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Creation of larger sugars and dextrines from small sugars during mashing

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I just came across something that goes against what we have been told so far about starch conversion in mashing. It seems obvious that glucose chains are only split during mashing and that over time the length of the glucose chains goes down. Narziss and Back mention in Technologie der Würzebereitung that malt does contain transferase enzymes which can fuse glucose and maltose to form dextrins. Now the effect is not dramatic and doesn't really affect our simple model of mashing. But they mention it as one of the reasons why resting the main mash at 145 F for an extended time during a decoction does not affect the fermentability significantly. The other reason is the already diminished b-amylase activity.

I thought that wa interesting. I'll have to see if I can find a reference in English.


Drunk though I may be, I'm curious. How does this mesh with the supposed Miller/Coors mash temps in the 145 range to create a highly fermentable wort? Is the idea that the "extended times" of the decoction rest do not approach the time necessary to break down the chains?

In past batches where I compared a Hochkurz decoction to an equivalent infusion mash I always pulled the decoction after a shorter rest than I was using for the infusion version. My recent Maibock was brewed like this where the infusion version had a 45 min rest at 145 and the decoction version pulled the deciction after 30 min of resting at 45 min. Both batches ended up with about 80% attenuation limit. The decocted version had a slightly higher attenuation limit (maybe by 1%).

I think that there are many factors at play here that make it difficult to state that the rest at 145 F during the decoction processing doesn’t affect fermentability. But it is not such that one has to worry about it that much. Even if it takes a long time it will not dry out your beer. There are also plenty of dextrines that are formed from the starches and long dextrines in the decoction once it is added back to the main mash.

The interesting take-away here was the existence of enzymes that put sugars back together to form dextrines. If you think about it, those enzymes have to exist in the kernel while it is growing since that is how starch is formed. And it is just logical that some of them survive into malt although these are not the enzymes that are formed during germination and their effect on mashing is more of a theoretical and geeky nature than a real practical one.

I searched for “mash transferase enzyme malt” but didn’t find anything useful.


I forgot to mention this. But the existence and activity of these enzymes was also mentioned as one factor why thick mashes don’t necessarily give higher fermentable worts even though the b-amylase is more stable in thick mashes. The latter should cause longer b-amylase activity. But the high sugar concentration causes inhibitory effects and also leads to the re-formation of dextrines through aforementioned enzymes.


So to carry this over into practical brewing where say  a brewer wanted
to produce more food (complex sugars) for a Brettanomyces strain that was to ferment
after a Saccromyces ferment, a brewer should.....uh...uh.....mash at...uh...

___________  _________  _________ (fill blanks please) :-\


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