Snip
By having a low temperature mash (64 to 69) with no mash-out you get a very fermentable wort. I still sparge but only at Top Heat, you get a slightly lower Og and a nice and dry Fg, long mash long boil. Quite a few breweries do this to certain of their beers I have read this on a number of Yorkshire breweries. It gives a certain taste to the beer, which is why I brew, that I like…. putting a few oats in too. Works a treat with some pale Ales and Bitters
I also like beers on the dry side and often mash in the low 60’s for an hour before lifting the malt pipe, sparging with cold water, then recirculating for 10 mins, let the malt pipe drain and then boil. I’ve done a lot of beers this way and haven’t noticed any downside that I’m aware of.
Fundamentally doesn't make any sense at all. Don't take offence but I'm pretty sure there is something wrong with the thinking that got you to this point. If its something you have read please tell me where I for one would like to know where this is coming from.
Ok you want dryer beer, no problem you can get apparent attenuations >100% with a fairly intensive mash regime.
The two main enzymes Alpha and Beta Amylase aren't the only ones that will be playing a role, there is at least one Protease and a type of Glucanase that can both still be slightly active up to the Beta peak around 62-63oC. They aren't going to be making a huge difference to your beer but might be thinning it out a bit.
Mostly we need to look at the Amylases
About the driest beer you can make would come from something like a 120 minute mash at the beta peak, problem is you would probably have a fair amount of unconverted starch and there is a very good chance that you would have a blue wort (not normal to iodine) you would know because when you start the boil it will foam like a mad thing.
The one thing that may help you is that there is a lot of Alpha Amylase in the wort and as you heat to a boil it will act on the starch, if you are heating fairly slowly (<say 0.5-0.75oC/Minute) it will have time to degrade most of the starch. Wont help with your yield though, that's guarantied to be lower than expected.
Mash at a compromise temperature usually that 65-67oC and you get enough Alpha activity to provide more sites for the beta to act on and its not so hot that the beta is all killed of before it does its work.
Two points that may help.
Once starch is degraded into fermentable sugars, you cant undo that later in the mash. Means if you do a reasonably long cool mash that fermentable sugar will still be in the wort, so a step up in temperature wont mean less fermentable sugars.
Second is that Alpha Amylase can and will make fermentable sugars to. A long mash at Alpha peak will not only degrade all the soluble starch giving a higher yield but will make more both fermentable and non fermentable sugars.
OK the wort in total will be a bit less fermentable but if you aren't making extra dry you really don't want an FG under 1.000
I think you will get more of better beer if you do a step mash. Apart from the fact that there is more extract the hotter your wort is (<80oC) the more fluid it so the faster and cleaner it drains and sparges. The same applies all the way to the boiling point its just that over 80oC its hard to control the extraction of husk tannins.
I suspect that you are flirting with one group of problems to avoid another, the better answer is to understand both and take the benefits of each while ducking the problems they can cause.
Mark
The article linked by WEAL is good
As is this one