For those newly found bakers out there who have dabbled with the art of baking bread, you may be familiar with sourdough starter. The unique blend of fermented flour and water. It’s been around for centuries due to its amazing leavening capabilities and loads of beneficial nutrients. But what is sourdough starter and how does it work?
Although sourdough has been around for a long time, it has become a huge social media trend recently. Anyone and everyone is making sourdough bread at home with the help of a trusty starter. Some may have inherited theirs while you may be working at your first attempt. Either way if kept in the right conditions it can last a lifetime or two. But how in the world can you eat something that old and why would you?!
In this blog we’ll break down what sourdough starter is, what it means to feed it, and how it can help you with your next bake.
What is Sourdough Starter?
Sourdough starter is a fermented blend of flour and water. Natural yeast and bacteria feed on available sugars releasing carbon dioxide and lactic acid, also known as fermentation.
These microbes are sourced from your flour and the surrounding air. The carbon dioxide is what makes sourdough an excellent leavening agent. Other fermentation byproducts include acetic acid, lactic acid, and ethanol.
Discard
When making a starter from scratch it can be tricky at first. Knowing when to feed and how much can make all the difference. After all, you are working with living microbes, and with most living things, they need the best food to thrive.
To feed your starter, and essentially the microbes, additions of flour and water are added. During feedings, a portion of your starter is removed or discarded to keep microbes from overpopulating.
Discard can be collected separately and incorporated in other recipes that don’t require large amounts of leavening agents.
When using discard it is important to remember that it should not be used until your starter is mature. Inactive discard can be more harm than good. It has a higher susceptibility to mold growth and can contain undesirable bacteria.
Perfect conditions
The activity of your starter can all depend on temperature, location, and the type of flour used. Using flours like freshly milled wheat flour or rye flour can help activate a starter due to the abundance of microbes.
On the other hand, flours that are bleached lack prevalent yeast and bacteria which can hinder activity.
Adjusting temperature can also impact the time it takes for your starter to activate. Placing your starter in a warm environment can provide ample conditions for fermentation. Just like us, your starter likes comfortable temperatures. If kept too hot, the bacteria and yeast will die off. If kept too cold, fermentation will slow down and leave your sourdough flat.
What do Microbes and Bacteria do for Sourdough?
We’ve talked about how yeast and bacteria can come from multiple sources such as the air and the flour you use, but what is their purpose?
Lactobacillus bacteria, or lactic acid bacteria (LAB) is the primary bacteria found in sourdough. These bacteria consume simple sugars and produce lactic acid in the process.
LAB is responsible for the distinct sour flavor of sourdough breads. In fact, breads made with baker’s yeast (Saccharomyces cerevisiae) use little to no fermented bacteria. This means they yield no sour flavor.
Lactic acid bacteria can also alter the activity of your starter. Both lactic acid and acetic acid can inhibit harmful bacteria and pathogens due to low pH levels. Acidic conditions allow for shelf stability which is why sourdough starters can be kept for so long.
Lower pH levels also keep unwanted mold growth at bay which is the number one killer of most sourdough starters. For any signs of mold, it’s always best to throw out your starter and start again.
How to Use Sourdough Starter?
Now that we know what sourdough starter is, we can learn how to use it to bake the best sourdough bread! Making bread with the most perfect, well risen loaf is super easy to achieve with sourdough starter.
Remember when I said carbon dioxide makes sourdough starters an excellent leavening agent? Well, it’s true! When mixing starter into bread doughs, proofing allows the bacteria and yeast to break down available sugars releasing more carbon dioxide gas. As the production of carbon dioxide begins to increase, the dough begins to rise.
Techniques like stretching and folding your dough strengthen the gluten present which prevent carbon dioxide from escaping. Other techniques like bulk fermentation can prevent your dough from rising too far by slowing the activity of the yeast.
To keep your future loaves light and fluffy, try adding in some sourdough starter and see the science for yourself!
Now that you know the general science behind sourdough starters, you have the perfect means to achieve what is arguably the best tasting bread on the market! Whether you’re new to sourdough or baking in general, baking is a science and there’s lots to learn.
If you’re a baking newbie like me, check out my other posts to see common mistakes you might be making and how science can fix them!
