Author Topic: sourdough culture contamination question  (Read 1955 times)

0 Members and 1 Guest are viewing this topic.

Offline markus1984

  • Registered User
  • Posts: 10
sourdough culture contamination question
« on: March 22, 2010, 03:33:22 PM »
I wonder if anybody could tell me about possibility of culture contaminating by another culture, is it possible? The thing is, I have two different cultures from ed wood and i keep them togeather in the fridge one next to the other and at some point i proofed them togeather in the same box, my question is: is there anything bad that could happen? how will i know that something is going wrong? Will it lose taste? will it mix togeather or anything like that? if it did contaminated is there any way back? thanks for any help, Adam


Offline Bill/SFNM

  • Lifetime Member
  • *
  • Posts: 4039
  • Location: Santa Fe, NM
Re: sourdough culture contamination question
« Reply #1 on: March 22, 2010, 04:28:06 PM »

Offline skan

  • Registered User
  • Posts: 38
Re: sourdough culture contamination question
« Reply #2 on: January 27, 2012, 07:44:29 PM »
I've read that sourdough can be contaminated by Escherichia coli and botox
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC380829/pdf/applmicro00055-0157.pdf

Although is not very common because pH is very low .
http://www.ehow.com/how_5824175_sourdough-starter-bad.html
http://www.schoolofbaking.com/sourdough_tips.htm

Offline TXCraig1

  • Registered User
  • Posts: 12833
  • Location: Houston, TX
Re: sourdough culture contamination question
« Reply #3 on: January 27, 2012, 09:41:19 PM »
I've read that sourdough can be contaminated by Escherichia coli and botox
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC380829/pdf/applmicro00055-0157.pdf

Although is not very common because pH is very low .
http://www.ehow.com/how_5824175_sourdough-starter-bad.html
http://www.schoolofbaking.com/sourdough_tips.htm

The first article you cited does not even mention Clostridium botulinum (botox is short for botulinum toxin which is the toxic waste product of the bacteria). In any case, C. botulinum growth and toxin formation are completely inhibited at pH values below 4.6*. E. Coli may survive at slightly lower pH, but not much. Most sourdough cultures top out at around 4.5, so it is difficult to imagine botulism or even pathogenic E.coli is a significant concern especially if even rudimentary sanitation practices are employed.

E. Coli K12 (the strain mentioned in the article) is a cultivated lab strain that is not pathogenic nor toxicogenic. In the context of the article cited, it was added deliberately as a standard in the calculation of the DNA base compositions.

The second two articles both sound like they were written by people with little understanding of microbiology. The ehow article says You want yeast to grow in your starter, not bacteria. Im not sure where the author thinks the flavor comes from if not Lactic Acid Bacteria.

In the school of baking article, the author writes that "Schizomycetes (acidifiers)" are desirable in your culture. First, Schizomycetes is a long obsolete term (like from the 1800s). Second, it included much more than acidifying bacteria including pathogens! S/he also lists also lactic and acetic acids as organisms???

Im thinking neither of these sources is an authority worthy of citation.

Just my $0.02

Craig

*I have read of C. botulinum growth below a pH of 4.6 in a lab, but not elsewhere.
Pizza is not bread.

Offline skan

  • Registered User
  • Posts: 38
Re: sourdough culture contamination question
« Reply #4 on: January 28, 2012, 06:59:29 AM »
Your words make me think you know what you are speaking about. I hope you are right, I'm a little bit afraid of sourdough contamination.

Anyway what worries me is the initial contamination, before one could get the proper sourdough cultures, before we get a pH below 4 that prevents other organisms from spreading.
In those conditions many people have had their sourdough contamined with mildew and had to throw it.
(I've read complaints of people trying to start their own sourdough).

regards

Offline TXCraig1

  • Registered User
  • Posts: 12833
  • Location: Houston, TX
Re: sourdough culture contamination question
« Reply #5 on: January 28, 2012, 09:47:28 AM »
A healthy respect of food safety is a good thing. That being said, Im not aware of sourdough cultures being much of a risk.

Certainly many of us have had a new culture get contaminated with some sort of bacteria or mold when it was just starting out and had it go bad. However, I have not heard of any healthy, established cultures getting contaminated. Could you do it if you really wanted to, probably, but I think you would have to put some effort into it deliberately contaminating the culture. If you keep your culture well fed or refrigerated and use basic sanitations techniques just keeping anything that goes into the culture clean if nothing else I dont think you will have a problem. That being said, like anything in food safety, if you are in doubt, error on the side of safety!

As for a new culture, if it gets moldy or turns some strange color, or stinks, throw it away and start over. If you buy a dry culture, follow the instructions. They will tell you how to deal with minor contamination early on. It is possible (maybe likely) that it will smell bad at first. Perhaps there is a contaminant in your flour not at all uncommon. With proper handling and care, it is usually the case that the sourdough culture will take over and kill off the contaminant and then establish itself as dominant.

Most sourdough cultures are pretty robust. The yeast and bacteria form a symbiotic relationship that not only helps feed each other, but also produces natural defenses against contamination.

If you are new to sourdough, I would encourage you to get Ed Woods Classic Sourdoughs book.

CL
Pizza is not bread.

Offline ThePieman

  • Registered User
  • Posts: 37
  • Location: Pittsburgh, PA
Re: sourdough culture contamination question
« Reply #6 on: February 20, 2012, 08:03:26 PM »
I believe that OP was talking about one starter "contaminating" another starter which is nearby. In other words, certain strains of wild yeasts and lacto from one culture, "jumping ship" and "contaminating" the other culture, changing the culture. I don't believe they were talking about pathogenic organisms.