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Sourdough 101: A blog post about caring for yeast starters


Sourdough bread is bread made with natural yeast (also called a sourdough starter) that has been fermented by the baker, rather than fresh or dried yeast which comes from a packet.  The word on the street is that it’s a healthier alternative to baking with mass-manufactured yeasts.  I found it daunting when I started making my own starter. What if I killed my yeast? To help you to not be as daunted as I was, I’ve pooled the information that I’ve learned about creating, keeping and maintaining a sourdough yeast culture – here it is, I hope it helps… (First published in January 2017). 

1. How to make a yeast starter 

USE IF: You don’t have a starter and want to make one from scratch. 

Day 1: In a clean, sterilised container, mix 200 g water and 200 g flour. You can use whichever kind of flour you like, whole-grains like wholemeal and spelt tend to speed things up, but you can use anything.  Yeast bacteria lives on the flour – the water acts to kick-start the organisms into life, and then once they are awake, they feed off the sugars on the flour. Once you have mixed the flour and water together so that it is combined, cover the container and leave it in a warm place.

Day 2: You are now going to give your starter its second feeding. Tip out a third of the flour and water mixture down the sink. Then, add in another 100 g of flour and a 100 g of water and mix well. 

Day 3 to Day 5: Repeat the steps from Day 2 , and give your starter a feed every day until Day 5. Keep an eye on the way your yeast changes, it will start to bubble and the smell will change - from floury, to cheesy to alcohol-y or fruity. Smells and bubbles all depend on many variables, so different flours, different temperatures of water and different temperatures in your kitchen will alter the results.

Day 7: Happy Birthday, your starter is a week old. Give it another feed as a birthday present - at this point it can start to be stored in the fridge. 

Day 9, Day 11 & Day 13: You will have started to notice changes and the fact you’re your yeast is growing in size with every feeding! Keep feeding it every other day and keep it in the fridge. After 2 weeks, you will have a lovely bubbly starter that is ready to bake with. 

Day 14: You can begin making bread! A good way of testing whether the sourdough starter is ready to bake with is by dropping a teaspoon of it into a glass of water. If it floats, it is ready! This is known as 'the float test.'


2. How and when to feed your yeast starter

USE IF: you want to keep your starter active

AFTER YOU HAVE MADE BREAD: Feed the depleted sourdough starter water and flour, in equal parts.  The amount of water and flour needed depends on the amount that you have used for your last loaf and how much you need for your next loaf.  At home, I usually use 200 g of water and 200 g flour for most feeds, unless I am making a particularly large batch of dough. 

BETWEEN BREAD MAKING SESSIONS OR TWO DAYS BEFORE YOUR NEXT LOAF: Once you achieve a nice, active starter, you will want to keep it fed so that you can use it in your next loaf.  On each feeding, tip out a third of the mixture and add water and flour, in equal parts. The amount that you feed your starter depends on how much needed for the next loaf. Make sure that there is always enough sourdough to bake another loaf AND have some left over - never use all of the starter up when baking, or it will be have to be made from scratch all over again. 

3. How to revive your yeast starter 

USE IF: You've been given someone else's starter or you haven't fed your starter in months (I'd say if you haven't fed it at all for over 3 weeks)


Day 1: If the top of the starter is covered in a liquid or a crust, scrape this off the top.  Tip the rest of the yeast into a clean, sterilised container. Add in 200 g flour and 200 g water and mix until fully combined.  Cover and leave somewhere warm. 

Days 3, 5, 7:  Tip out a third of your starter, add 100 g flour and 100 g water and mix well. After the seventh day, your starter will be bubbly and ready for bread-making again. Test this out using 'the float test' (see: How to make a yeast starter...)

4. Troubleshooting Questions

How often should I feed my starter?

How often you need to feed it depends on how often you make bread. The rule that I generally go by is that, if I want to make bread on Wednesday, I will feed it on the Monday before, so that the yeast has time to do its thing.  However, this is only applicable for a starter that is being regularly fed, say once a week. If you haven’t fed your starter in a while, take a look at the next section... You always need to feed your starter after you make bread (see: How to feed your yeast starter).

Do I need to keep it in the fridge?

If you are making bread less than twice a week, then you should definitely keep your sourdough starter in the fridge. Let it come to room temperature before baking with it.

What if I don’t feed it?

Remember – water wakes up the yeast that lives on the flour, the flour provides it with food. If you don’t add in water and flour, it will starve then go to sleep. (But it won’t necessarily die…)


Is it dead?

Probably not. Yeasts are tough cookies. If it looks dead, try going back to the ‘How to revive your yeast starter’ and feed it up for a week or so until it is bubbling again. 

Seriously though, I really can't be bothered to feed it. 

If you aren’t going to make bread for ages or are going on holiday or really can’t be bothered to spend your life caring for miniscule organisms in your fridge, don’t worry. If we go by the principle that water wakes up the yeast and flour feeds it, then don’t add so much water into your mixture, so that it is less active, or 'awake.' Therefore, rather than creating a mixture made from 50% flour and 50% water, make a mixture that is, for example, 70% flour and 30% water and keep it in the fridge – the stiffer the starter mixture is, the less you need to feed it.  

What should it smell like?

Starter is a ferment, so it should smell similar to other fermented things like cheese, beer, wine, champagne. The best starter I ever made smelled like miso and there is a rumour in the baking world that The Ultimate Starter smells like bananas.  Starter can also smell quite floury at times, or like fruit - both of these are ok.  If it smells like mould or death, don’t bake with it - this is the only time I will tell you to throw it away. 

What’s this brown goo?

Very often, you will end up with a thin layer of brown or grey liquid sitting on top of your starter. It looks terrifying but, essentially, it’s hooch - pure alcohol that the yeast excretes (kind of like yeast wee).  But just because it's alcohol, doesn’t mean you can drink it - instead, just throw it away. 

How much yeast starter do I need for a loaf of bread? 

Recipes vary! Many recipes will ask you to make a 'leven' or a 'sponge' (see: below) using the starter before you make bread. I personally do not do this at home, and use 150% baker's percent straight sourdough starter - for those not familiar with the baker’s percent, that means for every 1000 g of flour, I would use 150 g of yeast starter (go back to Bitesized Baking and have a look at all the vlogs/blogs on the baker's %). 

I keep hearing other words for yeast starters, can you translate please?

There are lots of types of ferments used in bread making. A 'leven,' or a 'sponge,' is a sourdough starter that has been separated from the main starter mixture and fed with more water and more flour a day or two before bread production.  There is also 'biga' and 'poolish,' ferments made from dried or fresh yeast instead of natural yeast. The Mother or 'massa madre' are other terms for natural yeast starters.

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