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Need an expert here to diagnosis this

Started by bmilkq, October 06, 2023, 05:43:23 PM

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bmilkq

Hello,

I have been making buttermilk regularly with the same culture for about 10 years. Basically daily. About 6 months ago or so, I noticed that the surface of my buttermilk had globules of some sort, very much looking like the surface of a petri dish with a culture of some sort growing. 

I'm not certain, of course, that what is on the surface has never always been there, whether it is just on the surface or throughout (though it looks to be just on the surface).  Nor am I certain that it doesn't have to do with the brand of milk I use since I use different brands. It also seems like it is not always in every batch, though I haven't really paid attention (will going forward).  It is possible that it doesn't show up unless the temp in my house is 75 degrees or higher, but again, i need to pay attention to figure it out. It may be milk brand dependent. All this is conjecture at this point. I need to start keeping track.  Are these casein micelles, fat?  What I'd like to know from the experienced people on this site right now is whether what I'm seeing can plausibly be anything OTHER THAN an untoward organism that has decided to symbiotically join my LAB culture.

I will describe what I'm seeing (after the 24 hr wait and prior to putting it in fridge):  the globules are small, uniform, not much color (perhaps slightly yellowish) and even spread apart.  In terms of size, they are quite small and if I had other guess, I'd say that they are more oblong shaped than circular (again, hard to tell because they are small).  In terms of quantity, each globule has significant amount of space around it.  In short, the surface of my buttermilk looks somewhat dotted with evenly spaced, very lightly colored globules.

As for taste and smell, the culture tastes and smells great, the same it has smelled and tasted for 10 years.  Not a hint of anything being off.  I used whole milk, pasteurized.

Any help is appreciated!

Also, an unrelated question:  I use a 24 hr period for my buttermilk.  Any thoughts on whether to cover  the container or let air get to it (cheesecloth)?  I've read conflicting info on this subject.

Thank you,
Bianca

mikekchar

I was trying to find a picture for you, but I can't quite find one that's early enough in the process.  This is a picture of David Asher's "Mason jar St. Marcellin":

Likely you have geotrichum candidum or some other yeast growing on top of your buttermilk.  If you leave it long enough it will look a bit like that picture (assuming it *is* geotrichum).  If it is geotrichum, it's perfectly safe and is useful in many cheeses.  It is everywhere and will basically always grow on cheese (or yogurt) eventually.  Likely you've built up a fair amount in your mother culture over the years.  I hate to say it, but it's a sign that you've been a bit lax on your hygiene.  You really should pasteurise your equipment every time and you should always make your new buttermilk from buttermilk you have just opened.  But, to be fair, even with great hygiene after 10 years, it's probably going to show up :-)

Could it be something else?  Yes.  Is it dangerous?  I personally think it's unlikely.