Author Topic: Cross Contamination?  (Read 2062 times)

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Offline tonymark

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Cross Contamination?
« on: April 19, 2006, 05:48:53 PM »
What is up with the possible cross contamination of 2 different starters?  I read somewhere on the forum where someone only likes to have one culture per fridge.  Why is this?

I currently have Jeff's culture, but I would like to also purchase the 2 Italian cultures from  Am I just asking for trouble with 3 cultures in one fridge/kitchen?

What advice does one have for maintaining 3 cultures at once?


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Offline Pete-zza

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Re: Cross Contamination?
« Reply #1 on: April 19, 2006, 06:20:31 PM »

It would be nice to have separate places to keep my starters but I haven't been able to justify the cost. I also don't operate in a "clean room" environment. I have simultaneously kept two different starters in different sections (top and bottom) of my refrigerator and have not detected any cross contamination. By that, I mean that I can tell the two starters apart, mainly by smell, which has been consistent throughout their entire lives in my refrigerator. I do use different sets of spoons (sterilized in hot water) with the two starters and I occasionally transfer the starters to newly sterilized bottles. My recollection from something Marco said is that there may be some small amount of local wild yeast that might get into a developed starter, but it is minor and doesn't overtake the starter, especially one that has been around and survived intact for a few hundred years, such as the Ischia and Camaldoli starters.

I'm confident that Marco or someone else with the two Italian starters will weigh in on this matter.


Online Wazza McG

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Re: Cross Contamination?
« Reply #2 on: April 19, 2006, 06:23:34 PM »

I would say that it has to do with the fact that CO2 will build up and has to be released somewhere within the fridge - no doubt with some yeast cells going with it.  Hence, over time, the fridge may have a yeast strain available for other yeast strains to be affected by it.

I also have a similar query about contamination.  I had my Camaldoli Hill going great until recently when it become smelling a tad rancid - I thought it may of been caused from using tap water all the time - we chlorinate our water here. 

I have now used my last bit of starter yeast to re-activate a new starter and after 1 week it looks really healthy.  What I would like to know is how do I protect my last healthy batch.  I do not have a hydrater - can I freeze some of the starter when I refresh it as a back up??  I would rather the dried form rather than freezing - any ideas?


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Offline pizzanapoletana

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Re: Cross Contamination?
« Reply #3 on: April 20, 2006, 08:20:23 AM »
This is indeed one of my area of maximum expertise...  8)

I always assume that you keep the starters in a sealed container (either a jar or a Pyrex glass container with a plastic lid, depending in which form you keep your starter) and therefore I do not see problems with the refrigeration storing. The contamination issue is at room temperature, in your kitchen environment, were spores may build up. You can minimize the risk by keeping an absolute clean and disinfected environment and tools. The risk do still exist, and therefore it is also important to keep the cultures at a good level of acidity.

The other issues is that it become more difficult when the cultures keep increasing in numbers. For me two are already too much to look after. As well as Peter quoted, it is extremely difficult that an established starter get overtaken by local microflora. Just to be precise and by no means it affect performance and reliability, the Camaldoli one is not really old, just few years.

Wazza McG,

It is quite normal for a culture (specially if kept in a liquid form) to become to acetic and loose it's characteristics. Do not panic, yo do not need to go back to the dry form (in fact each time you reactivate from a dry state you increase the contamination issue), it just need proper wash procedures, and in the booklet you find such examples. I personally use a technique that I have developed together to microbiology researcher at the University of Naples. It works great for me, but I believe Ed advice are also bullet prof.

Just for example, when I came back from my three weeks trip in America, my Ischia starter was completely unbalanced and lost all the leavening power. Thanks to my "washing" technique, it was back to the status I found him many years ago, within 36 hours... Ciao

Offline Bill/SFNM

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Re: Cross Contamination?
« Reply #4 on: April 20, 2006, 08:56:39 AM »
I currently maintain 4 starters, 3 of which I use frequently. Never had a problem yet with cross contamination; each continues to have unique flavor and characteristics. Like Marco, everything is sterilized. Also, I never work with more than one culture at a time.


Offline tshands

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Re: Cross Contamination? Sourdo cultures.
« Reply #5 on: April 20, 2006, 10:29:03 PM »
Just started reviving the 2 Italian cultures from sourdo. Instructions say you may or may not see a few bubbles after the first 24h. Well, mine almost expanded to the top of the jar. Wonder what the heck I'm growing...sounds like it likely isn't what I hoped for. One smells slightly sour ( but it is a "sourdough" culture), the other has a slight off smell. Neither smell really good and yeasty. Talking about cross contam, I have been proofing these together in the same box with lids on loosely. Didn't see anything in the instructions about separate boxes but is that a problem? Think I have to chunk it and order another? Thanks for any advice.   Tom Shands.

Offline Bill/SFNM

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Re: Cross Contamination?
« Reply #6 on: April 20, 2006, 11:30:53 PM »
In my experience, if it smells even a little off, it's going to get worse with continued feedings. I don't think you have to chuck anything yet - just keep washing as directed. It seems like a hassle, but these Italian starters are worth the effort, IMO. I would suggest working on one culture at a time to avoid accidental contamination.

Of the 4 starters I currently maintain, 3 of them came from (one I captured myself).  IIRC, two of the pnes from showed signs of contamination and need repeated washings.