Overnight mashing. I may have been wrong!

[Duxuk]

I have overnight mashed for quite a few years. It makes for a shorter brew day and I have always believed that efficiency improved.
Today I decided to brew without having mashed last night.
My efficiency was at the top end of my usual range, which surprised me. It took about 75 minutes longer today but I saved the 20 minutes last night. I had some breakfast during my 100 minute mash, which could have been shorter.
All told, then, I saved no significant time and got the same value from my ingredients. My previous theory may well be wrong!
Still, I'm only 126 AG brews in so it may just be my inexperience.
What do other overnighters think?

 

[peebee]

I don't mash over-night. But if I did it would be because it suits how I manage my time, not to improve efficiency. The mash temperatures we use are a compromise between getting the job done quickly and retaining sufficient active enzymes to complete the job. The commonly used temperature of 66C is quite hot enough to knock out beta-amylase, but at that temperature what is surviving it is racing along converting complex sugars into maltose. After a couple of hours there isn't much beta-amylase left.

Alpha-amylase is tougher, but also much quicker. After two hours it has long done its job of breaking up starch into long-chain complex sugars. It will continue to work longer than beta-amylase but is only chopping complex sugars into slightly less-complex sugars.

Mashing longer (over-night) might very slightly alter the proportion of maltose to complex sugars, but probably not by a noticeable amount.



Does that answer make me "experienced"? I think advanced age might make me "experienced", but I only began to appreciate what I've written above quite recently.

 

[Duxuk]

Yes, the efficiency is not important. The time saving is useful. As above I don't think there's much of an overall time saving but it's useful for me to finish early to walk the dog.
One thing I do feel certain about is that overnight mashing gives a drier beer. This can be counteracted by using a higher initial mash temperature.

 

[peebee]

Hum. My explanation does pose a bit of a question though. Many of the "facts" behind what I said are dragged up from "A"-level Biology which I did rather along time ago: Animal enzymes have evolved to work best at "body temperature" whereas there is no such constraint on plant enzymes so they keep working faster and faster until the enzyme gets too hot and is destroyed. Where does that leave enzymes in cold-blooded creatures?

But I got a criticism recently for bandying about this info because some plant enzymes will start working optimally again if cooled (i.e. they haven't been destroyed). Is that right? So plant amylase enzymes are destroyed at about optimum performance because "optimum" has it sailing too close to the wind?

Doesn't matter, as far as amylases are concerned my explanation will do. Just keep in mind my explanation could be a bit too simplistic and may not apply too well to other plant enzymes.

… overnight mashing gives a drier beer ...

Quite possible, because the alpha amylase will keep going a bit longer. You probably wouldn't notice this so much (at all?) with a low attenuating yeast - i.e. one that won't ferment the complex sugars anyway.

Which makes me think: Does alpha-amylase give up the job when it cuts sugars down to three carbon strings (malt-triose) or will it keep going to produce maltose like beta-amylase? If the latter over-night mashing would increase efficiency - or more accurately a more fermentable wort. Probably not important if either way - but it keeps the brain-cells happy mulling over such things. Why don't these amylases produce glucose by chopping up maltose? … (stop it, I get the impression I need a life! I'll go downstairs and finish off that DIY I started - modifications to the brewery! … tum-tee-tum ...)

 

[IainM]

Hum. My explanation does pose a bit of a question though. Many of the "facts" behind what I said are dragged up from "A"-level Biology which I did rather along time ago: Animal enzymes have evolved to work best at "body temperature" whereas there is no such constraint on plant enzymes so they keep working faster and faster until the enzyme gets too hot and is destroyed. Where does that leave enzymes in cold-blooded creatures?

But I got a criticism recently for bandying about this info because some plant enzymes will start working optimally again if cooled (i.e. they haven't been destroyed). Is that right? So plant amylase enzymes are destroyed at about optimum performance because "optimum" has it sailing too close to the wind?

It just so happens that I work at the interface between protein chemistry and evolution! An enzyme work by binding to a substrate and lowering the energy barrier needed to be passed in order for the substrate to turn into the product, then letting go of it. The more thermal energy there is (i.e. higher temperature), the more likely the substrate is to pass the barrier and get converted. Plus, the faster the substrate diffuses to the binding site, and the quicker the product is let go, freeing up the enzyme to convert another molecule. This is more than enough to counter the fact that the enzyme isn't as good at clinging on to the substrate at higher temps. So, higher temp yields more turnover, in general. However, the enzyme itself also responds to higher temperature, eventually unfolding and losing its function altogether. For most enzymes, as long as they don't get so hot they cross-react irreversibly with other things or themselves, or get caught up in amorphous aggregates, then they can refold when the temp comes down again, because of something called Anfinsen's dogma. Evolution acts only on temperatures that the organism encounters. For humans that is a pretty narrow range, while for plants, bacteria, yeast, fungi and cold-blooded creatures, it's generally a lot wider. As the protein hasn't evolved to behave in a specific way when it's outside of that temperature, what happens is somewhat random, within what is possible by protein chemistry. 60C is certainly outside of what barley or it's ancestors ever experienced frequently enough for it's behaviour at that temp to be subject to natural selection. The protein may retain some residual activity, and that may go up or down with increasing temperature depending on how perturbed by thermal energy the part that grabs onto the substrate gets. Eventually, it will unfold, cross-react and lose function, but again the point at which that happens depends on how that particular protein sequence just so happens to behave when at a temperature it wasn't evolved to deal with. The fact that alpha and beta amylase respond the way they do is down to the happenstance of nature.

 

[peebee]

It just so happens that I work at the interface between protein chemistry and evolution! ...

Thanks very much. It'll take me a while to digest that but I get the gist of what you're saying.

You realise you've just branded yourself as a "geek" with everyone else who reads this. I might just get away with that fate 'cos nearly everyone has by now already got me branded as a loony anyway.

It will make @Likbas happy if he reads this; it was him trying to put me straight relaying my more simplistic view.

 

[The Baron]

I only do overnight mashes to save time the next day and have never done it to improve efficiency. It is good as long as used for time saving the next day so that most brews can be completed before lunch the next day.

 

[IainM]

You realise you've just branded yourself as a "geek" with everyone else who reads this.

Completely fine by me.

 

[Duxuk]

I'll be interested to see the effect, if any, on the finished brew. If the last brew is better I will accept a slightly later finish. The dog will just have to accept it.

 

[Duxuk]

Freddie asking for a walk. He doesn’t care if a long mash breaks down long chain unfermentables into shorter fermentable sugars. He does, however, quite like licking a drop of the finished beer off my finger, unlike my last dog who wouldn’t touch it.