How to make bread taste more sourdoughy?

Like Abe mentions above, longer fermentation will definitely give you a more tangy bread.  

He also mentions increasing the hydration level of your starter, but I have read that making a firm starter, i.e., more flour rather than more water, can yield a more sour bread.  However, I can't point a finger at the rationale for this assertion.  There are a lot of very knowledgeable folks that post here and maybe someone can give the reasoning for why one hydration level would be more sour than the other.  

I myself would love to see an answer for this, because Abe's idea of adding more liquid makes more sense to me than adding less.  

     --Mike

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How to Make Sourdough More (or Less) Sour — Part I

 We recently had the good fortune to attend a class a King Arthur Flour on the science of sourdough. The class, taught by microbiologist Debra Wink, focused on all the different tools the baker has to control the natural sourdough fermentation process.

 Below, we survey three key factors for influencing acidity in sourdoughs: temperature, flour choice and maturity. There are other factors as well, but these are the ones we find to be both easy to implement and highly effective.

 Key Factors Influencing Acidity in Sourdough

Sources: Debra Wink, Michael Gänzle, Brød & Taylor

 Temperature. Temperature is the one variable that bakers can control at every stage of the bread making process, from Mother culture through the final shaped proof. It’s an easy variable to manage using water temperature and a Proofer.

• For less acidity, use water at around 80F / 27C and a Proofer setting of 70-76F / 21-24C to favor the yeast and create milder flavors. When the Mother culture is being kept at room temperature (for instance, for a few feeds leading up to bread making), consider giving it one or two short feed cycles, rising at 75F just until peaked.
• For more acidity, use 90F / 32C water and consider fermenting the Mother culture (when not in the refrigerator) and pre-ferment at about 82-85F/ 28-29C, which is warm enough to begin to give desirable acid-producing bacteria (LAB) an edge. Yet it won’t be hot enough to damage yeast populations, which are necessary for the ongoing health of the Mother culture and for good structure and rise in the bread.

 Whole Grain and Rye Flours. Whole grain and rye flours provide minerals and enzymes that can influence acid production in sourdoughs. The higher mineral content of whole grains acts as a buffer in the dough so that more acid can be produced during extended fermentation. And the complex carbohydrate and enzyme content of rye flour helps produce unique sugars that tip the balance of acids in favor of acetic acid, which has more aroma and flavor and is more noticeable in the dough than lactic acid.

• For milder sourdough, use less whole wheat and less rye, or consider sifting the bran out of whole wheat flour to create high-extraction flour. If using small amounts of whole grain, save it for the main dough, where it will have less time to contribute to acidity.
• For more tang, incorporate some rye flour and/or whole wheat flour early in the bread-making process, such as regular Mother culture feeds and the pre-ferment. Rye flour in particular will help your culture produce some acetic acid.

 Maturity. In our experience, tweaking maturity is a highly effective way to control sourdough flavor. This applies to refreshing the Mother culture, fermenting the pre-ferment and rising the main dough (bulk fermentation). It does not apply to the final proof, because the point at which the shaped loaf is ready to bake should only be determined by the balance between gas production and structure. As Ms. Wink taught in her class, the reason maturity is so effective is that the acid producers (LAB) have a faster growth rate than yeast, so harvesting the culture when it is more ripe quickly shifts the population balance towards greater numbers of LAB.

• To limit acidity, refresh the Mother culture when it has just risen to its final height. Similarly, harvest the pre-ferment when it has just peaked or even before the peak, and limit the main dough (bulk) fermentation to a doubling of volume.
• To push for more acidity, allow the Mother culture to rest at its peak rise height for a while before refreshing. During the rest, the yeast population will hold steady while the acid producers (LAB) grow. Allow the pre-ferment to do the same – rest for a period after reaching its peak rise, then use it to mix the main dough. For the main dough (bulk fermentation), rise the dough to more than double its volume. Many sourdoughs can rise to 2½ times their starting volume and some will do great with a threefold rise.

How to Make Sourdough More (or Less) Sour — Part II

 We created a “less sour” loaf with mild, yet complex flavors and an acidity that stays in the background, as well as a “more sour” loaf that is not only quite tangy but also packed with whole grain flavor.

We applied a slightly different approach to each stage of the bread making process. The loaves detailed below have been pushed fairly close to the limit of what can be accomplished without running into problems with structure or undesirable microbes.

 Mother Culture — Focus on Healthy Balance

In order to ensure the ongoing health and balance of both yeast and LAB (lactobacilli – acid producers) populations in the seed culture, we kept changes modest: cooler temps, white flour and peak maturity for our “less sour” loaf, versus warmer temps, a little acid-friendly rye flour and a more ripe maturity for the “more sour” bread. We fed our starter twice leading up to the mixing of the Levain, but even after just one feed under these conditions we noticed a difference in the stronger, more acidic aroma of the “more sour” culture.

 If there is too little acid in the ongoing culture, undesirable microbes (such as leuconostoc or mold) can multiply and infect the culture. If there is too much acid and an overripe culture, yeast populations are compromised and enzyme activity may get out of hand. To avoid this in our “more sour” loaf, we limited the proportion of whole rye flour to 20% and were careful not to go too far when allowing the culture to mature to a more ripe state.

 Mother Culture

 Levain – Get Ready to Encounter Salt
We made significant changes to the levain size for these breads. While our standard County Sourdough recipe has 16.6% of the total flour pre-fermented in the levain, our less sour version has a much smaller levain, containing only 10.5% of the total flour, while our more sour bread has a large levain containing 35% of the total flour. The reason for the difference is the presence of salt in the main dough. Salt inhibits the acid producers more than the yeast, which means that once the levain is mixed into the main dough, the ability to produce acid is somewhat diminished. To achieve a “more sour” bread, it’s important to add a larger quantity of acid and acid producers to the main dough.

 For the “less sour” loaf, using a small levain not only limits the amount of acid in the loaf, but also slows down fermentation. Slower fermentation allows enzymes in the flour to break down starch into sugar, further limiting the perception of a sour taste.

 In addition to getting ready for the addition of salt, we have also incorporated similar maturity, temperature and flour choices as in the Mother culture. For the less sour version, we use the levain a little earlier in its cycle than we could for the Mother culture — when it is well-risen but has not yet reached its peak. This type of small, less ripe levain has been popularized by Chad Robertson and Ken Forkish in their bread books.

 Many bakers’ normal practice is to take part of the levain and use that to perpetuate the ongoing culture. The best way to do that with a small, young levain is to take the portion needed to mix the main dough, then leave the remainder to continue to ripen to full maturity before using it to perpetuate the culture.

 Levain

 Main Dough — Maturity is Key to Controlling Flavor

In considering how much whole grain to put in the overall formula for these breads, we increased the whole grain in the “more sour” loaf from 15% of the total flour up to 20%; for the less sour version, we not only reduced the proportion of non-white flour to 10%, but also switched from whole grain to high-extraction flour and omitted the acid-friendly rye altogether. High-extraction flour can be made easily at home by passing whole wheat flour through a fine strainer to remove the larger bran flakes. As Debra Wink points out, the bran in whole grains buffers acidity and allows the acid producers (LAB) to produce more acid in a more ripe culture. And rye flour produces sugars in the dough that feed the LAB that produce acetic acid, which is more flavorful and noticeable than the other main sourdough acid, lactic acid.

 Since the larger levain of the “more sour” loaf carries more enzymes (that degrade protein) into the main dough, we used higher-protein bread flour (instead of AP) for the white flour portion of the loaf and added one extra fold to the bulk fermentation to help ensure good structure.

 Main Dough

 We have generally found that the most effective factors for controlling acidity in sourdough are:

1)    maturity (the degree of ripeness),

2)    the choice of temperature (warmer for more acid, cooler for less), and

3)    the choice of flours (whiter for less acid, more whole grain, particularly rye, for acidity).

 The key to making changes is to keep them modest and use only one or two at a time, then assess how they affect other aspects of the dough before deciding which to jettison and which to embrace.

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Thanks for the awesome info!

I finally gave up trying to make my sourdough taste more sour using more or less starter, longer fermentation, different starters....so, I gave up and put a good size pinch of citric acid, sour salt, into the dough and that made it sour and with a long fermentation to develop good flavors I got my sour, sourdough breads.  Sorry about the cheating, but, it worked for me.  The best flavorful sourdough bread comes from the bakeries of San Francisco.  I have made very nice breads, but.......I even was given some starter from a perfect sourdough mother, but, over time it changed to be a Minnesota mother.  Now I bake bagels like New York bagels and am content.

done lots of experiments the most recent with a fellow fresh lofian Doc.Dough

By far the most important thing to develop sour in my book is using the bran only from whole grain rye and wheat to build starters and levains.  The 2nd most important thing is temperature.

LAB out reproduce yeast dramatically at high and low temperatures 88-92 F and 36 - 40 F.   The normal SD culture has 10 times as many LAB to yeast in it.  To make more sour you want to increase this ration of Lab to yeast by uing temperature and time.  Once you get over 84 F then peak repriduction temperature for yeast the reproduction rate for them falls of while the peak distribution rate for LAB is over 90 F.  By doing all the work outside the Fridge at 90 F will increase the :LAB to yeast ratio.  You end up with more LAB and yeast population is restricted so the more LAB now have more time to produce acid since the low yeast counts take more time to proof the bread.to make it ready to bake.

Low temperatures also do the same thing but since low temperatures slow reproductive rates significantly it takes a very long time to have this happen significantly - but why i store my 66% hydration starter unmaintained in the fridge for 20 weeks or more.  I really don't notice much difference until it has been stored for at least 8 weeks.

Hydration is relative.  Yes LAB like the wetmore than the dry but 66% hydration is pretty wet for them and they thrive at that hydration.  Making anything 100% hydration doesn't make that much difference when it comes to sour.

The reason bran is so important is that it avts like a buffering agent so that the LAB can continue to produce acid at lower pH than they can with a white flour - lower pH means more acid and sour

Sour taste comes in 2 kinds - lactic acid which gives you sour and the 'tang'  comes from acetic acid.  LAB can produce both but have to be encouraged to produce acetic acid - they are called lactic acid bacteria for a reason - Because they have no problem doing so.  For them to make acetic acid you want low hydration and temperature - like 66% hydration at 36 F - for a very long timel  This is the basis of Demolder process of levain building.  The most sour breads have both sour and tang.....so you need to promote both if you want a really sour bread.

But most folks don't like sour bread and why the great bakers in SF and West coast devised their process to make their bread less sour as possible - read room temperature using white flour  and Tartine and Forkish - that is what makes a less sour bread.

Lastly, there is only 1-2% fructose in grain.  Once LAB run out of fructose they stop producing acid and start making ethanol and CO 2 just like yeast does.  Fructose supplies and additional electron receptor for the LAB to make more acid.  If you a bit a HFCS to you dough your LAB will make more acid.

As opposed to lastly, finally, much sour depends on the LAB you have in your culture.  Not all LAB and yeast are the same.  Some LAB produce twice as much acid as others and some yeast produce twice as much CO2 as others.  The the right LAB and yeast in your culture can make all the difference too.

Happy baking