Wednesday, August 12, 2009

Bread Starter Test

Way back in July (7/21 to be precise) Michael Ruhlman posted about a method of kick starting sourdough starter. The method, which he learned from Carri Thurman of Two Sisters Bakery in Homer, Alaska called for the addition of a red cabbage leaf to a mixture of flour and water.

Both Ruhlman and Thurman, as well as several of the former's readers, reported remarkable results. Yet no one could explain why the cabbage had the reported effects.

Some speculated that the cabbage was loaded with wild yeast, while others (myself included) thought that bacteria might be responsible for the uptick in microbial activity and signs of fermentation (gas bubbles). Since no one could provide a plausible explanation for what might be occurring, I decided to test the idea with a series of tests.

Last night I conducted the first test. The purpose of this particular test was to answer the question "Will adding rinsed and un-rinsed organic red cabbage to a mixture of flour and water make any difference in the rate at which the mixtures ferment?"

Test Design

I made up 7 samples. Each sample contained 20 g of unbleached non-organic bread flour (I wanted as little as possible yeast in the flour) and 50 g of unchlorinated tap water.
  • In three of the glasses I put 5 g each of red cabbage that had been rinsed (as per Carri's method) under luke warm water.
  • In three glasses I put 5 g each of red cabbage that had not been rinsed
  • In one (Control) glass I put only flour and water
Each sample was mixed with a spoon which was washed with hot water and soap to avoid cross-contamination of the samples. The I left the samples uncovered on the counter in my (68 degree F) kitchen overnight before checking them 13 hours later.

By 7 Am this morning, none of the samples, not even the control have shown any signs of fermentation. Even now (almost 14 hours after mixing) there are no obvious signs of fermentation.

Ruhlman and Thurman suggest that additional flour (a "feeding") and 48 hours of incubation is required to produce vigorous bubbling. I will let my sample go at least that long before drawing any conclusions. (I will not add more flour.) If after 48 hours, two or more of the samples with cabbage appear to be fermenting more rapidly than the control, I will assume that the cabbage is contributing something to the process and move to the next phase of the testing which will be designed to answer the question

"Will limiting the supply of oxygen have an effect on how the flour cabbage mixture ferments?"

This question is designed to begin to get a handle on what (if any) microbe on the cabbage is responsible for the enhanced fermentation reported by Ruhlman, Thurman and others.





17 comments:

Carri said...

It's so funny you're doing this now...with my tomatoes quickly ripening and bacon ready, I decided to re-test my process on the starter and do a batch at home to make my bread for the BLT challenge. Last night I rinsed 2 broccoli leaves from my garden off in warm water and mixed in equal part of flour. that was at around 8 pm. At 5:30 this morning it had no real activity and had separated. I fed it 1 cup of warm water and 1 cup of flour. Upon reading your post I went and looked at it and in the 3 hours since feeding the starter is already nice and bubbly! I hope to make bread later today. I am so curious to see how your experiment ends up...Thanks for doing this!

Carri said...

one question...how come you are not feeding it again? I think we are not 'fermenting' as much as we are 'breeding' no? If you don't feed it, how will it grow and get active?

michael said...

i would agree, i think part of why it works is the second feeding.

Bob del Grosso said...

Carri-Michael
If the cabbage is contributing anything to the mix it should be apparent from the outset. Adding more flour is not significant.

Put another way, there is no reason to feed it if there is no evidence that there are microbes to feed.

Keep in mind that I am not making starter but only trying to answer the question "does the cabbage have an effect" under these circumstances. As of now, the answer looks like "no."Let's see what happens in 48.

Carrie said...

I'll be very interested to see what the results of your experiment are! I set up two starters last night (one whole wheat, one white). I rinsed a cabbage leaf thouroughly in the warm water I used to make the starter but didn't actually put the leaf IN with the starter.

This morning they were both going nuts! They were bubbly and had expanded; when I poked them with a spoon before stirring them up to feed them they were almost stringy. I'm not sure if that's good or bad. LOL It's almost a tropical environment around here right now - 95 degrees and 85% humidity outside - so I'm sure there's plenty of wild yeast hanging around. Although I covered both of the starters, so I don't know how much that would matter either.

This is fun! :)

Bob del Grosso said...

Carrie
My gut tells me that if the cabbage leaf does anything it is that it contribute bacteria and not much yeast. Moreover, the bacteria that it brings in is not good for bread.

I suspect that this bacteria has not been a problem for you because as a bakery your environment is so loaded with yeast that they quickly enter the flour you use. Moreover, if you use organic flour that is heavy with yeast coming in the door.

The bottom line of this line of resoning is that even though the cabbage is intorducing bad bacteria into the starter it is not a problem for you because your ambient yeast out competes it.

I've talked to other people who have used the cabbage technique and came up with starter that stunk like sauerkraut. I suspect that the reason this happened is that they had much less yeast, so the bacteria went berserk. (Also they covered the starter, making it anaerobic and conducive to the growth of this particular strain of leuconostoc bacteria).

I don't know if I am right about this but I would not be surprised to find that I am.

Jessika said...

Interesting.
I will follow closely.
I bake with yeast, all my attempts with sour dough leaveners have failed.

Carri said...

Carrie, I think Bob thinks we are the same person? Bob, I don't get it. Why is it working so well for so many and why is it working for me at home as well as at the bakery, using broccoli insted of cabbage? I have just started a control batch of just flour and warm water, I'll let you know what happens...

Jessika said...

Carri,
It's an interesting question indeed but not just for Bob but generally. I follow instructions to the letter about sour dough starters, feeding etc., and mine have all, sooner or later, failed. I know others that are excellent with sour dough starters. I have no idea why I, and more with me, are so fumbly as to not get them to work at all or to have them work too much so that they die or go bad. Eventually, with too many starters behind me, I quit and returned to regular but active yeast.

Bob del Grosso said...

I guess Carrie sounded like Carri and I responded in kind. I'll try to read more carefully next time. I actually Carrie with the "e" ending was a mistake!

Carrie said...

LOL Bob! Being mistaken for Carri isn't so bad - she has my dream job.

For what it's worth, my starter smells really good!

Carrie said...

Ummm, is starter supposed to have foam? And stink really bad? Because I came home from work and my starter has apparently mutated from a slightly bubbly, slightly yeasty smelling happy little bowl to an enormous, stinky blob with foam bubbling out of the top. Maybe I'm starting to buy Bob's bacteria theory after all.

Carri said...

Carrie, had you fed your starters before work? Try feeding again and report back...I think that the foam and smell might be from the yeast over-eating, though our friend Bob may disagree with me on that!

Carrie said...

I fed them this morning - I'll feed them again before I go to bed and let you know what happens in the morning. :)

Bob del Grosso said...

Carrie
Starter is not supposed to stink. It should smell like more or less like fermenting bread. Please tell me if

1) you used cabbage
2) it was covered/ airtight
3) what type of flour you used

Bob del Grosso said...

Carri
I'm afraid that I will have to "sort of" disagree.

Yeast produce mostly carbon dioxide (odorless) and alcohol. I have read that under certain conditions they can produce butyric acid, which stinks, but it is not clear whether or not those conditions are related to how much food is available.

More likely the smell is from bacteria.

Carrie said...

I did use cabbage and I did cover both starters. I think I may have actually overdone the cabbage. While trying to pull off one leaf they kept breaking so I kept dumping little pieces at a time in there. I may have ended up with two pieces per batch. Also I'm thinking my cabbage may not have been fresh enough - it sat in my fridge for a few days before I got around to using it.

One was whole wheat flour and the other was bleached white. This morning they both smell even worse and appear to have come to life - they're expanding and contracting and slowly spewing gouts of white foam. My five year old loves them and wants to keep them as pets. LOL