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Obviously, it can be done, as dry yeast works for fermenting beer. I go sometimes a month or two between batches, and carrying over one yeast culture across beers seems a bit of a pain. How is dried yeast made/ packaged? Is it something a homebrewer can reasonably do?

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up vote 3 down vote accepted

Simply put it is not practical for the homebrewer as you need to perform the drying under sterile conditions.

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This seems to be the ultimate answer for my question. The other answers were good too. – Jeremy Holovacs Jan 23 '12 at 16:39

I don't think the process of commercially drying yeast is straightforward - it involves a partial vacuum or a stream of filtered air to make the liquid suspending the yeast evaporate faster - and it's probably difficult to reach the levels of hygiene required in a homebrew setting.

If you want to preserve yeast for a long period, 1 year or more, you can store the yeast with glycerine and keep it in the freezer. There's a good writeup on HBT with the process and equipment needed. It's fairly simple and achieves good results. I've successfully brewed with yeast that I froze 3 years ago.

Even if you don't freeze the yeast, but keep the yeast in the fridge, the yeast remain in better condition in glycerine than when kept in wort.

If you are already making a starter then freezing is a simple process that allows you to keep a variety of strains in your yeast bank over a long period.

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I know you can make a dry sourdough starter by just spreading it thinly on a sheet pan and leaving it in the sun to dry. That doesn't seem nearly sterile enough for our beery exploits, however.

You may want to look into yeast slanting and yeast washing. I also have an article on how I wash yeast on my website.

There was also an interesting thread recently on HBT about farming and freezing yeast using glycerine to protect the cell walls from rupturing.

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"nearly sterile enough" is an interesting understatement. – brewchez Jan 21 '12 at 13:43

Although I do not know the exact process, if sterility is the aim, it seems that all that is required is to create a positive air pressure sterile box(PAPSB). This can be done with lexan, a strong fan, and a few high grade HEPA filters. You can create a near sterile environment in this manner with the aid of a strong sanitizer and UV lights. Using this PAPSB you should be able to perform all of the necessary procedures outlined. Of course the box will need to be outfitted with gloves to allow manipulation of objects in the box. The system I am suggesting is similar to those used by CDC members when handling various bacteria and virii. A guide to creating such a box is here.

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This question is pretty old now, but I just found this thread, while searching for the same answer. In my opinion some of the answers given are a bit ambiguous, and are lacking references.

I think that some home experimentation would be well worth it, and with a little forethought and hygienic practice, should be well within the grasp of a homebrewer to run some experiments.

It would be very easy to produce a good healthy strain of yeast in a reasonably controlled environment in a gallon jug producing a large amount of yeast available for harvest. Even a wild yeast. I primarily only ferment Cider now. I have Harvested and propagated Wild Apple Yeast to produce a working Gallon Jug that will washed out to provide me with enough tubes of yeast to make a years worth of starters. I consistently get good results and flavor from this method.

It would not be a huge effort to wash out several batches to be dried. I would experiment by making some foil pouches, placing them onto a foil covered cookie sheet and heating them an oven to 300F. Shut down the oven and monitor for the temp to drop to 100F. At 100F remove a tube of Yeast Culture from the refrigerator, open the oven door, and pour the tube into a pouch, maintain 100F until it dries to a cake. Close the pouches (before removal from the oven) and store. Once every few months pull a pouch, use it as if it were a package of dry, and add it to a cup of warm water with a 1/2 teaspoon of sugar and maybe a pinch of Nutrient and see if it blooms. Not scientifically sterile, but as good as any home practice is. Even if you pitch only a prepackaged yeast after heating your ingredients, you invite some level of unknown contamination while pitching.

I'll let you know in a year how I make out... :-)

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