No discard? Impossible!

A comment from someone on reddit sparked an idea.

It went something like this: I’ve never understood the whole discard thing, don’t you just build up your starter a few times and then pop the rest back in the fridge when you’re done?

And, well, I was a bit dumbfounded. There really is no reason why this can’t be done. All of those recipes designed around using sourdough discard rendered useless in one pithy statement. While I appreciate having an excuse to make sourdough pancakes that sits permanently at the back of the fridge, I now use this method to prevent myself from becoming overwhelmed by discarded sourdough starter.

The key to this epiphany is understanding the exponential nature of feeding sourdough. Hang on! You’re not leaving already, are you? I know maths is a bit of a turn off for some people, but I promise I won’t use any fancy language.

First of all, let’s just break down that reddit comment. Most books and guides on the internet will tell you to discard some portion of your starter at feeding time. This is usually required to avoid ending up starring in your own version of attack of the blob. But what does it look like if we don’t discard anything at feeding time? Well, quite simply, when our starter is ripe, all we do is add flour and water and mix it all up thoroughly. We just have to make sure that we remember what round we’re up to and in turn how much it’s expecting to be fed.

Breaking it down

The TL;DR for those who are time poor, is that starting with a small amount of starter (I mean, <10g) will save you a whole heap of discarding down the track.

There are three things we need to consider here when feeding our starter:

  1. How many times we feed after taking our starter from the fridge and before making bread.
  2. The feeding ratio, or amount of ripe starter, flour and water in the mix. This is often written as ripe starter : flour : water.
  3. The bulk starter we need when we’re ready to make bread.

To simplify things, I’ll follow conventional wisdom and say that we feed our starter three times to get it nice and lively before folding it into our bread. I’ll also set our feeding ratio at 1:1:1, which is pretty standard and will prevent us from having too much starter when we’re ready to cook.

Exponential sourdough

Let me demonstrate how things blow out quite quickly (that’s the exponential part) if we follow a less-favourable feeding ratio when we’re not discarding. Take, for example, a feeding ratio of 1:2:2, or twice as much flour and water as ripe starter. If we start with 10g of starter, then this is how our three feedings will go:

Feeding RoundStarter (1 part)Flour (2 parts)Water (2 parts)TOTAL
110g20g20g50g
250g100g100g250g
3250g500g500g1.25kg

As you can see, 10g quickly became more than a kilo after just three feedings! Clearly, we would need to discard some starter if we were feeding at this rate.

A better way

Now, what if we stick to the 1:1:1 ratio I mentioned earlier? Well, take a look:

Feeding RoundStarter (1 part)Flour (1 part)Water (1 part)TOTAL
110g10g10g30g
230g30g30g90g
390g90g90g270g

We end up with a much more manageable number. But for my purposes this is still too much.

And this is where my third point comes in. I bake two 800g loaves of bread once a week, which each require 80g of starter. So that means come mixing time I need 160g of ripe starter. I’ll spare you the maths, but after some calculations, I landed on the number 7. Lucky me!

Feeding RoundStarter (1 part)Flour (1 part)Water (1 part)TOTAL
17g7g7g21g
221g21g21g63g
363g63g63g189g

That’s right. If I start with 7g of starter, and follow a 1:1:1 ratio, I end up with 189g of starter, just 29g in excess of what I need. And all I have to do is chuck the leftovers back into the fridge for next time. If 189g is too much or too little for you, then an easy way to work out the numbers is to divide whatever dough mass you want to end up with by 27 to get your starting weight.

Some tips for success

At the outset, it may seem like you’re working with minuscule amounts of starter, but bear with the process; that morsel will soon fill up your container. If you resist the urge to start with a small container, and you go big upfront instead, then you won’t have to wash up and migrate your starter at every feeding cycle.

It’s also helpful, especially in those early stages, to have your flour at the ready. That also means mixing up your flours beforehand if that’s your MO. It is very difficult to get the correct blend when you’re weighing out a few grams at a time. Better to measure out large quantities and apportion them as needed later.

You forgot something

Now, those haven’t fallen asleep might tell me that I’ve got 29g left to go back into the fridge. And when I take it out next time I only want to start with 7g. That leaves us with 29 – 7 = 22g (oops, maths!) to account for. And because, as I’ve shown you, shaving off just a few grams off at the start goes a long way towards saving discard, we don’t want to use the whole 29g and wing it. Well, the answer is yes, I lied a little and you may need to find something to do with that 22g.

But I think that’s a much easier problem than finding a use for kilos of flour, don’t you?

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