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Storing sourdough starter short & long term

GAPOMA's picture
GAPOMA

Storing sourdough starter short & long term


I’ve been baking bread nearly every week at home for more than 10 years now.  After several failed attempts to get a sourdough starter going I finally was successful about 18 months ago.  After feeding my starter nearly every day for the first 6-8 weeks and making several successful loaves, I began to worry about losing the starter to contamination (or neglect).  I wanted access to a good starter when I felt like sourdoughs but I didn’t want to feel as though I was tied to keeping the starter going daily (or even weekly) for the rest of my life.  I really wanted to be able to put it away for a while (months at a time), but go back to my starter when I felt the urge for sourdoughs in the future.  So I started looking into how to store my starter. 


I came across a post here on The Fresh Loaf (http://www.thefreshloaf.com/node/6737/help-storingfreezing-starter-please) in which Mike Avery said he kept starters of 65% hydration “in the fridge far longer than I care to admit with good results.”  In that same post, Bill (bwraith) said he too kept 65% hydration starters in the fridge, for as much as 6 months!  Mike said he didn’t like to leave the starter more than 2-3 months without feeding.


Obviously this is what I was looking for, but questions still remained.  How long can I really leave it?  Should it be refrigerated, or frozen?  Although it worked for Bill long term (6 months), would it really work for me for that long?  I decided to do an experiment.  I took my robust 100% hydration starter, made it into a 65% hydration starter, split it into eight (8) aliquots of 50g (1/4 cup) each I refrigerated 4 of the aliquots and froze the other 4 aliquots, and decided to take an aliquot of each out at various times later (1, 3, 6 and 12 months) to see how well they reconstituted my starter. 


At each time point I took the 50g of refrigerated/frozen starter, let it warm for about 30 minutes, and then added 200g of water.  After a thorough mix, I then added 200g of flour, stirred until smooth, and then watched and waited.


 


1 Month


Refrigerated – Smelled quite sour but had little if any liquid on top.  Doubled in 30 hours.  Looked and smelled great.


Frozen – When thawed there was no real scent and no liquid of any kind on top.  No activity seen at 24 or 36 hr.  By 48 hr there were a few small bubbles on top, and by 72 hr it had doubled.  At this point it looked bubbly and smelled like it should.


 


3 Months


Refrigerated – Sample smelled very sour at this point and had a gray colored layer on top of it.  There was no liquid on top.  The starter underneath was “whiter” and when stirred it made a surprisingly watery mix.  Activity noted at 12 hours and had doubled by 24 hours. Had fallen by 48 hours but was bubbly and smelled great at that point.


Frozen – When thawed the starter had a very faint sour scent and a shiny wet surface, but no accumulated liquid on top.  Some slight bubble activity at 36 hours.  At 48 hr it had quite a few large bubbles on top.  I decided to refresh it at this point by removing 50g and adding this to 100g water and 100g flour (I also kept and watched the original frozen starter).  By 72hr the original frozen starter had lots of small bubbles on top and increased in volume by about 25% and it had doubled and was just fine by 84 hr.  The refreshed frozen starter had not increased in volume at all by 72hr, had grown about 25% by 84 hr, and it had doubled by 96 hr.  Looks and smells just fine at this point.


 


6 Months


Refrigerated – As at 3 months the sample smelled very sour and had a gray layer on top of it.  There was no liquid on top.  The starter underneath was “whiter” and when stirred it made a watery mix.  After 24 hr this sample had increased in volume by about 60% and it doubled by 30 hr.  At this point the top was bubbly and wet and it smelled nice and sour.  No problems here!


Frozen – No smell, no change in color, kind of a sticky lump when warmed.  There was slight bubble activity at 24 hours.  At 72 hr it had a distinct sour smell but it hadn’t changed much in volume from the 24 hr sample.  So I again decided to refresh it at this point by removing 50g and adding this to 100g water and 100g flour (I also kept and watched the original frozen starter).  By 96 hr the original frozen starter had doubled and was just fine.  The refreshed frozen starter had also doubled in volume and smelled/looked just fine by 96 hr.


 


13.5 Months


Refrigerated – The sample was very gray colored both on top and underneath.  There was some liquid on top of it, and even when stirred it had an “off” scent.  The smell reminded me of cider vinegar.  No activity at 24 or 48 hr although it did smell a little less at 48 hr than it did at the beginning.  I decided to try the “refresh” trick at 60 hr by removing 50g and adding this to 100g water and 100g flour (I also kept and watched the original starter).  By 84 hr there was perhaps a hint of activity, but no more activity at 96 hr.  I tried a second refresh at 96 hr.  At 144 hr (6 days) there is no sign of activity in any of the 3 refrigerated samples.  At this point it still had a bit of a vinegar odor and had some gray/green hooch on top.


Frozen – Again no smell, no change in color, kind of a sticky lump when warmed.  No activity at 24 or 48 hr.  Like the refrigerated sample I decided to try the “refresh” trick at 60 hr by removing 50g and adding this to 100g water and 100g flour (I also kept and watched the original starter).  No activity at 72 hr there was perhaps a hint of activity, but no real activity at 96 hr.  I tried a second refresh at 96 hr.  By 108 hr there was a 50% increase in volume of this second refresh sample, and by 120 hr it had at least doubled in bulk.  At this point (120hr) it had lots of small bubbles on top and it smelled like a good healthy sourdough starter should.  At 132 hr I took all (~200g) of this 96hr refresh sample and added 200g of water and 200g of flour to see if it would work as a real starter.  It had more than doubled 3 hours later demonstrating that at this point it was a robust starter.


 


Conclusions:  It is clear from this experiment that storing starter at 65% hydration in the refrigerator is fine (and probably the method of choice) for at least 6 months but a year or more is probably asking too much.  Freezing the starter works fine, even out to a year or more.  However it takes longer to restore a vigorous starter from the frozen state.   


Early on in this experiment I came to the conclusion that keeping a sourdough starter in the refrigerator for a month or two (or even six) is absolutely no problem.  It is now my routine.  I pull it out every 2-8 weeks or so, feed it for a weekend (probably use it once or twice), and put it back in the fridge.  I also keep an aliquot at 65% frozen as a backup, and I plan to refresh this backup on an annual basis.  (I also must admit that I don't always go to the trouble of making a 65% starter for refrigeration.  If I'm planning on taking it out again in the next few weeks I usually just put my 100% starter in the fridge.)


In the end, I now feel much less stressed about ignoring my starter in the back of the refrigerator for a few months.  Thanks to Mike and Bill for their inspiration in this experiment.


- Greg


 

GregS's picture
GregS

It is wonderful that you did this. I wouldn't have the "gumption" to manage an orderly project for over a year, so I doubly appreciate what you did. Also, I haven't seen any similar organized test like this in my reading on the subject. It's a real contribution to those of us whose temperaments and lives don't fit with a precise pattern of feeding our beasties.


You'll probably want to hit me with a batard for this additional idea; but I also found myself thinking about the longevity of home-dried and sealed culture. My impression is that the life would be years in the dried form, either frozen or just airtight.


Thanks again for the good work.


GregS

copyu's picture
copyu

Well-said, GregS!


copyu

GAPOMA's picture
GAPOMA

GregS


You read my mind!  I finished up the refrigerator/freezer project this week and planned to try re-starting from some 16 month old dried/frozen stock next week after I return from a business trip this weekend.  My daughter has used some simliar dried/frozen stock at 9 months without a problem, so I suspect this should come out of "hibernation" pretty easily.  I'll let you know late next week.


As for the length of the project, I'm a scientist that routinely sets up long term (>6 months) experiments so I'm used to delayed gratification. :)


- GregP

Ford's picture
Ford

You did not have to tell me you are a scientist!  Your use of the term "aliquot" gave you away.  If that had, not your procedure in the experiment definitely was scientific in nature.  Good work and thank you!


Ford

GAPOMA's picture
GAPOMA

This past weekend I got the chance to try this.  I had some dried starter in my freezer that had been dried and put in the freezer 14 months ago.  I took 1/2 tsp of 14-month-old dried starter, 1 Tbsp of water and 1 Tbsp of flour; mixed them together and let sit in my oven with the light on.  24 hours later I saw some small bubbles but no real increase in volume.  At that time I added another 1 Tbsp of water and 1 Tbsp of flour, stirred and let them sit overnight in the oven again with the light on.  By the next morning I had a lot of good bubbles going!


To increase volume and to see if it was working well, I added this mixture to 200g of water and 200g of flour, mixed and set it on my counter.  24 hours later I had a very vigorous starter working!!  At this point I had lots of small and medium bubbles in the starter and it had a nice sour tang smell to it.


So, going from 14-month-old dried & frozen starter to a vigorous culture took me about 72 hours.  There is no question that at least at 14 months dried/frozen starter still works!  Thanks to Eric at Breadtopia.com for a good method!


- Greg

Mini Oven's picture
Mini Oven

I haven't tested to a year (my respect!) yet but I have gone 8 months on refrigerator storage.  I do my long term hybernation a bit dryer with more dry flour in the mix.  It just holds together as dough, boarderlined with packed crumbs.  Interesting to see how dryer compares to wetter and frozen.


My theory being that the dough gets wetter with age and a compact ball when compared to liquid is very easy to hydrate after trimming off the gray outside "skin."


Refrigerator starter... did you include the "gray matter" into the refreshment?  Hootch?


I do not include "gray matter" and select the "white matter" for reviving, assuming the gray is full of concentrated waste product, too acid (unbalanced) and the buffer zone or shell that protects from outside contaminants including possible dormant invaders.


When any of the starters are going on 5 days to wake up... there is the possibility that the yeasts are dead in the starter and the yeasts from the flour are playing a major role.  The diluted acidity in the starter favoring new yeast growth is always a plus point and worth remembering even if the yeasts are truly dead. 


I tend not to favor freezing as the starter does not travel well, whereas dried or very low hydrations travel better.  I prepare a starter to take with me and one to stay at home for months at a time.  A neat ball in a jar refrigerated is less apt to be discarded as a liguid in the same jar reguardless of the warnings and labels I plaster all over the jar.  (note: I am not present to protect them.)  Possibly looks more appetizing?  Although I have my son and husband trained, something that looks like food or leftovers gone bad is in danger when the fridge is cleaned. 


Are you testing with wheat flour or rye?   My starter is rye.


Mini

GAPOMA's picture
GAPOMA

I did go ahead and include the "gray matter" and any hootch .  While the gray area may be due to that portion containing more "concentrated waste" than viable yeast, I tend to believe that the gray discoloration is due more to long term oxidation of the surface due to its proximity to the air.  These stored aliquots didn't have much if any hootch on them.  The frozen samples were basically pretty dry (like a 65% starter) when they were thawed.  The refrigerated samples were pretty thin but still didn't have much if any hootch accumulation on them.  As you know hootch accumulates over time as the yeast and flour particles sediment out due to gravity, and the hootch becomes more gray/green over time.


You are right about the possibility that after 5 or more days the intrinsic yeast of the flour may play a large role in the reinitiation of the starter culture.  But in the end it really doen't matter that much ... either way you're getting a viable starter going again.  And the reinitiated culture has that distinct sour smell of a long term culture that you don't get from a recently initiated starter, so I tend to think that even if the yeasties are new the lactobacillus is still happy and active.


I've run both wheat and rye starters from my original starter, but the one I'm dealing with here is made with regular old all-purpose flour and it grows like a champ.


- Greg 

andrew_l's picture
andrew_l

What a useful thread! I've just had some real trouble with a starter stored about 3 months (see thread "Sick Starter").


 


I've previously kept starters up to 4 / 5 months with absolutely no problem but this time both starters went grey, with mould patches, and smelled of pear drops.


 


They did revive with care and feeding, but I think I shall freeze a back-up.


 


How do you dry starter? I'd like to try that too.

GAPOMA's picture
GAPOMA

I found a very simple method for drying and storing sourdough starter at Breadtopia.com (http://www.breadtopia.com/drying-sourdough-starter-for-long-term-storage/) that has worked well for me.  Eric even has a video there for both drying starters and reviving dried starters.


Basically you take a robust starter and smear some onto a piece of parchment paper on a cookie sheet.  Smear it on in a very thin layer using a spatula, then put it in the oven with the light on and leave it overnight.  Next morning you'll have a dry sheet of starter.  I usually break the dried starter into small flakes, do a gentle grind in my mortar and pestle, then put it in small ziplock plastic bags and store it in the freezer.


It's Eric's method at Breadtopia.com so I can't take any credit.  But I do get the benefits! :)


- Greg

Mini Oven's picture
Mini Oven

Some of them can get too hot and kill the yeasts.   Just letting a fan blow on them will do the trick and be sure there is an edge or something to catch the flakes from flying off when dry.


If you have high humidity, it doesn't hurt to refresh the starter if the drying time takes much longer than a normal refreshing time.  I've saved some of those little "keep dry" non-edible packages that get thrown into vitamins jars and put them in with the dried starter.

MadAboutB8's picture
MadAboutB8

It is a such a great experiment done at such a length of time. Big round of applaud for your efforts and initiatives.


This couldn't come in at a better time for me. I'm going away for over a month in the next few weeks and was thinking what I'm going to do with Jerry, my pet starter. You've provided perfect answer for that.


I shall convert my starter to 65% hydration and Jerry should be fine and alive when I get back:)


Sue


http://youcandoitathome.blogspot.com/

Mira's picture
Mira

Hi Greg,


I applaud you for conducting such a rigorous experiment and sharing your results with us!  Thank you!  May I ask why you've converted to 65%? 


I've been maintaining my 4-month old 100% starter in the refrigerator with once weekly feedings.  When I want to bake bread, I'll take it out of the refrigerator and will refresh daily on the counter for a couple of days; once it smells sweet I know it's good to use.


I went away last weekend for a girlfriend shopping trip in NYC and for the first time was negligent with my starter; I let "Alphie" sit in the refrigerator for 10 days...I have now been feeding it on my counter for the past three days and praying that I haven't negatively affected my starter.  You've given me reassurance. 


Mira

GAPOMA's picture
GAPOMA

Hi Mira,


I converted it to a 65% starter simply for long term storage.  This was the percentage suggested by Mike Avery and bwraith in previous posts about long term storage on TFL.


Like you I keep a 100% starter in the refrigerator, and have for about 18 months now.  Unlike you, I'm more forgetful and don't get to feed it every week.  Mine often goes 2 or 3 weeks in the refrigerator without a feed.  When I bring it out after not feeding for 2-3 weeks I feed in a 1:2:2 (starter:water:flour) ratio and within 24 hrs I've always got activity.  Once I see any increase in volume (usually at 24hrs) I feed again and within 24hrs (usually 48hr total) I've got a very vigorous culture re-established.


Greg

Mira's picture
Mira

I, too, feed mine using a 1:2:2 ratio. Good to know that leaving it in the fridge for that long is okay to do:)

breadforfun's picture
breadforfun

Hi all,

I'm really glad to have found this thread, though I'm a bit late to it.  I have been trying to figure out the best way to store my 100% hydration starter, which is about 10 months old.  I have been keeping it in the refrigerator, feeding it generally at least once per week, without any ill effects.  It reactivates quite nicely, has a nice taste, and I've made many successful breads.  In trying to learn more, however, I came across a passage in Hamelman's Bread (p. 355) that seems to say that starters shouldn't be refrigerated at below 45˚F because the yeast will be killed while the acid-forming bacteria will remain viable.  This hasn't been my experience, and apparently not the experience of many other posters to this and other threads.  Does anyone have any further thoughts with respect to Hamelman's comments?  I'm wondering whether the storage might have changed the mix of wild yeast from the original.

Thanks,

Brad

tisrach's picture
tisrach

Hi.  I once lived for several years with 2 lovely Ethiopian ladies who use sourdough to make "ingera" - a sour pancake to eat with hot spicy sauce.  One time they went home for a lengthy wedding celebration which lasted several months (seriously!) I looked in the fridge and found the starter which the fluid had turned black and it smelt sour so I threw it out. When they returned they said that all they do is just change the water on the top when it discolours, no feeding, no stiring - just refresh the fluid, and it keeps indefinately in the fridge. Their latest batch has been on the go for nearly 8 years, despite lengthy absences!

clazar123's picture
clazar123

One HOT summer day a few years ago, I was at a flea market and found a dark brown jar. It was sitting in the sun and tha label and tag were faded from the sun and the jar was quite dusty and dirty. Inside the bailed jar was a little cellophane packet of a tan colored powder that looked like old dry milk or flour. It was an original Sourdough Jack a tourist would buy when they visited San Francisco back in the 60's! It was at least 40 years old! For 25 or 50 cents, I bought it. I waited a few years to active him since I didn't know very much about sourdough yet.When I was ready, I held my breath,crossed my fingers adadded fresh water and flour. He activated IMMEDIATELY! It quadrupled in a few hours-almost out of the small jar I used. I could not believe how active the first hydration went but he tasted awful-the media (prob dry milk and WW flour) was rancid. No bath in 40 years.Phew! After several days of active discards and feedings, he is the best tastig and most consistent starter I have-5 years later. I have since dried some of him and store some of the dried starter in the refrig and some in the freezer.

Drying starter works very well!

BTW, don't yeasts encapsulate as they dehydrate so they can emerge when conditions are more favorable? Do they do this in liquids, also, when the pH is unfavorable to emerge later when the pH is "better"?

 

GAPOMA's picture
GAPOMA

Just an FYI ...

This past December (Dec 11, 2012) I was tired of keeping my starter going and wanted to work on other breads.  This is the same starter I've been working with for years now.  I made it into a 65% hydration starter and put it in the back of the refrigerator until I was ready to play with it again.

Well I was finally ready again this past weekend (June 8, 2013; about 6 months).  I put the starter (about 200g) directly into my sourdough jar/crock, and added 200g of water and 200g of flour.  Within 12 hours it had doubled, was all bubbly and smelled great.

It's nice to see my old friend again! :)

atty's picture
atty

I wonder if a vacuum seal, whether frozen or refrigerated, would help?  

David Esq.'s picture
David Esq.

I would worry that there was enough gas produced that the jar might explode. 

atty's picture
atty

Actually I was thinking of the dried starter.  I'm sure you couldn't maintain a vacuum with 100%, but I was wondering if any gain in longevity could be obtained by storing the dried flakes in a vacuum sealed bag. 

David Esq.'s picture
David Esq.

Dried starter would probably last indefinitely with or without a vacuum seal. If you have the equipment it can't hurt to vacuum seal the powder before putting it in the freezer.

PetraR's picture
PetraR

I think for long term storing the dried Starter option for the freezer is the one for me.

I also dried some Starter and send it to Germany to my Sisters.

I have my backup starters in the fridte, only small amounts of my Rye Starter and my Bread flour Starter , but I do feed them once a week, it is not a big deal , the amounts are very small, so feeding is done in 5 Minutes.

My * main * Starter sits on my Kittchentable as I do bake all our bread and we are a family of 6.

I enhance my basic white with Sourdough so it needs to be fed every 24 hours so that I can always bake.