Inline:Don't want to hijack OP's thread here, but I'm considering a reiterated mash on a big stout. However, everything I've read, I can't find the answers to the questions that I still have...
>1A - splitting evenly by weight but first half is all base and the second half is remaining base + roasted grains.
So you guys do it differently. Why add roasted grains to only one vs splitting in both?1. I split mine evenly this time and that worked for me. Fixed PH on first mash, second won't change it much
I get 1.127 - 1.129 pretty reliably from my stout recipe reiterative mash after the (2 hr) boil. I use a total of 7.5 gal of water (3.3 gal water strike 1, 2.0 gal water sparge 1, 3.3 gal runnings for strike 2, 2.2 gal water sparge 2) and each grain bill is about 12#. I also add about 2# DME after the mash and keep the boil vol over 5.5 gal.I've done several reiterative mashes. Check my posti g history. They are great for attaining high gravity at high efficiency
18# 2-row paleWould you share your base recipe?
Brewers yeast can metabolize sugars made up of one ( glucose, fructose, galactose ), two ( primarily maltose, lactose and sucrose ) and three ( primarily maltotriose and raffinose ) monosaccharide units. Anything larger than that and they can not metabolize them. Thus, carbohydrate units of of 4, 5 ,6 etc monosaccharide units remain in the beer as unfermentables to provide a sweetness, viscosity and elevated final gravity. Mashing at higher temperatures produces more of these larger carbohydrates due to the high temperature activity of alpha amylase. Beta amylase cleaves disaccharides (maltose) off of the end of a starch chain but is active above 140F and denatures rapidly above 160F whereas alpha amylase breaks starches less discriminately leading to higher order saccharides, is most active above 150F does not denature rapidly until you hit 170F.
Every mash I do is a step mash, iterative or not. Starting around 100F (38C) for an acid rest, I raise the temp slowly pausing for a protein rest at 120F (49C) until I get to 142F (61C) where I stay for at least 30 min (optimum beta-amylase activity) before hitting the sweet spot around 153F (67C) where alpha and beta both thrive. After at least another 30 min, I mash out at 158F (70C) which is optimal alpha-amylase activity temperature, then sparge with 170F (77C) water.Did mash rather high, first at 66C second at 68C. But did take that into account. Dark malts have lots of unfermentable sugars, which I also took into account. 8P should have been realistic. Maybe too little yeast? 3 packs of dry yeast should have been enough though.