Skimming Out Barms: Is That A Legitimate Way To Lower Attenuation?

[madscientist451]

That's a pretty high mash temp, will be looking forward to hearing about how it turns out.

 

[Knox]

Got 80% mash efficiency and the weirdest wort I've ever produced: thick, murky and completely devoid of sweetness, 1.033 OG to fermenter.

The murky part sounds like a lot of starches were left in the finished wort. A way to getting them to floc is to simply boil some more. As for your lack of sweetness, what was your cold wort volume?

Because 1.033 in 5ls tastes very different from 1.033 in 20ls.

 

[DBhomebrew]

As for your lack of sweetness, what was your cold wort volume?

Because 1.033 in 5ls tastes very different from 1.033 in 20ls.

Huh?

 

[Knox]

Huh?

Sorry for not being clear.
Sweetness has a threshold before being detectable, I don't remember the total amount. But when I was taking my brewing course we had to taste to worts with the same gravity but made in various batch sizes. This was to illustrate that you can't simply scale a recipe 20x one or the other way, as the wort you will get will taste different from your reference. I found this exercise very useful, but it is probably more variable the larger you go in the business.

I hope that clears it out.

 

[DBhomebrew]

I hope that clears it out.

Not at all.

 

[bracconiere]

i'd do a seperate mash with flaked barley, maybe toasted though, with just alpha amylase added....mix em...just don't drink too much!

 

[bracconiere]

Huh?

i might be way off here, but it's like BMI? it depends how tall the fermenter is?

 

[Protos]

The murky part sounds like a lot of starches were left in the finished wort. A way to getting them to floc is to simply boil some more. As for your lack of sweetness, what was your cold wort volume?
Because 1.033 in 5ls tastes very different from 1.033 in 20ls.

The cold wort volume was 5 L, but I'm comparing its taste to the taste of worts of exactly the same gravity and volume - f. ex. a 5L batch of 1.033 Grätzer I brewed just recently, a 6L batch of 1.032 Grisette I made in autumn, or a 5L batch of 1.032 English Mild of the last spring. Being thin, they weren't particularly sweet either, but this one is significantly less sweet than those three worts.

Currently I'm somewhat concerned about that after a week in primary the beer still shows signs of active fermentation (the yeast is M10 Workhorse, a strain close to S-33). My other extra-low-gravity beers usualy calm down at the day 3 or 4. Knowing that this kind of low-gravity starchy wort is particularly succeptible to infection, I went nuclear with sanitation, using peroxyacetic solution. I don't dare to open and check gravity to not introduce airborne bugs.

 

[Knox]

The cold wort volume was 5 L, but I'm comparing its taste to the taste of worts of exactly the same gravity and volume - f. ex. a 5L batch of 1.033 Grätzer I brewed just recently, a 6L batch of 1.032 Grisette I made in autumn, or a 5L batch of 1.032 English Mild of the last spring. Being thin, they weren't particularly sweet either, but this one is significantly less sweet than those three worts.

Currently I'm somewhat concerned about that after a week in primary the beer still shows signs of active fermentation (the yeast is M10 Workhorse, a strain close to S-33). My other extra-low-gravity beers usualy calm down at the day 3 or 4. Knowing that this kind of low-gravity starchy wort is particularly succeptible to infection, I went nuclear with sanitation, using peroxyacetic solution. I don't dare to open and check gravity to not introduce airborne bugs.

I would give your fermenting wort a taste. See if some funky bugs decided to live in it and if the raw wort flavour has gone away. Because if it hasn't the yeasts are probably experiencing a hard time fermenting the wort as it stays very dense as they move around in it.

I wouldn't be too scared of infection tbh. If you at least had some isomerization from hops, lactic acid bacteria wont spoil it right away. The beer is producing carbon dioxide to protect it from acetic bacteria. So take a gravity reading, just stray your equipment with some alcohol sanitizer and you will be fine.

 

[Protos]

Thanks for encouragement! Well, I went to check the gravity.

From one side, the beer is fine: although it's a bit more tart than I'd enjoy, it definitely doesn't show signs of acetic or diastatic infection, which sometimes taint my brews. It has some hint of a flavour completely new to me, I'd call it "rustic", "wood-like" or "hay-like", it's not unpleasant and I think it's the flavour of unconverted starches (the beer is still murky and opaque).

From another side, I failed to get the desired attenuation of 30%: the gravity went down from 1.033 to 1.012, which gives a 2.75% Alc. content instead of 1.26% in the recipe and a pretty standard for this strain attenuation of 63%. With this yeast, I'd get same attenuation with mashing at 70C, so mashing at the super-high temp turned out to be pointless.

I decided to let it sit in the fermenter as long as it takes for the starches to settle, at least partly. Might transfer it to a secondary for a prolonged lagering, will see in a week.

 

[dmtaylor]

It has some hint of a flavour completely new to me, I'd call it "rustic", "wood-like" or "hay-like", it's not unpleasant and I think it's the flavour of unconverted starches (the beer is still murky and opaque).

Starch is flavorless. Sounds more like husk compounds and perhaps tannins and/or tannic acid.

Interesting that the hot mash still gives normal attenuation. More fuel for hypotheses that mash temperature might just not matter as much as people think! At least with respect to low attenuators like M10 / S-33 / London, and their close relatives Windsor / M15 / Munton's.

 

[Protos]

I doubt the woody flavour might come from the husks: I know husk flavour well as I have very hard and alkaline tap water and prior to starting modifying it I experienced a lot of problems exactly because of its interaction with husks.
The water I used this time had been decarbonated by slaked lime, but not acidified so it had quite a high pH. That's probably what made my Hvidtøl a bit more tart than I expected. However, I find zero familiar husk flavour in it. The woody note is completely new to me, I've never experienced one before as I've never had fermented an underconverted wort. So I suspect it to be an impact of starch, as the beer has a plenty of it still in suspension.

It may be also me being a bit too quick to assume it was exactly the Workhorse that was responsible for the 63% attenuation. I better wait for 1 to 2 weeks more and see where the fermentation proceeds. If attenuation keeps going down, the overattenuation (not really yet, but who knows where it is in a week) and the woody flavour may well be from some bug, happily munching on unconverted starches.