The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Sourdough not sour!

Nimyue's picture
Nimyue

Sourdough not sour!

Ok so recently my sourdough has stopped being sour.  I haven't changed anything!  Recently I started feeding my started twice a day and leaving it out on the counter.  It's doing as it should, doubling, bubbling, etc.  It smells sour.  I follow my recipe and the bread is not sour!  It rises, it doubles, it's fluffy etc but not sour anymore!  It used to get really sour.

 Now I bought my starter from King Arthur Flour, but I live in Texas... so I'm wondering if it's maybe that all the natural yeasts that I'm capturing are just not sour??? Or do I for some unknown reason need to try a different recipe?? 

 

I culture half the flour with starter and water for 16 hours before baking, 4 hours out, 12 hours in the fridge.  Then let it rise till almost doubled, shape it, let it rise, then bake it.  Bread quality is great, just not sour! 

loydb's picture
loydb

When I lived in Austin, the KA New England starter was for sure way more sour than the bread made with my locally-collected culture (so much so that I ended up only using the KA for the most part). Mine mostly lived in the refrigerator, and was fed once/week if I wasn't cooking with it, or the day before starting the recipe if I was.

 

 

MangoChutney's picture
MangoChutney

The sour that you can taste after baking is lactic acid.  It is produced by lactic acid bacteria (Lactobacillus sp).  The sour that you can smell is acetic acid (vinegar).  This may evaporate during baking, leaving no sour taste.  Acetic acid is produced by acetic acid bacteria (Acetobacter sp).  I think it is possible that the temperature in your kitchen is favoring the acetic acid bacteria over the lactic acid bacteria, because I have always heard it said that bulk fermentation at lower temperatures will produce a more sour-tasting loaf.

mwilson's picture
mwilson

It's not Acetobacter that produce acetic acid in sourdough but Hetero-fermentative Lactobacillus.

G-man's picture
G-man

Sorry, it's a small point but acetobacter do produce acetic acid, lactobacillus produce lactic acid. Either type of bacteria and thus acid can be present in sourdough and impart different flavor profiles.

Acetic acid is vinegar-like, lactic acid is yogurt-like. 

MangoChutney's picture
MangoChutney

Hetero-fermentative Lactobacillus sp produce ethanol as well as lactic acid.  Acetobacter sp produce acetic acid from ethanol, which can come from either yeast or hetero-fermentative Lactobacillus sp.

mwilson's picture
mwilson

http://www.thefreshloaf.com/node/10375/lactic-acid-fermentation-sourdough

In Debra's post, linked above, there is no mention of acetobacter and yet acetic acid is shown as being produced under a particular pathway. Can you explain?

MangoChutney's picture
MangoChutney

To quote from Debra Wink's very informative article:

"Contrary to popular belief, all three groups of sourdough lactobacilli prefer wetter doughs a bit on the warm side, many growing fastest at about 90ºF or a little higher. For the homofermentive species producing only lactic acid, increasing activity by raising the hydration and/or temperature will increase acid production. Decreasing activity by reducing hydration or by retarding will slow production. There is a direct relationship between activity and lactic acid. During heterofermentation, for each molecule of glucose consumed, one lactic acid is produced, along with one carbon dioxide (if a hexose is fermented), and either one ethanol or one acetic acid. But under wetter, warmer conditions, where sugars are metabolized more rapidly, the tendency is toward lactic acid and alcohol production in obligate heterofermenters, and all lactic acid (homofermentation) in the facultative heterofermenters. Lactic acid production is directly related to activity during heterofermentation just as in homofermentation, even if only half the rate."

My reasoning goes as follows.  The OP states that the dough smells sour but the bread does not taste sour.  Therefore, the dough contains a lot of acetic acid and not much lactic acid.    Debra Wink's paragraph says that a culture out on the counter-top in warm weather will produce lactic acid and ethanol, not lactic acid and acetic acid.  Therefore, it is not heterofermentative LAB who are making the acetic acid in the OP's dough.  This reasoning assumes that the OP does not live in the southern hemisphere, of course.  *slight smile*

Below is a link to an article on Acetobactar aceti, which states "Acetobacter aceti is a benign microorganism that is ubiquitous in the environment, existing in alcoholic ecological niches such as flowers, fruits, honey bees, as well as in water and soil" and goes on to say "The optimal temperature for growth is between 25 to 30C, and the pH optimum between 5.4 to 6.3."

http://www.epa.gov/biotech_rule/pubs/fra/fra001.htm

mwilson's picture
mwilson

Thanks for the link. I never can read enough information. I've been doing a little reading into acetobacter and a common agreement is that they require oxygen to convert ethanol into acetic acid and since there really isn't any oxygen in the dough I don't believe acetobacter can be responsible for acetic acid production.

MangoChutney's picture
MangoChutney

Acetobactar sp can be found in some sourdough cultures, according to the study below.  Since they make their living, as it were, by making acetic acid from ethanol, it stands to reason that they are doing so in those sourdough starters.  Starter is, after all, stirred well at some point in time.  It's not likely to be completely devoid of oxygen.  It's not oxygenated like a fishtank with bubblers, but there is doubtless some oxygen in it.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2293155/

mwilson's picture
mwilson

Also your reasoning of sourness and lactic/acetic balance is incorrect. Lactic acid always outnumbers acetic in any sourdough - always. Both lactic and acetic contribute to sourness. Acetic is more volatile yes and so smells sour, much more than lactic but it's total acidity (TTA) that is responsible for sourness. 

MangoChutney's picture
MangoChutney

I think you have painted yourself into a corner.  If the OP's bread lacked sourness, then there was no lactic acid to speak of in the dough because acetic acid cooks out of bread.  While the OP only said that the dough smelled sour, lactic acid is a solid at room temperature and I doubt anyone can smell lactic acid in starter.  This kind of behavior is typical of dough that contains acetic acid, but little or no lactic acid.   If, as you say, lactic acid is always produced in larger quantities than acetic acid by LAB, then the LAB could not have been responsible for the acetic acid because there was little or no lactic acid produced.  Since you refuse to believe that Acetobactar sp are a factor, and the LAB evidentally are not producing the acetic acid both per Debra Wink's article and your assertion about the proportions of the acids produced, you are left with no explanation for the acetic acid.

mwilson's picture
mwilson

We're talking about a sourdough culture that raises bread and to suggest that there could be no lactic acid to speak of is quite frankly madness!

You mis-understand lactic acid. In moderate quantities it's not sour. 

I keep an Italian starter and because it's so specific it forces me to understand it very well. I understand how lactic and acetic taste and smell.

Acetic acid in small quantities is baked off but in large quantities some remains and contributes to sourness. I have run experiments spiking yeasted dough with vinegar which confirms this.

A cold and wet white flour starter tends to smell yoghurty. The smell of lactic acid. In the same white flour wet starter lactic acid causes a fizzy sensation (like licking a battery) on the tongue.

Acetic acid which always exists in much smaller quantities is very sharp in taste and smell.

I don't deny the existence of Acetobacter but without oxygen they just don't function and I think the presence of oxygen is very minimal. It really is hetero-fermentative lactobacillus under the right conditions that cause a build up of acetic acid.

Frazestart's picture
Frazestart

You probably answered your own question. If you recently changed your starter maintenance routine and your bread lost its sour taste, then go back to your old routine and see if it comes back. I have the KA starter, which I feed about once a week and keep in the refrigerator, except for a few hours after feeding. I usually retard dough overnight before baking and get a very nice sour taste in the finished breads. As a matter of fact,  I just made Leader's Pain au levain with the overnight retardation and ended up with a lovely bread with a good balance of subtle wheaty flavors and tang.  This could be my favorite sourdough so far.

Hope your starter gets its groove back!

Nimyue's picture
Nimyue

Ok so how do I get it back?  I'm in Texas, and I keep my house at 77F but the kitchen is usually warmer.  The fridge is too cold for much to go on in there.  I do have a room that gets to be about 70F (also the beer room for this exact reason).  Should I try to reinfect it with the right bacteria?  Or just keep it in the cool room and mix with my hands to try to get some other bacteria going???

mwilson's picture
mwilson

Cooler temperatures favour yeast growth over Lactobacillus.

To potentially achieve a more sour bread you need to ramp up the number of these bacteria. Maintaining your culture warm and wet will help. 

Feeding size is also very important. Bigger feeds / small inoculation is the way to go.

A culture that is fed more often will also favour yeasts. You said you now feed twice a day, not helpful if you want sourness.

A starter that repeatedly triples in 12hrs will be more acidic than one that repeatly triples in 6hrs.

 

Hopefully this will help you.

Michael

 

Grenage's picture
Grenage

I'm wondering if it's maybe that all the natural yeasts that I'm capturing are just not sour

Quite possibly; I have never made a remotely sour loaf of bread in my life, nor have I tasted sour bread.  How long ago did you receive your KA starter?

mwilson's picture
mwilson

Wild yeasts live happily together with Lactobacillus bacteria and it's the bacteria that create the acids (lactic and acetic) that are common in sourdough bread.

Non-sour sourdough bread appers to be quite common. It's all about maintenance.

Nimyue's picture
Nimyue

It was very sour until left it out.  When it was refridgerated most the week and only out for 2 feedings it was very sour.  I always start my sourdough with the starter 3 cups of flour and 1 3/4 cups water and fridge it for 24 hours.  Then I add 2 cups of flour and smidgen more water on baking day, knead, let rise, punch down, rise, bake.  The baking routine has not changed at all.  The bread is still soft and fluffy, but even letting it sit for 24 hours is not making it sour AT ALL. Not less sour... no sour!  When I forgot to put it back in the fridge one night after feeding, and it ended up sitting on the counter for another 2 feeds is when it lost the sour.  So I'm thinking the warm is part of what made it not sour :/  Maybe the cooler room with daily larger feeds?  I'll take a piece of my current starter and start experimenting I guess to see what works!

 

Oh and I've had the KA starter for about 2 months now. 

Frazestart's picture
Frazestart

I would start by going back to your old routine, i.e., keeping it refrigerated and only taking it out for feedings to see if the sourness comes back. If you still have all the original bacteria and yeasts, that should give them a chance to build back their old ecosystem- I don't know how long it would take . Good luck!

Nimyue's picture
Nimyue

I'm just worried I lost my bacteria???  Is that even possible?  If it is are there ways to get it back???  Or are the bacteria so common that mixing with my hands should do it?

mwilson's picture
mwilson

Possible? No, well yes but only with severe neglect. Keeping it fed will keep the bacteria alive.

When your starter has fully risen, taste it and then report back.

FlourChild's picture
FlourChild

IMHO, your bacteria are totally fine, no need to worry.  The change in taste is likely due to higher ambient temperatures, and will return in a hurry when you cool things down.  Higher temps affect which flora are dominant (as the discussion above suggests) but perhaps more importantly, they shorten the time dough takes to mature or rise, thereby reducing the amount of time the acid-producing bacteria are able to make tasty flavors for you. 

You can do one or both of two things:  first and foremost, ferment the ongoing culture at 70F so that the bacteria you prefer flourish (I'm with you there, 70F also produces my favorite sourdough flavor); second, extend the bulk fermentation (so that the acid-producing bacteria have more time to do their thing), either by lowering the temperature or by making sure there is enough residual sugar available and doing stretch and folds regularly to keep all the beasties happy while the fermenation is extended.

Hope there's something there that helps!