O2 Cylinder

[MontPel]

I have been having issues with my ferments taking a long time to finish (3+ weeks). I assume this is sluggish yeast. I always make 2L starters (liquid yeast) and active fermentation takes off within 24hrs, which I believe suggests I’m not under pitching. Lots of rapid airlock activity for the first 2-3 days but seems to taper off to one bubble every 3-4 seconds for weeks after. Not trusting airlock activity I also measure gravity which confirms the slow finish to fermentation. For example, a recent 1.050 ale dropped to 1.018 after 1 week, 1.016 after 2 weeks, and finally 1.014 after 3 weeks. Temp was 19C for first week then up to 21C for remainder. I now think the slow finish is from insufficient oxygen at the beginning. I currently transfer from kettle into a kegmenter and shake it for ~3 minutes to oxygenate.

Now looking at getting a pure O2 setup to get the DO levels up. I am tossing up between a disposable O2 cylinder (Brewman, Kegland etc) or a larger Coregas cylinder from bunnings. I understand there are safety issues with storing oxygen at home. Do these cylinders leak? I would not want a leak to build up in my garage (likely where it would be stored) and create an oxygen enriched environment for when I start my car engine. Is a Bunnings cylinder with valve stem and proper regulator a safer option than the disposable bottles?

 

[Grmblz]

I've got oxy and acetylene from Bunnings, these are commercial bottles not throw away hobby stuff, and do not leak.

 

[duncbrewer]

I have been having issues with my ferments taking a long time to finish (3+ weeks). I assume this is sluggish yeast. I always make 2L starters (liquid yeast) and active fermentation takes off within 24hrs, which I believe suggests I’m not under pitching. Lots of rapid airlock activity for the first 2-3 days but seems to taper off to one bubble every 3-4 seconds for weeks after. Not trusting airlock activity I also measure gravity which confirms the slow finish to fermentation. For example, a recent 1.050 ale dropped to 1.018 after 1 week, 1.016 after 2 weeks, and finally 1.014 after 3 weeks. Temp was 19C for first week then up to 21C for remainder. I now think the slow finish is from insufficient oxygen at the beginning. I currently transfer from kettle into a kegmenter and shake it for ~3 minutes to oxygenate.

I never really had issues of ferments taking that long warmer or cooler.
Do you add nutrient?
Are you all grain or extract? If extract is it all really, really well mixed.

Before I got O2 cylinder I just used to let the wort fall in from a height and made lots of bubbles then pitched. Never picked up and shook.
A 1.050 beer isn't exactly big and going to stress the yeast.

What yeast are you using? Some yeasts do need rousing but they are the exception.
What attenuation do you expect from the yeast are you achieving that or over achieving?
I normally count ferment finished when no gravity change after 3 days.

 

[MontPel]

I never really had issues of ferments taking that long warmer or cooler.
Do you add nutrient?
Are you all grain or extract? If extract is it all really, really well mixed.

Before I got O2 cylinder I just used to let the wort fall in from a height and made lots of bubbles then pitched. Never picked up and shook.
A 1.050 beer isn't exactly big and going to stress the yeast.

What yeast are you using? Some yeasts do need rousing but they are the exception.
What attenuation do you expect from the yeast are you achieving that or over achieving?
I normally count ferment finished when no gravity change after 3 days.

The slow finishes have been very frustrating and took a long time to try and work out why, as based on your response it is not normal or expected. The most likely reason I can find is not enough oxygen at the start of fermentation.
I have used all kinds of different yeast, although they were all liquid and with a starter. I have changed my starter method several times (short cold crash ~24-36hrs/decant, long cold crash ~5days/decant, scrapped the crash and pitch the whole starter etc) it doesn’t make a difference. Yeasts have been 1056, 1084, 1275, 2206, built up dregs from allagash wit, 3522, 1318. I have used nutrient in the starter & in the main boil, and every combination of that. I will likely try dry yeast next to eliminate that.

 

[MontPel]

When it finally does reach FG the attenuation is as expected. It is not dropping low so I don’t think it’s diastaticus or an infection slowly working. My beers actually taste quite good but the timing is frustrating.

 

[MHB]

I would go and take a long hard look at your starters.

People appear to thing making a starter is easy and fail safe, the truth is that it’s very easy to be 1/ getting a lot less than you think 2/getting a lot less healthy yeast than you think 3/ not getting the ferment you expect.
Cropping, harvesting or building up a large enough population to do the job properly is far more complex than many expect.
If you are going to make starters you need some way to count the yeast (there are lots of cheap and relatively reliable ways) and some way to tell if the yeast is in fit condition to pitch, There are tests but they are a lot harder, at our level (HB) it’s probably down to how the yeast performs.

Having the ability to aerate properly is a big help with propagation and pitching. Shaking and running beer from a height is to my mind more likely to get an infection than it is to really help with aeration. People here have often complained about the increased risk of infection from racking - that’s nothing to the risk of pouring unfermented wort around in open air.
Do a bit of reading up on how to make a starter properly, I would recommend Braukaiser (fermentation), he covers slants and starters and all that, he also gives some simple instructions for propagating yeast and how to get some idea of yeast health and population.
Mark

 

[Grmblz]

+1 ^ 100% agree, starters are way more complicated than many people think, two options for you, dump a new wort onto the yeast cake or pitch 2 packs dried yeast (do not make a starter, direct pitch or rehydrate according to manufacturers recommendation) this will remove one of the variables (your starters)

 

[mcgarryb]

I have been having issues with my ferments taking a long time to finish (3+ weeks). I assume this is sluggish yeast. I always make 2L starters (liquid yeast) and active fermentation takes off within 24hrs, which I believe suggests I’m not under pitching. Lots of rapid airlock activity for the first 2-3 days but seems to taper off to one bubble every 3-4 seconds for weeks after. Not trusting airlock activity I also measure gravity which confirms the slow finish to fermentation. For example, a recent 1.050 ale dropped to 1.018 after 1 week, 1.016 after 2 weeks, and finally 1.014 after 3 weeks. Temp was 19C for first week then up to 21C for remainder. I now think the slow finish is from insufficient oxygen at the beginning. I currently transfer from kettle into a kegmenter and shake it for ~3 minutes to oxygenate.

Now looking at getting a pure O2 setup to get the DO levels up. I am tossing up between a disposable O2 cylinder (Brewman, Kegland etc) or a larger Coregas cylinder from bunnings. I understand there are safety issues with storing oxygen at home. Do these cylinders leak? I would not want a leak to build up in my garage (likely where it would be stored) and create an oxygen enriched environment for when I start my car engine. Is a Bunnings cylinder with valve stem and proper regulator a safer option than the disposable bottles?

If you go with a disposable bottle of oxygen from Kegland be sure to remove regulator after each use as they leak. I lost two full bottles before I realized the problem.

 

[Grmblz]

If you go with a disposable bottle of oxygen from Kegland be sure to remove regulator after each use as they leak. I lost two full bottles before I realized the problem.

Just buy decent gear in the first place, this forum is littered with leaking cheap "stuff" yes duo-things I'm looking at you. Barbs and clamps for bullet proof gas, John Guest for liquid. Bunnings for an Oxy bottle and BOC (or similar) Micromatic for reg's, Not happy flying lucky snapping dragon. In the long run it will work out cheaper.

 

[Outback]

If you are going to make starters you need some way to count the yeast (there are lots of cheap and relatively reliable ways) and some way to tell if the yeast is in fit condition to pitch, There are tests but they are a lot harder, at our level (HB) it’s probably down to how the yeast performs.


Mark

Yeast viability is the thing nagging at me currently. What is available to home brewers, which is effective and won't cost me a third kidney?

 

[MHB]

I was referring more to Vitality - how healthy the yeast is rather than Viability - being alive
To check for viability just letting a sample settle in a tall thin tube overnight in a fridge should show the amount of dead yeast to live yeast as two quite distinct coloured bands.
Vitality is harder, about all we can do is see how well a small sample of the yeast kicks off in a new small ferment. Just a couple of mL of yeast from a starter in say 250 mL of wort would be a fair test. It’s something you would need to try a few times and get a feel for. Commercially this requires selling body parts and they do things like measure Glycogen reserves in the yeast, the pH inside the cells, rates of O2 take up...
One thing that makes a big difference to starters is your timing. You want the yeast to go into its rapid growth stage and stay there. To pitch it at ideally the peak of the growth phase and not allow it to switch over to making alcohol.
It sort of wants to hit the wort running and just keep going.
The most harm comes from the yeast running out of one of the nutrients it needs to reproduce, it is usually Oxygen!
Personally I think the chances of getting enough O2 into an Erlenmeyer flask covered in foil to prevent harm is nil.
If you want to grow yeast it needs wort and Oxygen.
Again have a look at Braukiser, right at the top is some info on his experiments, worth reading.
Mark

 

[Half-baked]

You want the yeast to go into its rapid growth stage and stay there. To pitch it at ideally the peak of the growth phase and not allow it to switch over to making alcohol.

Mark, any recommendations for how to achieve this when the starter volume is large compared to the wort volume? E.g. planning a high gravity lager with a 3l starter and a 16.5l batch size

 

[MHB]

I would make the starter well in advance, so it has time to fully ferment, as yeast runs out of food it starts to store glycogen and other nutrients, in effect hunkering down for a drought.
Refrigerate overnight to settle the yeast, decant off the superannuate liquor, allow to reach pitching temperatures then pitch into a well aerated wort.
Basically just like pitching a cropped yeast cake.
Mark

 

[MontPel]

I would make the starter well in advance, so it has time to fully ferment, as yeast runs out of food it starts to store glycogen and other nutrients, in effect hunkering down for a drought.
Refrigerate overnight to settle the yeast, decant off the superannuate liquor, allow to reach pitching temperatures then pitch into a well aerated wort.
Basically just like pitching a cropped yeast cake.
Mark

Are you recommending it fully ferment out only for large starters that make up a large % of the batch size?
It seems you are advocating for more of a vitality starter approach to keep the yeast in growth phase. Yeast can be pitched into a small amount ~0.5L - 1L of the batch and aerated (either stirred, or injected sterile air, or both as Braukaiser does in his yeast propagator setup) and left for a small duration of time ~4-12hrs? to allow for growth but not fermentation, then pitched into the main batch. This time is variable depending on yeast strain, pitch rate etc. The timing is the tricky part in a home brew setup. Is this in the direction you suggest?
Would the main batch also need to be properly aerated, or just the starter?

 

[Outback]

thanks Mark, I actually meant vitality, not viability. To many V words.
I was hoping for a quick, cheap, easy fix. Sounds like one of those rare occasions there isn't one.

 

[MHB]

MontPel - pretty much the aim is to get the "Right" number of healthy cells into the wort. We want the yeast to reproduce; as it does it consumes some things we as brewers/drinkers would like removed from the beer (lipids and fatty acids...). If yeast runs out of any one of a number of nutrients either from its internal reserves or from the wort it will stop reproducing and start making alcohol.

The nutrient that is usually depleted first is Oxygen, with an ongoing supply of O2 yeast will usually keep reproducing until it runs out of sugars or it reaches a saturation population then switch to making alcohol.
The exact answers are often strain dependant, but in short if you pitch somewhere between 0.5-1 Million cells/mL/oP into a wort with 8-10ppm of dissolved oxygen. It will consume all the oxygen and all the other bits we want gone and reach a big enough population to ferment the wort in 3-5 days without being under enough stress to make off flavours.
Hard part is getting the right number of healthy cells into the wort to kickoff the ferment to make the beer we want.

There is a lot more to take into consideration that I won’t go on with, but it’s worth noting that there are textbooks written on yeast and people are constantly researching the subject. On Braukaisers approach one point is that if we keep reproducing the yeast for a long time the average age of the population goes up.
A yeast cell, produces a bud, under good conditions probably every 2 hours or so, when the bud detaches it leaves a scar on the mother cell, when a cell accumulates around 20 scars it starts to have difficulty getting enough nutrients across the remaining membrane to sustain itself eventually it will go dormant sink to the bottom - ultimately it dies. But by then its first daughter cell will have (on average) 19 scars, its first granddaughter 18....

So by starting with a small population and growing it to a large number will give you a large population of on average older yeast than would a larger population that is only doubled a couple of times (Braukaisers 4-12 hours) and believe me the two pitches will behave differently in the wort.

"We make wort, yeast makes beer"
Mark