Home Project for School - Capturing Wild Yeast and Drying

Hello All,
I am a biology student at a university (Second career. I am in my 30's) and I want to get into a particular bio lab of a microbiology professor that I would love to study for my PhD starting next year.

Anyway, I do not have any direct lab experience (I have done HR for the last 7 years) and learned through my little brother that these schoosl and profs love home experience. He got into an ace school by isolating ecoli plasmids at home using a home electropheresis set up).

I was thinking being a brewer and all, I could do my own little home scientific experiment that would also be tons of fun for brewing. I was thinking of capturing a wild yeast, growing it, and drying it.

I read in the lambic section how to capture a wild yeast by setting a bit of DME and water on the window seal for two weeks which is very doable. Maybe honey would work better because I would think thanks to the antimicrobial properties of honey, there would be a higher chance of catching yeast and not bacteria. I would rather do an agar plate and then microscope it to ensure I actually have yeast but I don't have access to a microscope at home...

Then I would imagine that I could grow more cells in a sugar(DME or honey) and water environment and collect cells that fell out in suspension.
How would I then go about making the cells dormant (cold obviously) and drying them while maintaining them as active? do you think spreading on a tray and drying in a refrigerator or in a cool environment with a fan blowing across it might accomplish this?

I do not only plan on documenting this for school related benefits but I also fully plan on brewing with the resulting yeast as well!

Thanks!
E

There are several threads here about capturing wild yeast. I'm sure you will find them to be a valuable resource in your research.

Its not so much the capturing part I need help with... I found and read most of those threads. It is more the drying part that I did not really find a lot of info on.

Via cookingforengineers.com:

Active Dry Yeast
Introduced in the 1940's, active dry yeast was a major innovation in how people would use yeast and bake breads. To make active dry yeast, live yeast cultures are dried after being removed from the fermentation tanks. A protective layer of yeast debris is allowed to coat the coarse clumps of yeast forming the tiny granules. Active dry yeast is simply dehydrated, dormant yeast cells clumped into grains that await reactivation. To revive the yeast, the grains must be soaked/dissolved in warm water (about 110°F or 43°C is considered optimal) prior to mixing with the dough or batter. Active dry yeast changed the world of baking because it was a shelf stable product that had consistent performance when used. Families on the move and cooks who didn't have constant access to a refrigerator could still use yeast once active dry yeast was made available. (Fleishmann's introduced their active dry product shortly after America entered World War II with the intent of providing yeast to soldiers.)

Instant Yeast
Instant yeast is made in a similar manner to active dry, but the drying process has been altered somewhat. According to Red Star, they use a lower heat to produce more porous granules while Harold McGee's On Food and Cooking claims it's a fast drying process. Whatever the process, the end result is that each yeast granule has more surface area and activates faster than active dry. In fact, they activate so quickly, you don't have to soak them in water first - the moisture of the dough or batter will be enough to get the yeast moving again.

Thanks. Yeah I read that as well. Unfortunately it didn't really cover process. More the what it is and not the how.

So it would be goal:

aiptasia said:

Via cookingforengineers.com:
To make active dry yeast, live yeast cultures are dried after being removed from the fermentation tanks. A protective layer of yeast debris is allowed to coat the coarse clumps of yeast forming the tiny granules. Active dry yeast is simply dehydrated, dormant yeast cells clumped into grains that await reactivation.

Click to expand...

Procedure?

sonofgrok said:

How would I then go about making the cells dormant (cold obviously) and drying them while maintaining them as active? do you think spreading on a tray and drying in a refrigerator or in a cool environment with a fan blowing across it might accomplish this?

Click to expand...

I'd be very interested to hear your plans for testing viability, and also for testing for contamination.

passedpawn said:

I'd be very interested to hear your plans for testing viability, and also for testing for contamination.

Click to expand...

I am debating between running several generations by collecting cells that fall out into the "trub" first and propagating those to separate, air isolated generations and repeating several times or just culturing, viewing through a microscope, isolating yeast cells, and growing a colony of those specifically. Hopefully able to avoid contamination to a point through these methods.

For viability, I may be able to get my hands on some stain (methylene blue) from one of the micro labs but if not, I will most likely just looks at lag times for CO2 production when pitching it.

I read about drying sourdough starters once (which also contain wild yeast, along with other wild bacteria). The common procedure for that is simply making the starter quite runny by adding water, then spreading it on parchment paper and letting it dry at room temp. Supposedly this should preserve all the yeast and bacteria appropriately for long term storage.
However, this would contain other things that your wild beer yeast won't have (flour, for example) Not sure if that has an impact or not.Also when you look at the ingredients on dry brewing yeast, they usually contain yeast and rehydration agent, whatever that is. I read that it is something that protects the cell walls when you rehydrate the yeast.

Thanks for the input all. I got into the lab without the lab experience but I got kind of excited about this so I am gonna try it anyway.

Not sure if you're still thinking about trying this out but I found this little tidbit on the web.
It seems that hot air is commonly used in the drying processes.

http://www.freepatentsonline.com/3962467.html

I also found this from BYO
http://byo.com/india-pale-ale/item/566-dried-brewing-yeast-on-the-rise

"Making Dried Yeast
I spoke with Bruce Patterson of the Lesaffre Group (producers of Fermentis dried yeast) about how dried yeast is manufactured.

Fermentis yeast strains are stored in a laboratory either at -80 °C (-112 °F) in glycerol or at 4 °C (39 °F) on slants. Each strain is genetically identified before it is sent to the factory for a production run. The yeast is transferred to a liquid media made from molasses (with a sucrose content of 45–55%) with added nutrients to supply nitrogen, phosphorous, vitamins and minerals. The culture is stepped up several times in the lab before being sent to the factory.

At the yeast plant, the culture enters a rapid cell production phase and the yeast are fed continuously with molasses, nutrients and oxygen. The yeast are grown in very large fermenters, much larger than at liquid yeast plants. (How big exactly is a trade secret.)

Next, the rate of cell division is slowed and, in preparation for drying, nutrients and unspecified agents are added to the yeast to help it survive the process. The yeast cells are then harvested, separated from their media and dried to a cream with between 15 and 20% solids. The cream is pressed into a cake and extruded through a mold to produce yeast “noodles.” The noodles are then dried in an air lift dryer.

In an air lift, the yeast sit on a grate and hot air is forced up through the yeast “noodles.” The yeast are churned sort of like corn kernels in a hot air popper. (An older way of drying the yeast is to put the yeast in trays and have it ride on a conveyer belt through a long oven.) The yeast are slowly dried until they contain 94% solids. The dried yeast is then vacuum packed into sachets, which have a shelf life of two years when stored under 10 °C (50 °F). The viability of the dried yeast is 86%, but each dried yeast packet contains about 10 billion living cells per gram. Thus an 11 g pouch would contain about 110 billion cells. (These are the numbers for Fermentis yeast. The numbers for Danstar Nottingham and Windsor yeasts are comparable.)

Dried yeast companies report a very low contamination rate. (Fermentis yeast, for example, reports less than 5 bacterial cells/mL of wort in adequately pitched wort.) Patterson, however, mentions that sometimes the level falls below what can be detected in the lab. And, the experience of many brewers shows that this level does not result in problematic beer. "