Sourdough Starters and Temperature

Sourdough Starter

Sourdough Starter

How many times have you heard… “My starter had great flavor but over time, the flavor and sour disappeared.”

I keep many starters going at the same time. I have some of them frozen and all of them dried. I also keep motherdough under refrigeration quite frequently.I have found out that it is important to keep your sourdough starter at the right temperature for long term storage. Both Raymond Calvel (chemist, professor and iconic baker)and Frank Sugihara (microbiologist and discoverer of the San Francisco bacteria/yeast) recommend keeping a sourdough starter above average refrigerator temperatures. Temperatures between “8 – 10C (46.4 – 50 F)” are recommended by Calvel any time storage is longer than 48 hours. Temperatures above 42 degrees F are recommended by Sugihara. Many bakers experience a lack of flavor in their starter after using it for awhile, or find the original flavor gone. Refrigerator storage may be the culprit, after all refrigerators are made to keep fooods cold enough to discourage bacterial growth.

My recommendation is to get a small dorm or trailer refrigerator and keep it dedicated just for your starters. Keep a refrigerator thermometer in it and adjust the controls until your temperature is somewhere between 42 – 50 degrees F. If you only keep one starter, keep it at room temperature and feed it smaller amounts until you are ready to use it, pouring out any excess when there is too much. If you have several starters, and do not have a dedicated refrigerator, try storing the extra starters you don’t plan on using for a while in the freezer. It may sound counterintuitive, but keeping a starter long term in the refrigerator will cause an eventual die off of the flavor causing bacteria, whereas if you make up a very low hydration piece of dough and store it, well covered in your freezer, the same bacteria will fare well, at least for a while. Tests on frozen sourdough cultures have shown that they keep well for at least a few months. Using a frost free freezer would not be ideal because they have a heating cycle which would shorten the life of the frozen starter. The constant heating and refreezing is not good for a  frozen culture.

Motherdough in storage

Motherdough in storage

If you decide to find a dedicated refrigerator for your starters, it would be ideal if you could get a temperature controller to make sure the temperature is constant. You also have to realize that with the higher temperatures for storage, the starters would need to be refreshed more often than you were used to with a colder refrigerator. Some of the older refrigerators are small,have great insulation, have more sensitive controls, and will actually go below the “safe” temperature levels of food storage. Remember, don’t store your regular food in a dedicated refrigerator, the temperatures are in the danger zone for bacterial growth(that is what makes your starter culture happy).

For very long term storage, you can dry some of your starter and keep it in a cool, dry place. Keeping the dried starter in a hard sealed container will insure that bugs or rodents don’t have access. A starter dried and then sealed in a zip bag (with the name of the starter and the date recorded on the zip bag with an indelible marker), and then placed in a glass jar is ideal. Keeping a dried starter in the refrigerator isn’t a good idea because of the humidity in a refrigerator.

The very many people out there who feel that a starter once moved to another location, will take on the attributes of it’s new area and no longer be the same starter, were probably noticing the effects of long term refrigerator storage on their starter. The same microbiologist named above have stated that a stable, healthy culture, cared for properly, will remain the same culture wherever it is. A good, healthy culture of yogurt or Kefir will remain the same culture regardless of what milk is used to culture it, the same goes for cheeses, yeasts used for beers and wines, and many other cultured foods.   If you have been working with a starter that lacks flavor, think about what it’s long term storage has been.

Get a dedicated refrigerator

Get a dedicated refrigerator


7 Responses

  1. Thank you so much for this article. My starter has never fully developed a tangy flavor and now I know why.
    I’m not sure my dbf would understand why I need a dorm refrigerator so I’m not sure how I’ll swing that one so I have a question for you. If I were to start leaving my starter out on the counter, how little do you think I could feed it and still keep it alive?

  2. Thanks, very good information to know. I have just started new starters, so will give this a try. I always have backup in the freezer, rotating them every month.

  3. This is really interesting, and brings up a question I’ve been wondering about – how do you effectively dry a sourdough starter? I’m picturing something like baking at 200F for four hours, but have no idea if that’s the correct technique.

  4. I have heard that to effectively dry a starter, all you have to do is schmear (technical term) a thin layer on a piece of parchment or wax paper and let it dry naturally. When dry, flake/peel off and store in a zip-loc type baggie.

  5. Just thought I’d throw my 2 cents worth:

    I’ve been using and experimenting for abouot a year with a SF sourdough starter I purchased through Sourdough International.

    I keep my starter in the refridgerator with everthing else. I bake about once a week. The secret, at least by my experience, to keep the flavor good is to use a wash and feed 24 hour cycle before using the starter in a recipe. Here’s what I do:

    5PM 1st day Wash starter, waste about 2/3, then add 20%rye flour and 80%bread flour, and bottled water to make about 100% hydration. From here, I place the jar in a 85degree incubator until bed time.

    9PM 1st day Waste about half, feed again with rye/flour/water

    6AM 2nd day Waste almost all, then feed again with enough flour and water for the recipee

    5PM 2nd day Use starter in a recipe

    Have fun,

  6. Since I started baking again and created a variety of starters last November, I’ve kept them on my counter in my kitchen. They smell great!

  7. We live in a cold area of the country ( North Dakota ) and I was having problems getting a warm enough place in our kitchen to get the starter at the proper temperature. I tried a heating pad under my glass dish, but found the temperature wasn’t stable enough. It would get to hot at times and ended up killing the yeast. I finally found a solution that gave me GREAT RESULTS… I took a glass dish and filled it about 3/4 full of water and then inserted a fish aquarium heater. I adjusted the thermostat to get the water into the 80f range and then put my starter into a seperate bowl that I placed into the dish of water. Then I covered the dish that had the starter with some plastic wrap with holes in it… and then finally covered everthing with a thick cloth to act as an insulator. I now can get activity in my starter in a matter of hours.

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