The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Low Temp Limit for Wild Yeast?

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tgrayson's picture
tgrayson

Low Temp Limit for Wild Yeast?

Hamelman says on p 355:


 



According to Professor Raymond Calvel, "To maintain the viability of the culture, it is necessary to ensure that the temperature of the refrigeration chamber says between 8 and 10 degrees C (46.4 and 50 degrees) whenever the chef is retarded for periods of 48 hours or more.  At lower temperatures, part of the flora of the culture may be destroyed....Master Montreal baker James MacGuire adds, "Below 8 degrees C, it is usual for wild yeasts in the culture to be destoryed, while the acetic acid bacteria will continue to thrive.



 


I keep my refrigerator COLD...the thermometer I have in a warmer part of the fridge says 2 degrees C, maybe 36 degrees F.  I'm wondering if this is killing the wild yeast in my sourdough.  After I put the loafs into the fridge to proof over night, they never seem to rise again.  My commercial yeast products seem to do ok.  My mother starter also seems to live, although it doesn't seem as vigorous as it was a few weeks ago.


 


 

rockfish42's picture
rockfish42

Hammelman gives a sliding scale for times for retarding, how long are you retarding your loaves? I have good results with an 18 hour overnight retard for his vermont sourdough. I'd be more worried about loss of heterofermentive bacteria, as it seems like the vast majority of people on this site store their starters in the fridge.

tgrayson's picture
tgrayson

I did primary fermentation in the fridge and the proofing, so cumulative was about 30-40 hours.  My main concern is that my fridge is much colder than most people keep theirs.  Some things freeze, depending on where they are located in the fridge.


 


The same Hamelman paragraph say that the acetic acid bacteria will continue to thrive.


 


Thanks

flournwater's picture
flournwater

" Some things freeze, depending on where they are located in the fridge."


Unless you have one of those incredibly expensive professional refrigerator/freezer appliances, your refrigerator and freezer function on the same system.  The freezer temperature is set and the excess cold from that compartment is routed into the refrigerator to cool things in there.  The cold air is heavier than the warmer air so it will settle to the bottom of that compartment (where your vegetable crisper lives) so things in the bottom of the fridge tend to stay colder than things on the top shelves.  Some refrigerators intentionally route the cold air to the bottom and, if the vents from the input aren't properly adjusted, you'll find your lettuce (and other stuff) freezes quite easily.  I'd suggest you work on the settings of your particular model to reduce the amount of cold air leaving the freezer and entering the refrigerator.


At any rate. to say on topic, put your starter on the highest shelf and as near to the door as possible (on the top shelf of the door is good if it'll hold the starter container) to prevent it from being over cooled.

rockfish42's picture
rockfish42

I'm not sure I'd do bulk fermentation of sourdough that cold. Are you getting an ok rise, aka not turning out bricks?

tgrayson's picture
tgrayson

<<I'm not sure I'd do bulk fermentation of sourdough that cold. Are you getting an ok rise, aka not turning out bricks?>>


I actually did the bulk for about 4 hours in a cold oven with the light on and got a pretty good rise after 4 hours.  It wasn't quite doubled.  I put it in the fridge so that I could continue the next evening.  I didn't see much increase in volume the next night, but I divided the dough and then put the loaves directly into the fridge.  The next evening, I put the loaves, which showed no increase in volume, into a 90 degree oven and left them there for 4 hours or so.   Almost no rise.  I left them there until this morning and they show a small increase in volume, so the yeast isn't totally dead.


I'm thinking maybe I need to buy a small fridge that I use for this purpose and keep it no lower than 40 degrees F.


 


Thanks


 


 

Doc Tracy's picture
Doc Tracy

I questioned that part of Hamelman's book as well. Most fridges are much colder than the minimum cold temps he recommends for storage of the starter and for overnight cold retardation. For safe and efficient food storage your fridge should be just above freezing. Otherwise, you'll notice milk and meat spoilage very rapidly.


I've been overnight retarding outside this winter which is working nicely since most nights we've been down to about 40 degrees but only for a short while. If you look at our temperature it takes awhile to get down to 40 from the 55 degrees or so when we go to bed.


Haven't figured out what I'll do when it warms up, maybe try my wine cooler or something as it has an area where a wine box will fit that we never use.