Introduction to Sours
Sours will be used in five of the nine products covered in this class. A sour is a mix of water and flour, usually with equal amounts, by weight, of each. What makes it “sour” are naturally occurring (also called “wild”) yeast and bacteria. The yeast and the lactose-or-the-citric-acid producing bacteria in a sour are all single-cell organisms. You know that your water and flour mixture contains yeasts and bacteria when it has bubbles and starts to rise. The bubbles are a by-product of the fermentation process of the bacteria converting the starch into sugars plus lactic and citric acids and of the yeasts digesting the sugars and the starch and producing carbon dioxide and alcohol. Sugars are more quickly digested by the yeast and bacteria than starches, so products with any form of sugar, such as dextrose or lactose or malted barley syrup , will proof faster.
I have a Hungarian cookbook from 1982, George Lang, The Cuisine of Hungary. Lang was a famous restauranteur.
https://en.wikipedia.org/wiki/George_Lang_(restaurateur)
In his book he mentions several interesting things about starters/sours. He said that married women in his home villages would make their family’s bread, which was baked in a communal village oven. As a child Lang would take the proofed and shaped doughs to the village bakery and affix a paper label to the dough just before it would go into the oven. That way his family would get back the right loaves. His mother was given a starter by her mother when she married. That grandmother had also been given a starter by her mother. Lang didn’t know how many generations the family starter could be traced back. The second interesting starter story was that prior to WWI, when commercial yeast was still rare in Hungarian villages, some women made starters to sell. Presumably, they had reputations for really good bread.
The five products that will use a sour in this course are: whole wheat pita, sourdough bread, rye bread, pumpernickel, and bagels. There are three different reasons, depending on the product, for using a sour. Our primitive version of pita will use the sour as its only source of leavening. So will the sourdough bread. For these applications it is important to have a yeast-rich sour. Sours have much less yeast than commercial yeast AND the commercial yeast has been bred to have the maximum leavening power. Think of the commercial yeast as carefully bred race horses and the yeast cells in a sour as whatever types of horses have wandered into the barn. If your sour is short on live yeast, the products that rely solely on it for leavening will be flat no matter how long you proof. The process of caring for and feeding of a sour to in order to obtain more live yeast cells will be described below. At some point a longer proofing time with a product that relies solely on a sour for rising will turn counter-productive. As a sour becomes more acidic, which occurs naturally as the proofing time lengthens, the acids start to dissolve the gluten that holds the carbon dioxide gas in bubbles, which is the source of the rise.
The rye and pumpernickel require a sour because the rye flour in these products will come out gummy unless there is a sour in the dough with a higher acidity than the rye dough. Acidity is measured on the ph scale with 1 the most acidic, 7 is neutral, and 14 the most alkaline. Sours used for baking are typically in the range of 3.7 to 4.0 in ph. If you are really serious about making sourdough breads, getting the acidity of the sour just right, as well as the acidity of the proofed dough, will make a big difference in the rise, texture, and the taste. Bakers traditionally relied on the smell of the sour to judge its acidity. There are acidity probe meters that cost above $140. They let you measure the ph to two decimal places, e.g. 4.22. These were described in the section on equipment.
A technical discussion of the effect of the acidity in a sour on rye bread is in:
In rye and pumpernickel the commercial yeast provides most of the leavening and the sour simply improves the texture. Lastly, we use a sour in bagels purely for the taste. In these are the applications that also have commercial yeast, it is not important that the sour be used at its maximum rise. You actually obtain a more sour taste if the sour has started to fall back from its peak height.
Many bread products enhance the yeasty taste through the use of a pre-ferment made with commercial yeast instead of using a sour. For example, for French baguettes traditional bakeries start with a pinch of commercial yeast and a few handfuls of flour mixed with water. This pre-ferment goes into the regular dough. The dead yeast in the pre-ferment adds to the yeasty flavor. It is similar to effect on the final taste due to the dead yeast resting in bottom of the bottle in which the champagne is aged. Tasting notes on champagne often describe it as “yeasty”. Other traditional products have pre-ferments for the same taste-enhancement reason. These include pizza doughs (here the pre-ferment is called a “biga”) and in French boule doughs (here it is called a “poolish”).
Commercial bakeries hardly use real sours anymore. A few serious bakeries, such as Seven Stars in Providence, still do. The sourdough bakeries in San Francisco, such as Boudin, started in 1849, have built their businesses around their sour dough breads. Instead of having to worry about the inconsistent rises from a real sour or having to bother with the time consuming process of making the sour far in advance and setting aside the storage space, the work around in most commercial bakeries is to buy a ready-to-use mix that has a sour flavoring and some rye flour for rye breads or some rye flour and food coloring for pumpernickel breads. I think these products are garbage. A tell tale sign of fake rye or pumpernickel is being as soft as Wonder Bread.
Variations in Sours
There are many different types of yeast cells. There is a sourdough library in Belgium that stores and maintains sours used by bakers across the world. It has 84 sours. Its website claims that 700 types of yeast and 1,500 types of lactic acid bacteria have been identified. The different sours have different tastes.
When you make a sour from scratch there is, of course, chance variation in what yeasts will fall into your container. There is also an ongoing selection/breeding process that changes the mix of yeasts your sour contains. If you always discard and feed your sours after four hours at 85 degrees Fahrenheit then your predominant yeast types will be those that are fast rising. If you discard and feed at eight or ten hour intervals, slower acting yeast will be able to thrive and become more dominant. Since the sour gets more acidic the longer it ferments, longer feeding intervals will promote yeast that are more tolerant of acids. The constantly evolving nature of living sour is why commercial bakers prefer using commercial yeast, they always know what they getting. The few commercial bakeries that do use sours for leavening stick to an established routine for feeding.
In my Dad’s bakery we didn’t use sours for leavening. Still, we had a tight routine for our sour. We didn’t have to discard any of the sour because we used up 90% of it in the previous day’s baking. We always used first clear flour to feed the starter. We always mixed the sour first thing in the bakery’s production day so that it would be ready when we made rye and pumpernickel breads. We always mixed it by hand in a large wooden trough that could hold one-hundred pounds of flour and one-hundred pounds of water. The air temperature in the bakery was from 80 to 95 degrees and was plenty humid, because of the steam coming out of the oven. In this environment our sours were amazingly lively. They started rising slowly after mixing, but after three hours you could literally see the sour climbing higher in the trough. After four hours it peaked and fell back. The bakery had a six-days a week baking schedule. On Saturdays someone had to go in to the bakery just to feed the sour. That “someone” was often me.
The Ancient Israelites and Unleavened Bread
In Exodus 12.34 there are references to unleavened bread. “So the people took their dough before it was leavened, their kneading bowls wrapped in their cloaks upon their shoulders”. God also commands that the Israelites eat unleavened bread along with a roast lamb in their homes and that they smear the lamb’s blood on the lintels and doorposts of their home the night before He will kill the Egyptians’ first born. I am referencing the Bible for how it illuminates ancient bread making, as opposed to its religious significance. It appears that the Israelites ate unleavened bread in a ceremonial meal before they left Egypt. The kneading bowl is important for leavening. Wooden bowls are porous and if they are used daily for kneading bread, they will be full of yeast and bacteria. With such a bowl you don’t need a sour for leavening. Since the Egyptians put into their tombs small statues of servants doing everything needed in the afterlife, there are hundreds of statues of servants kneading bread in bowl.
The image above is from the Louvre. It is made from clay and was made sometime between 2700 and 2190 BC. Presumably, something like the bowls above were used by the ancient Israelites.
The same chapter of Exodus describes the requirement of eating unleavened bread during Passover (commemorating that the Lord passed over the houses of the Israelites while slaying the Egyptian’s first born). What constitutes unleavened bread has been worked out by rabbis long before Pastuer had discovered yeast. They came up with a rule that the bread has to baked within 18 minutes of mixing. Actually, the rule isn’t really 18 minutes. The link below discusses how rabbis came up with their rule and when more than 18 minutes is allowed.
https://www.chabad.org/holidays/passover/pesach_cdo/aid/5075941/jewish/Why-18-Minutes-for-Matzah.htm
We won’t cover matzah baking in this course, as the focus is on breads and rolls made in Jewish bakeries. Matzah making is a separate business. What is interesting to me is that according to the above link, kneading the dough can warm it and allow fermentation to start in less than the 18 minutes. Kneading on a bowl that was used daily for bread would speed up the process. That is why matzah making is usually a separate business. All of the equipment used is kept separate from regular baking.
As an aside, here is a story about how my father once got in trouble for helping a Jewish baker make matzah. He was in Hungary before WWII. Since Hungary required all males to serve in its army, he was pulled out of the bakery where he worked in Budapest and served from around 1936 to 1939, when all Jews serving in the Hungarian army were transferred to forced labor battalions. Naturally, when posted near a village when he was still in the regular Hungarian army, my Dad would visit its bakery. One of these bakeries was owned by a Jew and my Dad visited it just before Passover, when this bakery had switched to making matzah. (Note, in these circumstances all of the bakery’s equipment has to be cleaned according to ritual standards to reduce contact with yeast.) My Dad volunteered to help make matzah. An army officer who found out about it was angry because there was a rule against working for outside pay while on active duty. The officer couldn’t believe that my father was willing to make matzah for free. My Dad got out of trouble by explaining that the baker had a pretty daughter. Matzah baking in the pursuit of a pretty girl was considered “kosher”.
Care and Feeding of a Sour
The easiest way to start a sour is to borrow some from a friend who has an established sour. Another easy way is to buy the sour from King Arthur Flour or from Amazon. King Arthur used to claim that its sour has been kept alive since the company’s founding in 1790. Boudin claims its sour has been kept alive since 1849. The number of years the same sour has been kept alive is meaningless. A sour changes as it captures yeast from the air. King Arthur now just says it has been kept alive for decades and that a sour will change as its environment changes.
You can start a sour from scratch with just water and flour and wait for yeast and bacteria from the air to fall into an open bowl. This process can be tedious because you may have to dump out 90% of the mix each day and add more water and flour for weeks before your start-from-scratch sour has any life. In this class I will pass out sour starters in our first class that will save you the trouble and expense. We will also cover how to make a sour from scratch so that you won’t be stuck if your sour spoils.
The type of flour doesn’t matter very much since it will be a tiny percentage of the final dough. I use whatever is at hand. Zingerman’s, a high-end deli and bakery, uses only rye flour in its sour for rye bread. It also puts a bag of chopped onions and caraway seeds into the sour right after mixing. They take out this bag before using the sour. This is a very old technique from Eastern Europe that we didn’t bother with in my Dad’s bakery. Paradoxically, I push the percentage of rye flour to 30 or 40%, way higher than almost all commercial bakeries. That gives the rye bread more rye taste. To compensate for the lack of rise when there is a high ratio of rye flour and the only wheat I use is First Clear, I add some vital wheat gluten. First Clear flour has a high protein content, but it is not the protein that turns into gluten. As with the expression “there are many ways to skin a cat”, there are many ways to make a good Jewish rye bread. For that matter there may be an infinite number of ways to make a terrible one.
You will need a glass jar that holds at least 24 ounces with a lid for your home sour. Put in the starter from the first class and enough water and flour to fill half of the jar. The sour should rise to near the top of the jar after 24 hours. It will be faster if the jar is kept in a warm place or if the sour is already rich in yeast. Once the jar is nearly full, dump out 90% of the contents (they can be thrown away or used to make crackers or used to make pancakes) and refill the jar to the halfway point. I would weigh the flour and water to start. As soon as you are familiar with the amounts needed to get to half a jar you can eyeball the amounts. For the pita and sourdough breads that will rely entirely on the sour for leavening, try to time making the dough when the sour is at its peak. Since you will need the sour for the first product in the course (the pita) and the last (bagels) you will have to maintain your sour throughout the course. If you have to be out of town for few days, you can slow the rising process by putting the sour in your fridge. Otherwise keep it at room temperature.
David Kaplan’s detailed instructions for making a sour from scratch. (David was the co-coordinator for the second course offering)
| Day 1: Make the StarterCombine 60 g (1⁄2 cup) of whole wheat or rye flour and 60 g (1⁄4 cup) of warm water in a large(about 1 quart) jar.Mix with a fork until smooth; the consistency will be thick and pasty. If measuring by volume, add more water to thin out the texture if needed. Leave uncovered about one hour, then cover with plastic wrap or aluminum foil or a lid, and let it rest in a warm spot, about 75°-80° F if possible, for 24 hours. |
| Day 2: Check if any small bubbles have appeared on the surface.Bubbles indicate fermentation, which is what you want! However, it’s okay if you don’t see anything right away.You do not have to do anything else on day 2. It does not need any flour or water. Just rest the starter in your warm spot for another 24 hours.During the creation process, and even after your starter has been established, a dark liquid might appear on the starter. You can just stir it back in. If the dark liquid freaks you out, then just pour it off. If doesn’t mean anything has gone bad. |
| Day 3: Feed the starter. Remove and discard approximately half of your starter from the jar (you should have about 60 g left). Use a spoon. The texture will be very stretchy. Add 60 g (1⁄2 cup) of all-purpose flour and 60 g (1/4 cup) of warm water. Mix with a fork until smooth.The texture should resemble thick pancake batter or plain yogurt at this point so add more water as needed. Cover and let rest in your warm spot for another 24 hours. |
| Days 4, 5, and 6, keep on feeding as on Day 3. Remove and discard half of the starter, and feed it with 60 g (1⁄2 cup) of all-purpose flour and 60 g (1/4 cup) of warm water. As the yeast begins to develop, your starter will rise, and bubbles will form on the surface and throughout the culture. |
| Day 7 and beyond: Your starter is established. If you bake very frequently you can keep the starter at room temperature and feed it daily, by pouring off all but about ¼ cup starter and then adding equal amounts – by weight – of water and all-purpose flour. More likely you bake once a week or less frequently. If so, keep your starter in the fridge. Take it out of the fridge the day before you intend to use it. You can take it out in the morning, pour off all but ¼ cup and feed it in the morning with equal amounts by weight of water and all-purpose flour and in the evening again pour off all but ¼ cup and feed it with equal amounts by weight of water and all-purpose flour. Alternatively, you can just take it out of the fridge in the evening, pour out all but ¼ cup and feed it with equal amounts by weight of water and all-purpose flour. In either case your starter will be ready to use the next morning. It will probably be more active if you feed it twice the day before using it to bake, but your results will be good in either case. |
Long stretches without feeding a sour
If you will have long lapses between feedings, such as week or more, there is a danger that the sour will spoil. Long lapses can result in foul smelling sours with off-putting colors, such as green or purple growths across the top. Just putting the sour in the fridge will not prevent this spoilage. A solution is to pour an inch of water over the sour before leaving town and leave it in the fridge. The water above the sour provides an air barrier that prevents the spoilage. To revive the sour pour off some of the water and do a regular feeding. The sour will just pop back up.
All About Commercial Yeast
The original source of commercial yeast was from beer brewers. It is sometimes still called “brewer’s yeast”. The old fashioned way of obtaining yeast was to skim off the foam on top of the vats of just-brewed beer or hard liquor (before distilling the liquor). In the US the first pre-packaged yeast for commercial and home bakers was Fleishmann’s in 1868 in Cincinnati, Ohio. The Fleishmann brothers were Jewish immigrants from Hungary. I find the Hungarian and specifically Jewish-Hungarian innovations in milling and baking intriguing. The Fleischmann brothers immigrated to the United States in 1865. They did not originate packaged yeast, which was first produced in Vienna. However, they were highly innovative in manufacturing and marketing. At a time when almost all bread was still being baked at home, they gave out free recipe books that specified using Fleischmann’s yeast. Another marketing coup was, starting in 1929, sponsoring the radio show The Fleischmann Yeast Hour starring singer Rudy Vallee. It was often the nation’s top rated radio show. In 1936 it changed its name to another Fleishmann’s product, Royal Gelatin. At its peak market share in the 1920s, Flesichmann had 93% of the US yeast market. At that level of dominance in the yeast market, it made sense for the family to boost another of its products.
https://www.timesofisrael.com/how-fleischmanns-yeast-built-the-jewish-catskills/
Packaged yeast comes in three forms. The original form was fresh yeast in solid cakes, also called compressed cakes, that have to be refrigerated. Even with constant refrigeration, the life of this type of yeast was just two weeks. Commercial bakeries still use this type of yeast because they go through enough of it to not be bothered by the short shelf life. Its advantages are that it is absolutely consistent in terms of rise. It also has a better taste, although this advantage is both minor and subjective. Amazon sells Red Star brand fresh yeast, but the reviews on its website include complaints that the ice packs it is shipped with were melted and the yeast smelled bad. For what it is worth, the average rating on Amazon is 3.7. I have not seen any fresh yeast in a grocery store since Eastside Market went out of business. The only local source I am aware of is JAR Baking Supplies in Lincoln RI. It carries three types of “wet” yeast, which is another synonym for fresh yeast. The smallest package is two pounds. Given the two-week shelf life, that is a lot of yeast for a home baker. Supermarkets used to carry two ounce packages.
Flesichmann’s developed a dry yeast during WWII for military bakeries that did not have access to refrigeration. Their “active dry yeast” is the second of the three forms. Fleischman figured out how small granules or clumps of yeast cells could be dried and coated. The gain in shelf life for this form was substantial. Active Dry Yeast could last a year. Its major disadvantage is that it had to be soaked to dissolve its protective coating. Just putting the yeast into the dough mix wouldn’t work. Instead the yeast had to be put into a small amount of water, stirred, and then wait until it foamed. Also, its proofing power declines with age. You needed to use more yeast to get the same rise over its year-long shelf life. Commercial bakers hate any inconsistency that could mess up their products, so that is why they stick to compressed live (wet) yeast Lots of recipes for yeast-based bread products still contain the advice to pre-mix and stir the yeast. Some include adding a small amount of sugar or honey to speed up the yeast’s “blooming”.
The third iteration of yeast is “Instant Yeast”. No pre-mixing is required. This type of yeast has now largely replaced the Active Dry type in home use. It was invented in 1973 by the French company Lesaffre. They figured out how to make smaller granules of live yeast that have a thinner coating of dead yeast cells. In recipes that specify instant yeast, the advice to soak the yeast is an anachronism. Lots of published recipes are simply variations of older recipes that were not updated to reflect any new ingredients or even never actually tested in baking, or both. Instructions to pre-soak instant yeast are a “tell” for such shortcuts. The shelf life of active dry and instant yeast are similar. Both last the longest if the package is never opened, which is not a particularly useful way of preserving yeast. The second longest way of keeping these yeasts is to freeze them. The third is to keep them refrigerated. The shortest (albeit most convenient) is to keep an open package at room temperature.
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