Chapter: Fixing mold sourdough starter

book/book.tex

@@ -18,7 +18,7 @@
     allcolors=black
 }
 
-\graphicspath{ {./images/}{./troubleshooting/crumb-structures/} }
+\graphicspath{ {./images/}{./troubleshooting/crumb-structures/}{./images/external/} }
 
 
 \title{%

book/references.bib

@@ -50,4 +50,28 @@
   note         = {Accessed: 2022-04-29}
 }
 
+@article{baking+powder+reduce-acidity,
+  title        = {Use baking powder to reduce dough acidity},
+  author       = {Hendrik Kleinwächter},
+  howpublished = {\url{https://www.youtube.com/watch?v=c8GId0ByASo}},
+  year         = {2020},
+  note         = {Accessed: 2022-04-29}
+}
+
+@article{food-safe-ph,
+  title        = {Acidified Foods: Food Safety Considerations for Food Processors},
+  author       = {Felix H. Barron and Angela M. Fraser},
+  howpublished = {\url{https://www.intechopen.com/chapters/41654}},
+  year         = {2012},
+  note         = {Accessed: 2022-04-29}
+}
+
+@article{mold+lactic+acid+bacteria,
+  author    = {Ce Shi, Maryam Maktabdar},
+  title     = {Lactic Acid Bacteria as Biopreservation
+               Against Spoilage Molds in Dairy Products
+               - A Review},
+  journal   = {Front Microbiol.},
+  year      = {2022}
+}
 

book/troubleshooting/misc.tex

@@ -216,8 +216,77 @@ starter. The stiff starter by far created the most CO2
 compared to the other starters. The balloons were inflated
 the most. \cite{stiff+starter}
 
+Another non conventional approach could be to add baking
+powder to your dough. The baking powder neutralizes the
+lactic acid and will make a much milder dough.\cite{baking+powder+reduce-acidity}
 
 \section{Fixing a moldy sourdough starter}
+
+First of all - making a moldy sourdough starter is very difficult.
+It's an indicator that something might be completely off in your starter.
+Normally the symbiosis of yeast and bacteria does not allow external
+pathogens such as mold to enter your sourdough starter.
+The low pH created by the bacteria is a very hostile environment
+that no other pathogens like. Generally everything below a pH
+of 4.2 can be considered food safe\cite{food-safe-ph}. This
+is the concept of pickled foods. And your sourdough bread
+is essentially pickled bread.
+
+I have seen this happening especially when the sourdough
+starter is relatively young. Each flour naturally contains
+mold spores. When beginning a sourdough starter all
+the microorganisms start to compete by metabolizing the
+flour. Mold can sometimes win the race and out compete
+the natural wild yeast and bacteria. In that case simply
+try cultivating your sourdough starter again. If it molds
+again it might be a very moldy batch of flour. Try a different
+flour to begin your sourdough starter with.
+
+Mature sourdough starters should not mold unless the conditions
+of the starter change. I have seen mold appearing when the starter is stored
+in the fridge and the surface dried out. Also sometimes on the
+edges of your starter's container. Typically in areas where no active
+starter microorganisms can reach. Simply try to extract an
+area of your starter that has no mold. Feed it again with flour and
+water. After a few feedings your starter should be back to normal.
+Take only a tiny bit of starter. 1-2 grams are enough. They already
+contain millions of microorganisms.
+
+Mold favors aerobic conditions. This means that air is required in order
+for the mold fungus to grow. Another technique that has worked for me
+was to convert my sourdough starter into a liquid starter. This successfully
+shifted my starter from acetic acid production to lactic acid production.
+Acetic acid similarly to mold requires oxygen to be produced. After
+submerging the flour with water over the time the lactic acid bacteria
+out competed the acetic acid bacteria. This is a similar concept to pickled
+foods. By doing this you are essentially killing all alive mold fungi. You
+might only have some spores left. With each feeding the spores will become
+less and less. Furthermore it seems that lactic acid bacteria produce
+metabolites that inhibit mold growth. \cite{mold+lactic+acid+bacteria}
+
+\begin{figure}[!htb]
+  \includegraphics[width=\textwidth]{fungi-lactic-acid-interactions}
+  \caption{The interaction of lactic acid bacteria and mold fungi.
+           The authors Ce Shi et al. show how bacteria are producing
+           metabolites that inhibit fungus growth. \cite{mold+lactic+acid+bacteria}}
+  \label{fig:fungi-lactic-acid-interactions}
+\end{figure}
+
+To pickle your starter simply take a bit of your existing starter (5 grams for
+instance). Then feed the mixture with 20g of flour and 100g of water. You have
+created a starter a hydration of around 500 percent. Shake the mixture vigorously.
+After a few hours you should start seeing most of the flower near the bottom
+of your container. After a while most of the oxygen from the bottom mixture
+is depleted and anaerobic lactic acid bacteria will start to thrive. Take a
+note of the smell your sourdough starter. If it was previously acetic
+it will now change to be a lot more dairy. Extract a bit of your mixture the
+next day by shaking everything first. Take 5g of the previous mixture, feed
+again with another 20g of flour and another 100g of water. After 2-3
+additional feedings your starter should have adapted. When switching back
+to a hydration of 100 percent the mold should have been eliminated. Please note that
+more tests should be conducted on this topic. It would be nice to really
+carefully analyze the microorganisms before the pickling and after.
+
 \section{My bread flattens out after shaping}
 \section{Liquid on top of my starter}
 \section{Why does my starter smell like acetone}