Fermentation stopped but beer tastes/smells ok

Drix · Joined: 15 Oct 2014 Posts: 17

I'm trying to figure out if I should add more yeast, wait, or keg and carbonate.

I was thinking about taking the yeast from my harvester, adding to it 2 more vials of the white labs lager yeast and dumping the whole mixture back in the top.

I'm torn at this point because the beer actually tastes and smells pretty good and adding yeast now in the presence of alcohol and presumably low levels of O2 might be useless....

Thoughts on adding more yeast now?
Thoughts on why this stopped?

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I used Mr. Malty calculations for my lager yeast starter which ended up being 8 vials (33% viability) to ~4 liters of starter. Added servomyces, and feel I followed sanitation best practices. The starter sat on a stir plate for 18 hours at room temp. I put the starter in the fridge overnight while my wort was getting down to target temp of 55F. The next afternoon, I pitched the entire starter after using an agitator rod for about 2 minutes.

I also added servomyces to my boil as directed. Post Boil Wort pH was 5.64 (measurement taken after CFC).

I attached pictures of what yeast harvester currently looks like and what my starter looked like before pitching.

I'm using a morebeer temp controlled fermenter, so assume temp has been stable +/- 2F throughout.

27-Oct 1.050 12.4 Pitched Yeast Starter, 55F in Conical, 50F starter flask
28-Oct 1.050 12.3
29-Oct 1.049 12.2
30-Oct 1.047 11.6
31-Oct 1.039 9.8
1-Nov 1.032 8
2-Nov 1.031 7.7
3-Nov 1.031 7.7
4-Nov 1.028 7 1st trub dump. Raised temperature to 58F +/- 2F
5-Nov 1.023 5.9
6-Nov 1.023 5.8
7-Nov 1.020 5
8-Nov 1.022 5.5
9-Nov 1.023 5.9 Raised temperature to 65F and maintain for 3 days
10-Nov 1.023 5.8
11-Nov 1.023 5.8
12-Nov 1.023 5.8
13-Nov 1.024 6.1 2nd trub dump. Attempted Cold crash in primary conical but…
15-Nov 1.024 6.1 …fermenter only able to reach 49F.
17-Nov 1.024 6.1 Raised temp in conical back up to 54
18-Nov 1.000
19-Nov 1.023 5.8 calibrated unit and re-measured. Went from 6.1 to 5.8…

foomench · Posted: Thu Nov 20, 2014 4:33 pm Post subject:

How are you obtaining the gravity numbers? It looks like you have Brix numbers there too, so are you using a refractometer? I ask because a refractometer does not give accurate gravity readings in the presence of alcohol. A refractometer only gives real gravity readings for sugar solution. Alcohol throws things off, and you can do some arithmetic approximations, but you can't use just the number from the device.

Drix · Joined: 15 Oct 2014 Posts: 17

I'm using a Hanna refractometer and doing a brix to SG conversion in excel. I suspected that might be my problem after reading through the various blogs, so I ordered a hydrometer a few days ago. It just arrived this afternoon and my gravity is 1.016

Alcohol throwing off refractometer readings wasn't obvious, so I'll have to chalk that one up to 1st time brewers initiation. Thanks for the help.

Anyone have comments about my yeast starter picture? I've read a lot of blogs over the past few days and seems that 18 hours for a starter this large was probably not enough. I've also read that putting the starter in the fridge for several days to let the yeast settle out is good as well..

**kal** · Posted: Fri Nov 21, 2014 1:08 am Post subject:

brianbarley · Joined: 18 Oct 2011 Posts: 8 Location: Austin, TX

I use the Hanna digital refractometer as well, but only for wort (pre-fermentation). Thereafter I use a final gravity (FG) hydrometer that is very easy to read (.990-1.020 only so the individual gradients are extra large).

Here's a great link discussing starters: http://www.mrmalty.com/starter_faq.php

I don't usually do stepped starters and even though I use a stir plate I dose it with some O2 or shake it very well in the beginning (depends on size of starter, as I've made up to 10L starters). The yeast uptake the oxygen in the beginning so it's best to have it available for them right out of the gate.

The pH of the starter should be around 5 (4-6). Temperature rule of thumb is to keep the starter between 65 and 75 (I hold 72 for ales, and this is also a good balance for both lager and ale yeasts).

Just like in the fermentor we don't want to rush the yeast in the starter. Although it is mentioned that max cell density is reached within 12 to 18 hours for most starters, it can extend out to 36 hours or more. However 24 hours is a good rule of thumb. I shut the stir plate off after 24 hours and then give the yeast an additional 8-12 hours at temp to build up their glycogen reserves. Then I'll start crashing to 34F (over a 6 hour period). Yeast activity will stop at this point and will settle out of suspension. I keep it at 34F until brew day, when I decant and then slowly raise the temp up to pitching temp. Decanting is recommended when the starter size is more than 5% of the beer volume. You can leave a little "beer" on top of the yeast to help mix the yeast with. This will make it easier to pour and is sanitary.

I have never brewed lagers but how many billion yeast cells were you attempting to pitch? With your assumptions it seems that you could have around 450B cells (400 - 500B). How did you come up with 33% viability with the 8 vials of yeast? What's your batch size? Current approximate ABV? I believe that to restart fermentation you would need to create another starter and then pitch at high krausen (peak activity). Otherwise it's going to be very difficult for the yeast to get going in the current fermentor environment. Make sure that the starter temp is within 5F of the fermentor beer temp. I think I read that you can use another yeast strain as well, one that is neutral (clean) and can tolerate the higher levels of alcohol. That's another option but you'd still have to pitch it at high krausen.

Good luck!