What I was wanting to do was add the grains to the water at room temperature and allow the water to heat to about 160 F so it would go from about 65 thru 160 hitting the 145 and passing through this. Wasn't that kind of mashing done in the past? Why is it not done as routinely today? Is this what is called "step mashing"? I wasn't planning on stopping at any temperature until I hit the top

 

[govner1]

I guess that would be fine if you were aiming for a very dry beer and your target mash temperature was low anyway (like 145-149° F), but if your target mash temperature is, say, 156° and you want a beer with more body and some unfermentable sweetness, the risk is that those beta amylase enzymes will chew through all those sugars and convert them to fermentable sugars before you reach your target mash temperature where the alpha amylase enzymes will wake up. By the time you get there, there might not be any sugars left for the alpha amylase enzymes to convert to longer-chain, unfermentable sugars. You'll end up with a dry beer, whether you intended to or not.

Just as a clarification, the alpha amylase enzymes do not convert sugars to "longer chain" I fermentable sugars. Alpha amylase acts on long, straight chain starches to "break" the glycosidic bond on one end into fermentable maltose groups.
Alternately, the beta amylase is active at lower mash temps and acts on amylose & amylopectin to produce maltose.
Alpha amylase also acts to "open" up large starch molecules ( amylopectin) to beta amylase action. Too much alpha amylase breaks down starches to smaller dextrins quickly & can lead to less fermentable wort.

 

[kombat]

Thanks Kombat. I guess I thought that these enzymes (alpha and beta) produced (different?) sugars from the starch at different temperatures so if you mashed at a high temperature you would not get at the sugars that the beta amylase would modify and if you mashed at a low temperature you would not get the sugars that the alpha amylase would modify.

Yes, that's true, but you described slowly heating the entire mash up to that target temperature. My argument is that by the time you heat it through the range where the beta amylase enzymes are active (140's), there might not be anything left for the alpha amylase enzymes to act on. The conversion may already be complete. Recent anecdotal evidence I've seen from other posters suggests that conversion actually happens much faster than previously believed. Some brewers only mash for 15 minutes and still report complete conversion.

Wasn't that kind of mashing done in the past? Why is it not done as routinely today? Is this what is called "step mashing"?

Yes and no. Yes, it was called "step mashing," but they didn't heat the entire mash slowly to each step. They removed a portion of the mash and heated it to boiling, separate from the rest of the mash, then returned it to the main mash and stirred it back in. This was called a "decoction," and it resulted in steep temperature "steps" of the main mash. So if the mash was sitting at, say 130° F and no conversion was going on, the brewer would remove several quarts of the mash, heat it to boiling, then return it to the mash tun and stir, which would elevate the temperature of the overall mash to (for example) 156° F. How this differs from what you described is that this temperature increase occurs much more quickly, such that the enzymes that would be active in the 140's don't actually get any time to do their work, as the overall mash temperature pretty much "jumps" from 130 to 156 within a minute or so (or however long it takes you to stir the boiling mash into the rest of the mash such that the temperature is even throughout).

I wasn't planning on stopping at any temperature until I hit the top

It doesn't matter - like I said, the 15-20 minutes you spend heating through the 140's might be enough to convert all the starches before you even reach your target temperature.

 

[bernardsmith]

Just as a clarification, the alpha amylase enzymes do not convert sugars to "longer chain" I fermentable sugars. Alpha amylase acts on long, straight chain starches to "break" the glycosidic bond on one end into fermentable maltose groups.
Alternately, the beta amylase is active at lower mash temps and acts on amylose & amylopectin to produce maltose.
Alpha amylase also acts to "open" up large starch molecules ( amylopectin) to beta amylase action. Too much alpha amylase breaks down starches to smaller dextrins quickly & can lead to less fermentable wort.

Trying to wrap my arms around the implications of your post. Would this mean that allowing the grains to sit in the mash while the temperature rose from room temperature through 140 to 160 WOULD enable the enzymes to modify the starch to produce as at least as much fermentable sugar as adding the grains to water at around 160 and letting the grains mash at around 153 or thereabouts. My idea was simply to put the mash pot in the oven and set the oven at its lowest setting and go from there...

 

[govner1]

Beta amylase works best at 55 to 60 C (130-140 F) while alpha amylase works best about 10-15 C higher. Both enzymes survive better in thick & cooler mashes. beta amylase action decreases more rapidly than alpha amylase activity.
Mashing is beta amylase sensitive, i.e., fermentability sensitive. The key is to hit that "sweet spot" (no pun) where you maximize the activity of both. Usually the range is about 144-158F.

 

[kstiglich]

Kombat is totally right. Actually mashing is not an electronic device with On/Off switches. There is a lot of enzymes that will work at any temperature, but some enzymes will be more active on certain range of temps, and other enzymes will be more active on a different range of temps.
As a result, it you mash your grains at room temp (probably 68º) all enzymes will be working very low, but as soon as you get to 120º you are having a protein rest, and if your temperature raise is very low, probably you will need 10 minutos to go from 120º to 130º and therefore you are having a 10 minutes protein rest.

In the same way if you need 30 minutes to get from 140º to 154º that is your desired temp, then actually you had a mash of 30 minutes in the lower range of scarification, therefore your will have few body on your beer.

Anytime spent on a mash temp, will let some enzymes work very hard at that temp...so it is important to know how long time you stay at any temp to know what is happening to your wort.
If you want a beer with a lot of body, probably mashing your grains at 154º will be your best choice.

 

[kombat]

Would this mean that allowing the grains to sit in the mash while the temperature rose from room temperature through 140 to 160 WOULD enable the enzymes to modify the starch to produce as at least as much fermentable sugar as adding the grains to water at around 160 and letting the grains mash at around 153 or thereabouts.

Yes. Not only "at least as much," but rather way, way more.

My idea was simply to put the mash pot in the oven and set the oven at its lowest setting and go from there...

It's tempting, but no, this will give you a highly unpredictable mash fermentability. It's best to heat your water to about 8-10° F above your desired mash temperature, then turn off the heat and stir in your grains. This should get your right around the target temperature, immediately.

Regarding the oven, I actually use it when I brew 1 gallon batches, but I use it to hold my mash temperature, not heat to it. That is, I preheat my oven to 170°F (it's lowest setting), while simultaneously heating my water to 158° F. I then stir in my grains until it settles at 148° F. I then put the lid on the pot, turn off the oven, put the pot in the oven, and set the timer for 60 minutes. The oven will slowly lose heat over the next hour, but at a rate that should not add much additional heat to the mash, but rather simply allow the mash to stay at exactly the same temperature (as opposed to if I just left the pot on the stove, at room temperature, where it would lose several degrees over the hour-long mash).

 

[stpug]

The interaction of enzymes during mashing is very complex and not overly simple to explain. The numerous enzymes at play in a mash work within a fairly large range, just at different levels and speed of activity. Do some reading/research and you'll have a better idea of what you can accomplish by temperature adjustments while mashing, while keeping in mind the type of malt you're using (i.e. how well modified it is).

Yes, people do step mashing via direct heat (i.e. no infusions, no decoctions) - even dextrinous worts. Generally though, movement between the steps take place fairly quickly - not slowly.

Decoction and step mashing are different. Decoction and step mashing may move the mash through similar temperature rests, but their end product can be significantly different.

 

[kombat]

Decoction and step mashing are different.

Well, strictly speaking, decoction mashing is a form of step mashing, as is infusion mashing. I was trying not to confuse the poor fellow.

 

[bernardsmith]

I appreciate everyone's help here and I think I am have been convinced to heat the water and then add the grain..and then shove the metal tun I use into the oven at its coolest setting.
Thanks everyone. Have a great Thanksgiving

 

[kombat]

I think I am have been convinced to heat the water and then add the grain..and then shove the metal tun I use into the oven at its coolest setting.

And turn off the oven.

 

[stpug]

I've found that leaving the oven on for the mash (or half of the mash) works better in my situation for maintaining the temperature. In fact, I preheat to 185, put the mash in the oven when it's ready, reduce heat to 170, and leave it like that for the 30 minute mash. If I'm going for a 60 minute mash then I'll shut the oven off at 30 minutes and leave it alone for the last 30 minutes. This is just what I've found works best in my situation. YMMV.

 

[kombat]

What happens to the temperature of your mash when you do it that way? I would think the temperature would climb above the desired value. Have you ever checked it?

 

[stpug]

What happens to the temperature of your mash when you do it that way? I would think the temperature would climb above the desired value. Have you ever checked it?

I check the mash temp after each time I've done it this 185F way (which has only been 3 times), and the temperature has either remained where I last saw it (30 minute mash) or climbed a degree or two (60 minute mash) - both of which are preferable to me. This was checked after stirring the mash when I pulled it out from the oven.

One time (the first time) I did the 170F preheat and shut-off method, I dropped 2-3 degrees over the hour. After that time I adjusted my method to a warmer preheat, leave oven on, and have been happy with it. I don't think the 2-3 degree drop over the hour is any big deal but back then I was really concerned about maintaining a consistent mash temp. I worry less now

In the grand scheme of things, the amount of heat transferred into the pot of about 2 gallons mash is very little over the course of an hour. Especially when the temperature differential is generally 30F. For me, this is what I have found to work the best for those batches (decoction, cereal mash, partial mash).