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Debra Wink

The Pineapple Juice Solution, Part 2

Pineapple juice is a simple solution to a problem that many people encounter while trying to start a sourdough seed culture from scratch. Oftentimes, a new culture will appear to start off very strong, only to die a day or two later. The early expansion is caused by a prolific gas-producing bacterium which many mistake for yeast. Pineapple juice can be added to flour instead of water at the beginning, to insure against unwanted bacteria and the problems they leave in their wake. It doesn't change the end result, but it does seem to keep things on the track to finish on time. Part 1 tells the story of where the pineapple remedy comes from and how it was conceived. The rest of the story probes deeper into how it all works. But first, here is a recap of the key patterns revealed by notes and data collected during experimental trials:



  • When starters expanded significantly on the second day, a period of stillness followed, and the appearance of yeast was delayed.

  • Gas-producing bacteria stopped growing when the pH dropped to 4.5, but yeast growth didn't begin until the pH fell to around 3.5, accounting for the period of stillness.

  • Lowering the pH in the initial mixture, by adding ascorbic acid or by replacing the water with pineapple juice, kept gas-producing bacteria from growing and brought about a more timely and predictable result.


But it wasn't enough just to find a fix. The problem-solving efforts of my team were creating a buzz which we hadn't anticipated and this thing, like the seed cultures we were creating, was taking on a life of its own. Some were jumping to premature conclusions, and speculation seemed to be spreading as fact. It made me very uncomfortable, because I'd rather be dispelling myths than adding to them. I wanted to find some real answers, and find them fast, so I started making phone calls. I found two local labs that could help me out. One had the capability to identify leuconostocs, and the other to detect lactobacilli and other bacteria of interest. I submitted samples of a day two starter during the big expansion. Both labs found that there were three organisms growing. But there were no lactobacilli or yeasts found, which supports what I observed time after time on microscopic examination. My gas-producer was identified as Leuconostoc citreum. At the time, I couldn't find much information specific to this organism, although it seems to share many characteristics with other Leuconostoc species found in foods. Most will not grow below pH 4.8, and this one doesn't appear to be an exception.


Until recently, I could only theorize that the Leuconostoc may actively hinder the process, because the pattern supports it, and because it's not uncommon for microorganisms to produce substances which inhibit competitors. But in updating this article, a new search of the scientific literature finally uncovered the piece of the puzzle I was looking for. Who would have thought the answers would be found in kimchi and sake? It turns out that kimchi fermentation has a lot in common with sourdough development, and mirrors the early days of the seed culture process. Leuconostoc citreum plays a dominant role in the early and mid-phases of fermentation where it causes a slow and prolonged drop in pH, and retards the growth of other lactic acid bacteria.[1] In a study on sake fermentation, Leuconostoc citreum was found to produce bacteriocins (bacterially-produced antibiotic proteins) which inhibit the growth of similar lactic acid bacteria (i.e., lactobacilli).[2] It appears that these bacteriocins linger for a time even after the organism stops growing, although their effect is diluted through successive feeding. A dosage effect would explain nicely the apparent relationship between the vigor with which this bacterium flairs up initially, and the number of days the starter remains still afterward. The higher the rise, the longer it seems to take to recover.


In addition to Leuconostoc citreum, there was also a large amount of Aerococcus viridans. The first lab I visited found Leuconostoc to be in the greatest quantity, but Aerococcus was multiplying so fast that it soon passed the Leuconostoc in number. That is important, and could very well have contributed to the delayed progress. Even though Aerococcus doesn't produce gas, and so was not responsible for any of the expansion, it is not an acid producer either. So while it was using up a large share of the available sugars, it was not helping the pH to fall. Aerococcus is an occasional spoilage organism in unpasteurized milk, which is the extent of information that I have found on its involvement in foods. Its lower limit is not given in my reference books, but since pineapple juice seems to keep it at bay, I suspect that it must be in the same ballpark with leuconostocs. I'm still not sure how big a part each of these organisms plays in slowing the progress of a seed culture, but lowering the pH at the outset seems to be a blanket fix.


I mentioned in Part 1 that some of the bacteria were flipping, twirling and zipping around under the microscope. Those were Enterobacter cloacae. Enterobacter produces gas, but since it was present in only a scant amount compared to the others, I think it safe to say that the Leuconostoc was responsible for the majority of it. However, Enterobacter contributes to an unpleasant odor, as do Aerococcus and Leuconostoc. Because some people report a very stinky smell and others not as much, I'd have to say that even among starters that grow Leuconostoc, not all necessarily have the same combination of bacteria. There are others that can grow as well. Results vary from flour to flour and year to year, because the number and species of microorganisms are influenced by conditions relating to weather and grain crop production.[3] I wish I could have all the organisms identified at every stage, but there aren't any laboratories in my area that are equipped to identify wild yeasts or sourdough bacteria. And even if they could, the cost would be prohibitive. I was fortunate to be in a position to have two of the organisms identified as a professional courtesy.


With the additional information, and having watched the drama unfold under the microscope, I started seeing the seed culture process not as good guys out-competing bad or gradually increasing in number, but as a natural succession of microorganisms that pave the way for "the good guys" in the way that they transform their environment. There are bacteria in flour that prefer the more neutral pH of freshly mixed flour and water (like Leuconostoc and company). They are the first to start growing, some producing acids as by-products. This lowers the pH, and other bacteria begin to grow; they produce their acids, lowering the pH even more. It soon becomes too acidic for the first batch and they stop growing. One group slows down and drops out as the next is picking up and taking off. Each has its time, and each lays the groundwork for the next. It's much more like a relay than a microbial free-for-all. The baton is passed to the next group in line as conditions become suitable for them. The acidity increases a bit more with each pass, and the more acid-loving bacteria can eventually take over. The appearance of yeast seems to be tied in some way to low pH---maybe directly, maybe indirectly, but the correlation shows that it isn't random in the way that "catching" yeast from the air would be, or their gradually increasing in number.


In the late fall/early winter of 2004, I was coaching a group of women on Cookstalk, Taunton's Fine Cooking forum, and I noticed something else. My starters sort of liquefy the day before yeast starts to grow. Gluten disappears, which shows the work of proteolytic enzymes. At first I thought it signaled the appearance of lactobacilli and their proteases. But now I think it was simply an indicator that the pH had dropped low enough to activate aspartic proteinase, a pH-sensitive enzyme abundant in wheat.[4] Because I prefer to seed a new culture with whole grain flour for at least three days, there are more cereal enzymes present than in a starter fed with white flour (most of them are removed with bran in the milling process). But either way, it is a good sign of Lactobacillus activity, whether by production of bacterial proteases or by the organism's effect on pH and activation of cereal proteases.


The starters were developing a little more slowly this time around, which inspired me to describe the different stages that a new culture transitions through, rather than try and pin it to a time frame. Room temperature is different from one kitchen to the next, as well as season to season. Sometimes rye flour works faster, sometimes whole wheat is faster. Sometimes a culture doesn't start producing its own acid for the first two days instead of one. Because this process involves variable live cultures under variable conditions, it doesn't always work in a prescribed number of days, but it follows a predictable pattern. While this has been a discovery process for me, it is not a new discovery:



"There has been nice work done in Rudi Vogel's lab on the microflora of a freshly started sourdough: first, there are enterobacteria (Escherichia coli, Salmonella, Enterobacter), highly undesirable organisms that stink terribly. Then there are homofermentative lactobacilli (good lactic acid producers, but they don't produce gas or acetic acid), then acid-tolerant, heterofermentative lactobacilli that make lactic and acetic acid, as well as CO2. I think this took about forty-eight hours at 30ºC in Vogel's study. The stink at the beginning does not matter as the organisms will be diluted out or die eventually. No L. sanfranciscensis appears by forty-eight hours, though: these will occur only after repeated refreshments. Peter Stolz told me that it takes about two weeks of repeated inoculations to get a good 'sanfranciscensis' sourdough."[5]



That paragraph didn't have any special significance for me until I had gotten to this point. But when I read it again, I had one of those aha moments. Not only did this describe a succession, but it filled in some of the blanks, and I could see clearly how all these microorganisms related to the four phases I had defined. Here is the updated version marrying the two. You don't need a microscope for this, because there are outward signs which serve as useful indicators of progress.


The First Phase:
For the first day or so, nothing really happens that is detectable to the human senses. It doesn't taste any tangier or develop bubbles. It remains looking much the same as when it was mixed, except a little lighter in color if an acid was used, and a little darker if not. While nothing appears to be happening, the first wave of bacteria (determined by pH and the microflora in the flour) are waking up, sensing their new environment and preparing to grow. This phase usually lasts about one day, sometimes two.


The Second Phase:
The starter will begin producing its own acid and develop a tangy taste (although it might be difficult to distinguish from pineapple juice). Lactic acid bacteria are actively growing at this point. When using only water, this phase represents two waves of microbes---first Leuconostoc and associates, followed by homofermentative lactobacilli and possibly other lactic acid bacteria. By controlling the pH, you can by-pass the leuconostocs and other "highly undesirable organisms that stink terribly," and skip to the second wave. It will get bubbly and expand only if the pH is not low enough to prevent growth of gassy bacteria, otherwise there won't be much else to see. There probably won't be much gluten degradation, and it may smell a little different, but it shouldn't smell particularly foul unless started with plain water. This phase can last one to three days or more. If it is going to get hung up anywhere, this is the place it usually happens, especially if it is put on a white flour diet too soon. If after three days in this phase, it still doesn't become more sour and show signs of progress, the best thing to do is switch back to whole grain flour for one or more feedings. Whole grain flour has a much higher microbial count and will re-seed the culture and get it moving again.


The Third Phase:
The starter will become very tart---an indication of more acid production by more acid-tolerant bacteria. The gluten may disappear and tiny bubbles become more noticeable. These are signs that heterofermentative lactobacilli have picked up the baton. Once a starter becomes really sour, it usually transitions right into phase four. Note that lactic acid doesn't have much, if any aroma, and so smell is not a very reliable way to judge the level of sourness.


The Fourth Phase:
Yeast start to grow and populate the starter relatively quickly at this point. It will expand with gas bubbles all over and begin to take on the yeasty smell of bread or beer.


This pattern suggests that wild yeasts are activated by low pH. Or perhaps the activator is something else produced by lactobacilli, but it happens predictably at this point for me, as long as the whole grain flour has not been diluted out. There may be some variation among wild yeasts as to the exact pH or activating substance. I have been unable to find the answer in scientific literature, and my contact at Lallemand did not know. I have only found studies done with cultivated strains of Saccharomyces cerevisiae, which don't seem to require much more than a fermentable sugar (and may explain why seed cultures take off much quicker in a bakery environment where baker's yeast is everywhere). The most useful information I have found on the subject is this, about microbial spores in general:



"Although spores are metabolically dormant and can remain in this state for many years, if given the proper stimulus they can return to active metabolism within minutes through the process of spore germination. A spore population will often initiate germination more rapidly and completely if activated prior to addition of a germinant. However, the requirement for activation varies widely among spores of different species. A number of agents cause spore activation, including low pH and many chemicals... The initiation of spore germination in different species can be triggered by a wide variety of compounds, including nucleosides, amino acids, sugars, salts, DPA, and long-chain alkylamines, although within a species the requirements are more specific. The precise mechanism whereby these compounds trigger spore germination is not clear."[6]



What this means is that for dormant cells to return to active growth (germinate), they need to break dormancy (activate) which is initiated by different things for different species. In the case of these wild sourdough yeasts, if all they needed were food or oxygen, which are there from the get-go, then they would start growing immediately. The fact that they don't, is probably why many people think they need to be caught from the air, or that large quantities of flour must be used to round up enough of them. There are enough dormant cells present even in relatively small quantities of whole grain flour, but it's like a game of Simon Says. You can try to coax them into growing, with food and all the things you may fancy to be good for actively growing yeast. But they're not active. They are dormant, and will remain so until they receive the right message from their surroundings. Compare this to the plant seed that sits in soil all winter long, waiting until spring to sprout, when conditions are most favorable. Is it a survival mechanism? I don't know, but waiting for the pH to drop does increase the likelihood that the yeast will wake up in the company of lactobacilli, with which they seem to share a complex and mutually beneficial relationship. It is also important to point out here that active sourdough yeasts thrive in a much wider pH range than what appears to be required for activation of dormant cells. The point to keep in mind is that active and dormant cells are physiologically and metabolically different, which also means their needs are different.


This pattern of growth is not unique to the formula in the Bread Baker's Apprentice. I have seen the same progression, in whole or in part, with all the starter formulas I've tried. And it doesn't really matter how much flour you start with. In fact this can be done with very small quantities of flour. All else being equal, it proceeds just as fast with a teaspoon as it does with a pound. Procedures that call for two or three feedings per day, or large refreshments before yeast are active, can actually get in the way of the process. Overfeeding unnecessarily dilutes the acid, which slows the drop in pH, and keeps it from moving through the succession of microorganisms in the timeliest manner. But while it can take up to two weeks or more this way, with Mother Nature as the driving force, things do fall in line eventually. It's just a question of when. Three to five days is about all it really takes to reach the yeast activation stage at average room temperature, somewhat longer if Leuconostoc and associates grow. The strategy is quite different from reviving a neglected starter, which is likely to have an overabundance of acid, and a large population of yeast and sourdough bacteria, however sluggish they may be.


So, what can we do instead to facilitate the process? Start by providing conditions for the first two to three days which are favorable to lactic acid bacteria. A warm spot if you can easily manage one (but not too much higher than 80ºF), and a reasonably high hydration (at least 100%). Use pineapple juice if you like, to bypass the first round of bacteria. Feed with whole grain flour until yeast are actively growing, not for the wider spectrum of sugars it may offer, but for its higher numbers of yeast and lactic acid bacteria to seed each phase in its turn. Don't feed too much or too frequently, so as to allow the acids to accumulate and the pH to fall more rapidly. The ideal feeding quantity and frequency would depend on the temperature, hydration, and how fast the pH is falling. However, I usually recommend once a day at room temperature, simply because it is the easiest to manage, it works, and the daily manipulation helps to keep mold from getting started. Mold is the biggest stumbling block for procedures in which a young mixture is allowed to sit idle for two or three days at a time. Turning surface mold spores into the center by re-kneading or stirring and scraping down the sides daily, is the best way to get around it. Mold is not inhibited by low pH or pineapple juice, and anti-mold properties don't fully develop until sourdough is well established.


While you don't actually need a formula to do this, no article on making sourdough starter would be complete without one. This procedure was designed with simplicity in mind, to be efficient and minimize waste. It was developed with the participation of four willing and very patient women whom I worked with online---DJ Anderson, Karen Rolfe, Deanna Schneider and the still-anonymous 'lorian,' whose plea for help is what renewed the quest to find a better way. I learned a great deal from the feedback they gave me as we worked out the kinks, and this formula is a tribute to them.


There is nothing magic about the two tablespoons of measure used throughout the first three days. Equal weights didn't provide a high enough ratio of acid to flour to suit me, and equal volumes did. Two tablespoons is enough to mix easily without being overly wasteful (and just happens to be the volume of an eighth-cup coffee scoop, which is what I kept on the counter next to the flour and seed culture for quick, easy feeding). These first few days don't really benefit from being particularly fussy with odd or precise measuring, so make it easy on yourself. Keep it simple, and let Mother Nature do the rest.


Day 1: mix...
2 tablespoons whole grain flour* (wheat or rye)
2 tablespoons pineapple juice, orange juice, or apple cider


Day 2: add...
2 tablespoons whole grain flour*
2 tablespoons juice or cider


Day 3: add...
2 tablespoons whole grain flour*
2 tablespoons juice or cider


Day 4: (and once daily until it starts to expand and smell yeasty), mix . . .
2 oz. of the starter (1/4 cup after stirring down-discard the rest)
1 oz. flour** (scant 1/4 cup)
1 oz. water (2 tablespoons)


* Organic is not a requirement, nor does it need to be freshly ground.


** You can feed the starter/seed culture whatever you would like at this point. White flour, either bread or a strong unbleached all-purpose like King Arthur or a Canadian brand will turn it into a general-purpose white sourdough starter. Feed it rye flour if you want a rye sour, or whole wheat, if you want to make 100% whole wheat breads. If you're new to sourdough, a white starter is probably the best place to start.


On average, yeast begin to grow on day 3 or 4 in the warmer months, and on day 4 or 5 during colder times of the year, but results vary by circumstance. Feed once a day, taking care not to leave mold-promoting residue clinging to the sides or lid of your bowl or container, and refer back to the different phases to track progress. Once you have yeast growing (but not before), you can and should gradually step up the feeding to two or three times a day, and/or give it bigger refreshments. This is the point at which I generally defer to the sourdough experts. There are several good books on sourdough which address the topic of starter maintenance and how to use it in bread. Just keep in mind that the first days of the seed culture process have nothing to do with developing flavor or even fostering the most desirable species. The object is simply to move through the succession and get the starter up and running. The fine-tuning begins there. Once yeast are growing well, choose the hydration, temperature and feeding routine that suits you, and the populations will shift in response to the flour and conditions that you set up for maintenance.


One more thing I have found is that with regular feeding at room temperature, new starters seem to improve and get more fragrant right around the two week mark. Maybe this coincides with the appearance of Lactobacillus sanfranciscensis mentioned previously. It is generally regarded as the most desirable species, as well as the one found to be the most common in traditional sourdough.[7] A Fifth Phase? Obviously, there is still more to learn.   -Debra Wink


References


1. Choi, In-Kwon, Seok-Ho  Jung, Bong-Joon Kim, Sae-Young Park, Jeongho Kim, and Hong-Ui Han. 2003. Novel Leuconostoc citreum starter culture system for the fermentation of kimchi, a fermented cabbage product. Antonie van Leeuwenhoek  84:247-253.


2. Kurose, N., T. Asano, S. Kawakita, and S. Tarumi. 2004. Isolation and characterization of psychotrophic Leuconostoc citreum isolated from rice koji. Seibutsu-kogaku Kaishi 82:183-190.


3. Doyle, Michael P., Larry R. Beuchat, and Thomas J. Montville. 2001. Fruits, Vegetables, and Grains, p. 135. Food Microbiology Fundamentals and Frontiers, 2nd ed. American Society for Microbiology Press, Washington, DC.


4. Katina, Kati. 2005. Sourdough: a tool for the improved flavour, texture and shelf-life of wheat bread, p. 23.VTT Technical Research Centre of Finland.


5. Wing, Daniel, and Alan Scott. 1999. Baker's Resource: Sourdough Microbiology, p. 231. The bread Builders. Chelsea Green Publishing Company, White River Junction, VT.


6. Doyle, Michael P., Larry R. Beuchat, and Thomas J. Montville. 2001. Spores and Their Significance, p. 50. Food Microbiology Fundamentals and Frontiers, 2nd ed. American Society for Microbiology Press, Washington, DC.


7. Arendt, Elke K., Liam A.M. Ryan, and Fabio Dal Bello. 2007. Impact of sourdough on the texture of bread. Food Microbiology 24:165-174.


------------------------


This article was first published in Bread Lines, a publication of The Bread Bakers Guild of America.
Vol. 16, Issue 2, June 2008.


Related Links:
  The Pineapple Juice Solution, Part 1 | The Fresh Loaf
  Lactic Acid Fermentation in Sourdough | The Fresh Loaf 
  Basic Procedure for Making Sourdough Starter | Cooks Talk

Debra Wink's picture
Debra Wink

Lactic Acid Fermentation in Sourdough

A few years ago, I was asked to explain lactic acid fermentation in sourdough, and the difference between homo- and heterofermentation. Not an easy task, partly because I wasn't satisfied that I knew enough, or that I could reconcile what I was reading in bread-baking books with what I had learned in school. To sort it out, I had to dig deeper into the scientific literature. Answers are there in bits and pieces, although not in a context that is easy to make sense of. As I plugged away at deciphering current microbiology textbooks and scientific research, I started to see things in a new light. And so now, I want to share what I've learned with those who wish to know more.

First, I'd like to introduce the concept of a metabolic pathway. On paper, a metabolic pathway can be illustrated in a flow diagram that represents a sequence of enzyme-controlled chemical transformations. While the pathways in this discussion start with sugar and finish as various end-products, there are several intermediate compounds formed along the way as one thing is converted to the next. The names may be intimidating at first glance, but don't let them scare you. Knowing their chemical reactions and what all the compounds are is not as important here as understanding their overall purpose, which is to produce energy for the organism. Like all living things, microbes need energy to perform the tasks that enable them to live, grow and multiply.

Some pathways generate more energy than others. Through respiration, glucose and oxygen are turned into carbon dioxide and water via the Krebs cycle, also known as the tricarboxylic acid or TCA cycle. You may have seen it before if you've studied biology, because it's the same pathway we humans use. It is aerobic, meaning that oxygen (O2) is involved, and it generates far more energy than any fermentation pathway. Whenever oxygen is available, respiration is favored by facultative anaerobes like yeasts, because they will always take the path that generates the most energy under the prevailing conditions. For the most part though, bread dough is anaerobic (without oxygen), and fermentation is an alternative pathway that doesn't require oxygen. When yeasts ferment sugars, they produce alcohol (ethanol) in addition to carbon dioxide. Fermentation produces much less energy than respiration, but it allows microorganisms to carry on when no oxygen is available, or they lack the ability to respire as is the case with lactobacilli.

Bacterial fermentation is more varied than fermentation by yeast. Bacteria produce organic acids that contribute, for good and bad, to the quality of bread. Controlling acid balance and degree of sourness is something that artisan bakers strive to do, so it may be useful to understand where the acids come from and how their production can be influenced by things that are within the baker's control. In yeasted breads, acids come in small doses from naturally occurring bacteria present in flour and commercial yeast. (Fresh yeast generally has more bacterial inhabitants than dried, and whole grain flours more than refined.) In sourdough breads, acid-producing bacteria are supplied in much greater numbers from starter. There are many different species and strains of bacteria found in various types of starters, and because they produce lactic acid while fermenting sugar, they fall under the heading of Lactic Acid Bacteria (LAB).

Lactic acid bacteria common to sourdoughs include members of Leuconostoc, Pediococcus, Weissella and other genera. But by far, the most prevalent species belong to the very large and diverse genus, Lactobacillus. Based upon how they ferment sugars, lactic acid bacteria can be sorted into three categories. Please bear with me now, because while these terms may look impossibly long and technical, they are actually self-descriptive. Take homofermentative LAB for example. Homo-, meaning "all the same," refers to the end product of fermentation (by lactic acid bacteria), which is only, or "all" lactic acid. Heterofermentative then, means "different" or mixed end products. As lactic acid bacteria, heterofermentative LAB produce lactic acid, but they also produce carbon dioxide gas, alcohol or acetic acid as well. 

SUGAR STRUCTURE

As carbo-hydrates, sugars are made up of carbon (C) and water, which is composed of hydrogen (H) and oxygen (O). The hydrogen and oxygen atoms are arranged in various configurations around a chain of carbon atoms which form the structural backbone of the molecule. The carbon chain may be various lengths, but sugars common in bread fermentations are of the 5- and 6-carbon types, referred to generically as pentoses and hexoses, respectively. Glucose and fructose are examples of hexoses. Pentoses are sugars such as arabinose and xylose.

                                                                         
                              Glucose                    Fructose                  Arabinose                     Xylose

Pentoses and hexoses can exist in the chain form, or in a ring structure which forms when dissolved in water. Single sugars, or monosaccharides, are often linked together into larger carbohydrates of two or more units. Disaccharides, containing two sugars, are important in bread fermentations. Maltose, which is made up of two glucose molecules, is the free-form sugar most abundant in dough. Sucrose, another disaccharide consists of one glucose and one fructose.

                                                   

                                  Glucose                                             Maltose    

                                           

                                 Fructose                                            Sucrose

-Sugars illustrated by Antonio Zamora. For a more complete explanation, with diagrams of starches and pentosans, please see his lesson, "Carbohydrates - Chemical Structure" at: http://www.scientificpsychic.com/fitness/carbohydrates.html

Sugars that can be fermented, and their end-products are variable from one species of LAB to the next. But the key lies in the structure of the sugar---particularly, the number of carbon atoms in the backbone of the molecule. Homofermentative LAB can only ferment 6-carbon sugars. In the homofermentative pathway, a hexose is processed and split into two identical 3-carbon pieces, which are passed down through the reaction sequence and transformed into lactic acid molecules. In contrast, heterolactic fermentation is based on 5-carbon sugars. Pentoses may be used directly, although more often, a hexose is cut down by removing one of its carbons. The extra carbon is cast off in the form of carbon dioxide gas, and the remaining 5-carbon molecule is split unequally into 3- and 2-carbon units. The 3-carbon piece is turned into lactic acid, while the 2-carbon piece will become either ethanol or acetic acid. Up to this point, heterolactic fermentation doesn't produce as much energy as homolactic, but it does give an advantage over homofermentative LAB, which cannot utilize pentose sugars.

Additional energy can be produced by turning the 2-carbon piece into acetic acid, but it requires the assistance of another substance. The term for this is co-metabolism, meaning that two substrates are used simultaneously---a hexose for its carbon backbone, and a co-substrate to facilitate the formation of acetic acid and generation of additional energy. The co-substrate can be one of a number of things including oxygen, citrate, malate, short chain aldehydes, oxidized glutathione, fructose and 5-carbon sugars. In the absence of co-substrates, the 2-carbon piece is turned to ethanol instead. Alternatively, when pentose sugars are fermented (used as the carbon source), acetic acid may be produced without the help of co-substrates.

Some lactobacilli can use oxygen as a co-substrate. Some cannot, and are inhibited by aerobic conditions. In any case, there is a small amount of oxygen in dough only at the beginning of fermentation, and generally not enough to affect acetic acid production to any extent. Likewise, citrate and malate aren't naturally present in significant amounts, and pentose utilization varies by species and strain as well as availability. While all these things may be used to the extent that they are present, it turns out that fructose is generally the one most available in bread dough. 

 

  

 

All of the pathways in this discussion are glycolytic pathways. Glycolysis is the conversion of glucose to pyruvate, which is the springboard to both respiration and alcohol fermentation in yeast, to lactic acid fermentation in LAB, and to many biosynthetic pathways (manufacture of compounds used in other life processes). Oxygen is not required, so glycolysis is especially important to microorganisms that ferment sugars, like the yeast and bacteria which grow in the anaerobic environment of sourdough.

Homofermentative lactobacilli share the same glycolytic pathway with yeasts---the Embden-Meyerhof-Parnas, or EMP pathway. But in contrast to alcohol fermentation, pyruvate is reduced to lactic acid. In either of the two pathways here, the sugars are split into smaller molecules---two identical 3-carbon units (glyceraldehyde-3-phosphate) in the EMP pathway, or a 3- and a 2-carbon unit in the heterofermentative pathway. The 3-carbon pieces all follow the same path to become pyruvate and then lactic acid, while the 2-carbon acetyl-phosphate on the other side of the heterofermentative pathway can become either ethanol or acetic acid.

Glucose is not the only sugar that can be utilized. With appropriate enzyme systems, other sugars can be converted into glucose or one of the intermediates in the pathway such as glucose-6-phosphate (or in the case of pentose sugars, ribulose-5-phosphate). The ability to use other sugars varies by species and strain. Most sourdough lactic acid bacteria ferment glucose preferentially, but Lactobacillus sanfranciscensis separates maltose into a glucose-1-phosphate and a glucose. The glucose-1-phosphate portion is converted to glucose-6-phosphate to enter the heterofermentative pathway, and glucose is excreted from the cell.

In addition to obligately hetero- and homofermentive, there is a third type of lactobacilli characterized as facultatively heterofermentive. These are lactobacilli that are not restricted to one pathway or the other, but can use both. Facultative heterofermenters switch back and forth between the homo- and heterofermentative pathways depending upon which sugars are available. In general, they ferment hexoses via the homofermentive route, and pentoses heterofermentively. Most will use the hexose sugars first, although some strains ferment pentoses preferentially. Many co-metabolize fructose with maltose through the heterofermentative pathway, but use the homofermentative pathway when only maltose is available.

To put all this technical information to practical use, we need to consider factors that influence LAB activity and pathway selection. The end products are determined by the species and available sugars, which for lean doughs, depend upon the flour and the activity of enzymes. Whole grain and high extraction flours can affect acidification in two ways. First, the higher mineral (ash) content serves as a natural buffer system, which allows bacteria to produce more acid before the pH drops low enough to slow their growth. And second, grains supply pentose sugars in the form of pentosans. Although rye flours are best-known for these, pentosans are also present in wheat and other grains. (But, because they occur in the outer layers of the kernel, they are largely removed along with enzymes and many other substances in the milling of refined flours.) Cereal enzymes act on pentosans to some degree, freeing pentose sugars like xylose and arabinose that heterofermenters may be able to use according to species and strain. Pentoses will increase acetic acid production if they can be fermented or co-metabolized, either one.

Acidification is also influenced by hydration and temperature. 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.

At lower hydrations and temperatures (lower activity), more acetic acid is produced, but not because of temperature per se. Acetic acid production is influenced indirectly by temperature, in that it affects the kinds of sugars available. The fructose that drives acetic acid production, is liberated from fructose-containing substances in flour, largely through the enzyme activity of yeast. And, because lower temperatures are more suited to yeast growth than higher, more fructose is made available to the bacteria at lower temperatures. At the same time, the bacteria are growing and using maltose more slowly, so the demand for co-substrates goes down as the fructose supply goes up. The ratio of acetic acid to ethanol and lactic acid goes up, because a higher percentage of the maltose is being co-metabolized with fructose. Reducing hydration has a similar effect of slowing the bacteria more than yeast, which I believe is the real basis for increased acetic acid production in lean breads made with refined flours.

Contrary to myth, the species that grow in sourdough starters are not tied to geographic location, but rather to the traditional practices in the different regions. Several organisms go into the mix, but the environment created inside the starter from the combination of flour, temperature and maintenance routines is what determines which ones will thrive. In type I, or traditional sourdoughs (i.e., those maintained by continuous refreshment at room temperature), the obligately heterofermentive Lactobacillus sanfranciscensis is the species most frequently and consistently found---not just in San Francisco where it was first discovered, but all around the world. And so it deserves special attention.

Lactobacillus sanfranciscensis is fairly unique among the obligately heterofermentive lactobacilli, in that it ferments no pentose sugars. And unusual among lactic acid bacteria in general, because it prefers maltose over glucose. But it will co-metabolize fructose with maltose to produce acetic acid. L. sanfranciscensis converts maltose into one glucose-6-phosphate which enters the heterofermentative pathway, and a glucose which is excreted back into its surroundings. This is a good arrangement for common sourdough yeasts, since maltose is the most abundant sugar in wheat doughs, and some lack the ability to break it down for themselves. Yeasts and other bacteria that can ferment maltose, generally prefer glucose. And so by providing glucose to competing organisms, L. sanfranciscensis actually helps to conserve the maltose for itself---just one of the ways in which it gets along well with other sourdough microorganisms, and perhaps one of the reasons it is found so often.

Alternate pathways are a recurring theme in the microbial world, because microorganisms have less ability to control their environment or to leave when conditions become difficult. They sometimes have to switch gears to survive. In that effort, lactic acid bacteria will utilize whichever fermentation pathway that generates the most energy within their capabilities and resources. In order of preference, the hierarchy seems to be heterofermentation with co-substrates (forming lactic acid and acetic acid), followed by homofermentation (all lactic acid) and heterofermentation without co-substrates (lactic acid and ethanol).

While traditional sourdough starters usually support one or more strains of Lactobacillus sanfranciscensis, it is often found in combination with the facultatively heterofermentive Lactobacillus plantarum, many strains of which can either ferment or co-metabolize at least one pentose sugar. Various other obligate and facultatively heterolactic acid bacteria are also common (obligately homofermentive LAB are only transient in the startup process and do not persist in established type I starters). Sourdough starters are sensitive ecosystems with complex associations of lactic acid bacteria, and combinations can be highly variable from one starter to the next. Lactic acid fermentation is as complex and varied as the organisms involved, and so sourdough processes may need to be optimized on a starter by starter basis.
- Debra Wink  

 

Bibliography

Arendt, Elke K., Liam A.M. Ryan, and Fabio Dal Bello. 2007. Impact of sourdough on the texture of bread. Food Microbiology 24: 165-174.

De Vuyst, Luc and Marc Vancanneyt. 2007. Biodiversity and identification of sourdough lactic acid bacteria. Food Microbiology 24:120-127.

Doyle, Michael P., Larry R. Beuchat, and Thomas J. Montville. 2001. Microbial physiology and metabolism, p. 19-22; Lactose metabolism, p. 653-655. Food Microbiology Fundamentals and Frontiers, 2nd ed. American Society for Microbiology Press, Washington, DC.

Gänzle, Michael G., Michaela Ehmann, and Walter P. Hammes. 1998. Modeling of growth of Lactobacillus sanfranciscensis and Candida milleri in response to process parameters of sourdough fermentation. Applied and Environmental Microbiology 64:2616-2623.

Gänzle, Michael G., Nicoline Vermeulen, Rudi F. Vogel. 2007. Carbohydrate, peptide and lipid metabolism of lactic acid bacteria in sourdough. Food Microbiology 24:128-138.

Gobbetti, M., P. Lavermicocca, F. Minervini, M. De Angelis, and A. Corsetti. 2000. Arabinose fermentation by Lactobacillus plantarum in sourdough with added pentosans and "alpha-L-arabinofuranosidase: a tool to increase the production of acetic acid. Journal of Applied Microbiology 88:317-324.

Holt, John G., Noel R. Krieg, Peter H. A. Sneath, James T. Staley, and Stanley T. Williams. 2000. Regular, nonsporing gram-positive rods, p. 566. Bergey's Manual of Determinative Bacteriology, 9th ed. Lippincott Williams & Wilkins, Philadelphia, PA.

Katina, Kati. 2005. Sourdough: a tool for the improved flavour, texture and shelf-life of wheat bread. VTT Technical Research Centre of Finland.

Ng, Henry. 1972. Factors affecting organic acid production by sourdough (San Francisco) bacteria. Applied Microbiology 23:1153-1159.

Paramithiotis, Spiros, Aggeliki Sofou, Effie Tsakalidou, and George Kalantzopoulos. 2007. Flour carbohydrate catabolism and metabolite production by sourdough lactic acid bacteria. World J Microbiol Biotechnol 23:1417-1423.

Wing, Daniel, and Alan Scott. 1999. Baker's Resource: Sourdough Microbiology, p. 230. The Bread Builders. Chelsea Green Publishing Company, White River Junction, VT.

This article was first published in Bread Lines, a publication of The Bread Bakers Guild of America. Vol. 15, Issue 4, Dec. 2007.

 

Revised:  November 4, 2009

Cinnamon Rolls

There must be a hundred different cinnamon roll recipes, from the French pain aux raisin to the British Chelsea buns to Philadelphia style sticky buns to the Midwest American truck stop cinnamon rolls that are as big as your head.

Here is the recipe I grew up with and still bake most often.

Cinnamon Rolls
Makes 12 rolls
Dough:
16 oz all-purpose flour
10 oz warm milk
2 teaspoons instant yeast
2 tablespoons melted butter
1/4 cup sugar
1 teaspoon salt

Filling:
4 tablespoons melted butter
1 cup raisins
1/2 cup brown sugar
1 teaspoon cinnamon
1/2 cup choppped walnuts or pecans

Glaze
1 cup powdered sugar
1 tablespoon lemon juice

Make the dough by combining all of the ingredients and kneading until smooth, 5 to 10 minutes. The dough should be tacky but not sticky. If it is too moist add a handful of extra flour. Place the dough in a bowl, cover the bowl, and set aside to rise until it has doubled in size (roughly an hour).

While I'm waiting for the dough to rise, I like to plump the raisins by pouring very hot water on them and letting them sit in the water for 15 minutes before draining them. This keeps them moister when you bake them, but this step isn't necessary if you are short on time.

Sometimes I prepare my filling as you'll see below: by combining the softened butter, cinnamon, and brown sugar in a bowl so they can be spread together. Again, this isn't necessary: you can simply spread the butter and sprinkle the sugar and spices as best as you can by hand. It is up to you.

When the dough is risen, roll it out on a floured surface.

Cinnamon Rolls

Spread the filling on the risen dough.

Cinnamon Rolls

Also sprinkle the raisins on top.

Roll the dough up, trying as best as you can to prevent the filling form spilling out. Slice the roll into 12 even pieces.

Cinnamon Rolls

A tip from the Department of Slow Learners: I have no idea why it took me 25 years to figure out this trick, but it did. In the past, when I needed to slice something like this into 12 even pieces, I would eyeball it and then start carving one slice at a time off the end. Inevitably as I reached the final couple of slices I'd have either too much or too little left, so the final couple rolls are never the same size as the rest.

The trick I learned is to first slice the roll into two even pieces. Then slice slice each of these pieces into two even pieces, so you have four pieces total. Each of those pieces only needs to be cut twice more for you to have twelve pieces. Eyeballing how to cut a small piece of dough into three even pieces is much easier than eyeballing a twelfth of a large piece of dough.

Cinnamon Rolls

Moving on....

Now that your roll is cut into twelve even pieces, place those pieces in a baking pan.

Cinnamon Rolls

Cover the pan and let the buns rise for another 45 minutes to an hour until they've roughly doubled in size.

Cinnamon Rolls

Bake them at 375 for 20 to 25 minutes. Be careful about oven positioning and overbaking: because there is quite a bit of sugar in the filling it is quite easy to burn the bottom of the rolls. I find that the second rack from the top works best in my oven, and I try to pull them out as soon as they look baked.

Cinnamon Rolls

Let the rolls cool for 20 minutes or so before glazing them. The glaze will thicken as it cools, but if it is extremely runny feel free to add some additional powdered sugar to thicken it up.

Cinnamon Rolls

There is it.

Cinnamon Rolls

I'd be interested in hearing about other people's favorite Cinnamon Roll recipes/techniques. Please share your recipes, ideas, and photos.

Kaiser Rolls

Kaiser rolls are great for picnics, sandwiches, and other summertime meals. The hardest part about making them is shaping them. If you want them to be perfect, order yourself a kaiser roll stamp. Or you can roll out the dough out and knot it the way Peter Reinhart suggests in The Bread Baker's Apprentice. Below I'll show you the technique I've found easiest.

The recipe I'm using is a cross between Bernard Clayton's recipe and Peter Reinhart's recipe. Peter's recipe uses a pre-ferment, the one I've listed below does not. You can adjust this recipe to use a pre-ferment quite easily: simply throw in some old dough if you want to use a pate fermentee. Or pull out a cup of the flour and 1/2 a cup of the water and 1/4 teaspoon of the yeast, mix them together, and let them sit out in a covered bowl overnight to create a poolish. Either technique will result in a more flavorful roll, but if you are going to be making sandwiches slathered in mustard or a sharp cheese, something likely to overwhelm the flavor of the bread, the extra work is probably not warranted.

Kaiser Rolls
Makes 8-12 rolls, depending on how large you like them
3 1/2-4 cups (1 lb.) bread or unbleached all-purpose flour
1 1/2 teaspoons instant yeast
1 teaspoon salt
1 tablespoon sugar
1 tablespoon malt powder
1 tablespoon shortening, butter, or oil
1 egg
1 egg white
1 1/4 cups (10 oz.) water

Combine 3 cups of the flour and the other dry ingredients in a mixing bowl or the bowl of a stand mixer. Mix in the water, eggs, and shortening. Knead by hand for approximately 10 minutes or 5-7 minutes in a mixer, adding more flour by the handful as necessary. The dough should still be tacky but not terribly wet. Place the dough in a greased bowl, cover, and allow to rise until doubled in size, approximately 1 hour. Allow it to rise a second time for an hour before shaping. To shape the rolls, divide the dough into smaller pieces (if you are particular, use a scale to get them the same size). Roll the pieces of dough into balls and cover them with a damp kitchen towel so they can relax for 5 minutes.

To shape them, first I press them out into flat disks on a well floured surface (Clayton suggests using rye flour, though any type of flour will do). I let them rest, covered, another 5 minutes. Then I stretch the dough a bit thinner again and fold pieces up into the center.

Finally I press down in the center to seal it up tight.

I place them face down on a sheet pan covered with poppy seeds while they are rising for the final hour.

One could just as well let them rise face up and then spritz them with water and sprinkle the poppy seeds on, but doing it this way prevents the seals from splitting while they rise.

Preheat the oven to 450 during the final rise. Just before placing them in the oven, flip the rolls upright. You want to have steam in the oven when you bake them, so use whatever technique you prefer: squirting them with water, squirting the oven sides with water, pouring boiling water in a preheated cast-iron pan or a cookie sheet. These rolls take around 20 to 25 minutes to bake. I suggest rotating the pan once 10 minutes into it so they'll brown evenly.

Related Recipe: Potato Rosemary Rolls.

Baker's Math

Let’s have a quick math lesson.

Math?! Yes! Professional bakers don’t usually talk about recipes, but rather about formulas. Bread is all about proportions, and baker's math is a way of breaking down ingredients into these proportions so that you can scale up or down as needed. It also makes baking much easier because, once you understand the basic proportions, you can freely mix and match ingredients to invent all kinds of breads on your own.


It's not necessary to learn baker's math to bake good bread, of course, but it can expand your ability to mix and match ingredients and break free of recipes to create your own formulas.


In baker's math, every ingredient is expressed in terms of the flour weight, which is always expressed as 100 percent. For example, let's take a typical formula for French bread:

    * Flour: 100%
    * Water: 66%
    * Salt: 2%
    * Instant yeast: 0.6%
    * Total: 170%

So, let’s say we’ve got 500 grams of flour. If I wanted to make French bread, here’s how I’d figure out the weight of the other ingredients

•    Water: 500 * 0.66 = 330 grams
•    Salt: 500 * .02 = 10 grams
•    Instant yeast: 500 *.006 = 3 grams

We can also first decide how much dough we want, and work backwards. Let's say we want to make 1 kilogram of dough. First, we need to figure out how much flour we need. To do this, we divide the total of all the ingredient percentages added up (170% = 1.7) into the total weight of the dough:
1000 grams / 1.7 = 588 grams of flour (rounded to nearest gram).

Now that we know the flour weight, we figure out the weight of each of the ingredients by multiplying their percentage by the flour weight, just as we did above.

    * Water = 0.66 * 588 = 388 grams
    * Salt = .02 * 588 = 12 grams (rounded)
    * Instant yeast = .006 * 588 = 6 grams (rounded)

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bwraith

Maintaining a 100% Hydration White Flour Starter

The following is a description of how I maintain my 100% hydration (1:1 flour:water by weight) starter. The term 100% hydration refers to the baker's percentage of water in the starter, i.e. the water in the starter is 100% of the weight of the flour in the starter.

This maintenance regime assumes that your starter is already healthy, fresh, and active. This is not what I would do to "start a starter", but rather it is the maintenance regime I follow to store, revive, and use my starter over time.

The following characteristics are for a 100% hydration starter. The characteristics, signs of health, problems, and readiness for use are different for starters maintained at different hydration levels.

Characteristics of my 100% hydration white flour starter:

  • The weight of flour and water in the starter are equal.
  • The flour is either bread or AP flour with protein content around 11-13%.
  • The water is bottled (Poland Spring).
  • Normally fed at room temperature.
  • Stored in the refrigerator when not being fed.
  • The consistency can be described as a thick, stirrable paste after it is fed.

Characteristics of a recently fed, fresh, active 100% hydration starter:

  • It rises by double in about 4-5 hours at room temperature after a feeding of 1:2:2 (starter:flour:water by weight)
  • It maintains a reasonably thick, elastic consistency after rising by double.
  • It smells very pleasant. The smell could be described as flowery, tangy, and slightly sweet.
  • No liquid layers develop on top or in the middle even hours after rising by double.
  • Hooch (an alcoholic layer of liquid on top) forms eventually when it is stored in the refrigerator for a week or more or left out for a long time at room temperature after doubling.

Characteristics of a 100% hydration starter that is not yet ready or is possibly unhealthy:

  • Unpleasant odors a few hours after feeding.
  • Separated layers of liquid form a few hours after feeding.
  • Takes longer than 4-6 hours to rise by double at room temperature after a 1:2:2 feeding (starter:flour:water by weight).
  • Develops a runny consistency a few hours after feeding.

An Important Note on the Large Effect of Temperature on Rise Times

Before launching into the information below on maintaining starters, it is worthwhile to point out one of the largest points of confusion in sourdough starter maintenance. Temperature has a big effect on the speed of reproduction and the activity of the organisms in a sourdough culture. For example my kitchen may average 76F in the summer and only 69F in the winter. At 76F, my starter may rise by double after a 1:2:2 feeding in 4.2 hours, whereas at 69F it will double in 6.4 hours. At 64F, it would take 9.4 hours. It is not a problem to follow the procedures below in a kitchen with a temperature averaging 64F; but clearly, you need to allow for rise times of roughly double in the various discussions below. So, adjust your expectations and timing accordingly, if your temperatures don't hover fairly close to 74F or so, which is the temperature assumed for the discussions below.

Assuming a healthy, active starter, here is the maintenance regime I follow to feed, store, revive, and use my starter.

Feeding

I almost always feed my starter 1:2:2 (starter:flour:water by weight) and then allow it to rise by double at room temperature, which should take about 4.5 hours when it is fully active and recently fed. Once it has risen by double, it is placed in the refrigerator. The starter can then be used directly from the refrigerator in a recipe for the next 3 days. On the first day, it is almost the same as it was right after it rose by double. On the second day, it has a little more flavor and may be ever so slightly weaker, but it is still at an excellent point to use in a recipe. After 3 days, it can still be used, but it will have stronger, more sour flavors, and it will be noticeably weaker in terms of rising power. If you have a recipe that uses a very small percentage of starter in the dough, it won't matter much if you use old starter. I've used week old starter in recipes where the flour contributed to the dough was only 5% of the total flour weight. If you are using the starter in a recipe that has a high percentage of starter, it may be better to use the starter after 2 days or less in the refrigerator.

Although it may not make much difference, I actually maintain my starter with a 1:2:2.2 feeding ratio, i.e. at a 90% hydration. With the bread flour I use (KA Bread Flour) that results in a consistency of a thick paste that is a little difficult to stir once you mix it up well. The amounts you work with don't matter much, either, other than the amount of flour being thrown out. I typically work with a total culture size of about 80 grams. My scale will measure down to 1 gram of precision. A typical 1:2:2.2 feeding would be (16g:30g:34g) of (old starter:water:flour). Below I am doing 1:10:11 feedings, which are done by feeding (4g:40g:44g) of (old starter:water:flour).

The above method works great, but see in the variation section below for an update on how I am feeding most recently to better accomodate a 12 hour feeding cycle. Also, I now use an even thicker consistency, around 80% hydration. It seems to keep longer this way on the counter or in the refrigerator.

Storage

Once the starter has been in the refrigerator for more than three days, I consider it to be in storage. It can't be used directly in a recipe, but instead will have to be revived. If I plan to store my starter for a period of time longer than 2 weeks, I usually will thicken it up, as it keeps better at a thicker consistency. However, even at 100% hydration, I've had no problems reviving my starter after 2 months. At thicker consistencies, the starter can last for many months in the refrigerator. I believe Glezer says it can last more than a year in a very stiff consistency, like 50% hydration. However, the longest I've gone with my starter is 2 months. I use glass canisters for both feeding and storage. I usually pour the ready to refrigerate starter into a fresh container, so that the sides are clean and the starter is stirred down to take up less volume. The containers have a rubber gasket that seals them from the air in the refrigerator but allows some gas to escape if pressure and gasses build up in the container.

Revival

When the starter has been in the refrigerator for more than a few days, it must be revived first before it can be used in a recipe. I do this by simply feeding it once or twice in the manner described under "Feeding". After being stored for a week or two or more, rising by double after a 1:2:2 feeding may take something like 6-8 hours at room temperature. If it only takes 6 hours, one feeding works fine. However, if it takes more than 6 hours to rise by double at room temperature, I generally feed it one more time. The second feeding usually takes much closer to 4.5 hours, which is an indication it is fully revived. On the occasion where it had been stored for 2 months, it took a third feeding at room temperature before the starter would rise by double in 4.5 hours at room temperature after a 1:2:2 feeding.

One subtle aspect of all this is the question of how long after the starter has doubled should you wait to feed it again. The starter needs to ripen enough to bring the cell counts up to their maximum level. In the period after you feed the starter, the cell counts of yeast and lactobacillus will double every couple of hours or so. Once the starter is ripe enough, the yeast and lactobacillus cell counts will stop increasing. The pH and acid levels get to a point where they attenuate the cell activity, and they can no longer multiply in numbers. So, you want to let the starter mature enough to reach that maximum cell count, and then feed it again or store it. Just based on experience, it seems like my starter does well as long as I let it sit for an hour or two beyond the point it doubles. I usually "stir it down" at the point it doubles, and then let it rise some more. However, I refrigerate it right when it doubles, since it will continue to ripen in the refrigerator. Recently, I was rushing my feeding schedule and slowed my starter down by trying to feed too early, just before it had completely doubled, in fact. The result was that it was taking longer than usual to rise. The solution was to let it sit a while longer for a few feedings in a row. It didn't take long at all for it to bounce back to doubling in 4.5 hours from a 1:2:2 feeding at room temperature.

Variations

You can feed at a lower or higher ratio than 1:2:2 in order to adjust the amount of starter you want to build to match a recipe or to better match the times when you can feed the starter conveniently. However, I never feed at a lower ratio than 1:1:1 to avoid any problems with acid building up or the starter becoming too ripe or underfed. Higher ratios can be used to lengthen out the rise time if you know you will not be back within 4-6 hours to store the starter in the refrigerator before it becomes too ripe. At warmer temperatures, the starter will rise by double much more quickly after a 1:2:2 feeding, taking something like 2.5 hours at about 85F, for example. At 85F the timing for rising by double will be very roughly half as long as at room temperature, and at 65F the timing will be very roughly twice as long (very, very roughly).

Recently, I've been experimenting with feeding ratios for a 12 hour room temperature maintenance schedule. I have found that feeding 1:10:11 (for a slightly thicker consistency I'm using 90% hydration), results in a 12 hour cycle. The starter will double 8 hours after the 1:10:11 feeding, and then I stir it down and let it ripen some more. If I feed every 12 hours on this cycle, the starter is at full strength from about 8 to 12 hours after being fed (all this at room temperature). When you feed a starter routinely at higher ratios, like 1:10:11, it will ferment for longer periods of time at higher pH. The result should be that the starter will have relatively more lactobacillus in it compared to a starter maintained with a 1:2:2 feeding ratio, since the lactobacillus thrive in a slightly higher pH environment (around 5 pH).  I can't say what the effect on flavor would be, but it makes sense that the aromatic compounds and acids produced by the lactobacillus would be more evident in the one maintained with the high feeding ratio. Although this is not at all scientific, I do think that the starter I've maintained with a 1:10:11 feeding ratio has a more intense aroma than the one fed with a 1:2:2 ratio.

Even more recently (added 12/14/2007), I've settled on feeding every 12-17 hours using a feeding of 1:4:5 (starter:water:flour by weight). Using this procedure, the starter doubles in volume in about 4.75 hours at 76F or about 7.25 hours at 69F. Even at 69F, the starter has peaked in 12 hours, so it can be fed again. At 76F, it will peak and fall after 12 hours, but it is still at full strength and will rise vigorously when fed. It seems like a good compromise that can be used year-round for a 12 hour cycle. The starter can be maintained on the counter at room temperature indefinitely using this procedure. If I know I won't be baking bread for a while, I thicken up the starter by feeding it 1:4:7 to thicken it up when I feed it next, and put it in the refrigerator immediately after feeding. Then, I take it out a day or two in advance of the next bread-making session and revive by letting it rise by double and feeding 1:4:5 every 12 hours. Although I generally go through the revival procedure, I've found that the starter is at close to full strength even after 7 days in the refrigerator when stored this way. So, it's possible to take the starter out of the refrigerator, let it rise by double, and use most of it in a bread recipe, and take a tiny portion of it to revive for a couple of feeding cycles before returning it again to the refrigerator using the 1:4:7 feeding and refrigerating immediately.

When to Refrigerate

I like flavors to be less sour and more mild in sourdough breads I make. I've found that the right flavors and lower amounts of sour flavor seem to be there when I don't let the starter become overly ripe before using it in a recipe. That's why I tend to refrigerate when the starter has just doubled. You can experiment with feeding schedules that allow the starter to become more ripe before refrigerating. It will change the balance of organisms in the culture and therefore the flavor. Also, when you use a large percentage of starter, the larger amount of accumulated byproducts of fermentation in a more ripe starter will contribute directly to the flavor and texture of the dough, in addition to the contribution made by the subsequent fermentation.

An Additional Tip on Refrigerated Starter Storage

If you are using your starter fairly frequently, like once a week, then just refrigerating it when it doubles will work very well. You can use the starter directly out of the refrigerator for a period of time if stored that way. For storage it works well, as I've had no problem reviving my starter after 2 months when stored just after doubling. However, as Mike Avery commented below, and I've verified as well, feeding a well revived and healthy starter in such a way as to thicken it to a firm consistency and then refrigerating it immediately allows the starter to keep very well for longer periods of time. It can be removed from the refrigerator and allowed to rise by double or a little more and used directly in a recipe, even after a week, I've found. If you use this procedure, the starter should still be "revived" with enough feedings, usually one or two more, at room temperature to verify that the starter is rising at full strength again before it is again stored in the refrigerator.

Converting Starters

I sometimes make a recipe starter for a whole grain bread by feeding some of my starter with spelt or whole wheat. I have never fed a starter with whole grain repeatedly to completely convert it, so I have to accept the flavor as is and a small amount of white flour in my whole grain recipes. I'm sure there are many subtle flavor differences if you feed repeatedly and fully convert a starter from being fed exclusively with white flour to being fed exclusively with a whole grain flour. I've found the feeding and rising process works about the same way with whole grains for a recipe starter, except that the rise times seem a little bit faster with the whole grain flours.

Mistakes

It's pretty hard to kill a healthy starter, but here are a few ways to possibly send yours over the edge.

  • Heat the starter to over 95F and kill the organisms - easier than you might think, for example...
    • Use actual oven heat and get up over 100F very quickly.
    • Place the starter in an oven with the light on - check carefully first - it can be much hotter than you think in there with just the oven light on and the door closed.
    • Use hot water to feed your starter
  • Put acids in the culture
    • The culture doesn't need acid if it's healthy. It generates all the acid it needs on its own.
    • Sometimes a small shot of vinegar or other acid, such as pineapple juice, may help fix a sluggish culture, but if you feed acid repeatedly, you can put too much in and kill the starter.
  • Not feeding the culture for too long at warm temperatures or repeatedly underfeeding over long periods.
    • When out of the refrigerator, the culture will be very active and must be fed to stay healthy.
    • It is especially easy to underfeed a culture when temperatures are warmer.
  • Overfeeding the culture
    • If you feed before the culture has ripened enough repeatedly you can dilute the culture and eventually kill it.
    • More likely to happen at colder temperatures, stiffer consistencies, or higher feeding ratios. Let the culture rise by double, then let it ripen for a number of hours beyond that. A dip should form in the middle when the culture is at its peak. You can let it go for a number of hours beyond the point it dips, but it should be ready to feed at the point it is dipping or collapsing on itself.
    • If you refrigerate the culture for storage, you can let it just rise by double and then refrigerate it. It will continue to ripen in the refrigerator. However, allow it to come to full ripeness at room temperature over a couple of feedings once in a while, normally done when reviving the culture for baking, to avoid any decline similar to overfeeding caused by repeatedly refrigerating when it has just doubled.

Given the above, it makes a lot of sense to keep back a small amount of old starter in the refrigerator, even if just the scrapings from the inside of the container that came out of the refrigerator, until you're sure the feeding went well. It's also not a bad idea to make a small amount of stiff starter and keep as a backup. Some dry their starter and freeze or store it for backup.

Tips on Quantities Used, Mixing Technique, and Volumes (a scale is highly recommended, but to use measuring spoons...)

As I've gained experience, the amounts of starter I work with have dropped. I haven't found any disadvantages to using smaller quantities. For example, my most recent feeding routine (mentioned in the variations section above) is 1:4:5 (starter:water:flour by weight) is done by taking a clean jar, putting it on the scale and adding 5 grams of starter and 20 grams of water. I stir vigorously with a tiny whisk to aerate and thoroughly mix the starter into the water. Then, I add 25g of flour and use a fork to thoroughly mix the flour into water, forming a fairly thick paste - not quite a dough, but very thick. I then take a small spatula and scrape down the sides, put the lid on the jar, and place the jar in a nice unobtrusive spot on my counter where hopefully no one will disturb it.

If you don't have a scale, my first advice is to get one. It makes baking much more reliable, especially when you are trying to reproduce another baker's recipe. A good digital scale costs about $25 and is very much worth the trouble. Still, the procedure in the previous paragraph is easy to do by taking 1 teaspoon of starter, adding 2 tablespoons of water, and stirring vigorously to aerate and completely mix the starter into the water. Then, add 3 tablespoons and possibly another teaspoon or so of flour, and mix thoroughly with a fork. Scrape down the sides of the jar, cover, and place on the counter.

If you are planning to store the starter for a long time in the refrigerator, it helps to carefully drop the recently fed and thickened starter into a clean jar, so that there is no film of flour or paste stuck to the sides at all. Over a longer period, it is possible for mold to grow on a residue of flour paste left on the sides of the jar.

Comments

What I describe above is just one way to do it. I'm sure there are many other ways, but I find this method convenient and robust. It's hard to kill a healthy freshly fed and risen starter that is stored in the refrigerator. It is convenient that the starter remains in a good usable state for several days. Very small amounts can be used when storing it for long periods to avoid large amounts of flour waste. I store something like 100 grams when I'm planning to store the starter for more than a few days, so my revival can be used in a recipe without wasting much if any flour. Maintaining only one starter and converting it for recipes each time is easy and convenient, although by not fully converting the starter to a whole grain flour some flavor or other characteristics may be missed with this approach.

ehanner's picture
ehanner

Eye opening techniques

I know when I first started baking I nodded dutifully when I was told to knead until the dough will pass the window pain test. If you can't stretch a piece until it is translucent and you can see light through it, knead some more. This advice is found through out the industry help and how to books and is considered to be a core understanding by many. Far be it for me who is a lowly novice in terms of time in the flour bin to question the conventional wisdom, however. There are a few misconceptions that have become accepted as gospel that I believe hinder the new baker and for that matter any baker who wants to truly understand what their potential is in the kitchen. The techniques I address here are not my ideas or content. These things were presented to me by others here on the forum in pieces over the last few years and together represent the basis of my capability today.


The first bit of advice I have is to stop what ever you are doing and watch this video. If you're like me it will take a few times to get the hang of what the poster is doing. This is Richard Bertinet doing a demo for Gourmet magazine. He is making a sweet dough but it doesn't matter. The technique is key. When I learned this move and method of handling dough, my results instantly went from unpredictable to reliable. 10 or maybe 15 seconds with your hands in the dough and that's it, you're done. No more kneading is required. You might do a couple folds every 20-30 minutes during the primary ferment. This will work with sourdough or yeasted recipes and white or whole wheat with the caveat that WW will need a fold or two during the ferment. Once I learned to do the French Fold, I have rarely used my mixer. When you understand how the dough is supposed to feel with your own fingers it is much easier to produce a dough that will perform to your expectations.


Further EDIT: A regular contributor to this forum has produced some really terrific video training aids that can be seen HERE. Mark Sinclair is the owner of The Back Home Bakery in Kalispell Montana. He is remarkably clear in the message he sends about how to handle several dough types and shaping.
Mark demonstrates how easily you can mix, stretch and fold and shape dough. His style is easy to follow and well done. I highly recommend you take a look at these instructional videos. He just posted a new video on shaping a high hydration baguette that is excellent. Many of his recipes are search-able here or if you email him he will probably send them to you. His bakery products are beautiful and the photography is inspirational.


Mark now has 2 DVD's for sale that take you from end to end with 3 different breads and another on technique. There are lots of places to get information on how bake good breads. Marks Video's are reasonable and very helpful to the new baker.


There is another video that should be included is the Julia Child/Daniel Forester baguette demonstration. This is a 2 part video that shows how to put together french bread dough by hand and uses the frisage method. Frisage is something that once seen, always understood. You can read about it repeatedly but it won't make sense until you see it in action. See it http://www.pbs.org/juliachild/free/baguette.html here.


Added by Edit: A great video is now available that I think is the essence of dough handling and shows how easy it is to mix dough without a mixer. If you can chew gum you can make great bread using Richard Bertinet's video HERE.


Secondly, Da Crumb Bum posted a concept that goes against all the common wisdom concerning pre heating your oven and using a stone for a thermal battery. Who hasn't thought that to get good rustic bread one must bake on a pizza stone or a tile surface? There are some instances where a stone and preheat is required like pizza and bread sticks but for the greatest majority of your baking, no stone or preheat is required. A link to the original post is http://www.thefreshloaf.com/node/1843/no-knead-preheat#comment-12597 . Most are skeptical this will work at first but trust me on this, you won't believe it until you see it with your own eyes. It is expensive to maintain 450F in a steel box both in terms of wasting money and by wasting the energy and resources of our planet. The minimal effect that preheating has on the crust is absolutely not worth the additional energy.


I share these thoughts and techniques as a way of thanking the many posters who have helped me to become at least a competent home artisan baker. The host of The Fresh Loaf (floydm) is top on the list with his lessons and frequent examples of solid baking. Hundreds of community members, posters, are here to answer your question or help with an issue. This is a great site because of the members. Don't be afraid to jump in, we are just like family.


ADDED EDIT:
It's been a while since I made this post and I wanted to come back and add a few things now that I have some experience under my belt.
1.) I still almost never use the mixer. A brief hand mix to break up the dry clumps of flour followed by a 30-60 minute rest and stretch and fold or French folding as per the top video will develop the gluten just fine. Stretch and fold every 30-60 minutes for the duration of the bulk ferments. Time will be your friend here. Be patient. If you use a very small amount of starter for inoculation or yeast, you slow down the bulk ferment. If you increase the hydration slightly, you will find you can fold every 40-60 minutes for about 4 hours. The dough will be perfectly satin smooth and will easily windowpane.


2.) Instead of starting from a cold oven, I now am starting the oven when the dough looks ready and the proof is about done. The dough is proofing on parchment, covered with a floured towel or a moist tea towel. When it looks like the proof is done, turn on the oven. My electric will go to 450 in 7 minutes. Slide the dough in, steam for a great crust. I rotate after 20 minutes.


3.) I think many people over ferment and over proof. Try fermenting for 60 minutes at 78F, shape and proofing for 45-60 minutes. Remember, the warmer it is where your dough ferments, the faster the dough will rise. Temperature matters.


4.) Make your slashes deeper than a 1/4 inch. You might be better to go back and retrace your initial slashes to make them just a little deeper. Be modest in the pattern. Remember what the purpose is of slashing.

5.) Not so much a technique but a suggestion. Adopt a basic formula that you can make in your sleep. Nothing fancy, a basic yeast or sourdough bread your family likes and work from that. You will be surprised at how many different types of bread you can make using your basic master formula by adding one or two ingredients or changing the handling slightly.
Have fun and learn at your own pace. The collective knowledge at The Fresh Loaf is being plugged into your own private baking school.


Eric


"It's not you he wags his tail for, but, your bread".

Better Banana Bread

Well, maybe not a better banana bread, but different banana bread: cakier, creamier, moister. I, personally, think I prefer this loaf to the previous banana bread recipe I posted, but my wife makes the point that this recipe produces a much more delicate bread than the previous one does. For a quiet cup of tea on a lazy summer afternoon, this is the one. For a picnic at the zoo with a rambunctious three year old, the previous one is the way to go: it'll survive the transport in the car and backpack much better.

Recipe below.

This is, in fact, the same recipe as before with a cup of vanilla yogurt added. The yogurt made the dough moister, so in response I needed to add more flour. Since I was adding more flour, I decided to try using some whole wheat flour. It turned out well.

So if there is a lesson to be learned here, it isn't that this is the greatest banana bread in the world. It is to make each recipe your own. Bake often and do not be afraid to experiment. If you don't screw up a recipe from time-to-time you probably aren't baking enough!

Better Banana Bread
Makes 1 huge loaf or 3 small loaves

Preheat the oven to 350.

In one bowl, combine:

1/2 stick (4-5 tablespoons) butter, softened
2 eggs
2 or 3 very ripe bananas
1 cup vanilla or plain yogurt
2/3 cup sugar

Use a potato masher, fork, or spoon to squish the banana and mix the ingredients together. It is alright for there to be small (1 centimeter) chunks of banana in the batter, but you want most of the banana to be reduced to mush.

In another bowl, combine:

1 1/2 cup all-purpose unbleached flour
1/2 cup whole wheat flour
3/4 teaspoon salt
1/2 teaspoon baking soda
1/4 teaspoon baking powder
1/2 teaspoon cinnamon (optional)

Combine the wet and dry ingredients and mix until the ingredients are blended together.

If you like, stir in additional ingredients here, such as chopped walnuts or pecans, dried cherries or apricots, or chocolate chips. A handful (about a half a cup) is about right.

Pour the dough into greased baking pans and bake until a toothpick inserted in the center comes out clean. Small loaves take around 30 minutes, a normal-sized loaf takes around 50 minutes.

Remove from the oven. This bread is great warm, but it is excellent cold too.

After they have cooled for 5 or 10 minutes the loaves can be removed from the pan to cool. Once they are cool they can be individually wrapped and frozen.

Enjoy!

Related Recipe: 10 Minute Banana Bread.

Flo Makanai's picture
Flo Makanai

1.2.3, An Easy Formula for Sourdough Bread

Hi Everyone!

I'm Flo Makanai, French "author" of the (in French, sorry...) blog Makanai (http://makanaibio.com/). I love bread baking, especially sourdough baking, and I've been doing it for about 15 years.

As I always have many obligations other than baking bread (who does'nt?!) AND lots of sourdough to use (I hate throwing it away once it has reached maturity), I eventually came to "invent" a formula that works for me in France (Janedo from http://aulevain.fr/, whom you certainly know, has also tested that formula and it works for her too).

Here it is:

I weigh the liquid (100%) mature sourdough I have on my counter. It gives me a weight which I shall call weight 1.

I then multiply "weight 1" by 2 to obtain the quantity of liquid (water, rice milk, milk...) I'll need. So the liquid will weigh twice as much as the sourdough.

Then, I multiply "weight 1" by 3 to obtain the quantity of flour(s) (always organic for me) that I'll need. So the flour(s) will weigh 3 times the sourdough. 

I mix those 3 ingredients, I let the dough rest 30 minutes and then I knead my dough, adding 1.8% to 2% of the flour(s) weight of salt.

So "1" = sourdough weight

"2" = liquid weight, which is "1"x2

and "3" = flour(s) weight, which is "1" x3

Example : with 125g sourdough, I'll bake bread with 250g liquid and 375g flour + 6 to 7g salt

The reason I'm writing today on TFL is that I wonder if that formula works in the States, where flours are so different from the ones we have in France. Is anyone interested in trying and then posting a comment on TFL? That would be interesting.

I posted this formula (in French, but you can use the Google translator, even if the result is quite ... unusual!) on Makanaibio yesterday (here: http://www.makanaibio.com/2008/10/123-pain-au-levain-une-formule-qui.html), if you can read French or if you'd like to see a few pictures of some of my breads.

(And please excuse my english, I certainly made mistakes I'm not even aware of...)

I hope to read you soon!

Flo Makanai

dmsnyder's picture
dmsnyder

Ficelles made with Anis Bouabsa's baguette formula

 

 

  • Flour500 gms Giusto's Baker's Choice
  • Water375 gms
  • Yeast1/4 tsp Instant
  • Salt10 gms
  1. Mix flour and water and autolyse for 20 minutes.
  2. Add yeast and mix by folding dough in the bowl.
  3. Add salt and mix by folding dough in the bowl.
  4. Mix dough by folding and stretching in the bowl for 20 strokes. Repeat this 3 more times at 20 minute intervals.
  5. Refrigerate dough, covered tightly, for 21 hours.
  6. Divide into 4 equal parts and preshape gently for baguettes.
  7. Allow preshaped pieces to rest, covered with plastic, for 1 hour.
  8. Shape into ficelles (short, thin baguettes).
  9. Proof en couche or on parchment paper dusted with semolina for 45 minutes.
  10. Pre-heat oven to 500F with baking stone in middle rack and a cast iron skillet and a metal loaf pan on the lowest rack. Preheat 45 minutes or longer before baking.
  11. 3-5 minutes before baking, place a handful of ice cubes in the loaf pan. Shut the oven door. Bring water to a boil.
  12. Transfer the ficelles to a peel and load them onto the baking stone. Pour one cup of boiling water into the skillet. Close the oven door.
  13. Turn the oven down to 480F.
  14. After 10 minutes, remove the loaf pan and the skillet from the oven.
  15. Continue baking for another 10-15 minutes until the loaves are nicely colored, the crust is hard all around and the bottom gives a hollow sound when tapped. Internal temperature should be at least 205F.
  16. Cool on a rack completely before slicing.
Anis Bouabsa is a young Parisian boulanger who won the prize for the best baguettes in Paris in 2008. He gave Janedo, a French home baker extraordinaire and a member of TFL, his formula, and Jane shared it with us. He uses a technique of a long, cold fermentation which has been used, with variations, by a number of contemporary French bakers.In addition to producing wonderfully flavored bread, it also permits the home baker to make bread using two blocks of about 2-3 hours rather than requiring longer time blocks. For example, I mixed the dough yesterday evening after dinner. I took it out of the refrigerator at about 4:30 pm this afternoon, and we ate it with dinner at 7:30 pm.These ficelles sang loudly coming out of the oven. I cooled them for only 20-30 minutes. The crust was very crunchy, and the crumb had a sweetness that would make one think there was sugar in the dough. Very yummy.Variations on Bouabsa's formula, adding 100 gms of sourdough starter and substituting 10% rye or whole wheat flour for an equal amount of white flour, make a delicious pain de campagne, which has become a favorite bread of several of us.This is described in my blog entries under "Pain de Campagne" and "San Joaquin Sourdough."Enjoy!David

 

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