Thread: Growing Yeast

Hi Everybody!

I'm going to keep this post short and sweet: I'm a freshman in high school and a few of my friends and I are planning on growing our own yeast for our term project. We don't have a huge amount of time (about a month for the entire project) so preferably we would need to grow the yeast in about 3 weeks. If there's a quicker way than I would be happy to know it! Another thing, this is supposed to be a controlled experiment so we were also thinking of growing yeast aerobically and anaerobically and comparing the results - is it possible to grow yeast anaerobically without expensive and hard-to-find equipment? Maybe in just a petri-dish?

Thank you so much!!

Anaerobic.
You mean like you would if you were brewing a keg of beer?
Aerobic.
Like making bread?

Yeah, basically. Except that we don't want to make bread, or beer (I know right shocker). We just want to grow yeast in an environment with and without oxygen and compare the results. Also, again, if anybody knows how to make an anaerobic environment...

Originally Posted by klaus30000

I'm going to keep this post short and sweet: I'm a freshman in high school and a few of my friends and I are planning on growing our own yeast for our term project. We don't have a huge amount of time (about a month for the entire project) so preferably we would need to grow the yeast in about 3 weeks. If there's a quicker way than I would be happy to know it!

Weeks? You can do it in a few days. Either brewer's yeast or baker's yeast will work for you. For nutrients you can use something like DME (dry malt extract) or even just plain table sugar. Keeping things sanitary is the only real "trick." (If you don't, you risk introducing other yeast or bacteria.)

Another thing, this is supposed to be a controlled experiment so we were also thinking of growing yeast aerobically and anaerobically and comparing the results - is it possible to grow yeast anaerobically without expensive and hard-to-find equipment?

Sure. Most alcoholic beverage ferment anaerobically during the final phase of their fermentation. You can do it in a bottle with an airlock. Airlocks are about $1 at a brewer's supply, or you can just use a latex balloon in a pinch.

Anaerobic fermentation by yeast is what produces the alcohol.
Aerobic fermentation by yeast produces the carbonation. (fizz in beer and wine, leavening in bread)

Originally Posted by dan hunter

Aerobic fermentation by yeast produces the carbonation. (fizz in beer and wine, leavening in bread)

Anaerobic fermentation definitely produces CO2 as well. (That's how bottle conditioning works.)

Originally Posted by billvon

Originally Posted by dan hunter

Aerobic fermentation by yeast produces the carbonation. (fizz in beer and wine, leavening in bread)

Anaerobic fermentation definitely produces CO2 as well. (That's how bottle conditioning works.)

OK, I just drink the stuff.

Thank you all for the helpful advice !!!

This may seem like a dumb question (sorry), but does anybody know how we can actually GROW the yeast (if possible)? I know someone mentioned nutrients, and keeping things sterile, but does anyone know a step-by-step procedure for growing yeast? I've been trying to find one online, but all the results just talk about making beer or bread - I just need to grow the fungus itself.
Thanks again everybody! I think I have a better idea of what we're going to do

Originally Posted by klaus30000

This may seem like a dumb question (sorry), but does anybody know how we can actually GET the yeast? Is it possible to grow our own without buying yeast from the store?

Easiest is baker's yeast (any grocery store) second easiest is a brewer's yeast (any homebrew place.) If you just leave a sugar water solution sitting out it will pick up wild yeast, but it will also pick up bacteria etc. Separating them out might be problematic. If you expose say 20 dishes of sugar water and culture the result some of them will be wild yeast only; you can identify them by CO2 production (in a large enough culture.) But you have to propagate the strain into a larger culture, once you have candidates.

Okay, so it sounds like growing our own yeast might be kind of problematic. Oh well. In that case we might do an experiment with sugar fermentation or something of that ilk. Thanks again everyone!