Yeast Culturing And Use

[lou]

Hi ya all

just thought i would share my experience using liquid yeast and some of the problems I have had

Firstly I have to say that using liquid yeast has produced the best beers I have made. Liquid yeast seems to give a beer an incredible freshness and zing that you just don't seem to get from dried yeast. Some dried yeasts are way way over rated imho and consistently produce very ordinary results irrespective of the brewer. Maybe I just need to try some of the expanding range ?

Saying that liquid yeast is very expensive and you want to get the most out of them but heres the problems.

Firstly I have reused yeast from one batch to the next with no problems ie using the yeast very soon or imediately after a batch. Storing yeast however can be problematic.

I have tried the stubby method and found that the yeast really doesn't enjoy the storage at all. My problem is that I just don't brew lots of beer and the yeast in the stubby is usually mostly dead by the time I get around to using it. Different yeasts also seem to react differently. For instance I found that Irish ale yeast starts producing a kind of dusty musty beer after storage for not that long. I have had this happen more than once so this rules out any specific sanittion issue.

One problem is that after a while pressure builds up in the bottle and yeast really doesn't like this. I have taken to putting yeast in flip top bottles and venting now and then - you would be amazed at how much pressure builds up and how quickly.

Also with other yeasts I have found a noticeable change in flavour profile after storage. I am not including actual infections here because they are very noticeable and I will talk about that later. Subtle flavour changes are still not usually for the better and in my experience fresh is always best.

This all tallies up with what the yeast manufacturers say about their product and i am skeptical about other claims. Of Course if you use the yeast quickly and frequently this would not occur.

This makes sense to me because when you think about it yeast is adapted to a certain environment - that is in a fermenting wort. When you take it out of that environment - put it under pressure in a fairly alcoholic environment at below 5C - most cells will die fairly quickly and the ones that will survive are the ones that like eating other yeast -don't mind cold temps - dont mind a bit of CO2 pressure and that generally don't mind going to sleep for long periods of time. These conditions are so different to what yeast normally like that you are seriously going to skew your 'natural selection adatation pressures' towards yeast that don't make nice beer.

The other issue is infections in stored yeast and in getting the stored yeast going into a nice big starter.

I have noticed that I get a number of infections trying to build up starters from stored yeast. Often these are mild infections but always there a a noticeable taint. Not big funky smells or the typical gushers but often mild taints and bad diacetyl.

Any suggestions here welcome. I can see several problems with my system for propagating but I can't see any solution - I use sterilized starter wort and put it into idophor cleaned pet bottles.

Thing is you have very little viable yeast going in - lots of air with lots of bugs in it
Also I don't have any problems when making starters from a fresh pack of liquid yeast. But you always up against it when making starters from small amounts of yeast. Also i dont have any good place to make up starters - just the kitchen and kitchens even when clean are bacterial play grounds.

It may be expensive but I think I may have to use fresh pack of yeast each time - its just not worth wasting 15L of AG wort that took half a day to make and then not have beer I like to drink at the end. I don't have the space for upgrading to a sterile lab for propagation

feedback anyone ?

lou

 

[DJR]

A very good way i had was when using Shite Labs, just pour 5mL of agitated slurry into a 100mL starter and step up from there (via 2 stages) to a 1L to 2L starter depending on batch type (ale or lager really), then you haven't changed the profile from actually fermenting with the tube.

With Whyeast, i just poured off the contents into 4x35mL sample vials and stored them for later, using the last dregs to make a small starter and step up as per the Shite Labs procedure.

I still do have some 0th generation vials around, and used the stored yeast after about 3-6 months and besides starter lag there was no other effects, Kolsch yeast still tasted like Kolsch yeast and that's a very transparent style indeed.

Of course all work was done next to a nice big flame (gas cooktop)

p.s before everyone flames me for using trick names for the yeast suppliers, since WB06 came out i just use dry, i don't have the time or the money to stuff around with yeast prop anymore...

 

[Sammus]

I got a pressure cooker, some pretri dishes and some culture tubes and keep a master of each yeast I like under distilled water from the original pack. Doing it this way you can select individual cultures to propagate, hopefully overcoming the mutation issue. And I read in my yeast culturing studies that stored properly under distilled water you still have at least 70% viable cell count after 6 months.

 

[newguy]

A long time ago I used to store yeast in an ordinary glass beer bottle (341ml) for up to 1 year with no ill effects. My standard procedure was to build up a 1 litre starter in 300ml increments from a wyeast smack pack. This was back in the days when a wyeast smack pack was really small - can't remember the exact quantity of liquid in them, but much smaller than the current XL packs available now.

On brew day I'd pitch almost the entire starter, save for a very small amount, maybe 30ml max. I'd then add about 300ml of that batch's cooled wort and set it aside to fully ferment. When the airlock would no longer bubble even when vigorously shaken, I'd bottle this and put it in the fridge. I never had a "gusher", but I do remember a couple being moderately carbonated.

The most times I "reused" yeast in this manner was 2 times for a total 3 batches of beer from a single smack pack (1 original, 2 reused). I never had infection issues, but I did store everything in glass containers. Some yeast varieties didn't seem to enjoy being stored in this manner (long lag times when stepping up), but I never had an infection. At present, I simply repitch directly onto the yeast cake of the previous batch to get 3 uses out of a single smack pack.

I think that there's nothing wrong with your reasoning, but your sanitation procedures should be examined. Also abandon the PET bottles for storage - glass is much easier to sanitize and will definitely not allow oxygen or anything else to get at your yeast. Iodophor is a good sanitizer (and what I used when I used to store the yeast in the fridge), as is star san (which I what I use at present). This may sound really paranoid, but I also was (and still am) careful about breathing directly on any open yeast containers or carboys or kegs. Same goes for drafts. I really don't want dust falling into my beer, nor any bacteria or wild yeast the dust is carrying.

Hope this helps.