diff --git a/book/basics/how-sourdough-works.tex b/book/basics/how-sourdough-works.tex index 966da64..bd7085b 100644 --- a/book/basics/how-sourdough-works.tex +++ b/book/basics/how-sourdough-works.tex @@ -41,10 +41,12 @@ activity so that it can thrive in its new environment. 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 not to mill grains at too high a temperature, as doing so could damage some of -these enzymes\footnote{In a recent study tests have shown that milling flour +these enzymes\footnote{In a recent +study~\cite{milling+commercial+home+mill+comparison} tests have shown that +milling flour at home with a small mill had no significant negative impact on the resulting bread quality compared to milled flour from temperature-regulated large-scale -mills~\cite{milling+commercial+home+mill+comparison}.}. +mills.}. Normally, the grain seed shields the germ against pathogens. However, as the grain is ground into flour, the contents of the seed are exposed. This is ideal @@ -83,15 +85,14 @@ certain temperatures to allow the different amylases to convert the contained starches into sugar~\cite{beer+amylase}. This process is so important that there's a frequently used test to determine whether or not all the starches have been converted. - This test, called the \emph{Iodine Starch Test}, involves mixing iodine into a sample of your brew and checking the color. If it's blue or black, you know you still have unconverted starches. I~wonder if such a test would also work for bread dough? -Industrial bakers that add especially active yeast to produce bread in a short +Industrial bakers who add especially active yeast to produce bread in a short period of time face a similar issue. Their approach is to add malted flour to -the dough. The malted flour contains many enzymes and thus speeds up the +the dough, this malted flour contains many enzymes and thus speeds up the fermentation process. The next time you're at the supermarket, check the packaging of the bread you buy. If you find \emph{malt} in the list of ingredients, chances are this strategy was used. @@ -115,14 +116,13 @@ the same process occurs in bread dough. If you've ever tried to make a wheat-based dough and kept it at room temperature for several days, you'll have discovered for yourself that the -gluten network breaks down so that the dough can no longer hold together. Once +gluten network breaks down to the point that the dough can no longer hold together. Once this happens, the dough easily tears, holds no structure, and is no longer suitable for baking bread. This happened to me once when I~tried to make sourdough directly from a dried starter. At three to four days, the fermentation speed was so slow that the gluten network broke down. The root cause for this issue was protease. - By adding water to your dough, you activate the protease, and this gets to work in readying amino acids for the germ. @@ -144,7 +144,7 @@ achieve a fluffy, open crumb with your sourdough bread. Aside from using great ingredients, the slow fermentation process is one of the main reasons Neapolitan pizza tastes so great: because the protease creates an -extensible, easy-to-inflate dough, a soft and airy edge is achieved. +extensible and easy-to-inflate dough a soft and airy edge is achieved. Because the fermentation process typically takes longer than 8~hours, a flour with a higher gluten content should be used. This gives the dough more @@ -154,10 +154,10 @@ that's broken down so much that it tears during stretching, making it impossible, for example, to shape it into a pizza pie. Traditionally, pizza has been made with sourdough, but in modern times it is -made with active dry yeast, as the dough stays good for a longer period of time -and is much easier to handle on a commercial scale. If you were to use +made with active dry yeast. As the dough stays good for a longer period of time +it is much easier to handle on a commercial scale. If you were to use sourdough, you might have a window of thirty to ninety minutes before the dough -begins to deteriorate, both because of the protease acting for a longer period +begins to deteriorate, due to both the protease acting for a longer period of time and the byproducts of bacteria, which we'll discuss in more detail later in this chapter. @@ -176,10 +176,10 @@ At the time, I~utilized an extended autolyse, which is just a fancy word for mixing flour and water in advance and then letting the mixture sit. Most recipes call for it as the process gives the dough an enzymatic head start, and in general it's a great idea. However, as an equally effective alternative, -you could simply reduce the amount of leavening agent used (in the case of -sourdough, this would be your starter). This would allow the same biochemical +you could simply reduce the amount of leavening agent used --- in the case of +sourdough, this would be your starter. This would allow the same biochemical reactions to occur at roughly the same rate without requiring you to mix your -dough several times. My whole wheat game improved dramatically after I~stopped +dough several times. My whole-wheat game improved dramatically after I~stopped autolysing my doughs. Now that I've had time to think about it, the result I~observed makes sense. @@ -201,7 +201,6 @@ doughs, I~usually add 10\textendash20\% whole-wheat flour. \label{whole-wheat-crumb} \end{figure} - By understanding the two key enzymes \emph{amylase} and \emph{protease}, you will be better equipped to make bread to your liking. Do you prefer a softer or stiffer crumb? Do you desire a lighter or darker crust? Do you wish to reduce @@ -212,14 +211,16 @@ tweak just by adjusting the speed of your dough's fermentation. Yeasts are single-celled microorganisms belonging to the fungi kingdom, and spores that are hundreds of millions of years old have been identified by -scientists. There are a wide variety of species --- so far, about \num{1500} have been -identified. Unlike other members of the fungi kingdom such as mold, yeasts do -not ordinarily create a mycelium network~\cite{molecular+mechanisms+yeast}.\footnote{For -one interesting exception, skip ahead to the end of this section.} +scientists. There are a wide variety of species --- so far, about \num{1500} +have been identified. Unlike other members of the fungi kingdom such as mold, +yeasts do not ordinarily create a mycelium +network~\cite{molecular+mechanisms+yeast}.\footnote{For one interesting +exception, skip ahead to the end of this section on +page~\pageref{aggressive-yeast}.} \begin{figure}[!htb] \begin{center} - \includegraphics[width=1.0\textwidth]{saccharomyces-cerevisiae-microscope} + \includegraphics[width=0.8\textwidth]{saccharomyces-cerevisiae-microscope} \caption[Brewer's yeast]{Saccharomyces cerevisiae: Brewer's yeast under the microscope.}% \label{saccharomyces-cerevisiae-microscope} @@ -228,11 +229,10 @@ one interesting exception, skip ahead to the end of this section.} Yeasts are saprotrophic fungi. This means that they do not produce their own food, but instead rely on external sources that they can decompose and break -down into compounds that are more easily metabolized. - -Yeast breaks down carbohydrates into carbon dioxide and alcohol in what we today -refer to as the fermentation process. This process has been known for thousands -of years and has been used since ancient times for the making of bread as well +down into compounds that are more easily metabolized. What we today +refer to as the fermentation process, is the yeast breaking down carbohydrates +into carbon dioxide and alcohol. This process has been known for thousands +of years, and has been used since ancient times for the making of bread as well as alcoholic beverages. Yeast can grow and multiply under both aerobic and anaerobic conditions. When @@ -250,7 +250,7 @@ cooler place and cultivate a sourdough starter from a nordic rye variety, chances are your yeast will prefer a colder environment. As an example, beer makers discovered a beneficial yeast living in the cold -caves around the city of Pilsen, Czech Republic. This yeast has since become +caves around the city of Pilsen, Czech~Republic. This yeast has since become known for producing excellent beers at lower temperatures and varieties of these strains are now used for brewing popular lagers. @@ -266,7 +266,7 @@ breaking down those cell walls so they can infect the plant. Some fungi and bacteria live inside plants without causing them any distress. These are known as \emph{endophytes}. Not only do they \emph{not} damage their -host, they actually live in a symbiotic relationship, helping the plants in +host, they actually live in a symbiotic relationship. They help the plants in which they dwell to protect themselves from other pathogens that might also come to infect them through their leaves. In addition to this protection, they also help with water and heat stress, as well as the availability of nutrients. @@ -319,6 +319,7 @@ inoculated with some of the 150 different wild yeast strains isolated from the leaves. They found that when the wound was inoculated with yeast, the grape sustained no significant damage~\cite{yeasts+biocontrol+agent}. +\phantomsection \label{aggressive-yeast}% Intriguingly, there was also an experiment performed that showed how brewer's yeast could function as an aggressive pathogen to grapevines. Initially, the yeast lived in symbiosis with the plants, but after the vines sustained heavy @@ -329,8 +330,8 @@ so that they could penetrate the tissue of the plants. \section{Bacteria} The other most dominant microbial antagonists in your sourdough are bacteria. -In fact, they are so dominant that they outnumber the yeast in your dough 100 -to 1. Whereas yeast provides leavening power, bacteria create the distinct +In fact, they are so dominant that they outnumber the yeast in your dough +100~to~1. Whereas yeast provides leavening power, bacteria create the distinct flavours for which sourdough has been named. These are due to the acidic byproducts that result from bacterial feeding. As a bonus, these acids can significantly increase the shelf life of sourdough @@ -384,7 +385,6 @@ fight would have to take place everywhere in the dough and not just in an isolated patch. More research on this topic is required to get a better understanding of the details of the relationship between yeast and bacteria. - One other interesting trait of sourdough bacteria worth mentioning is their ability to break down and consume the proteins in your dough. If you've baked sourdough before, chances are you've experienced this firsthand. You'll recall