Help With Stovetop Ag Biab Please

[PistolPatch]

I have only had a quick look at the above but from my quick glance, I can see a good example of a little brewing science being used incorrectly. That graph is misleading. (It could possibly apply to a stepped mash rather than a single infusion mash.)

Despite the fact that this graph os probably out of context, a lot more goes on in a mash than just converting fermentables. If it didn't, commercial breweries would mash for twenty minutes as they need to have as much volume going through their vessels as possible.

I don't have time to write the details but a short mash is not good practice especially for new brewers. New brewers should mash for 90 minutes not less. New brewers will also find it interesting to take gravity readings during the mash over several brews. They will see a significant rise.

Until you have done several brews and become confident in your measurements you should not consider doing less than a 90 minute mash. I still mash for 90 minutes on a single infusion mash as I know it is a very sensible time to work from.

Spot ya,
Pat

 

[Nick JD]

I've never done a 90 minute mash.

Hey Pat - what's the shortest mash you've ever done?

Commercial breweries need to get the most from their grain because they are in the game for profit. This also means they want to get the maximum from their hops so they use extraction techniques, they also use a lot of sugar.

I'm not so sure we should be emulating commercial brewery practices by rote.

I'd really appreciate a bit of insight into what the mash will be missing if it is stopped at 30 minutes apart from a few % lower efficiency. I can't find anything that tells me there are other conversions that only happen between 60 and 90 minutes that don't happen in the first 15 minutes.

 

[Thirsty Boy]

nope - Nick's graph is fine

But - the "so I can do a short mash" conclusion is only accurate for the higher temperatures, so if you are looking for a mash that is comparatively really quite unfermentable, then sure, you can mash at 70+ and it will be all over bar the shouting after 15 or 20 mins. Try the same thing at 63 and you will find that things don't work quite so well.

Choose a variable... you "can" control attenuation with mash time - or you can control it with mash temperature - most homebrewers find that their level of control is better when they choose temperature, and you are less likely to encounter brewing problems associated with incomplete conversion. Personally, I'd stick with a 60min mash on most cases - then you have one less variable to worry about. If you are trying to do something, or you encounter a problem that you cant solve by adjusting the temperature variable... then maybe look at mash time. But till then, make your life simpler, remove a variable in your day; and just use the most common homebrew times.

With BIAB because the mash conditions are not the most friendly to some of your enzymes - 90mins is a great "play it safe" mash time, and you should be able to achieve pretty much any level of attenuation you are shooting for. Once you are confident, you can probably go back to a 60min mash and note the change it makes to your brews... from there, I would only change if you have an active reason to do so.

TB

 

[Bribie G]

Under the guidance of the late great Butters I do low alcohol UK milds at 71 degrees for 50 minutes and have medals to polish. On the other hand for a typical bitter done at 65 degrees I go 90 minutes, sometimes even 2 hours.
However I have a very rudimentary knowledge of how alpha and beta amylase work: maybe someone with a more intimate knowledge might like to elaborate, I think 4* is right into this chemistry as well?

 

[donburke]

Under the guidance of the late great Butters I do low alcohol UK milds at 71 degrees for 50 minutes and have medals to polish. On the other hand for a typical bitter done at 65 degrees I go 90 minutes, sometimes even 2 hours.
However I have a very rudimentary knowledge of how alpha and beta amylase work: maybe someone with a more intimate knowledge might like to elaborate, I think 4* is right into this chemistry as well?

so is this telling me i should mash for 90 minutes to improve my efficiency ?

 

[MarkBastard]

I must say I enjoy Nick's unconventional practises from time to time. Even if he ends up being wrong at least he's really thinking about things and not just repeating gospel verbatim.

Looks to me like if you were in a hurry and just wanted to pump out okay beer quickly you could ferment at 70 degrees for 20 minutes and then add some sugar.

 

[RdeVjun]

Thanks chaps for an interesting and thought- provoking discussion. I've always mashed longer at lower temps for the drier beers I have been after, but as mentioned earlier, I've had hyperattenuation issues and so I've crept the mash temp back up slightly (66 was the peak), but it doesn't require much of an increase to take what was a dry beer to non- dry territory and one that doesn't hyperattenuate. There seems to be a precarious balance, and as TB says, BIAB wort isn't the friendliest place for some enzymes while I feel the repeatability, particularly for the drier types I've been making, BIABing may be slightly unpredictable. At least that's been my experience and I think it tees up with the bigger brains than mine?
In my situation, the deliberate absence of any spec malts may be a contributing factor too, I think I'm just about done with that caper- quirky, fun and educational though it has been. Plus I have a heap of spec malts sitting here patently, thankfully mostly unmilled... B)

Ps. Mark, I think you mean mash and not ferment? Starting to sound like a noob K&Ker there!

 

[Nick JD]

If I left my mash "tun" for 2 hours it would lose so much heat that even if I started at 70C, but the time it had finished the beta-amylase would have chewed up all the alpha-amylase's nice long tastysugaz, and I'd might as well had have just mashed for 60 minutes at 62C and added an extra 40 cents of grain.

I think that's how it works ... question is: does the beta enzyme break down the longer sugaz into maltose as well as starch, or does it leave them alone?

 

[Nick JD]

so is this telling me i should mash for 90 minutes to improve my efficiency ?

Only if you are mashing below 66C (ish).

...and sorry for complicating the hell out of your thread, mate.

 

[Thirsty Boy]

If I left my mash "tun" for 2 hours it would lose so much heat that even if I started at 70C, but the time it had finished the beta-amylase would have chewed up all the alpha-amylase's nice long tastysugaz, and I'd might as well had have just mashed for 60 minutes at 62C and added an extra 40 cents of grain.

I think that's how it works ... question is: does the beta enzyme break down the longer sugaz into maltose as well as starch, or does it leave them alone?

No - thats not really how it works. And Yes - Alpha amylase knocks the starches, very quickly as you have noted, into dextrins - the beta amylase works on both the starches and the dextrins and makes maltose out of them.

BUT beta amylase is far more heat liable than alpha amylase, so if you start at 70... very very quickly the Beta amylase will all (or mostly) be denatured and not be doing anything at all... so a 2 hour mash starting at 70, will give you a result remarkably similar to a 1 hour or even a 30min mash starting at 70. Alpha amylase will slowly convert dextrins into fermentable sugars, but it is slowly and if you extrapolate that table that Nick posted.. you can see how slowly its likely to be.

Yes - your efficiency will improve if you mash hotter (up to a point)... but you will also get a change in your fermentability profile. And so we get to step mashing.

You mash for a period at a nice Beta amylase friendly temp in the low 60s...you get yourself a bunch of fermentable sugars, then you step it up to a 70 rest, convert a bit of the more stubborn starch, suck out a little extra efficiency and add back in some dextrins, because at that temp the active enzyme is Alpha amylase, so dextrins are all you are gonna get.

You can strike a balance anywhere you like between rest times and temps, get better efficiency, still get the sugar profile you are looking for and if you do you steps with a decoction.. blast the hell out of an under-modified malt to render it usable plus get some flavour into the bargain.

Mashing for 90 mins just gives the mash a chance to finish properly.... on the conversion of the stubborn starches, you can get a few more of them with time.. but really you need both time and temp. But if you mash lower, like all chemical reactions, things take longer - 90 mins just gives everything plenty of time to happen and makes sure that the mash is actually fully complete and not still undergoing any major change in either extract or fermentability.

Lesson ends

TB

 

[Nick JD]

Aha! :icon_cheers: