Starter starter kit, 2023 edition
Yet another refreshment
It’s been awhile since I’ve talked about sourdough starters here, and given that, plus the fact that many more people have gotten them from me (or from others) recently, I thought it would be a good idea to revisit my go-to approaches to starter maintenance and levain builds for baking.
I still use the same two approaches I’ve outlined here before, but have recently added a third one that I think is worth trying if you have the time, since it can give your starter a little extra oomph, especially after it’s been stored in the fridge for a long time.
But first I thought an expanded starter & levain glossary would be useful.
Glossary of terms
culture: Any collection of organisms that is kept alive by periodic refreshment in new media (i.e., food). A levain or starter is a sourdough culture.
expansion (or ‘scaling’): Increasing the amount of levain by refreshing it with larger than normal quantities of flour and water.
This often confuses many who are new to working with sourdough. Many people don’t understand how you can convert a small amount of starter to a larger one, since they assume that you can only refresh it with the same amount of flour and water as usual.
For example, say you keep a 50g batch of starter that you refresh regularly with 20g flour, 20g water, and 10g starter (leaving 40g of “discard”), but you need 200g of levain for a dough. Easy-peasy: You just increase the amounts of everything to yield that amount—i.e., 80g water, 80g flour, and 40g starter (leaving only 10g discard).
If you need much more than that, you have two options: Use more fresh flour and water and a smaller amount of starter, and let the culture proof longer (since with less starter it will be slower to proof), or do it in several stages, i.e., make 200g in one stage, and then use that to make 1000g in the next one.
inoculation (or seed) rate: The amount of culture you add to a dough or levain build, relative to the weight of fresh flour used. For example, a combination of 20g flour, 20g water, and 10g levain has a 50% inoculation rate. One with 100g flour, 100g water, and 20g starter has a 20% inoculation rate. All else being equal, higher inoculation rates will yield faster proof times than lower ones, and vice versa.
levain (or leaven): A ripe sourdough culture, used as a preferment in a dough.
levain build: A levain refreshment step that is used to create a sufficient quantity of levain for a dough.
liquid levain: A levain at (around) 100% hydration, meaning equal parts flour and water, which gives it a pourable consistency.
ripe: A proofed levain that is mature enough to leaven a batch of dough (ready to use, in other words). In many cases, a levain is ripe when it is between two and three times its original volume.
refresh(ment): I use the term “feed” and “refresh” interchangeably, but it’s important to understand that the latter term is more accurate. You don’t really “feed” a sourdough starter like you do your cat or dog, where you just give it food and water to consume periodically. Instead, you “refresh” it by moving a portion of it to a clean, new mixture of flour and water and discard whatever is left over. (It’s kind of like giving it a brand new “home” to inhabit, except that home is made out of its favorite food. Some microbiologists refer to this as a substrate, meaning a material that an organism both inhabits and consumes.)
sourdough discard: Whatever portion of a levain that does not get used in a refreshment. I usually save the remainder in every batch in the fridge as a backup in case of disaster, then (once disaster has been averted), add it to a larger container of “discard.” You can also just, well, discard it at this point. (Unless you make a lot of excess every time, the amount of flour in the remainder is pretty negligible, so it’s not all that wasteful to dump it instead.)
starter: A sourdough culture, ripe or otherwise. Many people—including me—use starter and levain interchangeably, though some reserve the term “levain” for cultures made or ready for use in a dough, while using “starter” to refer to the culture used to make it.
stiff levain: Lower hydration levains around 60-70% hydration, giving them a dough-like consistency.
young levain: A levain that is used at the very earliest stages of ripeness, at about the doubled-in-volume stage. Yeasts typically predominate in young levains, which can yield a less sour bread, since the lactic acid bacteria are reduced.
I tend to use two main approaches to building my starter: either a relatively quick (4-6h) build or a slow overnight (12-14h) one. Either serves the same purpose, though I think the latter might be a better option if your starter has been neglected or otherwise seems to be a little sickly, since it uses so much less starter—5% rather than 50%—and probably helps “clean” the mixture of excess acid. Most of the time I choose one or the other based upon how quickly I need it to be ready, or when I remember to feed it.
Both use the same basic approach, the only difference being the amount of starter you add and the length of time it takes to be ready. While you can use a refreshed starter up to the point that it peaks (or just afterwards), I almost always use (or refrigerate) mine when it has about doubled in volume, both because I like the mild acidity it has at that point, and because it tends to keep better in the fridge when the culture hasn’t exhausted itself of nutrients yet.
The last method—a “booster” levain—is relatively new to me, and is something you do after you do a regular levain build of any kind. I’ll explain more below, but the idea is that you can “goose” a ripe levain with more flour and water to give it a bit more activity before adding it to a dough. Because the intermediate levain is so active at this point, and because you use a very high inoculation rate (100% or higher), it is usually ready for use in only a couple of hours.
My “recipes” are below, but you should think of them more as guidelines, since you might find eventually an approach that works better for you, given your needs and/or the environment you are working in.
You can use any flour you want for your levain builds, but I’d highly recommend using only white flours when you are feeding the levain for cold storage. The extra nutrients in whole grain or high-extraction flours will likely cause the levain to overproof in the fridge and weaken unless you are feeding it on a regular basis.
I either use high-protein AP (e.g.., King Arthur) or bread flour. I’ve recently switched over to using bread flour most of the time, since it yields a slightly taller, more lively levain (admittedly, this is mostly for my benefit, rather than the bread’s).
As for hydration, I almost always use a liquid levain with 100% hydration, meaning equal parts flour and water by weight. Not only is the math easy to work out, but it’s easier to incorporate into a dough, especially by hand. There might well be differences in flavor between liquid and stiff levains (something I need to test for my book), but as I am starting to realize, the differences between two related approaches in bread baking are often less dramatic than their similarities.
The one exception is when I know I’ll be leaving my starting in the fridge for a long time without refreshing it. In that case, I reduce the hydration to 60% (60g water for every 100g flour), since it slows things down and helps it hibernate longer.
The scale varies by the amount of levain I need at any one point, and the numbers below are just for reference. You can scale them up or down as needed, so long as you keep the ratios the same.
You want to the levain to be covered well to prevent drying out, but still able to breathe. If using a mason jar, invert the lid and leave the ring loosely tightened; if using a deli container, poke a small hole in the lid with a thumbtack.
Quick Build (~6h, 2:2:1)
The first method I use is the quick build, which—in my case, YMMV—takes between 4 to 6 hours to complete. I use a 50% inoculation rate, or a 2:2:1 flour-water-starter ratio, which I think is ideal for keeping a starter happy and healthy while still making for a relatively quick build.
Try to do your best to get the levain temperature to 78˚F by adjusting the water temperature using the simplified DDT (desired dough temperature) formula below (2˚F to either side is fine, so don’t stress if you end up a little off):
A + B + 78 = water temperature
A = 78 - [flour temperature]
B = (78 - [preferment temperature]) x [50%]
C = [DDT, 78 in this case]
A + B + 25 = water temperature
A = 25 - [flour temperature]
B = (25 - [preferment temperature]) x [50%]
C = [DDT, 25 in this case]
In other words: Measure the temperature of your flour, and subtract that number from 78 or 25. Measure the temperature of your starter, subtract that number from 78 or 25, and multiply the answer by 0.5. Add A + B + 78 or 25 and the number you get is the temperature your water should be to get the mixture to land at 78˚F/25˚C. Heat or chill the water to get it to that temperature, then use it to mix the levain.
During times of temperature extremes, adjust the DDT up or down. If your kitchen is above 85˚F/29˚C, set it to 65˚F/18˚C or so. If it’s well below 70˚F/21˚C, aim for 5˚F/29˚C or so. (Remember that you need to replace the DDT in each line of the formula, i.ee. any 78 or 25 in it needs to be replaced by the new DDT.)
For an “accelerated” refreshment at normal temperatures—doubling in just 3 to 4h—set the DDT to 85˚F/29˚C.
100g high-protein AP or bread flour
1. Combine the flour, water, and starter (return any remaining starter to the fridge as a backup in case of disaster) in a bowl and stir until uniform. Transfer to a clean, tall, and straight-sided container and cover. Mark the starting level with a rubber band or marker. Proof at 75-78˚F / 24-25˚C until about doubled in volume, 4 to 6 hours.
2. Use and/or transfer the mixture to the refrigerator. Store for up to 14 days before refreshing again. (Cold-stored levain is generally best used for baking within 7-10 days.)
Slow/Overnight Levain Build (~12h, 20:20:1)
I tend to use this one when I want to make a dough the following morning, or if I forget to feed mine earlier in the day. This is also the one I recommend if you want to give your starter an all-room-temperature “workout” for a few days. In that case, I’d scale it down to maybe 25g/25g/1g and refresh it first thing in the morning and late in the evening each day for as many days as you have time for (3 days is probably a good start).
When ambient temperatures are high, use cold (60˚F/16˚C) water and/or set the culture somewhere cool if possible (but not the fridge).
When ambient temperatures are really high, this method is less than ideal, unless you can keep an eye on it to catch it when it has doubled in volume.
Because the fermentation is so long, you don’t really need to worry about DDT as long as you start on the cool side, since the culture will have plenty of time to equilibrate to ambient temperatures.
If ambient temperatures are very cold, you can increase the amount of starter to 10%, or 10g.
If ambient temperatures are very high, you can decrease the amount of starter to 1%, or 1g, though that can be challenging to measure accurately.
One workaround for this problem is to do a serial dilution, in which you stir a larger amount of starter into a specific amount of water and then use only a portion of it. For example: Stir 10g of starter into 90g water, and then use 10g of the solution to yield 1g of levain.
100g high-protein AP or bread flour
Combine and leave at 75-78˚F / 24-25˚C until at least doubled in volume before using in a dough, 12 to 14 hours.
As I mentioned above, a booster levain is sort of an “add-on” to a regular, ripe levain, intended to give it a little goose, which can amount greater activity in the dough (and even lower acidity, since yeasts will predominate the culture). In this case, you really are “feeding” the levain, because you are just adding another hit of flour and water to it once it is ripe, usually in amounts less than the weight of levain, which means an inoculation rate of 150% or higher. Because a ripe levain is already very active, a booster leaven will typically double in volume and be ready for use in just a few hours.
A booster levain could also be useful for “rescuing” a slightly overripe levain, say one you let go a little too far (this sometimes happens to me when ambient temps are high and I misjudge how fast an overnight build will take). It most likely won’t bring it back to 100% strength, but it will definitely help.
The method I’ve been using so far involves a 170% inoculation rate, or 70g flour and water for every 100g levain. While I haven’t tried it yet, many recipes do a booster levain using rye instead of white wheat flour, for an even greater boost of activity.
Ideally, use the DDT formula from above to determine the ideal water temperature for a levain that is 78˚F/25˚C.
If you use rye flour, use 120% hydration, or 1.2x the weight of the flour, to keep the consistency the same.
100g ripe, fresh levain
70g high-protein AP, bread, or rye flour
Stir the water and flour into the levain and proof at 78˚F/25˚C until at least doubled in volume, 1 to 3 hours.
I think that’s a good round-up of everything I have to say on working with starters for now. Let me know if you have questions, and tell us all about how your approach differs, if it does.