Enzymes chapter (#5)

* Enzymes chapter

This adds detailed information on different enzymes that are contained
in your flour. A detailed focus on amylase and protease is provided.

* Add infographic on enzymes

* Add status overview

README.md

@@ -27,8 +27,21 @@ budget constrains.
 
 ## Status
 
-The book is still work in progress. History, introducing
-and troubleshooting sections have been finished so far.
+The book is a work in progress. This represents the current status:
+
+* ✅ Intro
+* ✅ Enzymes
+* ❌ Microorganisms
+* ❌ Making a starter
+* ❌ Sourdough starter types
+* ❌ Flour types
+* ❌ Bread types
+* ❌ Wheat sourdough
+* ❌ Non wheat sourdough
+* ❌ Baking
+* ❌ Storing bread
+* ✅ Troubleshooting
+
 
 ## Compiled book
 

book/basics/how-sourdough-works.tex

@@ -0,0 +1,199 @@
+In this chapter we are looking at the basics of how sourdough ferments.
+For that we will first look at enzymatic reactions
+that happen in your flour. These reactions are induced
+the moment you add water to your flour. They are also
+the basis that trigger the fermentation process. To understand
+the fermentation process we are having a closer look at the involved
+yeast and bacterial microorganisms.
+
+\begin{figure}[!htb]
+  \includegraphics[width=\textwidth]{infographic-enzymes}
+  \caption{How amylases and proteases interact with flour}
+  \label{infographic-enzymes}
+\end{figure}
+
+\section{Enzymatic reactions}
+
+When mixing flour and water several enzymatic reactions
+start. A plant produces seeds to reproduce. The seed
+contains all the nutrients a new plant needs to sprout.
+While the seed is dry the seed is in hibernation mode. It
+can be sometimes be stored for several years. The moment water is added
+to the seed the sprouting process starts. The seed turns
+into a germ. The stored nutrients have to be converted
+into something that the germ can use. The catalyst for these
+reactions is water. The first roots can be produced with the stored nutrients.
+Furthermore the seed typically contains the first leaves
+of the plant. The first leaves are built to start the photosynthesis
+process. This is the plants' engine. With energy from photosynthesis
+the plant can keep growing more roots. This way more water
+and nutrients can be accessed from the soil. The extended 
+nutrients allow the plant to form more leaves and thus
+increase the photosynthetic activity.
+
+Of course a ground flour can no longer sprout. But the enzymes
+that trigger this process are still present. That's why it's
+important to not mill the grains at a too high temperature.
+This could possibly damage some of the enzymes. Normally
+the seed of the flour shields the germ against pathogens initially.
+However as we grind the flour the contents of the seed
+are exposed. This is ideal for our sourdough microorganisms.
+The yeast can be considered a saprotrophic fungus.
+They can't prepare their own food. As the enzymes start
+to be activated more and more food becomes available
+for the yeast and bacteria.
+
+The two main enzymes for bread making are amylase and protease.
+Understanding their role is a key puzzle piece to be able
+to make better tasting bread at home.
+
+\subsection{Amylase}
+
+Sometimes when you chew on a potato or a piece of bread
+for a prolonged period of time you will notice a bit of sweetness
+arising in your mouth. That's because your salivary glands
+are also producing amylase. Amylase breaks down complex
+starch molecules into easier digestible sugars. The germ
+needs this in order to be able to produce more plant matter.
+Your body needs this in order to start the digesting process.
+Normally your microorganisms can't consume the freed maltose molecules
+as they are hidden in the germ. But as we ground the flour
+a feeding frenzy starts. Generally the warmer the temperature
+the faster this reaction happens. That's why a long fermentation
+is a key factor to make great bread. It takes time
+for your amylase to break down most of the starch. Furthermore
+not all sugars are consumed by the yeast. Some remain and
+are responsible for enhanced browning during the baking
+process.
+
+If you are a hobby brewer you will know that it's
+important to keep your brew on certain temperatures for a
+while to allow the different amylases to convert starches
+into sugar \cite{beer+amylase}. There's a test frequently used by brewers
+to determine that all the starches have been converted.
+It's called the Iodine starch test. You take a bit of your brew
+and then add a bit of iodine. If the color is blue/black
+you know that you still have starches left that haven't been
+converted by amylases yet. I wonder if such a test would work
+for a bread dough as well? Now industrial bakeries
+that use yeast to make speed doughs in a short period of
+time face this issue. Their approach is to add malted
+flour to the dough mix. The malted flour contains a lot
+of enzymes and will thus help to have a faster fermentation
+period. Check the packaging of the breads that you bought,
+if you find {\it malt} in the list of ingredients chances
+are that this strategy has been used. There are two categories
+of malts. You have enzymatically active malt and inactive
+malt. The active malt hasn't been heated to above 70°C
+when the amylases start to degrade under heat. The inactive
+malt has been heated to higher temperatures and thus
+has no impact on your flour.
+
+\subsection{Protease}
+
+The second very important enzyme is the protease. Proteases
+break down proteins into smaller proteins or amino acids.
+Gluten for instance is a storage protein built by wheat.
+The gluten is broken down and converted the moment the
+seed starts to sprout. That's because the seed needs
+smaller amino acids to build the roots and other plant material.
+If you ever try to make a wheat based dough and just keep
+it for several days at room temperature you will notice
+how your gluten network starts to break down. The dough
+no longer holds together. You can just fully tear it apart.
+I have had this happen to me when I was trying to make
+doughs directly with dried sourdough starter. The fermentation
+speed was so low that it took 3-4 days for the dough
+to be ready. The root cause for this issue is the protease.
+By adding water to the dough the protease was activated
+and started to ready amino acids for the germ in order to be
+able to sprout. Another interesting experiment that viusalises
+the importance of protease is the following. Try to make a
+fast dough within 1-2 hours. Simply use a large quantity
+of dry yeast. Your dough will be leavened and increase in size.
+Bake your dough and notice the crumb of your baked dough.
+You will notice that the crumb is quite dense and not as
+fluffy as it could be. That's because the protease enzyme
+didn't have enough time to do its job. At the start
+when kneading your dough is very elastic. It holds together
+very well. Over the course of the fermentation process
+your dough will become more extensible \cite{protease+enzyme+bread}.
+Some of the gluten bonds start to naturally break
+down due to the protease proteolysis. This makes it easier
+for your dough to be inflated. That's why a long
+fermentation process is important when you want to
+achieve very fluffy and open crumbs with your sourdough
+bread. Next to using great ingredients, the long and
+slow fermentation is one of the main reasons why
+Neapolitan pizza tastes so great. The soft and fluffy
+edge of the pizza is achieved because of the protease
+creating a very extensible easy to inflate dough. Because
+the fermentation process is typically longer than 8
+hours a flour with a higher gluten content is used. There
+is more gluten that can be broken down by the protease.
+By using a weaker flour you might end up with a dough
+that's already broken down too much and will then tear
+when trying to make a pizza pie. Traditionally the pizza
+has probably been made with sourdough. In modern times
+it is made with yeast as handling a yeast based
+dough can be done easier on a larger scale. The dough
+stays good for a longer period of time. If you were to use
+sourdough you might have a window of 30-90 minutes when
+your dough is perfect. Afterwards the dough might
+start to deteriorate because of bacteria breaking
+down the gluten network too much.
+
+\subsection{Improving enzymatic activity}
+
+As explained previously malt is a common trick used
+to speed up enzymatic activity. I personally prefer
+to avoid malt in most of my recipes. Instead I use
+a trick I observed when making whole wheat doughs.
+No matter what I tried I could never achieve baking
+a whole wheat bread with the desired crust and crumb
+texture I was looking for. My doughs would tend to
+overferment relatively quickly. When using a flower
+with a similar amount of gluten that didn't contain
+bran and other outer parts of the grain my doughs turned
+out great. I was utilizing an extended autolyse.
+That's a fancy word for just mixing flour and water in
+advance and letting that mixture sit. Most recipes
+call for it as the help to make a dough that has already
+started to break down by enzymes. In general it's a great
+idea but at the same time you can just reduce the amount
+of leavening agent you use. This way the same biochemical
+reactions happen and you don't have to mix your dough
+several times. My whole wheat game drastically improved
+when I stopped using the autolysis. It makes sense if I
+think about it now. The first parts of the seed that
+are in contact with water are the outer parts. Water
+will slowly enter the center parts of the grain. The
+moment the seed starts to sprout it needs to outcompete
+other nearby seeds. Furthermore it also directly becomes
+exposed to other animals and potential hazardous bacteria
+and fungi. To accelerate this process most of the enzymes
+of the grain are in the outer parts of the hull. They
+are being activated first (source needed). So by just
+adding a little bit of whole flour to your dough you 
+will improve enzymatic activity of your dough. That's
+why most of my plain flour doughs typically contain
+at least 10-20 percent whole wheat flour.
+
+\begin{figure}
+  \includegraphics[width=\textwidth]{whole-wheat-crumb}
+  \caption{A whole wheat sourdough bread}
+  \label{whole-wheat-crumb}
+\end{figure}
+
+
+By understanding the 2 key enzymes amylase and protease
+you will better be able to understand how to make a
+dough to your liking. Would you like a dough a softer
+or stiffer crumb? Would you like to achieve a darker crust?
+Would you like to reduce the amount of gluten in your
+final bread? These are all factors you can influence
+by adjusting the speed of fermentation.
+
+
+\section{Yeast}
+\section{Bacteria}

book/book.tex

@@ -65,10 +65,7 @@
 \input{history/sourdough-history}
 
 \chapter{How sourdough works}
-\section{Enzymatic reactions}
-\section{Yeast}
-\section{Lactic acid bacteria}
-\section{Acetic acid bacteria}
+\input{basics/how-sourdough-works}
 
 \chapter{Making a sourdough starter}
 \section{Baker's math}

book/history/sourdough-history.tex

@@ -112,7 +112,7 @@ soft and fluffy when tasting it. Similar to drinking
 raw cow milk your immune system might react to
 the consumed proteins. There is gluten intolerance
 and celiac disease. When people say they don't handle
-gluten will it's mostly a gluten intolerance they describe.
+gluten well it's mostly a gluten intolerance they describe.
 Some people describe similar issues when consuming
 too much lactose. If you eat a long-fermented cheese
 however most of the lactose has been fermented by

book/references.bib

@@ -120,4 +120,19 @@
   year      = {2021},
   howpublished = {\url{https://www.youtube.com/watch?v=vfDIfkqBCuk}},
   note         = {Accessed: 2022-05-06}
+}
+
+@article{beer+amylase,
+  author    = {Jim Busch},
+  volume    = {5,5},
+  title     = {The Starch-Busting Amylases},
+  note      = {Accessed: 2022-05-06},
+  journal   = {Brewing Techniques}
+}
+
+@article{protease+enzyme+bread,
+  author    = {Emily Jane Buehler},
+  title     = {Bread science : the chemistry and craft of making bread},
+  year      = {2006},
+  page      = {254}
 }