Denaturing rate of beta amylase (scientific paper)

[The-Engineer-That-Brews]

A successful mash needs at least some period where both alpha and beta amylase are working co-operatively together, because alpha produces very few fermentable sugars and beta works much better when the alpha has broken down the starch a bit.

But there's a problem: alpha amylase doesn't work much below 63ºc, but by the time the mash reaches that temperature, quite a lot of the beta amylase has already been permanently damaged ('denatured').

Therefore it's very useful to understand how quickly the beta amylase is damaged at different temperatures and mash thicknesses.

Unfortunately while there are some figures bandied about on this, it's difficult to find really reliable data that is sourced to a scientific study.

Therefore I was really glad to find this paper from July 1990 by Robert Muller at the Brewing Research Foundation in Redhill, Surrey.

The whole paper is worth a read but Figure 1 below is particularly useful. It shows (on different scales) how quickly each type of amylase is destroyed at 65ºc (in a 2.5 litre/kg mash), which is a fairly common temperature chosen for a "balanced mix" of alpha versus beta activity.

The key observation is that the beta is destroyed much more quickly than the alpha, with the usable amount remaining halving every ten mins.
So after 30 mins about 83% of the beta amylase has been destroyed, and after 60 mins 92% of it is gone.
More than 50% of the alpha amylase is still going at this point, and will continue to increase the 'body' and perceived sweetness, but remember that the alpha produces very few fermentable sugars.

Muller's results are fairly consistent with work at the university of Vienna (quoted by Braukaiser) in figures 2 and 3, which shows how the rate of enzyme deactivation changes at different temperatures (spoiler: it drops off pretty fast).

Figure 1: Inactivation of enzymes at 65ºC (2.5:1 liquor to grist) [Muller 1990]

Figure 2: Qualitative BETA amylase inactivation at different temps [TU Vienna]

Figure 3: Qualitative ALPHA amylase inactivition at different temps [TU Vienna]

 

[foxy]

That is the reason a mash temperature is generally between 63- 69 C.
I didn't see where the pH of the mash liquor was stated? One of the reasons that water chemistry is important is that it gets the optimum results out of the Beta and Alpha amylase and give them some insulation against mash temperature.

 

[Buffers brewery]

This post got me thinking….. Hypothetically speaking (thinking) I wonder, for the “perfect beer”, what percentage of grain should be mashed at, say 63C to produce a very fermentable wort, and the remainder of the grain mashed at, say 69C to produce a less fermentable wort to provide the “body”. I’m thinking of 2 separate mashes done one after the other with fresh grain for each. I guess it would depend on the style but for a bitter, I wonder what the split would be?

 

[The-Engineer-That-Brews]

This post got me thinking….. Hypothetically speaking (thinking) I wonder, for the “perfect beer”, what percentage of grain should be mashed at, say 63C to produce a very fermentable wort, and the remainder of the grain mashed at, say 69C to produce a less fermentable wort to provide the “body”. I’m thinking of 2 separate mashes done one after the other with fresh grain for each. I guess it would depend on the style but for a bitter, I wonder what the split would be?

You can do it, @Buffers brewery but it‘s tricky because to get a very fermentable wort you need not only beta amylase to snip maltase off the ends of starch and dextrine chains, but you also need alpha amylase to chop up the long chains to give the beta lots of ‘ends’ to work on.
You also need to do the ‘beta‘ stuff at a sufficiently high temp that the starch has gelatinised.

 

[The Baron]

I do 62c for 30 mins then 67c for 30 mins on a pretty regular basis and it always turns out well

 

[The-Engineer-That-Brews]

I do 62c for 30 mins then 67c for 30 mins on a pretty regular basis and it always turns out well

Me too, and I like the thick ‘mouthfeel’ it gives.
I did a single temp mash today at 65°c (following a recipe) and was thoroughly caught out by the comparatively low efficiency compared to my normal step mash.

 

[The Baron]

I always get a good free flowing mash too with the 2 step mash TETB

 

[The-Engineer-That-Brews]

I always get a good free flowing mash too with the 2 step mash TETB

That too, is very true. I often 'dough in' in the low 40'c range in the hope of getting a bit of beta glucanase action (especially if there's a lot of wheat around).
I don't know if it helps, but it makes me feel dead professional LoL

 

[The-Engineer-That-Brews]

You can do it, @Buffers brewery but it‘s tricky because to get a very fermentable wort you need not only beta amylase to snip maltase off the ends of starch and dextrine chains, but you also need alpha amylase to chop up the long chains to give the beta lots of ‘ends’ to work on.
You also need to do the ‘beta‘ stuff at a sufficiently high temp that the starch has gelatinised.

Actually @Buffers brewery I think the way to it would be like this:

1. start out with a fairly thin mash (say 3.5:1) at around 55ºc for ten mins or so
2. decant and reserve a third (or so) of the liquid, which should be rich in beta (and alpha) amylase and limit dextrinase
3. take the remaining mash up to 68-69ºc for 20 mins of good strong alpha amylase action - this should fully gelatinise the starch, and produce a lot of complex (but mostly non-fermentable) sugars
4. let the mash cool down to 60ºc, then add back the reserved liquid - hold at 60ºc for however long you want to process the complex sugars into maltase.
5. mash out.

The problem with such an approach is that while it might give you a mega-fermentable wort, it could also very easily give you a mouth-puckeringly DRY one!

 

[Buffers brewery]

Interesting. If a bit confusing (for me).
I was under the impression that a mash at below 64C produced a highly fermentable wort that would produce an alcoholic but thin dry beer. A mash at above 67C produced a much less fermentable wort that would yield a low(ish) alcohol sweet fuller bodied beer.
On that basis my hypothetical proposal was to mash 80-90% of the grain bill at 63C. Drain the wort and dispose of the grain. Then mash the remaining 10-20% of the grain at 69C. Then combine the 2 worts (a bit like blending wine) for the boil.
A bit of a palaver I know, and it was a hypothetical question, but I was intrigued to find out if anybody knew the ideal ratio of alpha/beta wort.

 

[Bolsover Brewer]

There are a few things to take into account. 5.2 pH is the optimum pH level for the enzymes to work at. Trouble is it isn't a suitable level for most styles, for bitter and IPA I look for 5.4 to 5.5 pH. Also there is not really any need to mash in any lower or doing a stepped mash with modified malts. Most flaked adjuncts are pregelatinised.
The high short mash I go for a longer rest at 63 for an hour and a 30 minute rest at 69 that's just my times they can be shorter.
All in all I mash at between 65 to 68 single infusion for most of my beers 67 probably being the most used.
If you really want to learn about brewing and enzymes, this is a great read.

Brewing by Dr. Michael Lewis and Dr. Tom Young.

 

[The-Engineer-That-Brews]

Interesting. If a bit confusing (for me).
I was under the impression that a mash at below 64C produced a highly fermentable wort that would produce an alcoholic but thin dry beer. A mash at above 67C produced a much less fermentable wort that would yield a low(ish) alcohol sweet fuller bodied beer.
On that basis my hypothetical proposal was to mash 80-90% of the grain bill at 63C. Drain the wort and dispose of the grain. Then mash the remaining 10-20% of the grain at 69C. Then combine the 2 worts (a bit like blending wine) for the boil.
A bit of a palaver I know, and it was a hypothetical question, but I was intrigued to find out if anybody knew the ideal ratio of alpha/beta wort.

@Buffers brewery it’s undoubtedly a huge subject, but fortunately one doesn‘t need to be a biochemist to brew decent beer :-)
Nonetheless I like to dig a bit more into the detail so I have a little more understanding of why what-we-do works... I have found this to be about the right level for me: The Science of Mashing - German brewing and more

 

[Bolsover Brewer]

@Buffers brewery it’s undoubtedly a huge subject, but fortunately one doesn‘t need to be a biochemist to brew decent beer :-)
Nonetheless I like to dig a bit more into the detail so I have a little more understanding of why what-we-do works... I have found this to be about the right level for me: The Science of Mashing - German brewing and more

Here is another article from Braukaiser, a mash that most brewers use professional and home brewers.
https://braukaiser.com/wiki/index.p...ash uses,fermentable sugars that are produced.