Kveik Yeast Pitch Rate

[Patrick Beaumont]

I've been trying to make an imperial stout using Kveik yeast https://mangrovejacks.com/products/kveik-yeast-10g
I've been starting with 15 litres of wort at a specific gravity of 1.13.

After a month of fermentation in a barrel the specific gravity seems to have stalled at 1.06 which has left the stout at about 9% ABV and tasting a bit too sweet for my liking. I was hoping to get up to about 13% ABV which I believe the yeast should be able to handle. This is also what happened with my previous batch.

Something that has been suggested to me is that 10g of yeast is not enough to ferment all that sugar. This has led me to trying to learn about pitch rates. I'm still confused though about some basic principles of yeast reproduction and pitch rate.

My naive assumption is that yeast will continue to reproduce and turn sugar in to alcohol and CO2 so long as the ABV doesn't go too high and kill the yeast. However it seems that if you "pitch too low" the yeast has to reproduce too much and will end up dying off before achieving full fermentation. Is that right? Does anyone have a good guide on why pitching too low can lead to a stalled fermentation? Or even just a good guide on pitch rates in general?

 

[Rodcx500z]

You could try putting some more yest in to try and get it going again,

 

[RoomWithABrew]

Kveik likes warmth, more oxygen, lots of yeast nutrient.
https://www.brewingnordic.com/farmhouse-ales/practical-guide-to-kveik-farmhouse-yeast-fermentation/

My Thomas Hardy clone using Wlp099 super high gravity ale yeast went from 1.128 to 1.044 with a huge pitch, re rousing with oxygen on day 3. Then into secondary and repitch of altbier yeast at month 1, 3, 6.
Final bottling gravity was 1.027 after 9 months.
I'd add some fresh yeast, nutrient and keep it warm.

 

[Patrick Beaumont]

Thanks guys.

I'm reasonably confident now that I'm running out of oxygen in the fermentation. Does anyone have any suggestions on how to add more oxygen in? I've got the fermentation sat in a plastic barrel with a tap on the bottom and small screw cap on the top. There is a reasonably large air gap at the top but I suspect that is now mainly CO2.

Would just draining some off and then pouring back in the top through a funnel introduce enough oxygen to start things going again?

 

[MashBag]

Low pitch rate isn't it. Like fat bloke at a buffet.. It will clear up.

Sorry to say I very much doubt it's oxygen either.

I would consider unfermentable sugars or yeast stress.

Thb we haven't got a huge ammount to go on. Share with us what the recipe is, grain bill, fermentation process, temps & steps.
Any sensory info too.. taste, smell mouthfeel etc.

The secret to what's going on will show itself.

 

[Patrick Beaumont]

15 litres water
1500g dark malt extract (mangrove jacks’s bag)
3000g Dark brown soft sugar (lidl)
1500g dextrose
1000g malto dextrin
200g flaked barley
400g crushed chocolate malt
200g roasted barley
200g carahels
200g carapil
200g acid reducer - (PH of 5.1 before adding yeast)
10g dried yeast (mango jacks kveik m12)

I mashed everything at about 70 celsius for about an hour except for the yeast. Let it cool down overnight in the fermenting barrel then added the yeast and screwed the cap on.

 

[RoomWithABrew]

I don't think your partial mash has any enzymes in it, unless that mangrove jacks is diastatic malt.
Hence the mash was a waste of time and was a steep instead.
Lots of unfermentables in the system and a pretty stressful environment for the yeast.
Your best chance would be a trial with more healthy active yeast and wait a bit longer.
Then if no success you could add glucoamylase enzyme and repitch more yeast.

Yeast starter calculator says you needed 5 packets of dry yeast for your batch or a 4 litre starter.

 

[MashBag]

Yup. Drop a beano in there.

https://www.ebay.co.uk/itm/27631067...JqzRlhvQpi&var=&widget_ver=artemis&media=COPY

Everything you said and I don't think 70c helped either.

 

[The Baron]

Mash @ 70c may be something to do with it or at least a contributing factor

 

[MashBag]

Technicality really.. I wouldn't pitch anymore yeast. They have done all they can. Bean assist (UK version of beano) give it a week and you should see movement. When more fermentables become available, the yeast will deal with it.

Enzymatic actions aren't quick, there is not fizz, flash or bang. They just slowly get to work.

The best way to see them work is color chromatography or failing that watch the drop on the hydrometer

 

[Patrick Beaumont]

Thank you for the suggestions guys.

1. Mash temperature - Do I need to go higher with this? Am I just not getting things hot enough to break down the sugars?
2. Enzymes (beano and glucoamylase) - I'll order some. Am I right in thinking this will probably lead to less of a "sweet creamy" mouth feel but will give the yeast more to work with?

While I'm waiting for the enzymes to turn up I'll try introducing some oxygen in to the barrel. It probably won't do anything but I'm treating this barrel as an experiment at this point so I might as well get another data point to use in future brews.

 

[The Baron]

When you mash at a higher temp the wort is harder for the yeast to digest because of the different types of sugar so a lower mashed wort is easily fermented by the yeast but if you go down to the lowest temps the body of the beer thins which is not what you want for Stouts etc.
Using the enzyme glucoamylase this will ferment the wort really low so use it wisely it is generally used in Rice Lagers etc to dry then right out.

 

[RoomWithABrew]

Temperature of the mash is irrelevant I think.
There are no enzymes in the ingredients list that will work at any temperature.

Lots of unfermentables though.

 

[The Baron]

Disagree where do the unfermentables come from, they are from the mash temp. High mash temps create more unfermantables lower temps make for more fermentables

 

[MashBag]

OK let's draw two pictures here for Patrick

First.. what should happen normally.

*Temps do matter
*67/68c would be a better temp
* no beano's in this type of recipe because they would make this to dry for the style.
*beano's imo are not a normal addition.
*at least 50% of a grain bill imo should be malted.


Secondly.. what are corrections / discussions about issues.

*70 was too high
*there was little in the grain bill with to deliver the enzymes needs for mash.
*beano's might help release some fermentatables.
*beano and glucoamylase are the same think. Order beano's that also make a terrific "rennie"

 

[MashBag]

On a person to person level Patrick.. you need a book mate. Don't get wrapped up in huge great bibles of technicality.
Don't buy a shed full of shiney first. Get a book.
Graham wheeler did it for me. Good understandable basics and recipes of all styles so you could pick one and have a go.

There are others.. Shout up and we can recommend.

It's more like golf than making a cuppa, you never get it right, it's a pain in the ***, and we are all learning as we go.

Grin in a bottle is all you need to get too. Your grin. Your bottle.

 

[RoomWithABrew]

Disagree where do the unfermentables come from, they are from the mash temp. High mash temps create more unfermantables lower temps make for more fermentables

200g flaked barley
400g crushed chocolate malt
200g roasted barley
200g carahels
200g carapil

Can you Explain how these grains get converted to fermentable sugars ?

70C immersion of these grains is the same as 60 degree immersion ( other than a minor change in solubility with the temp rise).

Of note as well only one of the grains is crushed and that's the chocolate malt, one is flaked, the rest are not mentioned as crushed.

 

[The Baron]

200g flaked barley
400g crushed chocolate malt
200g roasted barley
200g carahels
200g carapil

Can you Explain how these grains get converted to fermentable sugars ?

70C immersion of these grains is the same as 60 degree immersion ( other than a minor change in solubility with the temp rise).

Of note as well only one of the grains is crushed and that's the chocolate malt, one is flaked, the rest are not mentioned as crushed.

Sorry did not see the recipe just assumed it was a AG and it is a Extract with sugar.

 

[Patrick Beaumont]

200g flaked barley
400g crushed chocolate malt
200g roasted barley
200g carahels
200g carapil

Can you Explain how these grains get converted to fermentable sugars ?

70C immersion of these grains is the same as 60 degree immersion ( other than a minor change in solubility with the temp rise).

Of note as well only one of the grains is crushed and that's the chocolate malt, one is flaked, the rest are not mentioned as crushed.

My intention with the grains wasn't so much to use them for the sugars but to use them for flavour, colour and head retention. Most of the sugar for the yeast should come from dark brown soft sugar from Lidl.

The 70C mash temperature is very approximate. The temperature control on my mashing bin isn't great and I'm still learning how to keep an accurate temperature.

 

[RoomWithABrew]

My intention with the grains wasn't so much to use them for the sugars but to use them for flavour, colour and head retention. Most of the sugar for the yeast should come from dark brown soft sugar from Lidl.

The 70C mash temperature is very approximate. The temperature control on my mashing bin isn't great and I'm still learning how to keep an accurate temperature.

You have done an infusion really at the approx 70C so you will have extracted colour, also complex starches and proteins.
Good idea to use the adjuncts for head retention as extract brews are prone to less head retention.

There are other enzymes available that are used by gluten free brewers which also would be an option. But I'd try the glucoamylase first as easily available.
Patience will be needed.