I think I am doing something wrong

[TippHillBC]

I have done three AG brews and it looks like this is the 2nd out of 3 to not hit my F.G. My first was a big double IPA which I evidently should have used a starter. Didnt know anything about starters so i chalk it up to being new. Second beer came out fine. This one I brewed on Labor Day started fine but now has me worried so here goes. This is a Pumpkin Ale. I grew some pumpkins in my yard and wanted to used them in a beer. I found a recipe & here is what it calls for:


13.5 lbs American 2 row
0.75 lbs 40L Crystal
0.75 lbs wheat malt
6-10 lbs roasted pumpkin (mine was about 7.5 after roasting)
1 cup brown sugar

1.5 oz mt hood
Wyeast 1272 ( i made a starter which was about 1 L 40hrs prior to pitching)

My mash was good at around 152 for an hour and I got an OG of 1.060

Here 9 days later my SG is 1.024. The author of he recipe hit 1.008 but i wouldve been ok with anything from 1.010-1.015.

So, my question is does anyone see anything that may have happened here? It started bubbling like crazy 12 hrs later and slowed to a halt about 3 days later. Tonight i did stir up the batch (no bubbles) and added a yeast energizer hoping this could fire it up again. I guess i'll see in the morning. Thanks for any advice in advance.

 

[dysphoria]

Couple questions for you -

How do you typically aerate your wort before pitching?

What temp were you fermenting at?

I had a lot of issues with under attenuated beers when I first got going, and my issues were actually three fold - under pitching(massively), poorly aerated wort, and higher fermentation temps. I'd end up a good 10 points off from where I wanted to be and it was pretty dang frustrating, so I feel ya.

At 9 days out, if your gravity has been static we can probably assume primary fermentation has stopped. I've not had great luck repitching with liquid yeasts, but the neutral dry yeasts seem to get the job done (S-04 and US-05 are a couple I've had success with). Maybe some others will have suggestions as well.

 

[Prof_Chaos]

I have had good luck pitching some San Diego super yeast from white labs. Ferments fast and has extremely high attenuation and can handle a higher temp. If you are temp controlling you could try letting it rise a bit say to 74 that can get you a few extra points on the hydrometer.

Hope that helps

 

[TippHillBC]

Couple questions for you -

How do you typically aerate your wort before pitching?

What temp were you fermenting at?

I had a lot of issues with under attenuated beers when I first got going, and my issues were actually three fold - under pitching(massively), poorly aerated wort, and higher fermentation temps. I'd end up a good 10 points off from where I wanted to be and it was pretty dang frustrating, so I feel ya.

At 9 days out, if your gravity has been static we can probably assume primary fermentation has stopped. I've not had great luck repitching with liquid yeasts, but the neutral dry yeasts seem to get the job done (S-04 and US-05 are a couple I've had success with). Maybe some others will have suggestions as well.

I aerate by pouring my wort into the primary. i thought that it would mix it up good that way and it bubbles a lot. pretty much thats it.

My temp is rignt now around 72...ish. Its in my basement. this time of year the basement is around 72 and in winter gets to 68. Thats my temp control.

 

[junior]

This is what I do to achieve good attenuation with OG ales.1066-1.070. I mash between 145-150. I use 2Lt starter of washed yeast or two packages of (05/Notty), aerate with o2 before pitching yeast, then aerate once a day for two days during high krusen. I ferment between 63-65F. Once the krusen drops I then roll carboy and let the it go to room temperature for a total of 30 days. With this schedule I have been achieving between 80-86% attenuation. Hope this helps.

 

[dysphoria]

I aerate by pouring my wort into the primary. i thought that it would mix it up good that way and it bubbles a lot. pretty much thats it.

My temp is rignt now around 72...ish. Its in my basement. this time of year the basement is around 72 and in winter gets to 68. Thats my temp control.

So, not pouring back and forth, just straight into primary? No shaking, whisking, etc? If so, under aeration could be part of why the yeast stalled out. They need a good bit of oxygen to do their work properly. Not-enough, and the yeast will stop growing as they can only produce sterols and fatty acids(necessary for cell wall growth) in the presence of oxygen.

All the suggestions by junior are also good stuff. Mashing in at a lower temperature will generally give you a more fermentable wort; however, I think 152 is low enough not to end up with a dextrinous(less fermentable) wort. I usually mash in at between 150-154 depending on the style of beer I am making.

I tend to aerate at pitch (with o2) and then again 24 hours after pitching. I also use a starter culture. I have started using Wyeast nutrient blend which seems to have greatly helped keep my attenuation consistent -though definitely not 100% necessary to get good attenuation.

Your temps are a little on the high side, but I've made perfectly good beer(albeit estery) at higher temps.

 

[causeimthesquid]

So, not pouring back and forth, just straight into primary? No shaking, whisking, etc? If so, under aeration could be part of why the yeast stalled out. They need a good bit of oxygen to do their work properly. Not-enough, and the yeast will stop growing as they can only produce sterols and fatty acids(necessary for cell wall growth) in the presence of oxygen.

Unless you are going to put oxygen in through a diffusion stone, you don't need to shake as much as you think. After about 45 seconds you will have maximized how much oxygen your wort will be able to hold in solution from ambient air.

 

[Demus]

Unless you are going to put oxygen in through a diffusion stone, you don't need to shake as much as you think. After about 45 seconds you will have maximized how much oxygen your wort will be able to hold in solution from ambient air.

This is not correct. Boiled wort has effectively 0 oxygen present, and air is about 8 ppm. For average strength beers 8 to 10 ppm is best, higher is needed for bigger beers (1.080+). In the book 'Yeast' (a must read IMO), they did a test on oxygen levels on 1.077 wort. 5 full minutes of the standard shake and splash they only measured 2.7 ppm oxygen level! (Page 79) So, to get to the maximum oxygen level possible with ambient air you'd have shake or pour back and forth WAY longer than 45 seconds, probably 10 minutes or more. Wine whisks on electric drills can speed the process some but you can still never get above 8ppm. I believe this, more than any other single variable is what leads to fermentation problems among home brewers.

By the way, just :60 seconds of pure o2 in the same study resulted in 9.2 ppm dissolved oxygen. That's a pretty big selling point for oxygen injection.

By the way, back to the original poster, how did you use the pumpkin? Depending on when you used it in your process could influence the fermentability of your wort...

 

[dysphoria]

I believe this, more than any other single variable is what leads to fermentation problems among home brewers.

+1
I've even seen some information and videos from Wyeast that confirm what was said above about shaking vs oxygen.
The only difference was that they were able to achieve a saturation of ~8 ppm by shaking the carboy *vigorously*. They were able to get ~12ppm with 60 seconds of pure oxygen.

Check this: http://www.wyeastlab.com/hb_oxygenation.cfm

Moving to oxygen alone was a huge jump in fermentation performance over shaking for me. Besides, who wants to shake a 5 gallon batch, which equates to ~40 lbs(considerably more if you have a glass carboy) even for 45 seconds? Not to mention possibly dropping the carboy if it's glass.

 

[fmr_army]

I'll add my personal testimony on O2 leading to better fermentation. Same recipe, same yeast, same fermentation times for three batches (all about 1.060 OG) over the past few months:

1) batch with aeration and aquarium pump dropped to about 1.020, with a decent kreuzen after a lag of about 24 hours

2) batch with a quick (30 seconds), hard blast of O2 though the difusion stone dropped to about 1.015 FG, with good solid kreuzen and minimal (8-12 hours) lag

3) batch with a 60 second, soft shot of O2 (I tried to minimize the number of bubbles at the surface) dropped to 1.008 FG, massive fermentation after only a couple hours of lag​

Not perfectly scientific, but good enough to convince me to oxygenate my wort from now on!

 

[TippHillBC]

This is not correct. Boiled wort has effectively 0 oxygen present, and air is about 8 ppm. For average strength beers 8 to 10 ppm is best, higher is needed for bigger beers (1.080+). In the book 'Yeast' (a must read IMO), they did a test on oxygen levels on 1.077 wort. 5 full minutes of the standard shake and splash they only measured 2.7 ppm oxygen level! (Page 79) So, to get to the maximum oxygen level possible with ambient air you'd have shake or pour back and forth WAY longer than 45 seconds, probably 10 minutes or more. Wine whisks on electric drills can speed the process some but you can still never get above 8ppm. I believe this, more than any other single variable is what leads to fermentation problems among home brewers.

By the way, just :60 seconds of pure o2 in the same study resulted in 9.2 ppm dissolved oxygen. That's a pretty big selling point for oxygen injection.

By the way, back to the original poster, how did you use the pumpkin? Depending on when you used it in your process could influence the fermentability of your wort...

Well it sounds like the oxygenation is where I got hit. I will research the oxygenation process & what works best.

As far as the pumpkin, I roasted it until soft and carmelized on the edges and then added in with the mash. I had done a partial mash doing the same thing last year and I hit my numbers, so I am assuming it wasnt the pumpkin. This time around I used a starter for my yeast it looks like I under oxygenated..maybe in both cases.

 

[TippHillBC]

I'll add my personal testimony on O2 leading to better fermentation. Same recipe, same yeast, same fermentation times for three batches (all about 1.060 OG) over the past few months:

1) batch with aeration and aquarium pump dropped to about 1.020, with a decent kreuzen after a lag of about 24 hours

2) batch with a quick (30 seconds), hard blast of O2 though the difusion stone dropped to about 1.015 FG, with good solid kreuzen and minimal (8-12 hours) lag

3) batch with a 60 second, soft shot of O2 (I tried to minimize the number of bubbles at the surface) dropped to 1.008 FG, massive fermentation after only a couple hours of lag​

Not perfectly scientific, but good enough to convince me to oxygenate my wort from now on!

when I was doing extracts I never had this problem. I pretty much hit my desired gravities oxygenating the same way I do now....weird.

Oh and what the hell is a diffusion stone. I swear everytime I think I have AG figured out I get thrown another curve ball.

 

[TippHillBC]

Moving forward what should I do? Get some champagne yeast & aerate to kick up fermentation again?

 

[fmr_army]

A diffusion stone is the little doohickey that goes on the end of an air tube to make little bitty bubbles. You can get them at brew stores or a pet store.

I have this one: http://www.petsmart.com/product/index.jsp?productId=2752197&f=PAD/psNotAvailInUS/No

 

[TippHillBC]

A diffusion stone is the little doohickey that goes on the end of an air tube to make little bitty bubbles. You can get them at brew stores or a pet store.

I have this one: http://www.petsmart.com/product/index.jsp?productId=2752197&f=PAD/psNotAvailInUS/No

Oh man, thats it!! For fish tanks right? Awesome, I was thinking it was some expensive piece of equipment. I'll get one for my next brew & use it. Can i use it for this one now though? Ive read where O2 would actually hurt at this point.

 

[ballsy]

Just b/c it has not been asked yet, I'm interested...please take no offense. Are you certain your fermentation is "stuck"? Have you obtained 2 SG readings three days apart which both measured 1.024? I have had SG continue to lower even after 3.5 weeks in the fermenter....

 

[dysphoria]

In regards to restarting fermentation - I generally see several recommendations, two of which I have personally tried with some success.

1. Rouse yeast frequently(sounds like you've done this already)
2. Repitch some dry yeast (S-04, US-05, Notty, any of the hearty strains)
3. Gently rack on to an active yeast cake - haven't tried this but some have reported success with this.

I am always weary of aeration this late in fermentation due to potential oxidation, but I suppose if you don't over do it you'll probably be ok.

 

[TippHillBC]

Just b/c it has not been asked yet, I'm interested...please take no offense. Are you certain your fermentation is "stuck"? Have you obtained 2 SG readings three days apart which both measured 1.024? I have had SG continue to lower even after 3.5 weeks in the fermenter....

no offense taken abd unfortunately yes. took one Mon/Tues/last night...all 1.024

 

[causeimthesquid]

This is not correct. Boiled wort has effectively 0 oxygen present, and air is about 8 ppm. For average strength beers 8 to 10 ppm is best, higher is needed for bigger beers (1.080+). In the book 'Yeast' (a must read IMO), they did a test on oxygen levels on 1.077 wort. 5 full minutes of the standard shake and splash they only measured 2.7 ppm oxygen level! (Page 79) So, to get to the maximum oxygen level possible with ambient air you'd have shake or pour back and forth WAY longer than 45 seconds, probably 10 minutes or more. Wine whisks on electric drills can speed the process some but you can still never get above 8ppm. I believe this, more than any other single variable is what leads to fermentation problems among home brewers.

By the way, just :60 seconds of pure o2 in the same study resulted in 9.2 ppm dissolved oxygen. That's a pretty big selling point for oxygen injection.

Not sure where you came up with those figures. I know you credit White and Zanishef's "Yeast", but that is counter to what Neva Parker from White Labs stated here (https://www.youtube.com/watch?v=2vELwUsBmWQ&list=PLgOVeEqw5B8MkKdSZVKMHWdWpxNqn3uRv)

Also, air is 20.9% O2 at sea level - I don't know where you got the 8ppm figure from. That may be your maximum solubilty using 20.9% oxygen. As for time to achieve that, you see rapid diminishing returns based upon your time shaking. More important than shaking would be surface area, or exposure to air. Pouring into a container does more to aerate the wort than just shaking a carboy.

More importantly though is the only reason you are adding oxygen is to promote aerobic metabolism by the yeast, resulting in cellular reproduction. Its much easier to compensate for this by increasing your pitching rate than to go through the hassel of getting an O2 tank and diffusion stone.

I highly doubt oxygenation had anything to do with the OP issues.

 

[dysphoria]

~8 ppm was observed by Wyeast during testing of various methods with a dissolved oxygen meter. I've seen similar numbers from Whitelabs as well, but I can't find the source atm.

Maximum oxygen solubility in water at atmospheric pressure from normal air at 77F comes in right around ~8.9 ppm.

This can be calculated using Henry's Law - check the following site for the formulas:
http://www.engineeringtoolbox.com/air-solubility-water-d_639.html

It's temperature dependent, but to get much higher than 8-9ppm of oxygen dissolved with plain old air, you'd need to be down near fridge temps.

Proper aeration is extremely important - and DOES have a major effect on potential attenuation for exactly the reason you've stated. Some amount of reproduction in the wort is desirable, and increasing pitch rates to compensate for poor aeration isn't something I think most would recommend.

Wyeast gives a good excerpt on this:

"Inadequate oxygenation will lead to inadequate yeast growth. Inadequate yeast growth can cause poor attenuation, inconsistent or long fermentations, production of undesirable flavor and aroma compounds, and produces yeast that are not fit for harvesting and re-pitching."

 

[NewWestBrewer]

I aerate by pouring my wort into the primary. i thought that it would mix it up good that way and it bubbles a lot. pretty much thats it.

My temp is rignt now around 72...ish. Its in my basement. this time of year the basement is around 72 and in winter gets to 68. Thats my temp control.

Just a small reminder that if you basement temp is 72 , your initial ferment temp will be closer to 80 as it puts off heat. Get a swamp cooler (big plastic bucket, fill with water and frozen water bottles and keep the water around 65 so your ferment temp is only a couple degrees higher.

 

[TippHillBC]

Just a small reminder that if you basement temp is 72 , your initial ferment temp will be closer to 80 as it puts off heat. Get a swamp cooler (big plastic bucket, fill with water and frozen water bottles and keep the water around 65 so your ferment temp is only a couple degrees higher.

Thanks, i'll try this idea. I did notice that the temp rose to about 78 when the airlock was bubbling like crazy.

I appreciate all the help from everyone. I am going to pitch a champagne yeast to try & bring it down a couple points. I guess in the end, I made beer and that in itself is a good thing. Live & learn!