Lazy fermentation – Should I pitch a new yeast pack?

[Meaulnes]

Hello everybody!
I am brewing a wheat beer and I am facing a lazy fermentation. I wonder whether I should pitch a new yeast pack or not.
My OG is around 1.049 (I aim a low alcohol beer), fermentation started 26 hours after pitching and since then, i.e. since 16 hours ago, the slope is steady at around 8 points/24 hours.
Yeast is Safale US-05 and I used one pack. It seems to me that It's rather slow compared to what I am used to.
What should I do?

 

[Bzee]

Does fv feel warmer than ambient temp my brews do for first 24 hours after pitching if alls going well.

 

[Caramel Ox]

No that’s still very early to worry. Also dried yeast into partially fermented beer is technically incorrect- you would need to make a starter and pitch that at high krausen.

 

[MashBag]

What temp are you maintaining and how are you heating it?

 

[Meaulnes]

What temp are you maintaining and how are you heating it?

The fermentation vessel is in a freezer that regulates around 18 °C. I am not heating but cooling as ambient temperature is higher at the moment.

 

[MashBag]

Righto. That might be your answer.

How accurate is the cooling? Is then any lag?

 

[Meaulnes]

No that’s still very early to worry. Also dried yeast into partially fermented beer is technically incorrect- you would need to make a starter and pitch that at high krausen.

It's the first time I hear that pitching a dry yeast into partially fermented beer is incorrect. Is this true even if yeast has been re hydrated.?

 

[Meaulnes]

Righto. That might be your answer.

How accurate is the cooling? Is then any lag?

I monitor the wort's temperature with a Brewbrain Float device (min 17.44 max 17.75) . The setpoint of the freezer temperature controller is 19°C and from what I can see freezer temperature goes up to 19.3 °C and down to 17.2 °C.

 

[MashBag]

Have you used this freezer before?

 

[MashBag]

19°C and from what I can see freezer temperature goes up to 19.3 °C and down to 17.2 °C.

I am thinking a 2c drop will slow the yeast down.

 

[The Baron]

When you say it is rather slow to what you are used to is that because you use a different yeast normally in which case different yeasts ferment at different rates or is it that you have used the yeast before and it is your new freezer system that is slowing the yeast down

 

[MashBag]

+1 ... And is it only me that is a tinsey winsey bit jealous that someone needs a chiller when it is 14c outside

 

[Caramel Ox]

It's the first time I hear that pitching a dry yeast into partially fermented beer is incorrect. Is this true even if yeast has been re hydrated.?

Yes I think so because rehydration is not changing the metabolic state. This is what the yeast book says (this section is specifically about not reaching expected final gravity):

• Add more yeast. Many brewers ask if they can just toss in some dried Champagne yeast to finish out fermentation. Those who say it works were probably dealing with a beer that had large amounts of simple sugars remaining, as Champagne yeast will not consume the longer wort sugars. You can add more brewer’s yeast, but it is hard to restart a fermentation that stops. A partially fermented beer is not a yeast-friendly place, as it has alcohol and there is no oxygen, not enough nutrients, and not enough sugar. Only add yeast that is at its peak of activity. Add the yeast to a small bit of wort, let it reach high kraeusen, and then toss the whole thing into the beer. If you add enough yeast at their peak of activity, you should not need to add oxygen to the beer.

 

[MashBag]

I can see that, not one size fits all though.

So the question... is this not started, stalled or needs restart.

 

[Birdsnestbrewery]

From your original question it sounds like the reading is going down steadily, just not as fast as you expected. Is that right? I would leave it. As long as it's doing something it doesn't sound like it's stalled. . Some fermentations take longer, others blast through. I've never used US 05 on a wheat beer. 17 degrees is quite low for that yeast.

 

[Meaulnes]

Have you used this freezer before?

Yes I have but not each time.

 

[Meaulnes]

From your original question it sounds like the reading is going down steadily, just not as fast as you expected. Is that right? I would leave it. As long as it's doing something it doesn't sound like it's stalled. . Some fermentations take longer, others blast through. I've never used US 05 on a wheat beer. 17 degrees is quite low for that yeast.

Yes it is exactly this. The manufacturer says optimal temperature is between 15 °C and 22 °C.

 

[Meaulnes]

I am thinking a 2c drop will slow the yeast down.

I am afraid of this too.

 

[Meaulnes]

Yes I think so because rehydration is not changing the metabolic state. This is what the yeast book says (this section is specifically about not reaching expected final gravity):

OK. I note it.

 

[Agentgonzo]

Yes I think so because rehydration is not changing the metabolic state. This is what the yeast book says (this section is specifically about not reaching expected final gravity):

It's not obvious from that quote whether the brewers yeast they are talking about is dried or liquid. The part about not enough oxygen/nutrients may not apply to dried yeasts because they are prepared in a way that you don't need to oxygenate your wort as the yeast is chock full of nutrients, lipids etc.

I'm by no means an expert though (neither are most here) but there is a risk of making invalid assumptions.