My baking focus has lately been predominantly on my sourdough starter maintenance and maximizing fermentation. And recently, I've made some of the best bread I can remember (I took all the bread pictures in this post with this starter). So this post is somewhat a continuation of my Managing Starter Fermentation, but in this post, I'll focus more on the signs for spotting when a sourdough starter is ready for refreshment (ripe) and how to perform that refreshment.
Be sure to check out my post on what flour, water, and carryover ratios I'm currently using to feed my starter in my How Do I Feed My Sourdough Starter post.
There are many methods to keeping your starter healthy and in proper working order, likely as many methods as bakers. Each baker has a process for maintaining their starter according to what works for them and the bread they seek. Each starter is unique after all: a distinctive blend of wild yeast and beneficial bacteria that has evolved in the temperature it's kept at, the flour used for refreshments, and the time between those refreshments. I wanted to preface this article with that because the following is what works for me here in my kitchen and will most likely work for you as well, but I guarantee you'll find yourself modifying my method to suit your environment. That's to be expected. An essential requirement for a baker is flexibility and adapting techniques and inputs, so everything performs optimally in your kitchen. In the end, your sourdough starter maintenance routine might be similar to mine, or it might be quite different.
I can remember back to when I first dabbled with creating my sourdough starter. I read all the books I could get a hold of, I searched online, anywhere I could find information. Once I got things up and running (using the process described in my seven steps to creating a sourdough starter entry), I followed refreshment schedules outlined in various books, and things seemed to work pretty well. But my bread didn’t improve until I modified things to suit my environment, my schedule, and my unique starter. As I refreshed my starter each day (feeding sourdough starter), I began to take note of things, how it looked when I neglected to refresh it for too long, how it looked after a few hours with new food, and how the smell of the starter changed throughout the day.
My goal for this entry is to convey the signs I look (and smell) for during the single-day microevolution of my sourdough starter. What does it seem and smell like right as I refresh it (at the start)? What should it look like when I decide to refresh it again or use it for making bread? And finally, what does it look like if it’s gone too far and is starting to become overly acidic? I receive frequent emails on this topic, and I hope this entry will be a visual guide to those wondering how I care for my starter.
With this post, I'm hoping to help you answer the following questions:
- What is feeding (I usually call it refreshing) a sourdough starter?
- How soon after feeding (refreshing) a sourdough starter can I use it?
- What does feeding my sourdough starter once (or twice) a day look like?
A quick note for those out there who follow my writing very carefully: you'll notice this entire entry is about a liquid starter/levain and not about a “stiff” variety I had been baking with for almost a year. I recently shifted things back to using a liquid starter after a long while with a stiff variant, and I have to say I much prefer how my bread is turning out with my change. If you use a stiff starter, some of this entry will be relevant to you, but the visual cues will be different as the consistency of your starter will be different. If you haven't used a liquid starter/levain, I suggest you do an experiment of this and try it out, you might be surprised at the difference, and you might prefer it. I'm not suggesting one is better than the other, but rather a personal preference whereby I like the taste and performance of this liquid levain for the bread I'm currently baking.
If you're curious and looking to dig more into preferments, see my guide to the differences between a sourdough starter and a levain.
Sourdough Starter Background
The key to coaxing out maximal fermentation with your starter is to be observant. Watch how it evolves throughout the day and take note of how long it takes to reach full ripeness: a strong sour aroma, a breakdown of the mixture, significant bubbles on top and at the sides. If it’s doing this too fast (for example, you refresh at 8 a.m., and it ripens at 2 p.m. when you’re at work), you can reduce the water temperature, change the ambient temperature, or reduce the amount of mature starter you carry over at each refreshment (this is what I do). You want to try to refresh your starter right when it’s at its at peak ripeness, or shortly thereafter.
Once you have a healthy starter that is showing the same signs of fermentation every day, you will be able to adopt a consistent sourdough starter maintenance schedule. I work this into my daily routine: I refresh my starter when I eat breakfast in the morning, and then I refresh again in the evening as I’m cleaning up the kitchen getting ready for bed. It only takes a few minutes (see my tips later on tools to make things easier).
Your starter will go through the following phases each day, but the times will most likely be different. If fermentation is slow (due to temperatures or percentage of starter carryover for example) then the signs I point out below might be at greater intervals, and conversely, if fermentation is fast, then the ranges will be tighter. As I mentioned at the beginning, if you’ve not yet started your sourdough starter, or received a portion from a friend, I have an intro article to creating a starter that will get you going in a few days.
Let’s look at a day in the life of my starter.
Sourdough Starter Maintenance Timeline
Before we dive into the timeline, I want to point out that below I refer to two things: my starter, which is what you're here for in the first place, and also a levain. I talk about both almost interchangeably because mostly they are the same thing. Your starter (mother, chef, etc.) refers to your yeast/bacteria culture you continue to refresh and care for indefinitely whereas your levain is a splinter, or off-shoot, of your starter that you refresh and build only to eventually be used in a bread recipe.
For the timeline below I used 25% whole grain dark rye flour and 75% Central Milling Artisan Baker’s Craft (this is a lower protein flour, similar to “all-purpose” here in the States). The percentage of flour types is really up to you, I used a little rye flour to help increase fermentation and acetic acid production, but you can use any ratio of flour you’d like (e.g., 100% whole wheat, 100% white, a mix of both, etc.). Just take note of how each flour type aids or slows fermentation.
10:00 a.m. – Sourdough starter maintenance beginning
The first step is to take your mature sourdough starter, discard some part of it, refresh it with fresh flour and water, and cover (I only loosely cover with a glass lid that does not seal tight). My kitchen is currently around 75°F (23°C), and my mixture is 75g white flour, 25g rye flour, 20g mature starter, and 100g room temperature water.
You can get a sense of how “stiff” my starter is after mixing. You want to make sure you mix everything thoroughly, so it's completely smooth with no visible clumps of dry flour.
I’ve placed the green rubber band at the beginning level of my starter so we have a good sense of how far it will rise throughout the day.
After only a couple of hours, you can see only slight activity visible in my starter. The smell at this point would be very, very sweet, and practically the aroma of flour and water. Sit tight; things are about to get more interesting.
As seen below, four hours after refreshment and we have a significant expansion, a tad over 100%. You can see in the image at right that the top is domed with a few bubbles peaking through, the mass of dough is trapping quite a bit of the gas produced through fermentation. I like to use a glass container, particularly these Weck jars, not only because it allows me to see firsthand how fermentation is progressing but also because the flared top makes sticking your hand & spatula inside very easy. I not only use these tall jars for my day-to-day starter and refreshments, but I also use them to build my levain before baking.
You'll notice there's quite a bit of activity already. After this initial explosive growth things will slow down, but upward growth will continue for many hours.
At this point, there's only slightly more expansion than the last check-in. But, you can see many more bubbles on top and at the sides, showing signs of the momentous fermentation taking place. All of these are good signs.
When you build your levain in preparation for baking, you may not always be able to see through the side of the container; the top-down view is sometimes all you have to judge your starter's readiness. Bubbles and holes on top are a good sign, but my starter is not ready to be fed or used at this time1.
Another key indicator here is the aroma: how does it smell? Is it still sweet, sourer, or very acidic and vinegar-like? At this point mine still has a sweet aroma to it with a very subtle backdrop of sourness starting to creep in.
By this time we have significantly more bubbles at the sides and the top; overall fermentation activity is much higher. If I were to describe the aroma of the starter at this point, it would still smell quite sweet at it was at 3:00 p.m., but now the sourness is starting to escalate and build.
Given the look and aroma, I can expect my starter to rapidly come to ripeness very soon.
You'll notice here at 7:00 p.m. any dome that was once at the top of the starter is now gone, replaced by a reasonably flat surface. The flattening of the top usually indicates upward growth has significantly slowed and upward movement won't be as prominent. More holes on top and more fermentation visible at the sides. We'll continue to let it ferment.
8:00 p.m. – Ripe, time to make a levain
As seen below, we still see some rise since 7:00 p.m., but not much. The top is showing signs of more holes and bubbles and the aroma is what I would describe as “ripe” and ready for use. If I were to pull back a little bit of the top, I would smell a slightly sour, vinegary smell with hints of sweetness still present.
At this point, I'd use some of the sourdough starter to make a fresh levain or use this starter directly in making bread. After making the levain, I would then also refresh the starter by discarding and adding fresh flour and water.
While I find the “float test” to be a misleading test because it can sometimes give you false positives for when a starter or levain is ready to use, the float test would surely pass at this point.
10:00 p.m. – Just past ripe
In the photo below, you can see the culture is beginning to show signs of ripeness. There are streaks at the top that indicate where the top of the starter once was, and in the top-down view, you can see the center is starting to collapse.
The fact that it's starting to collapse is not the single most important factor in judging starter and levain readiness, it's the cumulative signs that matter: a general breakdown of the mixture, a stronger sour aroma, and significant gas production.
Again, if this were a levain I built in the morning to mix into bread, I would still feel comfortable using this to mix my dough. I've used my starter/levain at this point to make excellent bread. I've touched on the topic of a “young” levain in the past, but recently I've been using mine when it's more fully fermented to achieve more flavor.
This time is also when you would want to refresh (feed) your starter. If you are using the correct mixture of inputs—water at a specific temperature, percentage of mature starter, and flour mixture—this time will coincide with when you want to feed it. For me, 10 p.m. is perfect as it's when I start cleaning the kitchen in prep for bed (our little ones at home dictate my sleep/wake schedule, and thus my starter must conform).
If your starter has arrived at this point before you want it to, you can use a smaller percentage of ripe starter carryover or use colder water. If your starter is a bit sluggish and isn't quite at this level, use a bit more ripe starter at the next feeding or use 2° to 8° warmer water.
Being observant helps us help our starter to maximize fermentation activity. As you continue to care for your starter, take a moment before you rush through refreshments to observe the look and aroma of your starter—plan to adjust things either at the current refreshment or the next based on this observation.
My starter continued to fall at this point, with longer streaks on the side and the center has noticeably caved. I will normally have refreshed it by this point, but I continued to let this ferment until the morning so we can observe how it looks when it's gone farther than I'd usually allow.
6:00 a.m. (next day)
What a drop overnight! The sides are entirely streaked with how far the starter has fallen and the top was covered in small little bubbles. My starter has gone way too far at this point and needs a refreshment.
Even more collapse and more small bubbles. At this point, the aroma was very acidic, vinegary, and quite strong.
My final timeline entry shows just how far my starter has fallen after almost 24 hours. The acidity will continue to rise, and if left for even longer a clear liquid will form on the top (commonly referred to as “hooch”) that will be alcoholic and bitter tasting. Your starter might also look this way if you've left it for a long period in the fridge in “hibernation,” as I like to call it. When reviving a starter in this condition, I will pour off the clear liquid, mix the remaining, and refresh per usual.
There have been times when my kitchen heated up unexpectedly, or I wasn't able to get home before this had happened, and I mixed up my starter per usual, and it was just fine, but I try to avoid this scenario as much as possible.
General Sourdough Starter Maintenance Tips
See my sourdough starter frequently asked questions post for a long list of common issues, but here are a few tips which will prove helpful:
- Don’t let your starter collapse and sit for extended periods as excessive acidity will change the flavor of your resulting bread (sourer). If it's a levain, not your starter, and it's fermented much too fast for your schedule, you can always make an intermediate build (essentially discard and add new flour and water) and use the new build to mix
- Use your nose. Observe the aroma of your starter at each phase and get to know what a particular aroma indicates by drawing a connection between aroma and visual cues
- If your area has high chlorine levels in the water, use filtered (or distilled) water or let the water sit out on the counter overnight in a water bottle before using
- Stir your starter thoroughly until there are no clumps or dry bits of flour present
Above all, take a few seconds each time you refresh your starter to sit back and assess how things look, smell, and even taste (I don't typically taste my starter, but many bakers do). It's through constant observation and attention to small details that we can maximize fermentation in our sourdough starter maintenance routine.
Sourdough Starter Maintenance Tools
It’s funny how small tools make a huge impact when compounded over multiple times a day for every day of the year. I recently changed my stirring apparatus from an old Pyrex spatula to this newer Oxo spatula and wow… So much wasted time cleaning that old multi-piece thing. This Oxo one is covered with silicone at the top with no seams or joints, it’s very sturdy (which helps act as a firm mixer), and you can toss it into the dishwasher as well. Highly recommended.
Aside from the new spatula, I still use the same Weck jars, dark rye flour, and all-purpose flour. If you’d like to see more of the tools I use for my sourdough starter maintenance head to my tools page.
Sourdough Starter Maintenance Wrap Up
There you have it, a day in the life of my starter and my sourdough starter maintenance routine. I hope this visual guide has helped to convey the visual cues and aromas I look for at various points through the microevolution of my starter. The same signs shown above are also present when I build a levain when making bread.
Remember, the methods we have to impact fermentation rate: temperature of the water, inoculation percentage (amount of ripe starter left in the jar), flour selection (whole grain flours increase fermentation), and ambient temperature. If your starter is sluggish, increase any of these to speed things up or decrease them to slow things down. After a few days of experimentation and you'll discover the right mix of each for your unique starter.
Now that your starter is on a regular maintenance schedule, don't forget you can use the daily starter discard in many delicious things in the kitchen! Buon appetito!
If this were a levain and not my starter, and I was attempting to use this at a “young” stage, this is most likely where I would use it for mixing my bread↩