[erockrph]

I just mashed in on a porter and overshot my mash temp by quite a bit. I was shooting for 156 and I was at 162 after stirring in my grain. I threw in several handfuls of ice and was able to get my temps down to 156, but I'd say about 10 minutes went by before I got the temp down. Was this long enough at the higher temps to have a significant effect on enzyme activity?

[weithman5]

i think you will be okay. protiens denature quickly but i think at those temps it is still slow.  example of fast denaturing throw a steak on hot grill or really cool - nail clippings on a fire.

[Kaiser]

What I recommend when overshooting mash temps is to bring down the temp quickly, as you did, but aim for a lower temp target. This way the remaining b-amylase doesn't denature as quickly. I plan to talk about this at the ANHC next week.

This is an idealized chart that shows how b-amylase may be affected over time by different temperatures:



But I think this may not be as valid for you case since I also have seen data where the b-amylase doesn't drop down all the way to 0 that quickly

see here: http://braukaiser.com/wiki/index.php?title=Starch_Conversion#water_to_grist_ratio

Don't worry, but let us know how the beer turned out.

Kai

[erockrph]

Thanks for the info, Kai. I'm not too worried about the end result with this batch, but this is the first go at a recipe that I eventually want to develop into my house porter recipe. I'm more interested in how to best account for the mash temp, so the next time I brew it I'll know what baseline to tweak the recipe from. I think I'll treat it as if I mashed a bit higher (like 158-159ish) just to make an educated guess.

[mabrungard]

Kai,

I agree with the concept presented in the graph with higher temperature denaturing enzymes more quickly.  But is there data to back that graph up?  I see the reference that you cite from Kunze, but that is a single set of results at 65C.  Are there other results at differing temps to support the premise of the graph?   

By the way, what is ANHC? Ausie?

[Kaiser]

I agree with the concept presented in the graph with higher temperature denaturing enzymes more quickly.  But is there data to back that graph up?

There is no data to back up this graph. It has been compiled from a simple model of enzyme denaturation. I guess there is some data on this out there, but I haven't come across a reliable source yet. The chart itself is only used for illustration. I wish I had something better. Measuring b-amylase activity is rather difficult in home brewing lab.

By the way, what is ANHC? Ausie?

Yes this is the Australian home brewing conference.

Kai

[erockrph]

Well, I undershot my OG by 7 points. I don't know how much the mash temp affected that, however. I bought my specialty grains whole and cracked them with a rolling pin. The crystal and carapils were like rocks so im pretty sure I didn't get as good of a crush as I needed. Wort tastes great though. Added some DME to get to my target gravity. We'll see how it goes.

Looks like a grain mill and refractometer are next on my gear wishlist.

[Kaiser]

overshooting your mash temp should help with your conversion efficiency since that is largely determined by a-amylase activity and starch gelatinization.

Kai

[nateo]

overshooting your mash temp should help with your conversion efficiency since that is largely determined by a-amylase activity and starch gelatinization.

I don't know if it's true, but I read somewhere that Budweiser uses a reverse step-mash, where they start high then lower the temp to get more fermentability. Would that work? On a homebrew scale would a mash that starts at 160 > 140 over two hours have more fermentability than a wort just mashed at 148 for two hours?

[denny]

overshooting your mash temp should help with your conversion efficiency since that is largely determined by a-amylase activity and starch gelatinization.

I don't know if it's true, but I read somewhere that Budweiser uses a reverse step-mash, where they start high then lower the temp to get more fermentability. Would that work? On a homebrew scale would a mash that starts at 160 > 140 over two hours have more fermentability than a wort just mashed at 148 for two hours?

Intuitively it doesn't seem like it.  I guess it would depend on what the starting temp was and how long you held it.

[jeffy]

overshooting your mash temp should help with your conversion efficiency since that is largely determined by a-amylase activity and starch gelatinization.

I don't know if it's true, but I read somewhere that Budweiser uses a reverse step-mash, where they start high then lower the temp to get more fermentability. Would that work? On a homebrew scale would a mash that starts at 160 > 140 over two hours have more fermentability than a wort just mashed at 148 for two hours?

Intuitively it doesn't seem like it.  I guess it would depend on what the starting temp was and how long you held it.

I think the beta enzymes get denatured at the hi temp and it doesn't work that way.  At least it didn't work for me when I thought it might have been a brilliant idea a few years ago.

[denny]

overshooting your mash temp should help with your conversion efficiency since that is largely determined by a-amylase activity and starch gelatinization.

I don't know if it's true, but I read somewhere that Budweiser uses a reverse step-mash, where they start high then lower the temp to get more fermentability. Would that work? On a homebrew scale would a mash that starts at 160 > 140 over two hours have more fermentability than a wort just mashed at 148 for two hours?

Intuitively it doesn't seem like it.  I guess it would depend on what the starting temp was and how long you held it.

I think the beta enzymes get denatured at the hi temp and it doesn't work that way.  At least it didn't work for me when I thought it might have been a brilliant idea a few years ago.

Yeah, that's been my experience, too, Jeff.

[Kaiser]

If you want too do reverse mashing, you have to keep some of the enzymes on the side and add them after the mash cooled enough. That's how you can get very fermentable wort.

Or even add them to the fermenting beer.

Kai

[mabrungard]

overshooting your mash temp should help with your conversion efficiency since that is largely determined by a-amylase activity and starch gelatinization.

I always mash out with a 168F rest since my RIMS makes that an easy chore.  I observe several points increase in wort gravity with this step and feel it is worth while in my brewing. 

I see that a Congress mash has temp steps of 113F and 158F, so those Congress mashes never get to the temperature that I mash out at. I see that the temperature ramp from 113 to 158F is performed over 15 minutes, so there is a little residence at intermediate temps. One thing that the Congress mash includes is a finer grind that should liberate more starch since lauterability is not really a consideration in that testing.  I'm assuming that the higher temperature mash out that I perform helps alleviate the limitations of my grind and get my extraction performance closer to the high level set in the Congress mash.

I don't typically mash at anything less than a sacharification temperature (say the 140s), so I'm not sure that there would be an improvement in overall extraction with lower temperature rests.  Would a very low temp rest as with a Congress mash improve the extraction?  I'm sure it improves the fermentability, but not so sure with the extraction.  I feel that the mash out is a good practice with no downside.

Kai,  I see that the enzyme chart is set up in a relativistic format, so I'm on board with your conjecture.  I wish we had more data to make the chart more factual. 

Enjoy that long trip.  I know that Palmer is going too.

[a10t2]

On a homebrew scale would a mash that starts at 160 > 140 over two hours have more fermentability than a wort just mashed at 148 for two hours?

Maybe. I didn't do a single-infusion control, but I played with reverse mashing: http://seanterrill.com/2011/10/15/reverse-mashing-2/

For reference, a 60 min single-infusion mash yielded 63% attenuation. So even the very short mashes were higher.