fermentation speed

[tehnick]

I recently started doing all grain brewing instead of extract brewing and maybe I'm crazy, but it seems like my all grain brews ferment quicker than the extract ones. I generally use 1056 for most of it other than wits and others that require specific yeast styles. I'm also pretty lazy when it comes to making starters and haven't really made many but generally have good luck by pitching a fully swollen smack pack.

Sunday I pitched at around 9pm and noticed krausen had fallen on Wednesday. Took a gravity reading and I'm down to 1.016 from 1.062. Not bad for three days. Temps were mid 70s. I racked to secondary last night and the airlock is pretty inactive. I'd think it would finish around 1.012 or 1.011 but maybe not?

Anyone else notice this or am I drunk and crazy?

 

[Hex23]

Sounds like you may be basing this on one batch? I don't think there is any reason at all for extract or AG to ferment faster, all else equal. I'd look to other factors which could differ: aeration, yeast health/age, ferm temp, etc.

 

[tehnick]

It's been about 5 batches. They all have finished way quicker compared to the extract ones. I also notice there's less krausen residue lining the fermenter but the beer ferments just fine. I've yet to ferment in a glass carboy so I'm doing that soon to get more visuals of progress. Right now I have a couple 8 gallon buckets that I've been using for primary.

I could just be crazy. I've been doing basic amber and pale ales to get the technique dialed in so I'm not brewing anything too bold or daring yet.

 

[tehnick]

Yeast health is also fine. I live in Portland and have access to very fresh packages of wyeast. Manufacture date is 6/13/13 so probably 90%+ viability. Ferm temp was around 74-75. Probably going to start fermenting in the basement soon to get cooler temps since summer temps are going to affect it in the house very soon.

Also double checked beer smith and it says 1.015 for FG so it looks like it's done and ready to bottle after clearing. Will probably cold crash soon. Doing a light dry hop.

 

[tehnick]

Read this today via the Beer Smith site:

"Beers made with malt extract will tend to ferment slower and finish at a higher gravity than corresponding all-grain beers. This is due to a variety of factors including the presence of unfermentable dextrins from the concentrating process, the lack of free nitrogen in extract malt needed for yeasts, and the potential for oxidization of the malt for malts stored for an extended period."

Guess I wasn't crazy lol.

 

[Hex23]

Sorry ... I'd need something more scientific to believe it.

I think the quote is mostly conventional thinking that has some logical explanation attached to it. At best it's an over-generalization. Heck, I even got called out once for perpetuating the higher gravity part of it: https://www.homebrewtalk.com/f39/2-batches-2-problems-265687/

I'd buy it if an experiment were run to prove it. I think it would have to be an experiment where you took half the mash and dehydrated it to an extract, then used that to build a second beer. The first half of the mash would be used to make a first beer. They'd have to be fermented under the same conditions. Unfortunately this would be hard to do on a home-brew level since the dehydration part is complicated.

As far as the aging explanation, it sort of makes sense, but do the fermentable sugars really oxidize into something not fermentable? Was your extract old?

 

[tehnick]

Extract was fresh. When the extract is made the process destroys the available nitrogen in the syrup. You don't get that with pure grain as it hasn't been processed and boiled down into concentrate. Fermentable sugars are still there, but they will ferment slower with less nitrogen available in the wort. Not sure what scientific proof you want, as I found John Palmer and other credited writers say the same thing too. I'm not a chemistry major so you're not going to get a detailed explanation from me other than reading multiple people saying the same thing who have done the research and have the background.

All I can say is my all grain brews ferment completely in 3-5 days. My extract brews usually took 7-10. I keep detailed brewing notes to keep as consistent as I can.

 

[Hex23]

So, while I did not read the article (just the abstract), this seems like the kind of scientific study that would be more convincing: http://www.asbcnet.org/journal/abstracts/backissues/49-03.htm

Unfortunately the worts don't seem to have the same origin, and the study is pretty old. I thought that many modern extract companies had addressed FAN problems.

 

[tehnick]

From what I understand, the process of boiling down to concentrated syrup kills the available nitrogen, which is not the issue with all grain. It will still ferment, just slower. Oh well.