Add flour types chapter (#14)

Adds an overview of different flour types

README.md

@@ -34,7 +34,7 @@ The book is a work in progress. This represents the current status:
 * ✅ Microorganisms
 * ✅ Making a starter
 * ✅ Sourdough starter types
-* ❌ Flour types
+* ✅ Flour types
 * ❌ Bread types
 * ❌ Wheat sourdough
 * ❌ Non wheat sourdough

book/book.tex

@@ -71,10 +71,7 @@
 \input{sourdough-starter/sourdough-starter-types}
 
 \chapter{Flour types}
-\section{Wheat like}
+\input{flour-types/flour-types}
-\section{Non gluten binding}
-\section{Gluten free}
-\section{Blending flours}
 
 \chapter{Bread types}
 \section{Wheat bread basics}

book/flour-types/flour-types.tex

@@ -0,0 +1,128 @@
+In this chapter we will have a closer look at different flour types
+and their respective categorization. We will also look a common
+ways to distinguish different flours of the same type. This way you can more confidently
+shop the right flour that you need.
+
+The most basic flour type is a whole flour. In this case the whole seed has
+been ground to smaller pieces. Sometimes depending on what you want to bake
+the hearty taste of the bran might not be desired. In this case you can use
+whiter flours. With sieves mills remove larger parts of the hull of the seed.
+The seed already contains a pre built germ from the plant waiting to be
+activated. The whitest flour you can get is mostly just the starch part of the seed.
+Depending on which layers are still present names are used to describe the
+type of flour.
+
+\begin{table}[htp!]
+\centering
+\resizebox{\textwidth}{!}{%
+\begin{tabular}{|l|l|r|r|r|}
+\hline
+\textbf{Type USA} & \textbf{Type UK} & \multicolumn{1}{l|}{\textbf{Type Germany}} & \multicolumn{1}{l|}{\textbf{Type France}} & \multicolumn{1}{l|}{\textbf{Type Italy}} \\ \hline
+Cake              & Soft flour       & T405                                       & T45                                       & 00                                       \\ \hline
+All purpose       & Plain flour      & T550                                       & T55                                       & 0                                        \\ \hline
+                  &                  & T812                                       & T80                                       & 1                                        \\ \hline
+                  &                  & T1050                                      & T110                                      & 2                                        \\ \hline
+Whole             & Whole            & Vollkorn                                   & T150                                      & Integrale                                \\ \hline
+\end{tabular}%
+}
+\caption{\label{tab:flour-types-comparison}A comparison of the different flour types}
+\end{table}
+
+In Germany the ash content is used to describe the flours. The lab will burn
+100 grams of flour in the oven. Then afterwards the remaining ash is extracted
+and measured. Depending on the quantity the flour is categorized. If the flour
+is of type 405 then 405 milligrams of ash have remained after burning the
+flour. The more hull parts the flour has the more minerals remain. So the the
+higher the number the closer the flour is to whole flour. The numbers are
+slightly different between each grain type. Generally though the higher the
+value, the heartier the taste is going to be.
+
+\begin{figure}[!htb]
+  \includegraphics[width=\textwidth]{wheat-kernel-overview}
+  \caption{An overview of a wheat kernel together with its content}
+  \label{fig:wheat-kernel-overview}
+\end{figure}
+
+Several recipes call for wheat bread flour. Bread flour can refer to different types
+of flour. It could be a T405 or a T550 in Germany. This is very often
+wrongfully classified. The term  \textit{strong or bread} flour in this case
+refers to the properties of the flour. A bread flour is considered to have a
+higher number of protein and thus gluten. This flour is excellent when you
+want to make a sourdough bread as your dough allows for a longer leavening
+period. As described earlier the gluten is consumed by your microorganisms.
+The more gluten you have the longer your dough keeps its integrity. If you wanted
+to make a cake you might want to use a flour with less gluten. The gluten binding
+properties might not be desirable. The final cake could have a chewy texture.
+
+In conclusion not every T405, T45 or T00 flour is the same. Depending on the properties
+of plant they have different properties. For that reason some countries like
+Germany have introduced additional scales to evaluate the quality of the
+wheat. The category \textbf{A} refers to good quality wheat that can be blended
+with poorer qualities to improve the flour. The category \textbf{B} refers to
+average wheat that can be used to create different baked goods. Category \textbf{C}
+is used for wheat that has poor baking qualities. This could happen for instance
+if the wheat already started to sprout and thus lost some of its desirable
+baking properties. This type of wheat is typically used as animal feed or
+as fermentable biomass for generators. Category \textbf{E} refers to \textit{Elite} wheat. It's
+the highest quality of wheat. This kind of wheat can be harvested when the
+wheat has grown under optimal conditions. You can compare this to a winery
+that uses only the best grapes to make a reserve wine. Unfortunately this is normally never printed
+on the packaging of the flour that you buy. You can look out for the protein
+value as a possible indicator. However large mills blend together flours to
+maintain quality throughout the years. Blended flour is also not listed on
+the packaging. It might be that bakeries extract gluten from some flour and
+then mix it in order to create better baking flours.
+
+In italy the so called
+\textbf{W-value} has been introduced to show better how the flour will behave.
+A dough is made and then the resistance of this dough to kneading is measured.
+The more gluten a flour has the more elastic the dough is and the more it will
+resist to kneading. A higher W flour will have a higher gluten content and allow for a longer
+fermentation period. But at the same time it is also harder for the microbes to
+inflate the dough as there is more balloon material. To make an excellent fermented
+product out of a high W flour you will need to have a long fermentation period.
+The long fermentation period also means that your microbes will enrich
+your dough with more flavor.
+
+\begin{table}[]
+  \centering
+  \resizebox{\textwidth}{!}{%
+  \begin{tabular}{|l|r|l|r|}
+  \hline
+  \textbf{W-Value} & \multicolumn{1}{l|}{\textbf{Hydration in \%}} & \textbf{Uses}       & \multicolumn{1}{l|}{\textbf{Fermentation times}} \\ \hline
+  0-150            & 50                                            & Cookies             & Very short                                       \\ \hline
+  150-250          & 50-60                                         & Cakes, Bread, Pizza & Short-Medium                                     \\ \hline
+  250-350          & 60-70                                         & Bread, Pizza        & Long                                             \\ \hline
+  350+             & 70-90                                         & Bread, Pizza        & Very long                                        \\ \hline
+  \end{tabular}%
+  }
+  \caption{\label{tab:w-value}An overview of different levels of W values and the respective hydrations and fermentation times}
+\end{table}
+
+
+Generally when aiming to
+bake free standing sourdough bread aim for a higher protein content. If the
+gluten value is relatively low your bread will collapse faster. Baking bread
+is still possible, but it might be easier to use tools such as a loaf pan, or
+to make pan bread.
+
+An additional rarely considered characteristic of good flour is the level of damaging of the
+starch molecules. This is a common problem when you are trying to mill your own wheat flours at
+home. Chances are that your home mill is not able to achieve the same results
+a larger mill can. The damaging of the starches is essential to improve the
+properties of the dough. You will have a better gelatinization and water
+absorption with properly damaged starch \cite{starch+damage+flour}. As more
+starch is damaged the surface area increases. This improves how water connects with the flour.
+This also provides a larger surface that your microbes can use to attack the molecules 
+and start the fermentation process.
+
+I am still
+yet to find a good way of milling my own flour at home. Even after trying to
+mill the flour 10 times with short breaks I was not able to achieve the same
+properties as with commercially milled flour. The doughs I would make felt
+good, maybe a bit coarse. Then during baking however the doughs would start to
+degas quickly and turn into very flat breads. I have had great success though when
+utilizing home milled flour together with a loaf pan or as a pan bread. If you
+have found great ways to work with home milled flour please reach out. The potential
+of using home milled flours is huge. It would enable even distant communities
+to grow their own wheat and be able to produce amazing freshly baked bread.

book/references.bib

@@ -266,3 +266,11 @@
   journal      = {Applied Microbiology and Biotechnology},
   volume       = {82,4673-4681}
 }
+
+@article{starch+damage+flour,
+  title        = {A review of milling damaged starch: Generation, measurement, functionality and its effect on starch-based food systems},
+  author       = {Qingfa Wang et al.},
+  year         = {2020},
+  journal      = {Food chemistry},
+  volume       = {15,31}
+}