I'm thinking that your last rest should have been in the alpha-amylase temp range (154-162 per http://www.howtobrew.com/section3/chapter14-1.html), which is in line with Greg Doss's presentation re single infusion mashes.
I did hold a 45 min rest at 161 F as well. I did not mention it since it was not a rest for fermentability.
I think the mash schedule I used was fine. The optimum numbers you have are for single infusion rests. With step mashes the mechanics are a bit different and one can get even better fermentability though rests are lower temps before the mash is brought to the higher temps.
I finally tasted uncarbonated samples of the beers and wrote about it on my blog:
http://braukaiser.com/blog/blog/2012/09/16/enzymes-in-the-fermenter/Excerpt:
I also got an opportunity to measure the current extract and pH. Most importantly I was able to taste uncarbonated samples. Here are the stats:
--(I don't know how to do tables in posts. This layout is messed up) ---
control malt extract Beano
corrected starting extract 17.8 17.7 17.7 Plato
days fermented 9 9 9 days
Final extract 4.3 2.5 2.2 Plato
ADF 75.9% 85.9% 87.6%
pH 4.48 4.4 4.35
As expected the addition of enzymes boosted attenuation. Beano seems to digest more dextins than a malt extract. I wonder to what extent the difference is caused by limit dextrins (1-6 glucose links), which can only be broken by limit dextrinase, an enzyme which likely did not survive the 30 min mash at 60 C. Beano’s glucoamylase is likely able to cleave both the 1-4 and the 1-6 links found in starch leaving only glucose and no limit dextrins.
It was surprising, however, that even with enzyme use during fermentation the apparent attenuation stayed in the mid 80′s. This suggests that the low wort fermentability may not have been the result of incomplete starch and dextrin break-down during the mash. After all, I was going for very fermentable wort and held 30 min rests at 55 C, 63 C and 65 C followed by a 45 min rest at 72 C. I was expecting to get an attenuation limit in the high 80′s with this mash schedule.
So much for the metrics, here are some brief tasting notes:
control: No noticeable off flavors. While this was a Weissbier yeast, it is a yeast that produces only limited amounts of phenolics. The mouthfeel is rather thick and the beer does not have the refreshing IPA character that I was going for
enzymatic malt extract: No off flavors. Whatever surviving microbes came in from the malt did not take hold and spoil the beer. I’ll have to see how this develops as the beer sits in the bottle for a month. The mouthfeel was much lighter and more easy drinking than the control. This was the taste I was shooting for.
Beano: No off flavors either. The mouthfeel was even lighter than the malt extract version. But it was not the dreaded “rocket fuel” that others have gotten from Beano before. I think this version felt a bit too thin in its taste, though. I’ll have to defer to tasting a carbonated sample.
Topic: surprisingly low wort fermentability (Read 6096 times)
