My baking focus has lately been predominantly on my sourdough starter maintenance and maximizing fermentation, and I’ve made some of the best bread I can remember (all the bread pictures in this post were made with this starter). This is somewhat a continuation of my Managing Starter Fermentation post that I wrote quite a while ago, but pinpoints on following my process of initial feeding, watching the rise to peak, building a levain and finally discarding a portion of my sourdough starter over the course of a day.
There are many, many methods to keeping your starter healthy and in proper working order — in fact, there are probably as many methods as there are bakers. Each has what works for them to create the bread they seek, and that makes sense if you think on it. Each starter is unique: a distinctive blend of yeast and bacteria (with various strains of each) that has evolved based on each person’s feeding schedule, ambient and internal temperatures, and flour types and mixtures. 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 if followed exactly but I guarantee you’ll find yourself modifying my method to suit your environment — and that’s a good thing. An important requirement for a baker is flexibility and adapting methods and inputs so everything performs optimally in your own kitchen1.
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 7 steps to creating a sourdough starter entry) I followed feeding schedules outlined in various books and things seemed to work pretty well. But my bread didn’t really improve until I modified things to suit my environment, my schedule and my unique starter. As I fed my starter each day I began to take note of things, how it looked when I neglected to feed 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 a single-day microevolution of my sourdough starter. What does it look and smell like right as I feed it (at the start)? What should it look like when I decide to feed again or use for bread (at its peak)? And finally, what does it look like if it’s gone too far and is starting to expend all food provided (collapsed)? 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.
A quick note for those out there who follow my writing very closely: 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 make an experiment of this and try it out, you might be surprised at the difference and you might prefer it. I’m definitely not suggesting one is better than the other, but rather a personal preference whereby I prefer the taste and performance of this liquid levain for the bread I’m currently baking.
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 a peak height, sit there, and eventually fall. If it’s doing this too fast (for example, you feed at 8 a.m. and it peaks at 2 p.m. when you’re at work), you can reduce water feeding temperature, change the ambient temperature, or reduce the amount of mature starter you carry over at each feeding (this is what I do). You want to try to feed your starter right when it’s at its peak height, or shortly thereafter when it begins to fall. This is typically a good sign that your yeast/bacteria have properly fermented all the provided food and need more.
The key to coaxing out maximal fermentation with your starter is to be observant
Once you have a healthy starter that is rising & falling predictably, you will be able to follow a timeline fairly closely each day. I work this into my daily routine: I feed my starter when I eat breakfast in the morning, and then I feed 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 intervals will be tighter.As I mentioned at the beginning, if you’ve not yet started your own 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 essentially they are the same thing. Your starter (mother, chef, etc.) refers to your yeast/bacteria culture you continue to feed and care for indefinitely whereas your levain is a splinter, or off-shoot, of your starter that you feed and build only to eventually be totally 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. While the flour type is up to you I do like to keep the mixture of flour used for feeding as consistent as possible, for as long as possible.
10:00 a.m. – The Start
The first step is to take your mature sourdough starter, discard some portion of it, feed it with fresh flour & water, and cover (I only loosely cover with a glass lid that does not seal tight). My kitchen is currently around 72ºF and my mixture is 75g white flour, 25g rye flour, 20g mature starter and 100g room temperature water.
You can get a sense for how “stiff” my starter is after mixing. You want to make sure you mix enough so it’s almost 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 over the course of the day.
After only a couple hours you can see there’s only very slight activity visible in my starter. The smell at this point would be very, very sweet and essentially the smell of flour and water. Sit tight, things are about to get more interesting.
Four hours after feeding and we have significant expansion, a tad over 100% in fact. 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 by our starter. 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 feedings, 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 still continue for many hours.
Only slightly more expansion than the last check-in but many more bubbles on top, allowing gasses to escape. From the side you can see momentous fermentation taking place, many small and medium sized bubbles.
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 by. Bubbles and holes on top are a good sign, but my starter is not ready to be fed or used at this time2.
By 5 p.m. we have significantly more bubbles and holes on top, much more activity at the sides and overall fermentation is progressing nicely. If I were to describe the smell of the starter at this point it would still smell quite “sweet” with very, very little hints of vinegar/sourness.
You’ll notice here at 7 p.m. any dome that was once at the top of the starter is now gone, replaced by a fairly 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 continue to let it ferment.
At this point we still see some rise, but not much. The top is showing signs of more holes and bubbles, the starter is resting at its peak by this point. By 8:00 p.m. you would definitely be able to use this to leaven your bread, and if you were to perform the “float test” with a little chunk of this it would surely float in water.
If this were a levain build I created in the morning, and not my starter, I would feel comfortable using this levain at this point to mix my dough. It’s showing signs of almost full fermentation that has plenty of activity at both the top and sides. 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.
10:00 p.m. – The Peak
At this point you can see the culture is beginning to start its decline. 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.
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. Even though the starter has started to collapse, I’ve used it at this point to make excellent bread many times. I’ve touched on the topic of a “young” levain in the past, but recently I’ve been using mine at the peak of its maturity with greater success.
This is also the point where you would want to feed your starter. If you are using the correct mixture of inputs — water at a certain 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 one at home dictates 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 mature starter carryover or use cooler water. If your starter is a bit sluggish and isn’t quite at this level, use a bit more mature starter at the next feeding or use 2-8ºF warmer water.
This is a good example of where being observant helps to maximize fermentation. As you continue to care for your starter take a moment before you rush through feeding to take note of how your starter looks and smells and plan to adjust things either at the current feeding or the next.
My starter continued to fall at this point, with longer streaks on the side and the center has noticeably caved. I will normally have fed by this point, but I continued to let this ferment until the morning so we can observe how it looks when it fully collapses.
6:00 a.m. (next day)
What a drop overnight! The sides are completely 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 to be fed.
Even more collapse and more small bubbles. At this point the smell 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 simply pour off the clear liquid, mix the remaining up, and feed 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 completely fine but I try to avoid this scenario as much as possible.
General Sourdough Starter Maintenance Tips
I am currently working on a more thorough “commonly asked starter questions” post where I’ve accumulated many questions sent to me here on the site and through email, but here are a few tips which will prove helpful:
- Don’t let your starter collapse and sit for extended periods before feeding as excessive acidity will change the flavor of your resulting bread (more sour). 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 feed new flour & water) and use the new build to mix
- Use your nose. Observe the smell of your starter at each phase and get to know what a particular smell indicates by drawing a connection between smell and visual cues
- If your area has high chlorine levels in the water, use filtered water or let the water sit out on the counter overnight in a water bottle before using
- Stir your starter fully until there are no clumps or dry bits of flour present
Above all, take a few seconds each time you feed 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 really maximize fermentation in our starters.
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 seems 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, as I mentioned earlier I still use the same Weck jars, dark rye flour and water canister (I leave the water out overnight to let the chlorine dissipate). If you’d like to see more of the tools I use for my sourdough starter maintenance head to my tools page.
There you have it, a day in the life of my starter Brutus. I hope this visual guide has helped to convey the signs and smells I look for at various points through the microevolution of my starter. The same signs shown above are also present when I build my levain when making bread, but since my levain build has a higher inoculation percentage, 50% vs my starter’s 20% or so, the timeline is shrunk down considerably. Remember the methods we have to affect fermentation rate: temperature of water, inoculation percentage (amount of mature starter not discarded), 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 trial and error you’ll discover the right mix of each for your own unique starter.
By remaining observant and attentive we can feed our starters when they are at their peak, just before they begin to run out of food and metabolization slows, to keep them strong and healthy.
Do you have any sourdough starter maintenance tips to encourage maximal fermentation? I’d love to hear from you in the comments below! Buon appetito!