The 12 FAQs on Sourdough Starter:
- What is the best flour for sourdough starter?
- Should I stir my sourdough starter?
- Should I cover my sourdough starter?
- What container to store sourdough starter in?
- Can I refrigerate my sourdough starter?
- Can I use tap water for my sourdough starter?
- How do you know when a sourdough starter has gone bad?
- Why do you discard half the sourdough starter?
- How often should I feed the starter?
- How do I know if my starter is ready to be baked with?
- Can you combine two sourdough starters?
- Can you overfeed a sourdough starter?
1. What is the best flour for sourdough starter?
The best flour for developing and maintaining sourdough starter is whole/dark rye flour. Whole/dark rye flour contains a high quantity of starches and natural microbial concentration, which is important for a strong and healthy fermentation process.
The best flour for sourdough starters contains a high quantity of starches. The higher the protein content of a flour, the less starches it contains. A high quantity of starches is important when developing sourdough starter as starch is the food source for yeast and bacteria to undergo fermentation.
Using flour of lower protein content (10-11%) ensures that there is a high concentration of starches for the yeast and bacteria to feed on and maintain a healthy and lengthy fermentation reaction in your sourdough starter.
Whole grain flour is preferred over white flour in the initial stages of developing a sourdough starter.
Bread flour can be made from different types of grains; wheat, rye and spelt grains are the most commonly milled into flour for bread making. The grain is made up of three layers much like an egg, there is the outer bran layer (the shell), the middle endosperm layer that contains starches and proteins(the white), and centre germ that is packed with minerals, vitamins and fats (the yolk).
White flour only contains the endosperm; the bran and germ that is packed with microorganisms and nutrients are left out. Whole grain flour on the other hand contains all parts of the grain and hence has the highest concentration of microorganisms and nutrients that is beneficial for fermentation.
Whole rye flour is used in the initial stages of developing a sourdough starter
We typically use whole rye flour in the initial stages of developing a sourdough starter as it contains the most nutrients and microorganisms to seed our sourdough starter. Sourdough starters made with rye flour shows the strongest signs of fermentation, and hence makes the strongest sourdough starter with the greatest leavening ability.
As some sourdough bread recipe do not call for rye flour, there is a need to develop a white wheat sourdough starter rather than a rye sourdough starter.
We always start with whole rye flour when developing our sourdough starter, once the rye sourdough starter has been discarded and fed with whole rye flour for 3-4 days, the yeast and bacteria population has been well established. We can then start feeding the sourdough starter with white wheat or whole wheat flour depending on the type of bread you would like to bake.
2. Should I stir my sourdough starter?
I always stir my sourdough starter before discarding or before I mix it into my final dough. Stirring ensures that the yeast and bacteria in the sourdough starter are evenly dispersed. If you do not stir the sourdough starter before discarding, you may end up throwing away a large portion of your healthy yeast and bacteria, leaving you with a weakened sourdough starter.
3. Should I cover my sourdough starter?
You should cover your sourdough starter but make sure it is not airtight.
We cover the sourdough starter to prevent any contaminants from falling into the starter that may disrupt the microbial balance in the starter; dust and fruit flies can easily find its way into an uncovered sourdough starter. Another reason to cover your sourdough starter is to prevent it from losing too much moisture over time.
Yeast and bacteria in our sourdough starter ferments and releases carbon dioxide gasses. Do not tightly seal your container as the pressure build up from the carbon dioxide gasses is greater than you would think; it can impair fermentation, and potentially force the lid open and leave you with a sticky and smelly mess.
4. What container to store sourdough starter in?
I prefer a glass container as it is chemically inert, does not rust or impart any flavor to your sourdough starter. The transparent glass container also allows me to easily observe the bubbles and rise of my starter over time.
My container of choice also has a loosely fitted lid, with a wide opening as it makes it much easier to discard, feed and stir in the fresh mixture of flour and water every day.
5. Can I refrigerate my sourdough starter?
It is very common to refrigerate a sourdough starter, especially when you do not intend to bake everyday. Refrigerating your sourdough starter slows down the fermentation process but it does not kill off the microbial population of the starter, and hence refrigerating is very useful if you do not want to feed your sourdough starter everyday.
Take your sourdough starter out of the refrigerator in the morning before work, discard, feed and let it warm up to room temperature and ferment over the entire day. In the late evening when you come home, the sourdough starter would have been revitalized, immediately cover and store it in the refrigerator. Repeat every alternate day.
Do not refrigerate your sourdough starter the day before you intend to use it for baking, to ensure that the yeast and bacteria has enough time to fully regain its vigor when you use it to bake.
6. Can I use tap water for my sourdough starter?
Tap water contains chlorine which is a disinfectant that can kill off the microbial culture in your sourdough starter. Using tap water in developing and maintaining sourdough starter is one of the most common reasons why some sourdough starters are inactive, and does not bubble and rise as well as others.
However, if you fill up a bottle with tap water and leave it uncovered overnight, all of the chlorine will have dissipated and it would be safe to use. Boiling your tap water does not remove the chlorine, chlorine will only dissipate over time.
7. How do you know when a sourdough starter has gone bad?
Sourdough starter has gone bad when it stops fermenting vigorously, a weakened sourdough starter does not bubble and rise as much as it used it.
The only sourdough starter that has gone bad and cannot be saved is one that has grown moldy. Mold typically grows on the surface of your sourdough starter and has a fuzzy appearance or appears as orange, pink, purple or red streaks.
All other problems with sourdough starter can be fixed by a consistent daily discarding and feeding schedule over 5-7 days; if it still does not regain its vigor after 7 days, try feeding it twice in a day.
8. Why do you discard half the sourdough starter?
We discard our sourdough starter before feeding to keep the quantity of sourdough starter manageable over time. If we do not discard, the sourdough starter will get so large that it would take an unreasonable amount of flour to maintain it.
A typical feeding ratio for sourdough starter would be 1:1:1 (old starter weight:new flour weight:new water weight). During the first feed, we would normally have 50g of old starter + 50g of new flour + 50g of water, which comes up to 150g of total sourdough starter after the first feed. If we do not discard any starter, the second feed would consists of 150g of old starter + 150g of new flour + 150g of new water, which comes up to 450g of total sourdough starter after the second feed.
You can see how the weight of flour required to feed the starter tripled after only 1 feed if we do not discard our starter.
Discarding the starter also prevents the starter from becoming too acidic. Acidity can accumulate in old sourdough starters to a point where it will disrupt the fermentation process. When acidity is too high, amylase enzyme activity is inhibited, which cuts off the food source for yeast and bacteria to undergo fermentation.
As we discard and refresh our sourdough starter daily, the acidity in the sourdough starter does not accumulate, and we can ensure that we will get a strong fermentation reaction after every feed.
9. How often should I feed the starter?
The most common feeding frequency is 1-2 times a day. Choose a feeding frequency that correlates to the most bubbling and strongest rise of your sourdough starter.
For example, during the cold season, you may only need to feed your sourdough starter once a day for maximum vigor as the microbes is less active in the cold and takes the whole day to peak in strength.
During the hot season, you may need to feed your sourdough starter twice in a day, as the microbes are very active in the hot weather, and it peaks out much quicker and runs out of food before the day ends.
10. How do I know if my starter is ready to be baked with?
The sourdough starter is ready to be baked with when it has risen and has many small visible bubbles on the sides and top of the sourdough starter. The amount of rise depends on the hydration level of your sourdough starter.
For a liquid sourdough starter ( hydration of 75% and above), the starter is ready to be baked when it has risen to its maximum point, any longer and the starter will has over ripen and collapse, leaving a high water mark on the side of the jar.
For a stiff sourdough starter ( hydration of 65% and below), the starter is ready to be baked when the domed surface at the top of the starter has just begun to collapse and recede.
The float test is not an accurate indicator of sourdough starter ripeness, as it only works for liquid sourdough starter. A stiff sourdough starter, although fully ripen and ready to be baked, is too dense and will fail the float test every time.
New sourdough starter typically takes about a week to fully mature and be ready to be baked. Once it has sufficiently matured, it should show signs of a strong rise and bubbling after 8-12 hours.
11. Can you combine two sourdough starters?
You can definitely combine two sourdough starters, but it will take some time for the yeast and bacteria in the new mixture to fight it out and find a new balance.
The yeast and bacteria in the new mixture will compete with each other for nutrient, leaving only the strongest strains to survive. During this time, fermentation will not be as vigorous, but with consistent discarding and feeding, the sourdough starter will regain its strength after a few days.
When you are combining two sourdough starters, you should also be mindful of the hydration level of the new mixture. Combining a sourdough starter of 65% hydration with a sourdough starter of 100% hydration of the same weight will result in an 82.5% hydration sourdough starter; sum up the two hydration levels (65%+100%) and divide by 2 to get the new hydration level (82.5%).
12. Can you overfeed a sourdough starter?
You can overfeed a sourdough starter if you feed it more than twice in a day. When a sourdough starter is overfed, we are discarding the important microbes for fermentation before they have a chance to reproduce and regain its strength.
We will be left with a weakened yeast and bacteria population in our sourdough starter, which will negatively impair how well it ferments.
Observe your sourdough starter closely as you increase its feeding frequency. If it starts to ferment poorly, reduce your feeding frequency.