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I need to double check those links. I don't want to waste your time. I should be able to dig up the good ones tomorrow.

I'd be interested in a used one if it worked.

There are some good free papers I need find the URLs and I'll post them.

Storing in the back of a freezer with 10% glycerin works well for me. I wouldn't think you would have to do cryogenic freezing unless you are considering storing the yeast for decades. As for identification, there are a couple PCR tests for finger printing yeasts. I could send you a couple...

This topic really deserves much more discussion, but I'll try to sum it up. Dry yeast is grown areobicly and dehydrated at a point when they have adaquate sterol content and glycogen reserve. (liquid) Yeast will quickly loose it's glycogen during storage (in the refrigerator) and requires...

Over the last few months I've been collecting fermentation metrics of yeast stored in water, beer, and frozen. I have data out 65 days and so far there is not a discernible trend in viability, lag time, growth rate, attenuation or biomass yield in the fermentation after storage. How long the...

This calculator will give you an idea of what is happening over time: http://www.woodlandbrew.com/2015/02/starter-calculator.html Essentially, if you do cold crash you want to make sure you are doing it when the glycogen level is high. This occurs at about the 90-95% complete mark.

Depending on if it is a yeast health or sugar composition issue there are two different paths to take. Which of the two it is can be determined by chromatography. (I'm working on a way to make this practical for us homebrewers) Giving the carboy a swirl (instead of sticking anything into...

It seems the consensus was W34/70 over here: https://www.homebrewtalk.com/showthread.php?t=524449

Plus one! I use a gram or two from a package to grow what I need for the batch. One package can go a long way. US-05 and S-04 are the same two I would choose as well.

I would be concerned with possible contamination as well. In my opinion, it doesn't matter how careful you are with sanitation, if you are doing extra steps, your asking for trouble.

It's all good yeast. What you do with it is up to you. I save enough in the fridge for the next few months of brewing, or whatever I have space for. I'll freeze smaller volumes if it's an expensive or hard to find yeast, then build these up when I want to use them.

I would start by plateing and select a few colonies from that to grow up.

Agreed. While you can get by with sprinkling the packet of yeast on the wort and make fine beer, it has been shown that viability is lower when yeast is rehydrated in wort. Here is one paper on the subject: Bolata, Irina C., Maria Turtoib, and Michael C. Walsha. "Influence of yeast drying...

It's hard to know for sure, especially with a sample size of one, and so many variables. It sounds like you are describing fusel alcohols which are normally associated with warm temperatures, especially at the beginning of fermentation. 70°F is on the hot side for S-04 according to the data...

Either way. I find it easier to estimate volume once it has been poured from the fermenter into mason jars and then crashed in the fridge.

Yes, that sounds fine. You can estimate your cell count as 1.5 billion cells per ml of settled slurry.

The growth rate of ale yeast is 0.4 h-1 meaning that it doubles every 2.5 hours. (this is at 20°C with no limiting nutrients) One day after pitching the yeast will have grown much more than one vial or package of yeast contains, so pitching more yeast after a day of fermentation has very little...

Your yeast looks fine. While the trub does not look pretty, the yeast is fine. See here for details: http://www.woodlandbrew.com/2012/12/yeast-washing-exposed.html and more here: http://www.woodlandbrew.com/2013/01/yeast-washing-revisited.html

Mr. Malty seems to under estimate cell growth, especially when you don't select the stir plate option, and starting with a low pitch rate. Mr. Malty also assumes a 9°P or 10°P wort, but yield is directly proportional to the amount of extract. I've found (by reading papers and doing experiments...