How to make a sourdough starter (#10)

* Making a starter WIP

* Improve texts

* Storage part

* Change intro

* Add conclusions

* Add images

* Add sources

* Fix space

* Complete chapter

README.md

@@ -32,7 +32,7 @@ The book is a work in progress. This represents the current status:
 * ✅ Intro
 * ✅ Enzymes
 * ❌ Microorganisms
-* ❌ Making a starter
+* ✅ Making a starter
 * ❌ Sourdough starter types
 * ❌ Flour types
 * ❌ Bread types

book/book.tex

@@ -23,6 +23,7 @@
 \graphicspath{
   {./images/}
   {./troubleshooting/}
+  {./sourdough-starter/}
   {./troubleshooting/crumb-structures/}
   {./history/}
   {./images/external/}
@@ -121,4 +122,4 @@
 \printbibliography
 
 
-\end{document}
+\end{document}

book/references.bib

@@ -185,4 +185,45 @@
   year      = {2001},
   journal   = {FEMS Microbiology Ecology},
   volume    = {37,2}
-}
+}
+
+@article{pickled+foods+expiration,
+  title        = {Hardcore hibernation},
+  author       = {David Adam},
+  howpublished = {\url{https://www.nature.com/articles/news001019-9}},
+  year         = {2000},
+  note         = {Accessed: 2022-06-23}
+}
+
+@article{old+spores,
+  title        = {Do Pickles Go Bad?},
+  author       = {thrillist.com},
+  howpublished = {\url{https://www.thrillist.com/eat/nation/do-pickles-go-bad-refrigerator-pickles-shelf-life}},
+  year         = {2017},
+  note         = {Accessed: 2022-06-23}
+}
+
+@article{mold+anaerobic,
+  title        = {Differences between Yeasts and Molds},
+  author       = {Sagar Aryal},
+  howpublished = {\url{https://microbenotes.com/differences-between-yeasts-and-molds/}},
+  year         = {2022},
+  note         = {Accessed: 2022-06-23}
+}
+
+@article{effects+temperature+flavor,
+  title        = {Effects of Fermentation Temperature on Key Aroma Compounds and Sensory Properties of Apple Wine},
+  author       = {Bangzhu Peng et al.},
+  year         = {2015},
+  journal      = {Food science},
+  volume       = {80,12}
+}
+
+@article{effects+temperature+flavor,
+  title        = {Analysis of domestic refrigerator temperatures and home storage time distributions for shelf-life studies and food safety risk assessment},
+  author       = {Anna Roccato et al.},
+  year         = {2017},
+  journal      = {Food Research},
+  volume       = {96,171-181}
+}
+

book/sourdough-starter/sourdough-starter.tex

@@ -28,7 +28,7 @@ of salt and around 100 grams of sourdough starter.
 modern pizzerias would use fresh or dry yeast. However
 traditionally pizza has always been made with sourdough.}
 The next day you suddenly have 1.4 kilograms of flour
-at hand and can thus make more pizza dough. What do you do?
+at hand and thus can make more pizza dough. What do you do?
 Do you multiply all the ingredients by 1.4? Yes you could,
 but there is an easier way. This is where baker's math
 comes in handy. Let's look at the default recipe with baker's
@@ -71,16 +71,16 @@ Salt                & 2\%                                        & 1400*0.02 = 2
 }
 \end{table}
 
-For each ingredient we calculate the percentage 
+For each ingredient we calculate the percentage
 based on the flour available (1400 grams.) So for the water
 we calculate 60 percent based on 1400. Open up your
 calculator and type in 1400 * 0.6 and you have
 the absolute value in grams that you should be using.
 In that case that is 840 grams. Proceed and do the same
 thing for all the other ingredients and you know
-your recipe. 
+your recipe.
 
-Let's say you would want to use 50 kilograms of flour 
+Let's say you would want to use 50 kilograms of flour
 the next day. What would you do? You would simply proceed
 and calculate the percentages one more time. I like this
 way of writing recipes a lot. Imagine you wanted to make
@@ -91,9 +91,331 @@ for 20 people. How would you calculate the amount of sauce
 you need? You go to the internet and check a recipe and then
 are completely lost when trying to scale it up.
 
-
 \section{The process of making a starter}
-\section{How flour is fermented}
+
+\begin{figure}[!htb]
+  \includegraphics[width=\textwidth]{sourdough-starter.jpg}
+  \caption{A very active sourdough starter shown by the bubbles in the dough}
+  \label{fig:sourdough-starter}
+\end{figure}
+
+Making a sourdough starter is very easy. All you need
+is a little bit of patience. The flour you should
+use to setup your starter is ideally a whole flour.
+You could use whole wheat, whole rye, whole spelt or
+any other flour you have. In fact gluten free flours such
+as rice or corn would also work.
+
+Your flour is contaminated with millions of microbes. As explained
+before in the chapter about wild yeast and bacteria, these
+microbes live on the surface of the plant. That's why
+a whole flour works better because you have more natural
+contamination of the microbes you are trying to cultivate
+in your starter. More of them live on the hull compared to the
+endophytes living in the grain.
+
+Simply weigh around 50 grams of flour and add another 50
+grams of water. It doesn't have to be exactly 50 grams of both
+water or flour. You could also be using less and/or simply eyeball
+it. The values are just shown as a reference. Don't use chlorinated
+water to setup your starter. It should be bottled water ideally,
+or here in Germany we can just use our tap water. The hydration
+of your dough is 100 percent. This means you have equal parts
+of flour and water. Stir everything together so that all the flour
+is properly hydrated. By adding water many of your microbe's
+spores become activated. They exit hibernation mode and
+become alive again. Cover your mixture with a lid. I like to
+use a glas and place another inverted one on top. The container shouldn't
+be airtight. You still want some gas exchange to be possible.
+
+\begin{figure}[!htb]
+  \includegraphics[width=\textwidth]{sourdough-starter-process.jpg}
+  \caption{The process of making a sourdough starter from scratch}
+  \label{fig:sourdough-starter-process}
+\end{figure}
+
+Now an epic battle starts to begin. In one study scientists
+have identified more than 150 different yeast species living
+on a single leaf of a plant \cite{yeasts+biocontrol+agent}.
+All of the different yeasts and bacteria are trying to get
+the upper hand in this battle. Other pathogens such as mold
+are also being activated as we added water. Only the strongest
+most adapt microorganisms will survive. By adding water to the
+flour the starches start to degrade. The seedling tries to
+sprout but it no longer can. Essential for this process is the
+amylase enzyme. The compact starch is broken down to more
+digestible sugars to fuel plant growth. Glucose is what the
+plant needs in order to grow. The microorganisms that survive
+this frenzy are adapt to consuming glucose. Luckily for us
+bakers the yeast and bacteria know very well how to metabolize
+glucose. This is what they have been fed in the wild by the plants.
+By forming patches on the leaf and protecting the plant from
+pathogens they received glucose in return for their services.
+Each of the microbes tries to defeat the other by consuming the
+food fastest, producing agents to inhibit food uptake or by producing
+bactericides and/or fungicides. This early stage of the starter
+is very interesting as more research could possibly reveal
+new fungicides or antibiotics. Depending on where your flour
+is from the starting microbes of your starter might be different
+than the ones from another starter. Some people have also reported
+how the microbes from your hand or air can influence your starter's
+microorganisms. This makes sense to a certain extent. Your
+hand's microbes might be good at fermenting your sweat, but
+probably not so good and metabolizing glucose. The contamination
+of your hands or air might play a minor role in the initial epic
+battle. But only the fittest microbes fitting the sourdough's
+niche are going to survive. This means the microorganisms that know
+how to convert maltose or glucose will have the upper hand. Or these
+microbes that ferment the waste of the other microbes. Ethanol created
+by the yeast is metabolized by the bacteria in your sourdough. That's
+why a sourdough has no alcohol. I can confirm the role of aerial
+contamination to a certain extent. When setting up a new sourdough
+starter the whole process is quite quick for me. After a few
+days my new starter seems to be quite alive already. This might
+be due to previous contamination of flour fermenting microbes in
+my kitchen.
+
+Wait for around 24 hours and observe what happens to your starter.
+You might see some early signs of fermentation already. Use your nose
+to smell the dough. Look for bubbles in the dough. Your dough
+might already have increased in size a little bit. Whatever
+you see and notice is a sign of the first battle. Some microbes
+have already been outperformed. Others have won the first battle.
+After around 24 hours most of the starch has been broken down
+and your microbes are hungry for additional sugars. With a spoon
+take around 10 grams from the previous day mixture and place
+it in a new container. Again - you could also simply eye ball
+all the quantities. It does not matter that much. Mix the 10
+grams from the previous day with another 50 grams of flour
+and 50 grams of water. Note the ratio of 1:5. I very often use
+1 part of old culture with 5 parts of flour and 5 parts of water.
+This is also very often the same ratio I use when making a dough.
+A dough is nothing else than a sourdough starter with slightly different
+properties. I'd always be using around 100-200 grams of starter
+for around 1000 grams of flour (baker's math: 10-20 percent).
+Homogenize your new mixture again with a spoon. Then cover
+the mix again with a glas or a lid. If you notice the top of
+your mixture dries out a lot consider using another cover. The
+dried out parts will be composted by more adapt microbes such as
+mold. In many user reports I saw mold being able to damage
+the starter when the starter itself dried out a lot. You will
+still have some mixture left from your first day. As this contains
+possibly dangerous pathogens that have been activated we will discard
+this mixture for now. Once your sourdough starter is mature never
+discard it. It's long fermented flour that is an excellent addon
+used to make crackers, pancakes and or delicious hearty sandwich
+breads. I also frequently dry it and use it as a rolling agent
+for pizzas that I am making.
+
+You should hopefully again see some bubbles, the starter increasing
+in size and/or the starter changing its smell. Some people give
+up after the second or third day. That is because the signs might no longer
+be as dominant as they were on day one. The reason for this lies in only a few
+select microbes starting to take over the whole sourdough starter. The most
+adapt ones are going to win. They are very small in quantity and will
+grow in population with each subsequent feeding. Even if you see no signs
+of activity directly, don't worry. There is activity in
+your starter on a microscopic level.
+
+24 hours later again we will repeat the same thing again until
+we see that our sourdough starter is active. More on that in the
+next section of this book.
+
 \section{Determining starter readiness}
+
+For some people the whole process of setting up a starter takes
+only 4 days. For others it can take 7 days, for some even 20 days.
+This depends on several factors including how good your wild microbes
+are fermenting flour. Generally speaking with each feeding
+your starter becomes more adapt to its environment. Your
+starter will become better at fermenting flour. That's why
+a very old and mature starter you receive from a friend might
+be stronger than your own starter initially. Over time
+your sourdough starter will catch up. Similarly modern baking
+yeast has been isolated like this from century old sourdough
+starters.
+
+\begin{figure}[!htb]
+  \includegraphics[width=\textwidth]{sourdough-starter-readiness.jpg}
+  \caption{A flowchart showing how to check if your sourdough starter is ready
+  to be used}
+  \label{fig:sourdough-starter-readiness}
+\end{figure}
+
+The key signs to look at are bubbles that you see in your starter
+jar. This is a sign that the yeast is metabolizing your
+dough and creates CO2. The CO2 is trapped in your dough
+matrix and then visualized on the edges of the container.
+Also note the size increase of your dough. The amount of size
+is irrelevant. Some bakers claim it doubles, triples or quadruples.
+The amount of size increase depends on your microbes, but also on
+the flour that you using to make the starter. A wheat flour contains
+more gluten and will thus result in a higher size increase. At
+the same time the microbes are probably not more active compared
+to when living in a rye sourdough. You could only argue that
+wheat microbes might be better at breaking down gluten compared
+to rye microbes. That's one of the reasons why I decided to change
+the flour of my sourdough starter quite often. I had hoped to create
+an all-round starter that can ferment all sorts different flour.\footnote
+{Whether this is actually working I can't scientifically say.
+Typically the microbes that have once taken place are very strong
+and won't allow other microbes to enter. My starter has initially
+been made with rye flour. So chances are that the majority of
+my microorganisms are from a rye source.} Your nose is also
+a great tool to determine starter readiness. Depending on
+your starter's microbiome you should notice either the smell
+of lactic acid or acetic acid. Lactic acid has dairy yogurty notes.
+The acetic acid has very strong pungent vinegary notes. Some
+describe the smell as glue or acetone. Combining the visual clues
+of size increase and pockets plus the smell is the best way
+to determine starter readiness.
+
+In rare events your flour might be treated and prevent microbe growth.
+This can happen if the flour is not organic and a lot of biochemical
+agents have been used by the farmer. In that case simply try again
+with different flour. 7 days is a good period of time to wait before
+trying again.
+
+Another methodology used by some bakers is the so called \emph{float test}.
+The idea is to take a piece of your sourdough starter and place it
+on top of some water. If the dough is full with gas it will float
+on top of the water. If it's not ready it can't float and will
+sink to the bottom of the glas. This test does not work with every flour.
+Rye flour for instance can't retain the gas as well as wheat flour
+and thus in some cases will not float. That's why I personally
+don't use this test and can't recommend it.
+
+Once you see your starter is ready I would recommend to give it
+one last feeding and then you are ready to make your dough in the
+evening or the next day. For the instructions to make your
+first dough please refer to the next chapters in this book.
+
+If your first bread failed chances are your fermentation hasn't
+worked as expected. In many cases the source is your sourdough starter. Maybe
+the balance of bacteria and yeast hasn't been optimal yet. In that case a good
+solution is to keep feeding your starter once per day. With each feeding your
+starter becomes better at fermenting flour. The microbes will adapt more and
+more to the environment. Please also consider reading the stiff sourdough starter
+chapter in this book. The stiff sourdough starter helps to boost the
+yeast part of your sourdough and balance the fermentation.
+
 \section{Maintenance}
-\section{Longterm starter storage}
+
+\begin{figure}[!htb]
+  \includegraphics[width=\textwidth]{sourdough-starter-maintenance-process.jpg}
+  \caption{A full flowchart showing how to conduct proper starter maintenance}
+  \label{fig:sourdough-maintenance-process}
+\end{figure}
+
+You have made your sourdough starter and your first bread. How do you perform
+maintenance for your starter? There are countless of different maintenance
+methods out there. Some people go completely crazy about their starter and
+perform daily feedings of the starter. The key to understanding how properly
+conduct maintenance is to understand what happens to your starter after you
+used it to make a dough. Whatever starter you have left, or a tiny piece of
+your bread dough can serve to make your next starter.\footnote{I very often use all my
+starter to make a dough. So if the recipe calls for 50g of starter I make
+exactly 50g starter in advance. This means I have no starter left. In that
+case I would proceed to take tiny bit of the dough at the end of the
+fermentation period. This piece I would use to regrow my starter again}
+
+
+As explained earlier your starter is adapt
+to fermenting flour. The microbes in your starter are very resilient. They
+block external pathogens and other microbes. That is the reason why when
+buying a sourdough starter you will preserve the original microbes. They are
+likely not going to change in your starter. They are outcompeting other
+microbes when it comes to fermenting flour. Normally everything in nature
+starts to decompose after a while. However the microbes of your starter have
+very strong defense mechanisms. In the end your sourdough starter can be
+compared to pickled food. Pickled food has been shown to stay good for a very
+long period of time \cite{pickled+foods+expiration}. The acidity of your sourdough starter is quite
+toxic to other microbes. The yeast and bacteria though have adapted to living
+in the high acid environment. Compare this to your stomache, the acidity
+neutralises many possible pathogens. As long as your starter has sufficient
+food available it will outcompete other microbes. When the starter runs out of
+food the microbes will start to sporulate. They prepare for a period of no
+food and will then reactivate the moment new food is present. The
+spores are very resilient and can survive under extreme conditions.
+Scientists have claimed they found 250 million year old spores still active
+spores \cite{old+spores}. While being spores
+they are howevever more vulnerable to external pathogens such as mold.
+Everything in nature is at some point decomposed and broken down by other
+microorganisms. Under ideal conditions though the spores can survive for a
+long time.
+
+But as long as they stey in the environment of your starter they live
+in a very protected protected environment. Other fungi and bacteria have a hard time decomposing your left over starter mass.
+I have seen only very few cases where the starter actually died. It is almost impossible
+to kill a starter.
+
+What happens though is that the balance of yeast and
+bacteria changes in your starter. The bacteria is more adapt to living
+in the acidic environment. This is a problem when you make another dough.
+You want to have the proper balance of fluffness and sour notes.
+When a starter has hibernated for a long period
+of time chances are that you do not have a desirable balance of microbes.
+Furthermore depending on the time your starter hibernated you might only have
+sporulated microbes left. So a couple of feedings will help to get your
+sourdough starter into the right shape again.
+
+The following are a couple of scenarios that help you to conduct proper
+starter maintenance, depending on when you want to bake the next time.
+
+\textbf{I would like to bake again the next day:}
+
+Simply take whatever starter you have left and feed it again. If you depleted
+all your starter you can cut a piece of your dough. The dough itself is
+nothing different than a gigantic starter. I recommend a 1:5:5 ratio like
+mentioned before. So take 1 piece of starter, feed with 5 parts of flour and 5
+parts of water. If it is very hot where you live, or if you want to make the
+bread around 24 hours later after your last feeding, change the ratio. In that
+case I would go for a 1:10:10 ratio. Sometimes I don't have enough starter.
+Then I even use a ratio of 1:50:50 or 1:100:100. Depending on how much new
+flour you feed it takes longer for your starter to be ready again.
+
+\textbf{I would like to take a break and bake next week:}
+
+Simply take your leftover starter and place it inside of your fridge. It will stay good
+for a very long period of time. The only thing I see happening is the surface
+drying out in the fridge. So I recommend to drown the starter in a little bit
+of water. This extra layer of water provides a good protection from the top
+part drying out. As mold is aerobic it can not grow efficiently grow under
+water \cite{mold+anaerobic}.
+
+The colder it is the longer you preserve a good balance of yeast and
+bacteria. Generally the warmer it is the faster the fermentation process is.
+The colder the slower the whole process becomes.
+Below 4°C the starter fermentation comes to a complete halt.
+
+\textbf{I would like to take a several months break:}
+
+Drying your starter might be the best option to preserve it in this case. As
+you remove humidity and food your microbes will sporulate. As there is no
+humidity the spores can resist other pathogens very well. A dried starter can
+be good for years.
+
+Simply take your starter and mix it with flour. Try to crumble the starter as
+much as possible. Add more flour continously until you notice that the is no
+moisture left. Place the flour starter at a dry place in your house. Let it
+dry even more. If you have a dehumidifier you can use this to speed up the
+process. Set it to around 30°C and dry the starter for 12-20 hours. The next
+day return your starter. It is in a vulnerable state as there is still a bit
+of humidity left. Add some more flour to speed up the drying process. Repeat
+for another 2 days until you feel that there is no humidity left. This is
+important or else it might start to mold. Once this is done simply store the
+starter in an airtight container. If you can proceed and freeze
+the dried starter. Both options work perfectly fine. Your sporulated starter
+is now waiting for your next feeding.
+
+Initially it would take 3 days or so for my starter to become alive again
+after drying and reactivating it. If I do the same thing now my starter is
+sometimes ready after a single feeding. It seems that the microbes adapt. The ones
+that survive this shock become dominant subsequently.
+
+So in conclusion the maintenance mode you choose depends on when you want to bake next.
+The goal of each new feeding is to make sure your starter
+has a desired balance of yeast and bacteria when making a dough. There is no need to provide your
+starter with daily feedings, unless it is not mature yet. In that case each
+subsequent feeding will help to to make your starter more adapt at fermenting
+flour.