Clear wort, slow fermentation

[cushyno]

I have noticed my last couple of batches took a long time to ferment out. The current batch using Voss kveik has been sluggish, as did a Black Sheep clone using West Yorkshire yeast.

So many variables across the two batches:

	Black Sheep clone	Amarillo APA
Mash Temperature	66 degC	66 degC
Yeast	West Yorkshire	Voss
Nutrient	none	2 tsp bakers yeast boiled 10 mins
OG	1.044	1.046
Fermenting Temperature	20 degC	33.5 degC
Malts	Golden promise, Munich, torrified wheat, crystal	Pilsner, Pale, Vienna, Wheat, crystal
Days to ferment	~20 (usually done in 10 days for English yeasts)	6th day so far (previously done in 3 days)

Nothing out of the ordinary regarding ingredients, yeast, mashing or fermenting. However, both these batches have been more thoroughly vorlaufed and lautered than I would normally do resulting in a much clearer wort into the kettle. Not clear by any means, but not as much grain material going in. Both batches still produced a good hot break and cold break. I skimmed hot break off the Amarillo APA batch but mot the Black Sheep. Both batches were splashed from a height into FV to oxygenate. I usually always have healthy fermentations with

Could the clearer wort into the kettle mean fewer nutrients in the wort going into the FV? How much would this seriously dent the yeasts ability to ferment?

 

[cushyno]

Jeez, I thought someone would have an expert opinion on this!?

Help me out someone? Have I just got unlucky with two batches in a row, or does creating a really clear wort mean you have to add back nutrients to the FV?

 

[matt76]

Hi @cushyno ,

I don't know for sure about any science that answers this, only that there is debate as to whether some trub in the FV is beneficial or not.

Speaking from experience, I've gradually tweaked my process over the last few years to get clearer and clearer wort in the FV, culminating most recently with adding a mash recirc pump. I haven't ever had any issues at all with sluggish fermentations.

If we look around the forum you'll see many brewers who get super clear wort in their FVs - @foxbat for example, if you take a look at his brew day thread. I'm not aware of loads of people having issues with clear wort and slow ferments.

Since you're no newbie I think we can reasonable assume for now clear wort is not your issue.

One thought I have is how, and how thoroughly, are you aerating your wort prior to pitching?

Another idea is to try a vitality (a.k.a. shaken not stirred) starter - although often maligned because that's not how most people do it, in my own experience it's tremendously effective.

 

[cushyno]

Thanks for your detailed reply @matt76, it helps to have someone else knowledgeable to point out things I may have overlooked.

I'm of a similar mind to you, I find it hard to believe that clear wort is devoid of nutrients. It's most probably a coincidence. As you say the debate goes on as to whether some trub helps fermentation.

My aeration is good. I don't use a hop spider or a bazooka filter so I always run 100% of my wort through a sanitised mesh bag into the FV. because of the fine mesh and lots of splashing the wort has a huge exposure to oxygen. I've never had an aeration problem on other batches and these batches used the same process. It's a good reminder though.

Looking into this further I may have identified two separate reasons for the slow fermentations.
1) It is possible the FV used for Black Sheep may have previously been used for a Saison, so rather than it being a slow fermentation of WY1469, what I have seen may be a slow chugging away of a diastatic infection from the Belle Saison yeast. even at 1.005 the batch was still fizzing away as I racked into a keg after 20 days. That's not typical WY1469!
2) The other slow ferment is probably the well established restriction of using kveik - it either has to be high gravity wort with lots of sugar and nutrients, or you have to add nutrients to give a nitrogen and zinc rich wort.

The kveik batch has now finished after 6 days. It took longer than expected but got there eventually. Airlock activity has suddenly and completely stopped. It's a learning point for me.

 

[foxy]

I have noticed my last couple of batches took a long time to ferment out. The current batch using Voss kveik has been sluggish, as did a Black Sheep clone using West Yorkshire yeast.

So many variables across the two batches:

	Black Sheep clone	Amarillo APA
Mash Temperature	66 degC	66 degC
Yeast	West Yorkshire	Voss
Nutrient	none	2 tsp bakers yeast boiled 10 mins
OG	1.044	1.046
Fermenting Temperature	20 degC	33.5 degC
Malts	Golden promise, Munich, torrified wheat, crystal	Pilsner, Pale, Vienna, Wheat, crystal
Days to ferment	~20 (usually done in 10 days for English yeasts)	6th day so far (previously done in 3 days)

Nothing out of the ordinary regarding ingredients, yeast, mashing or fermenting. However, both these batches have been more thoroughly vorlaufed and lautered than I would normally do resulting in a much clearer wort into the kettle. Not clear by any means, but not as much grain material going in. Both batches still produced a good hot break and cold break. I skimmed hot break off the Amarillo APA batch but mot the Black Sheep. Both batches were splashed from a height into FV to oxygenate. I usually always have healthy fermentations with

Could the clearer wort into the kettle mean fewer nutrients in the wort going into the FV? How much would this seriously dent the yeasts ability to ferment?

NO it is nothing to do with clear wort, I try to get as clearer wort in my fermenter as possible. I have found temperature to be a big player in time. Pitching yeast at an ideal temperature (wort and yeast) gets it off to a quick start. The other is the dissolved oxygen in the wort if using liquid yeast, make sure there is enough DO in the wort.

 

[cushyno]

NO it is nothing to do with clear wort, I try to get as clearer wort in my fermenter as possible. I have found temperature to be a big player in time. Pitching yeast at an ideal temperature (wort and yeast) gets it off to a quick start. The other is the dissolved oxygen in the wort if using liquid yeast, make sure there is enough DO in the wort.

Thanks @foxy . Pitching temperature is another variable. I usually pitch 1 or 2 degrees below the fermenting temperature and try to ensure yeast and wort are at similar temperature for pitch. I know the WY1469 was at the correct temperature, it had been out of the fridge for several hours and about 18 degrees. The kveik slurry may have been on the cool side, maybe 15 degrees when the 30 degree wort was splashed on top of it, so probably shocked it somewhat, though it was active 40 minutes later. Good point!

 

[foxbat]

1) It is possible the FV used for Black Sheep may have previously been used for a Saison, so rather than it being a slow fermentation of WY1469, what I have seen may be a slow chugging away of a diastatic infection from the Belle Saison yeast. even at 1.005 the batch was still fizzing away as I racked into a keg after 20 days. That's not typical WY1469!

I think you've nailed it right there. I wonder what the effect on the beer flavour will be? At least it's in a keg so you don't have to worry about exploding bottles.

 

[cushyno]

I think you've nailed it right there. I wonder what the effect on the beer flavour will be? At least it's in a keg so you don't have to worry about exploding bottles.

It's a shame as the Black Sheep seems to have some decent sweetness and body even at 1.005. It'll probably dry out too much but will take a month or so to do so. Rather than 4.1% it's already about 5% as the SG was a couple of points high to begin with. It's another batch that will need to be drank early. I was hoping to let this one condition more thoroughly. Should still be drinkable. Maybe I'll have stumbled across an unusual mixed fermentation winner!

 

[Sadfield]

I think I agree the answer may lie in how these two yeasts are traditional used

The kveik may be low on nutrient do to your wort being low gravity for a Kveik.
'Kveik cultures are heavily dependent on nutrients, and wort that is lower than 1.050 can benefit from doubling nutrient additions.'
http://www.milkthefunk.com/wiki/Kveik
The other, is perhaps an oxygen requirement issue from using a yeast traditionally used in a Yorkshire square where the wort is recirculated.