Chapter: Bulk fermentation (#30)

This adds the chapter covering the bulk fermentation
process.

book/wheat-sourdough/wheat-sourdough.tex

@@ -66,7 +66,7 @@ that tastes much better than any store bought bread.
     \path [line] (proof) -- (bake);
   \end{tikzpicture}
   \caption{The typical process of making a wheat based sourdough bread}
-  \label{fig:wheat-sourdough-process}
+  \label{j:wheat-sourdough-process}
 \end{figure}
 
 The whole process of making great sourdough bread starts with
@@ -650,6 +650,7 @@ traps the gases during the fermentation process. \cite{how+does+gluten+work}.
   deteriorates over time as enzymes break down the flour. The effect
   is accelerated for sourdough due to the bacteria's gluten proteolysis.
   }
+  \label{fig:wheat-yeast-sourdough-degradation}
 \end{figure}
 % See https://www.figma.com/file/wTUVe6Nm2INOvT82mJhQur/Dough-strength-visualisation?node-id=0%3A1&t=fjdPvXYuJpsdQfWN-1 for
 % the source of this visualization
@@ -718,9 +719,279 @@ However, if the dough is mixed too much, the compounds that contribute
 to the bread's flavor, aroma, and color may be destroyed, negatively
 affecting the quality of the bread.\cite{oxidization+dough}
 
+\section{Bulk fermentation}
+
+After mixing the starter into your dough the next stage of
+the process known as bulk fermentation begins. The term
+bulk is used because in bakeries multiple loaves are fermented
+together in bulk. If you are a home baker you might bulk
+ferment a single loaf. The bulk fermentation ends when you
+divide and preshape, or directly shape your final loaves or loaf.
+
+The hardest part when making sourdough bread is controlling
+the fermentation process. Bulking long enough but not too
+long is the deciding factor for making great bread at home.
+Even with poor shaping and baking techniques, you'll be able
+to make excellent bread, solely by mastering the bulk
+fermentation process.
+
+With a too-short bulk, your crumb will be
+perceived as gummy. Your crumb will feature large pockets of
+air commonly referred to as "craters". A too-long fermentation
+results in the dough breaking down too much. The resulting
+dough will stick to your banneton and spread while baking
+into a pancake-like structure.
+
+The key is to find the sweet spot between not too little
+and not too much bulk fermentation. I'd always recommend pushing
+the dough more toward a longer fermentation. The
+flavor of the resulting bread is better compared to a pale
+underfermented dough. 
+
+\begin{table}[!htb]
+  \small
+  \begin{tabular}{|l|l|l|l|}
+  \hline
+  \textbf{}                                                        & \textbf{\begin{tabular}[c]{@{}l@{}}Too short\\ fermentation\end{tabular}}                                                   & \textbf{\begin{tabular}[c]{@{}l@{}}Too long\\ fermentation\end{tabular}}                                    & \textbf{\begin{tabular}[c]{@{}l@{}}Perfect\\ fermentation\end{tabular}}                                                                                    \\ \hline
+  \textbf{\begin{tabular}[c]{@{}l@{}}Crumb\\ texture\end{tabular}} & \begin{tabular}[c]{@{}l@{}}Unbaked gummy areas\\ towards the bottom of\\ the bread\end{tabular}                             & \begin{tabular}[c]{@{}l@{}}Crumb can be\\ perceived as\\ gummy, as most\\ gluten broken\\ down\end{tabular} & \begin{tabular}[c]{@{}l@{}}Crumb evenly baked.\\ Crumb can be perceived\\ as moist, but not\\ gummy\end{tabular}                                           \\ \hline
+  \textbf{Alveoli}                                                 & \begin{tabular}[c]{@{}l@{}}Overly large alveoli\\ in the crumb "craters"\end{tabular}                                       & \begin{tabular}[c]{@{}l@{}}Many tiny alveoli\\ equally distributed\end{tabular}                             & \begin{tabular}[c]{@{}l@{}}Alveoli evenly\\ distributed, no\\ "craters"\end{tabular}                                                                       \\ \hline
+  \textbf{Taste}                                                   & Pale neutral taste                                                                                                          & \begin{tabular}[c]{@{}l@{}}Strong acidic flavor\\ profile. Acidity\\ overweighs when\\ tasting\end{tabular} & \begin{tabular}[c]{@{}l@{}}Balanced flavor profile,\\ not too mild but also\\ not too sour. Depending\\ on starter vinegary\\ or lactic notes\end{tabular} \\ \hline
+  \textbf{Texture}                                                 & Overall poor Texture                                                                                                        & \begin{tabular}[c]{@{}l@{}}Good consistency,\\ crumb is not as fluffy\\ as it could be\end{tabular}         & \begin{tabular}[c]{@{}l@{}}Great combination of \\ textures\end{tabular}                                                                                   \\ \hline
+  \textbf{\begin{tabular}[c]{@{}l@{}}Oven\\ spring\end{tabular}}   & \begin{tabular}[c]{@{}l@{}}Vertical oven spring,\\ mostly due to water\\ evaporating and\\ inflating the dough\end{tabular} & \begin{tabular}[c]{@{}l@{}}Very flat pancake like \\ structure after baking\end{tabular}                    & \begin{tabular}[c]{@{}l@{}}Great vertical oven\\ spring. Dough grows\\ more upwards rather\\ than sideways\end{tabular}                                    \\ \hline
+  \end{tabular}
+  \caption{The different stages of sourdough fermentation and the effects on crumb, alveoli, texture, and overall taste.}
+\end{table}
+
+The worst thing you can do when fermenting sourdough 
+is to rely on a recipe's timing suggestions. In 99 percent
+of the cases, the timing will not work for you. The writer
+of the recipe probably has different flour and a different
+sourdough starter with different levels of activity. Furthermore,
+the temperature of the fermentation environment might be
+different. Just small changes in one parameter result
+in a completely different timing schedule. One or two hours
+difference results in the dough not fermenting long enough, or
+turning it into a gigantic sticky fermented pancake. This
+is one of the reasons why the current baking industry prefers
+to make solely yeast-based doughs. By removing the bacteria
+from the fermentation, the whole process becomes a lot more
+predictable. The room for error (as shown in figure \ref{fig:wheat-yeast-sourdough-degradation})
+is much larger. The doughs are perfect to be made in a
+machine.
+
+Experienced bakers will tell you to go by the look and feel of
+the dough. While this works if you have made hundreds of loaves,
+this is not an option for an inexperienced baker. As
+you make more and more dough you will be able to judge
+the dough's state by touching it. 
+
+My go-to method for beginners is to use an \textbf{Aliquot jar}.
+The aliquot is a sample that you extract from your dough. The
+sample is extracted after creating the initial dough strength.
+You monitor the aliquot's size increase to judge the
+level of fermentation of your main dough. The aliquot
+jar is extracted after creating dough strength. As your
+dough ferments, so does the content of your aliquot jar. The moment your
+sample reached a certain size your main dough is ready
+to be shaped and proofed. The size increase you should
+aim for depends on the flour you have at hand. A flour
+with a higher gluten content can be fermented for a
+longer period. Generally, around 80 percent
+of your wheat flour's protein is gluten. Check your flour's
+packaging to see the protein percentage. The actual size increase
+value is highly subjective depending on your flour composition.
+I recommend beginning with a size increase of 25 percent and testing
+up to 100 percent with subsequent bakes. Then identify a value
+that you are happy with.
+
+\begin{table}[!htb]
+  \begin{tabular}{|r|r|}
+  \hline
+  \multicolumn{1}{|l|}{\textbf{Flour protein content}} & \multicolumn{1}{l|}{\textbf{Relative aliquot size increase}} \\ \hline
+  8-10\%                                               & 25\%                                                         \\ \hline
+  10-12\%                                              & 50\%                                                         \\ \hline
+  12-15\%                                              & 100\%                                                        \\ \hline
+  \textgreater 15\%                                    & \textgreater 100\%                                           \\ \hline
+  \end{tabular}
+  \caption{Reference values for how much size increase to aim for with an aliquot jar depending on the dough's protein content}
+\end{table}
+
+The beauty of the aliquot is that no matter the surrounding
+temperature, you will always know when your dough is ready.
+While the dough might be ready in 8 hours in summer, it could
+easily be 12 hours in winter. You will always ferment your
+dough exactly on point.
+
+
+\begin{figure}[!htb]
+  \includegraphics[width=\textwidth]{aliquot-before-after}
+  \caption{An aliquot jar to monitor the dough's fermentation progress.
+  It took 10 hours for the dough to reach a 50 percent size increase.}
+\end{figure}
+
+While the aliquot jar has enabled me to consistently bake
+great loaves there are limitations to consider. It's crucial
+to use a cylindrical-shaped container to properly judge
+the dough's size increase. Furthermore, it is essential
+to use room-temperature water when making your dough. If the
+water is hotter, your aliquot due to its smaller size
+will cool down faster. The aliquot will ferment slower
+than your dough. Similarly, when you use too cold water,
+your sample will heat up faster than the large dough mass.
+In that case, your aliquot is ahead of your main dough. You
+would probably stop the fermentation too early. Make sure
+to keep the dough and aliquot close together. Some people even
+place the aliquot in the same container. This makes sure that
+both are in the same environment temperature. The aliquot
+is also less reliable if your ambient temperature changes
+a lot during the day. In that case, your aliquot will adapt
+faster than your main dough. The readings will always be slightly
+off. If you are making a large chunk of dough with more
+than 10kg of flour the jar is also less reliable. The biochemical
+reactions happening inside your dough will heat it.
+The fermentation itself is exothermic which means
+that it produces heat.
+
+Another but more expensive option is to use a pH meter
+to monitor your dough's fermentation state. As the lactic
+and acetic acid bacteria ferment, more acidity is piled
+up inside your dough. The acidity value (pH) can be
+measured using such a meter. The more acidity the lower the pH
+value of your dough. The pH scale is logarithmic meaning
+that each digit change will have a 10x increase in acidity.
+A sourdough dough might begin fermenting at a pH of 6,
+then shortly before baking has a pH of around 4. This means
+that the dough itself is 10x times 10x (= 100x) sourer
+than at the beginning. By using the meter you can always
+judge the state of your dough's acidification and then act
+accordingly.
+
+To use the pH meter successfully you need to find pH values
+that work for your dough. Depending on your starter,
+water, and flour composition the pH values to look out
+for are different. A stronger flour with more gluten
+can be fermented for a longer period. To find out
+the pH values for your bread I recommend taking
+several measurements while making your dough.
+
+\begin{enumerate}
+  \item Measure the pH value of your sourdough starter before using it
+  \item Check the pH after mixing all the ingredients
+  \item Check the pH before dividing and pre-shaping
+  \item Check the pH before shaping
+  \item Check the pH of your dough before and after proofing
+  \item Check the pH of your bread after baking
+\end{enumerate}
+
+If the bread you made turned out successful with your values
+you can use them as a reference for your next batch. If the
+bread didn't turn out the way you like, either shorten
+the fermentation or extend it a little bit.
+
+\begin{table}[!htb]
+  \begin{tabular}{|l|r|}
+  \hline
+  \textbf{Step}       & \multicolumn{1}{l|}{\textbf{pH Value}} \\ \hline
+  Starter ready       & 4.20                                   \\ \hline
+  Mixing              & 6.00                                   \\ \hline
+  Dividing/preshaping & 4.10                                   \\ \hline
+  Shaping             & 4.05                                   \\ \hline
+  Before proofing     & 4.03                                   \\ \hline
+  After proofing      & 3.80                                   \\ \hline
+  After baking        & 3.90                                   \\ \hline
+  \end{tabular}
+  \caption{Example pH values for the different breakpoints of my own sourdough process}
+  \label{table:sample-ph-values}
+\end{table}
+
+The beauty of this method is its reliability. Once you found
+out your good working values, you can reproduce
+the same level of fermentation with each subsequent dough.
+This is especially handy for large-scale bakeries that want
+to achieve consistency in each bread.
+
+While this method is very reliable there are also certain
+limitations to consider.
+
+First of all the pH values that work for me likely won't work for
+you. Depending on your own starter's composition of lactic 
+and acetic acid bacteria your pH values will be different.
+You can use the values shown in table \ref{table:sample-ph-values}
+as rough ballpark figures. Regardless you need to find values
+that work for your setup.
+
+Another limitation is the price. You will need to purchase
+a high-tech pH meter. Ideally, a meter featuring a spearhead.
+This way you can directly poke the meter deep into the dough.
+At the same time, automated temperature adjustments are a
+feature to look out for. Depending on the temperature
+the pH value varies. There are tables you can use to
+do the adjustment calculations. More expensive meters
+have this feature built-in. The pH meter loses accuracy
+over time. For this reason, you need to frequently
+calibrate this. The process is cumbersome and takes time.
+Lastly, you need to carefully rinse the pH meter before
+using it in your dough. The liquid surrounding the
+head of your pH meter is not food-safe and thus should
+not be eaten. I rinse the meter for at least one minute
+before using it to measure my dough's fermentation stage.
+
+The last method to judge the state of bulk fermentation
+is to read the signs of your dough. The more bread you are
+made the more accustomed you will become to this process.
+Look out for the dough's size increase. This can sometimes
+be a challenge when your dough is inside a container.
+You can help yourself by marking your container. Some bakers
+even use a transparent rectangular bulk container. You
+can use a pen to mark the initial starting point. From there
+on you can nicely observe the size increase. Similar to the
+mentioned aliquot jar look out for a size increase that works
+for your sourdough composition.
+
+\begin{figure}[!htb]
+  \includegraphics[width=\textwidth]{bulk-finished-dough}
+  \caption{A dough in a good state to finish bulk fermentation. Notice
+  the tiny bubbles on the dough's surface. They are a sign that the dough
+  is inflated well enough.}
+\end{figure}
+
+Look out for bubbles on the surface of your dough. They
+are a good sign that your dough is inflated with gas. The
+further you push the bulk fermentation the more bubbles
+will appear. If you overdo this stage the dough becomes leaky and
+the bubbles will disappear again.
+
+Take note of the dough's smell. It should match the same
+smell of a ripe starter shortly before collapsing. As mentioned
+before, your dough is nothing but a gigantic starter. You
+can also proceed and taste your dough. It will taste like
+pickled food. Depending on the acidity you can judge how
+far the dough is in the fermentation process. The final bread
+will taste less sour. That's because a lot of acid evaporates
+during baking.\footnote{More on this topic later.
+Just by baking longer and/or shorter, you can control
+the tang of your final baked bread. The longer
+you bake the less sour the final loaf. The shorter
+the more acidity is still inside the bread. The resulting
+loaf will be sourer.}
+
+When touching the dough it should feel tacky
+on your hands. The dough should also be less sticky
+compared to earlier stages. If the dough is overly
+sticky you have pushed the fermentation too far.
+
+If you pushed the bulk fermentation too far you won't be able
+to bake a free-standing loaf with the dough anymore. But don't
+worry. You can move your dough into a loaf pan, or use parts
+of the dough as the starter for your next dough. When using
+a loaf pan make sure it's properly greased. You might have
+to use a spatula to transfer your dough. Allow the dough
+to proof for at least 30 minutes in the loaf pan before
+baking it. This makes sure that large cavities induced
+by the transfer are evened out. You could push the proofing
+stage to 24 hours or even 72 hours. The resulting
+bread would feature an excellent very tangy taste.
 
-\section{Controlling fermentation}
-This chapter is still pending and will be added soon.
 
 \section{Stretch and folds}
 This chapter is still pending and will be added soon.