- wholemeal organic bread flour
- A lidded plastic container, preferably one that’s fairly shallow and wide with an airvent in the top, eg Sistema 525ml Rectangle Microwave Container
- Digital kitchen scales
- Day 1: Place the container on top of the scales and add 10g flour and 10g water. Mix together with a spoon or your finger. Put the lid on the container but keep the vent open to allow some airflow. Leave in a warm place, away from draughts.
- Day 2: Add another 10g flour and 10g water, mix and leave as before. This is called refreshing the starter
- Day 3: Refresh with another 10g flour and 10g water.
- Day 4: Increase quantities — refresh with 20g flour and 20g water.
- Day 5 onwards: Hopefully you should start to notice bubbles forming in the mixture overnight, indicating that the yeast in the flour is becoming active. If not, keep refreshing with 20g flour and 20g water every day until bubbles start to form.
- If nothing has happened by Day 10, then give up and try again with a different brand of flour.
- Once the mixture roughly doubles in volume between refreshments (it might rise and then fall back, so look for a “tide line” in the container!) then the starter is ready. If necessary, do one final refreshment with enough equal parts flour and water so that the total amounts added since the beginning are at least 100g flour and 100g water making at least 200g starter in total. That should give you enough starter to use in one of my standard recipes, while leaving enough to be able to refresh for next time. Leave overnight to rise and then place in the fridge until you are ready to use it.
Notes and Explanation
The yeast in sourdough comes from the natural yeasts present on the outside of the wheat seeds as they grow in the field. When the wheat is milled, yeast spores remain in the flour ready to become active again when you add water. In the wild, yeast lives on the surface of things. It breathes in oxygen and breathes out carbon dioxide, just like us, so it needs access to air to thrive. That’s why I prefer a container with a large surface area and an air vent to hold the starter, because it helps the yeast to stay active without drying out too much.
Sourdough is sour because of lactic acid bacteria which also grow naturally in the starter and which compete with the yeast for the sugars in the flour. These bacteria don’t need direct access to oxygen to grow, but they produce lactic acid which turns the starter sour and makes conditions less favourable for the yeast. Keeping the starter refreshed and well aerated helps the yeast to compete with the bacteria and control the acidity.
Organic flour may have more active natural yeast because it won’t have been sprayed with fungicides before harvesting. White flour may contain less natural yeast than wholemeal flour because the yeast on the seed husks will have been sifted out. Different brands of flour will have come from different farms and will have different varieties of natural yeasts within them. Some of these varieties may be better suited than others to the particular conditions in your kitchen. It’s worth experimenting with brands of flour until you find one that works for you, then stick with it. If you later change the brand of flour that you use for refreshing the starter, then you may find that its character (smell, taste, and activity level) changes - this is not necessarily a bad thing, but just something to be aware of.
Using wholemeal flour to refresh the starter keeps the yeast active, but it means you will end up with a certain proportion of obvious wheat bran in any bread you make with it. I don’t mind this, but if it bothers you, take out a small portion of the starter into a separate container and refresh it a couple of times with white flour before using it in your recipe, to dilute out the bran. Alternatively, seive out the larger flakes of bran from the wholemeal flour before using it to refresh the starter, to make it less obvious in the finished bread.
Keeping the sourdough starter in the fridge between uses seems to work fine. There is no need to keep refreshing it every day (or roping in friends to babysit it while you go on holiday!) The yeasts and bacteria become mostly dormant (but still viable) at fridge temperatures and the starter will remain consistent and usable for several weeks.
After a few days in the fridge, you may notice a dull bloom on the surface of the starter, which is actually a layer of dormant yeast. When I use the starter for baking, I make sure I include all of this top layer so that the dough will rise as well as possible. If you leave the starter in the fridge for a long time without refreshing it, then it may start to go mouldy. Don’t panic - just scrape away the layer of mould and move the healthy starter underneath to a clean container. Refresh it with new flour and water for a couple of days while leaving it out of the fridge and it should get all its vigour back. You can also freeze the starter if you know you’re not going to use it for a long time, or simply to have a backup supply.
When you’re ready to bake, there is no need to warm the starter up before using it - just add the right quantity straight from the fridge into your dough mix, and then refresh the remainder in the starter container with a 50:50 mix of flour and water to the same wieght that you removed for the recipe. Keep the starter container beside your dough as it proves, and you should see the refreshed starter begin to bubble and rise. When you put your bread in the oven, put the starter container back in the fridge, ready for next time.
That’s it! You will see all sorts of different recipes for sourdough starter which can make it all seem very complicated: different ratios of flour to water; fruit and other ingredients added to the basic flour/water mix; using only bottled spring water; complicated refreshment schedules. I’ve tried to reduce it down to the simplest possible and least stressful method and it works for me, but as they say: “your mileage may vary”!
A final word of warning: you often see arty pictures of sourdough starters overflowing out of the top of glass Kilner jars. NEVER keep sourdough starter in a sealed glass container - it could explode and shatter dangerously