# yeast for baking and brewing **URL:** \ **Category:** Factual Questions\ **Created:** [March 28, 2007, 3:24am UTC](https://boards.straightdope.com/t/yeast-for-baking-and-brewing/397786 "2007-03-28T03:24:43Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![The\_Long\_Road](https://avatars.discourse-cdn.com/v4/letter/t/b5a626/32.png) [@The\_Long\_Road](https://boards.straightdope.com/u/The_Long_Road)\ **Post date:** [March 28, 2007, 3:24am UTC](https://boards.straightdope.com/t/yeast-for-baking-and-brewing/397786/1 "2007-03-28T03:24:43Z")
Sorry for such a simple question in a land of knowledge but I’m fascinated by way back when times. Before you could run down to the store and buy yeast either for baking bread or brewing beer, how was it obtained? I’ve seen forms of friendship bread where the yeast mixture is passed along but I’m wondering about getting it from scratch. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [March 28, 2007, 3:38am UTC](https://boards.straightdope.com/t/yeast-for-baking-and-brewing/397786/2 "2007-03-28T03:38:08Z")
You mix up a bowl of flour and water 1:1, add a pinch of salt, and let it sit open to the air for a few days. Yeast spores will land in it and grow. When you get a batch that smells good, and raises dough quickly, put a ventlated lid on the jar to keep out intruders, and feed weekly. ---
**Author:** ![Queen\_Bruin](https://avatars.discourse-cdn.com/v4/letter/q/e274bd/32.png) [@Queen\_Bruin](https://boards.straightdope.com/u/Queen_Bruin)\ **Post date:** [March 28, 2007, 3:43am UTC](https://boards.straightdope.com/t/yeast-for-baking-and-brewing/397786/3 "2007-03-28T03:43:25Z")
You can make sourdough starter with nothing more than a flour/water slurry and some time. Just leave it open to air for a few days, and voila! yeast colonies (along with the bacteria that give sourdough its kick). The starter colony must then be taken care of through regular “feeding” and proper storage. Yeast in beer was cultivated in much the same way. The wort was left in the open to collect wild yeasts. Lambics use this style of yeast cultivation. I understand that lambics are very sour, probably due to the collection of bacteria along with the wild yeasts. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [March 28, 2007, 3:49am UTC](https://boards.straightdope.com/t/yeast-for-baking-and-brewing/397786/4 "2007-03-28T03:49:20Z")
Some of the best bread is made by continuously “feeding” a starter (typically a rather soft mixture of moist flour, where yeast can thrive). Each batch of bread uses some of the starter, and thus gets a nice dose of yeast. Managed properly, such a starter can last years. I have never made beer, but I imagine it should be possible to do something similar: take yeast from a mature batch and use it to start a new one. ---
**Author:** ![psycat90](https://avatars.discourse-cdn.com/v4/letter/p/7ea924/32.png) [@psycat90](https://boards.straightdope.com/u/psycat90)\ **Post date:** [March 28, 2007, 5:28am UTC](https://boards.straightdope.com/t/yeast-for-baking-and-brewing/397786/5 "2007-03-28T05:28:40Z")
Probably more info than you wanted, but what the heck: The main yeast used for winemaking (and I assume brewing and baking) is [Saccharomyces cerevisiae](http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae) and is found on grape skins (they land on the skins, just like they would in a bread mixture as described by Squink.) Fermentation will happen naturally with grapes (as it did way back when) though now most winemakers kill the wild yeasts to use cultured yeast. [Here’s](http://www.bbc.co.uk/dna/h2g2/A2791820) a pretty decent and very brief history on Saccharomyces cerevisiae. > [@](#): > > We don’t know when or how the first leavened bread occurred; only that the first records of any sort of bread are in ancient Egyptian hieroglyphs. Possibly one day a mixture of flour meal and water was left longer than usual on a warm day and the yeasts that occur in natural contaminants of the flour - or even in milk that may have been added for flavour - began to ferment before baking. The resulting bread would have been lighter and more tasty than the normal flat, hard cake. > > Gradually it became the norm to produce leavened breads, keeping a soft lump of one day’s fermented dough to add to the next baking session’s fresh batch to speed up fermentation. The bottom of [this page](http://www.winebusiness.com/ReferenceLibrary/webarticle.cfm?dataId=44326) has a pretty decent list of yeast suppliers used by large scale winemaking productions (possibly brewing, etc., I don’t know), one of them might have a little more info on their website. Or you can peruse yeastgenome.org for lots of yeasty goodness. ---
**Author:** ![Zoe](https://avatars.discourse-cdn.com/v4/letter/z/a4c791/32.png) [@Zoe](https://boards.straightdope.com/u/Zoe)\ **Post date:** [March 28, 2007, 10:04am UTC](https://boards.straightdope.com/t/yeast-for-baking-and-brewing/397786/6 "2007-03-28T10:04:36Z")
I think I will found [freetheyeast.org](http://freetheyeast.org). Oh why not… ---
**Author:** ![Common\_Tater](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/common_tater/32/13846_2.png) [@Common\_Tater](https://boards.straightdope.com/u/Common_Tater)\ **Post date:** [March 28, 2007, 11:49am UTC](https://boards.straightdope.com/t/yeast-for-baking-and-brewing/397786/7 "2007-03-28T11:49:27Z")
Wild yeasts are too much of a crap shoot for beer brewers and they go to great lengths to avoid that. Certain belgian lambic beers are an exception I suppose. One of my favorite breweries has been in continuous operation for over 500 years so wild yeast probably aren’t a problem anyway. ---
**Author:** ![elbows](https://avatars.discourse-cdn.com/v4/letter/e/b3f665/32.png) [@elbows](https://boards.straightdope.com/u/elbows)\ **Post date:** [March 28, 2007, 1:38pm UTC](https://boards.straightdope.com/t/yeast-for-baking-and-brewing/397786/8 "2007-03-28T13:38:03Z")
You’re exactly right Xema. My husband is a craft brewer in a brew pub and that is precisely what he does for his yeast. He removes some from the last brew and puts it aside and saves it for his next brew. Should something untoward occur and it dies off, he can, of course, simply purchase more from a supplier. But it is only necessary very, very rarely. He frequently goes over a year, working from the same yeast. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 28, 2007, 1:41pm UTC](https://boards.straightdope.com/t/yeast-for-baking-and-brewing/397786/9 "2007-03-28T13:41:48Z")
If you’re making bottle-conditioned ale, the yeast sediment in the bottom of the bottle can be revived as a starter culture pretty much any time - it’s not dead, it’s just… restin’