What Percentage of Oatmeal in Grist?

[eddetchon]

thanks Aleman. I have often done a glucanase rest in the past - albeit when using flaked barley rather than oats, because i was getting head retention issues, though that could have been pH probs too - so no problem doing that. one thing i've always been curious about though. is there any enzymes left in pale ale malt to make it worth doing a glucanase rest? my understanding is that there certainly isn't any left for, say, doing a more conventional protein rest (say in a wheat beer), so wouldn't the same processes that have destroyed those enzymes have destroyed the ones for breaking down beta-glucans? because of this issue I have been wondering about using pils malt instead, which certainly does have the relevant enzymes.....i've used it with good success in stouts before.

and also - isn't the point of an oatmeal stout to have that silky mouthfeel and isn't running a glucan rest just destroying the very things you are putting oats into the grist to obtain?

for what it is worth, the durden park method (2nd edition as noted above) doesn't include a low rest. it just recommends soaking the oats in boiling water for 10 minutes prior to mashing (for 4 hours total!!). i'm anticipating a long and possibly problematic lauter, but then on the day i do it i will be off work and not mind a lengthy process.

[Aleman]

one thing i've always been curious about though. is there any enzymes left in pale ale malt to make it worth doing a glucanase rest? my understanding is that there certainly isn't any left for, say, doing a more conventional protein rest (say in a wheat beer), so wouldn't the same processes that have destroyed those enzymes have destroyed the ones for breaking down beta-glucans?

None of the enzymes are destroyed in the malting process, the reason no protein rest is required is that the malt is fully modified these days, and the protein degradation takes place during malting . . . doing a further protein rest while mashing really thins the beer out . . . . and thats even the case with German/Czech Pils malt. There used to be a supplier of Czech Moravian Malt that was under modified and required decoction . . . but sadly no longer available.

isn't the point of an oatmeal stout to have that silky mouth feel and isn't running a glucan rest just destroying the very things you are putting oats into the grist to obtain?/

Its not the glucans that provide that silky mouth feel, breaking the glucans down into smaller fragments aids lauter, and improved head retention

for what it is worth, the durden park method (2nd edition as noted above) doesn't include a low rest. it just recommends soaking the oats in boiling water for 10 minutes prior to mashing (for 4 hours total!!). i'm anticipating a long and possibly problematic lauter, but then on the day i do it i will be off work and not mind a lengthy process.

I can't comment on the Durden Park method other than to say that without a glucan rest I suspect that the lauter would be extended, I certainly wouldn't use that amount of oats without a glucan rest.

[eddetchon]

resurrecting something from a few weeks ago.

well, for what it's worth, i did this oatmeal stout yesterday, all 1.5kgs of rolled oats with 2.5kg pale, 250g amber, 500g black, and despite lack of glucan rest, the sparge was absolutely normal. maybe that 3 hr + 1hr mash really did do the trick. it left a lovely layer of protein material on top of the grain bed when i had stopped sparging, but didn't even threaten to stick. sparge took 40mins and i ended up with OG 1055 instead of recipe predicted 1046. superb!

should be a winner if anyone is half thinking of doing it (not that you probably are, heading into summer over there.....but in 3 days here in new zealand it is winter....)