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Organic San Francisco Sourdough Starter

Organic San Francisco Sourdough

Organic San Francisco Sourdough


£5 OFF by paying with Moona

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Organic San Francisco Sourdough Starter

Sourdough is made from the naturally occurring yeast and lactic acid bacteria in flour. It is often also used to name breads made using the culture. Yeasts and bacteria suitable for bread production are found in relatively high amounts on the surface of cereal grains, such as wheat. By grinding the grains into flour and allowing these micro-organisms to thrive – by adding water, keeping the mix at an appropriate temperature, and providing food in the form of more flour to create what is known as a ‘starter’ – they can be increased in size and concentration.

Our Sourdough comes sourced from starter cultures that have been in use for over a century. A mature, well-aged sourdough starter has a much stronger and distinctive sourdough flavour than one recently started from scratch. We have worked hard to obtain the very best sourdough from across the world. We feed our starter cultures twice a day; ensuring that what you purchase from us is a very active, starter culture.

San Francisco is legendary across the world for its sourdough. It contains a specific strain of bacteria- L. sanfranciscensis. Local bakers, including Boudin founded in 1849, swore that no one could reproduce it outside a 50-mile radius of the city – thus adding to its allure. The San Francisco foggy climate cultivated this specific type of yeast, which scientists have now identified in a number of places around the world. However, the strain of bacteria is still named after San Francisco, where it was first discovered.

Our San Francisco sourdough starter comes direct from the Fishermans wharf area. Although its heritage has not been officially confirmed, it is likely to have come from the original Boudin bakery starter culture. It produces a very distinct flavour and is a firm favourite of ours. We absolutely love it! Due to its tart, almost vinegar-like flavour, bread and pizza baked with this starter won’t be to everyone’s liking.

Learn how to bake San Francisco sourdough bread using this wonderful starter and our recipe that can be found here.

Allergens – Contains wheat.
Each pack contains 150g of fresh/wet sourdough starter.

Recommended activation date for culture:
15 days from the date of shipping. Best stored in the fridge if the product can not be activated on arrival.

Open printable PDF file

Please note that we do not send printed copies of instructions with your purchase. If you would like to have a printed version, you can open a printable PDF by clicking here.



If you have more than one fermenting food culture at home, we recommend that you keep them at least 1 metre apart from each other at all times. This is to stop cross contamination of the different cultures. If you are working with dairy in particular, this is very important. Please contact us is you require further assistance with fermenting more than one culture.

What to do once your Organic Certified San Francisco Sourdough Starter arrives:

If the sourdough can not be activated on arrival, store it in the fridge until the suggested use by date. Sourdough has a very good success rate.

What equipment do I need?

Glass jar with a sealable lid. Clip top kilner style jars work great.

What ingredients do I need?

Water and Sourdough

We use filtered, non chlorinated water with our sourdough. Some people use tap water and have no problems. The old saying “If it’s good enough to drink, it’s good enough to make bread” seems to work out for most people. We have also heard of people who have had problems with chlorinated tap water. We advise that you remove chlorine from your water when possible. You can leave tap water standing overnight to remove the chlorine or boil and and it allow to cool down again. Our preference as stated, is to use a charcoal based water filter such as a Brita.

What kind of flour to feed your sourdough:

  • San Fransisco – Plain white flour
  • Alaskan – Plain white flour
  • Hampshire White – Plain white flour
  • Gloucestershire Rye – White or wholemeal rye flour
  • Colorado Brown – Plain wholemeal flour

Activation Process:

IMPORTANT! These instructions are for our fresh/liquid sourdough starters. If you have one of our 5g freeze-dried starters which comes in the credit card-sized box and silver sachet, please follow the freeze-dried starter instructions also found on the instructions page.

Get a container that can be closed with a lid (glass jar, Tupperware, etc.). Wash it out well with hot water and a little soap. Allow the container to cool down if it is hot, then add your Sourdough.


Mix 75g of flour and 75g of water (weigh the water) into your starter and stir well. Ensure the type of flour you add matches the type of sourdough you have purchased (eg rye flour with our rye sourdough starter). Seal the lid on the jar. Remember, the starter will produce CO2 so pressure will build up in the container if closed tightly, so watch out when you open it again. Leave the Sourdough at room temperature for 24 hours.


Discard 150g of the starter. Feed the Sourdough again with 75g of flour and 75g of water on the second day and leave it for another 24 hours. After this, the Sourdough is activated and ready for use. If you want to bake with it, we recommend discarding another 150g of the starter and feeding once again with 75g of flour and 75g of water 3-4 hours before you plan to use it.

Fermentation Process:

As a rule of thumb, each time you want to feed the starter. weigh it and double its weight with 50% flour and 50% water. For example, if your starter weighs 300g you would discard 150g so that you are left with 150g. Now feed with 75g flour and 75g water so that your total starter is 300g again.

Sourdough is a very hardy culture. As long as you feed it water and flour on a regular basis it will survive. If you overfeed, underfeed or even forget to feed your sourdough. Don’t panic, it will be fine.

It can feel wasteful discarding so much sourdough. However, if you don’t discard any prior to feeding you will have to give it much more flour and water with each feed. This is because the volume of starter is increased with every feed which results in more yeast cells requiring more food. For example you take your 300g starter and don’t discard 150g, you will need to then double the amount of water and flour. So instead on 75g of each you would need to increase that to 150g of each. Over time, you will work out a regime that best suits your baking needs.

For the best success baking with sourdough, feed the starter at least 3-4 hours before working with it. Ideally, feed it once the night before and again 3-4 hours before using it.



My sourdough does not rise and looks very watery.

We recommend a 2:1:1 hydration method for our sourdough starters using pain flour. This equates to a very thin, liquid starter that does not rise much in the jar.

Over time, we have found this the best method for working with a starter. A rising starter will often spill out of the jar making a mess of its surroundings. Long term the 2:1:1 hydration method makes starter maintenance much simpler. If you would like to test the rise on your sourdough, simply use a 1:1:1 ratio using strong bread flour. So take 100g of starter and feed it 100g of strong  bread flour and 100g of water.  It should be a thick paste.

If you are using a rye or our gluten free starter, please use a 1:2:1 ratio to test rise. Take 50g of starter, add 100g of flour and 50g of water. It should be a thick paste.

Seal the jar and leave it the warmest place you have. You should see it double in size over 4-10 hours depending on temperature.

Although our 2:1:1 hydration method does not make the starter rise, this does not mean it is any less effective for baking. The starter should still show signs of activity in the forms of gas build up (bubbles) and smell (sourness).

Please note some of the images of sourdough used on the website are of a 1:2:1 hydration method to show the effect of the sourdough rise.

Working with Sourdough

Sourdough is a very hardy culture. As long as you feed it water and flour on a regular basis it will survive. If you overfeed, underfeed or even forget to feed your sourdough. Don’t panic, it will be fine.

You will find lots of different ways to keep a starter and use it. Each method with its own pros and cons. For the general weekend baker, they would keep the starter in the fridge. Removing it on a Friday evening, discarding some and feeding it fresh flour and water. Then on Saturday refreshing again 3-4 hours prior to baking. Once done, you simply replace whatever starter you have used from the mother jar by refeeding it and then popping it back into the fridge until next time.

It can feel wasteful discarding so much sourdough. However, if you don’t discard any prior to feeding you will have to give it much more flour and water with each feed. The larger the volume of starter you have, the more you will need to feed it to increase activity. You can also find many great sourdough discard recipes online. Everything from pancakes to crackers.

It can seem a lot of work looking after a sourdough starter, and it is easy to see why bakers yeast quickly became the preferred method of baking bread. Once you find your baking regime though, sourdough really isn’t that much effort to work with and the results are much tastier than any yeasted bread.

Storing your Sourdough

If you’re not baking every week and don’t want to feed your starter every day, you can keep it in the fridge. It is best to feed your sourdough every week. Even if you feed it and then return it back to the fridge without using it. This keeps it in good health long term.

If you forget to feed the sourdough in the fridge, don't panic. The low temperature of the fridge will make your starter inactive. It can sleep in your fridge for a long time. Generally up to 6 months. We have heard of people managing to store it in the fridge for over a year without feeding! However we always recommend as stated above that you feed your refrigerated flour sourdough weekly. It will keep it in the beast health and produce the best results when baking.

Always give you Sourdough a good feed before putting it into the fridge.

Sometimes some of the mixture can separate, leaving a layer of liquid on top (grey brown). This is normal, simply drain off and discard any liquid before use. You can also stir the liquid back in if you wish. The liquid is often very acidic. Leaving it in the sourdough starter will make a much more sour tasting product when baked with. If you like your sourdough bread with a tang, we recommend leaving the liquid rather than discarding it.

To use Sourdough that has been in the fridge, simply repeat the activation process. It will usually need 48 hours and a couple of feeds to become fully active again. You will need to prepare for this additional time when baking. For example, we take our sourdough out of the fridge Friday morning and feed it. We then feed it again Saturday morning and bake with it Saturday afternoon.

Can I feed my Sourdough starter a different type of flour?

Technically, you can use any type of flour with our sourdough starters. However, we have what is known as heirloom varieties of sourdough. This means that for generations they have only ever been fed with a specific type of flour. When you introduce a new type of flour, you also introduce different types of naturally occurring yeasts and bacteria specific to that type of flour. This changes the original profile of the original sourdough and that process can never be undone.

What if I want to bake with a different type of flour?

Sure, you can simply remove an amount of sourdough starter from the mother culture and then mix that with whatever flour type you want to use for baking. For example: The rye starter works very well with spelt flour. As long as you ensure your Sourdough mother itself remains fed on the intended type of flour, you're free to use whatever flour you wish to use for baking.

What can I make with it?

You can make all kinds of things with Sourdough. Bread is the most common use. If you want a really easy way to make sourdough bread that doesn't require any bread making skills, try our no knead dutch oven method found on our blog.

Will the natural bacteria present in the flour eventually override the native ones?

With our non-UK Sourdough starters, over time, the bacteria present in the flour and naturally in the environment will take over these starters and change the bacteria makeup. Although this will not affect the baking, it will alter the flavor.

We recommend freezing some of your starter from the original mother batch and every 6-12 months defrosting it reverting to the original version discarding the old starter. This will ensure you always have the bacteria you desire in the starter.

Can I freeze my sourdough starter?

You can and we always suggest making a backup starter to keep in the freezer. Sourdough freezes very well and revives quickly once defrosted.