Relative activity

Just out of interest I replotted Ganzle's data on the relative activity of lactobacillus sanfrancisco and the yeast candida milleri.

[img]http://www.sourdough.com.au/gallery/d/5020-1/relative+activity.jpg[/img]

You will see the lactobacillus dominates when it is cold (fridge temperature) or warm (above 85F). The baker can adjust the ratio of bacillus to yeast, and hence the taste of the bread by fermenting for all or part of the time at these temperatures. I like my bread tangy, so I tend to ferment the preferment quite hot, and retard cold.

The temperature of the mother starter is kept at, since there is so little in the dough, is less important, except during the time it is being established.

However if you are making salt-raised bread the leavening agent, the bacteria Clostridium perfringens (see

http://www.nyx.net/~dgreenw/whatissaltrisingbread.html

) prefers it warmer: the temperature range 95F-105F. It may be that is what is responsible for the characteristic cheesy smell

6 comments

Dom that is what I was seeing a lot too in that book as well as in the Red Hen baguette formula I did, some of the French formulas I see use both liquid and firm starters, Eric Kayser is liquid user, and I think the strangest thing when baking different sourdough breads,Italian, French or German there are distinctive flavors in those specific bread types!

Jeremy

Some time back, after Jack posted the graph on egullet, I asked Dan for his opinion because I'm one of those people who can't retain science in their brain. He say:

[quote]
In 1998 a thesis was accepted by Michael G. Gänzle, Michaela Ehmann, and Walter P. Hammes, at Universität Hohenheim, in Stuttgart, Germany, on growth of Lactobacillus sanfranciscensis and Candida milleri in sourdough fermentation. Subsequently, many bakers took that study to mean that L.sf and C.milleri were SF. sourdough, or even further, that all natural fermentations included L.sf and C. milleri. This just isn't true, and a misunderstanding of the precise nature of the original study. I've sent 5 samples of sourdough and naturally fermented leaven cultures for analysis and none have contained L.sf and C.milleri, and as these were consecutive tests I would question the papers initial statement that "in sourdoughs with a tradition of continuous propagation, Lactobacillus sanfranciscensis....[and] Candida milleri.....are the predominant microorganisms"

That doesn't mean that (a) they didn't produce great bread or, (b) weren't traditional cultures from continuous propagation. It's just that each mixture of flour and water will contain the selection of microflora that chance provides. You could, though, argue that "San Francisco Sourdough" should contain L.sf and C.milleri, though I doubt that every bakery in the SF bay area uses a culture that does. There are different types of lactic bacteria and yeast that are both suitable for dough production and comfortable in temperatures other than those described in Gänzle, Ehmann, and Hammes particular study.

I can't really comment further, though I am preparing an article with the help of the team at National Collection of Yeast Cultures (

www.ncyc.co.uk

), and will put it in the main section of the website next year.

On a more practical note, I have visited hundreds of bakeries around the world making great naturally fermented bread in varying conditions, on icy mountain tops in the Italian alps, or hot kitchens in Kuwait, and in most they simply used their room temperature "as is" and varied the method according to what produced the best result to their taste. The trick is to understand the environment you have at your disposal and to squeeze the best use and result out of it.
[/quote]

I am a great admirer of Jack's bread but it just isn't practical for me to carry out fermentation at the temperatures he advocates and anyway I'm producing reasonable bread at lower temperatures.

I prefer to go with the grain (excuse the pun) and make bread at ambient temperatures with ingredients that are readily available. A personal view ....

Mick

no I was thinking more about combining starters fermented at different consistencies.
For example a yeast-based baguette recipe that I was looking at in Maggie Glezer's Artisan baking uses one preferment made a little like your ultra-stiff starter (a pate fermentee - but with a little salt in it), and a second sponge preferment - both fermented for 12 hours using tiny amounts of yeast.

She talks about the more solid starter contributing to flavour, while the more liquid starter contributes to 'extensibility' of the dough (I am paraphrasing from memory as I don't have the book in front of me.)

Would there be any benefit in combining two sourdough starters made at different hydration and/or temperature?

Dom


I've not tried combining starters - my view is that after a comparatively short time in any environment, since you are feeding them with the local water and flour, and kitchens while clean are a long way from sterile, they become the same.
Similarly I'm doubtful about adding commercial yeast to sourdough breads, since they need rather different conditions to thrive. I think you get yeast bread flavoured with sourdough starter.
However I do think that most of the flavour comes from the preferment, rather than the dough step, so adjusting the conditions for that, and fermenting it out fully, since the gas production and dough structure is not relevant at that point, gives optimum flavour.

Jack,

your posts always make me realise how much I don't know.

I have read about the balance between lactic and acetic acid production, and it seems as though cooler fermentation (as well as the firmer starter) promote acetic acid, and a more 'sour flavour'

Some artisan breads use a combination of different starters. The German Detmold technique (about which I know very little) falls into this category.
Have you tried combining starters proved at different temperatures, or different hydration?

cheers
Dom


All right, but let me correct something..I think you mean this guy, [url=http://www.afns.ualberta.ca/People/Index.asp?Page=Directory&id=1459]Dr.Michael Gänzle[/url], his new University has castraTED HIM!
Correct name you can find [url=http://www.chairs.gc.ca/web/chairholders/viewprofile_e.asp?ID=1834]here[/url]

Very Happy

Nevertheless, he studied at the same university as our member carla, in Hohenheim must be a source to become sourdough fanatics

Razz

perhaps this post is in wrong secton? Research?