Author Topic: Mother Culture Questions  (Read 1761 times)

susanky

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Mother Culture Questions
« on: May 15, 2011, 04:53:36 PM »
I just made my first mother cultures! (Using Sailor's Photo Essay... thanks for that!  I'd put the link here if I were more tech savy)  Which led me to the following question.  I started to ask on other thread but makes more sense this way. 

I walked away and the temp got too high once.  What are the fatal doses for mesophilic cultures?  Thermophilic?  Is there a way to test viability other than give it a try?

I used MA 4001 which also has a thermophile in it. So when I cultured at 90 degrees did I only grow the mesophilic, such that I now have a different culture?

at 17 hours the pH were right on.  4.34 meso and 4.09 thero (although my meter reads my 4.0 calibration at 3.85 and my 7 at 7.1 so who knows?!).  The meso was 'chunky' but the themo was solid like yogurt.  So I shook it. I can't hurt it with a little vigorous shaking, can I?

And finally.. (lots of questions in my head right now).  I am going to try to grow some blue mold in this way from a piece of purchased blue cheese.  What would be the ideal temperature and what pH should I shoot for?  Or can that be done? 

Making cheese is fun!
Susan

linuxboy

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Re: Mother Culture Questions
« Reply #1 on: May 15, 2011, 06:39:58 PM »
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What are the fatal doses for mesophilic cultures?  Thermophilic?  Is there a way to test viability other than give it a try?
Answered in other thread. If unsure of culture viability, always a best practice to inoculate another small batch of just milk and propagate another generation. Always want to start out with the same amount of bacteria that are alive and well, in the same proportion for consistency.

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So when I cultured at 90 degrees did I only grow the mesophilic, such that I now have a different culture?
It's a range of activity with strains ans species having specific preferences. S thermophilus will do just fine at 90F.
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I can't hurt it with a little vigorous shaking, can I?
No, often, I will use a stirrer when propagating. Does nothing harmful (unless you somehow stir and keep introducing oxygen).
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What would be the ideal temperature and what pH should I shoot for?  Or can that be done? 
For which media? Can't use milk for that. If you're using liquid broth in a continuous fermentation or batch fermentation, you need to bubble oxygen through the media. It's often easier to grow it on bread or other solid media at home.


Tomer1

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Re: Mother Culture Questions
« Reply #2 on: May 15, 2011, 07:50:23 PM »
Like ager?

linuxboy

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Re: Mother Culture Questions
« Reply #3 on: May 15, 2011, 08:07:13 PM »
Not sure what you're asking. :) An agar broth can be used for slants, often easier to go with a broth for fermentation in bulk tanks. So, for example PDA and PDB (potato dextrose agar vs potato dextrose broth). But yes, that's the gist of it.

susanky

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Re: Mother Culture Questions
« Reply #4 on: May 15, 2011, 08:17:00 PM »
Thanks Linuxboy.  I'm learning a lot piece by piece and this forum is fantastic.  I wonder if there is a detailed sort of 'Microbiology for Dairy' book that I could read.  It would be helpful to me to get the 'big picture'. 

I guess I assumed if I could grow P roqueforti in cheese I could culture it in milk.  Just spent too much time googling it's growing conditions.  There must be a reference book....
There are certainly alot of strains and they seem to vary quite a bit in their activity.  How does one choose?  I am mostly interested in Stilton.  If I buy some commercially, is it worth culturing at home?  I may have access to agar.  But not sure about the growing conditions.  Because I doubt I want to worry about maintaining O2 conditions, temp etc.  But would be nice to be self sufficient.
Susan

linuxboy

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Re: Mother Culture Questions
« Reply #5 on: May 15, 2011, 08:41:48 PM »
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I wonder if there is a detailed sort of 'Microbiology for Dairy' book that I could read.
Yes, but it's not going to tell you things in a clear way. You're looking for a description for how to go about culturing yeasts, molds, and bacteria, how to run a basic lab, how to use it in cheesemaking, etc. Right? I'm working on this for my book series. In the meantime, google, or ask here.

I'll e-mail you a few things.
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Just spent too much time googling it's growing conditions.
For roqueforti? For what, growing on slants, or for a fermentation system? If you want to propagate, there are different approaches based on your needs. You can use solid state fermentation or liquid fermentation, and then from there, either do it in batches or in a continuous system. See how you read all that and have no clue what it all means? That's what I'm talking about, all the books are like this. You can't get a straight answer because the best answer really is "it depends".

Essentially, you need a C-N ratio of around 10 (this can vary drastically, being as low as 5 and as high as 20), and trace elements for food. I could invent a custom "bread" recipe if you want. This would likely be the easiest approach. To make croutons from a special bread, and then inoculate it with roqueforti, and then crush it all up and use the powder. That's likely the easiest thing to do at home. beyond that? You need acidity of 5.0-5.5, temp of 60-75F, and high oxygen availability (you would need to filter air and have it flow through the chamber, or vent and introduce oxygen somehow. Not too hard to do... think custom lid on mason jar with a few vents attached to hose.

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How does one choose?
Customarily, based on the needs of:
- Color of strain in cheese, from white to green to deep blue to sky blue
- Initial proteolytical capability
- Aroma formation
- Enzymatic capability for lipolysis
- Enzymatic capability for catabolism of amino acids/peptidolysis

Meaning it has to match your cheese and shelf life and market goals. You might want a mild flavor with a lot of proteolysis that's a deep blue color. Can pick that one.

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If I buy some commercially, is it worth culturing at home?
IMHO, no. Unless you get a lot of satisfaction from being a mad scientist, it's much easier to buy commercial strains. Like for my stilton recipe, any mild strain of blue works.

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Because I doubt I want to worry about maintaining O2 conditions, temp etc.
You can do it simply, like by opening the lid and shaking up the custom crouton cubes and letting oxygen in there. But IMHO, not the best approach, it can be inconsistent. And often not worth it unless you're doing things on a large scale.
« Last Edit: May 15, 2011, 08:55:14 PM by linuxboy »