How to Make Sourdough Yeast from Scratch
If a panettone or sourdough bread project is in your future, you'll need to make your own sourdough yeast! It's a very simple process, but takes time and patience. Be aware that the yeast will need to mature for at least one month before bread making can be attempted.
To start your yeast, you will need:
- A large, wide-mouthed glass jar
- A rubber band
- 100g all-purpose or bread flour
- 50ml water
In a bowl, mix the flour and water until a dough forms. Transfer the dough to a clean work surface and knead until smooth. Place the dough into the jar (make sure it's clean and dry!) and cover with the cheesecloth and a rubber band.
Keep the jar in a warm place for two days. After two days, the dough will begin to smell sour and develop bubbles inside. The fermentation process has begun and it's time to start feeding the yeast!
To feed the yeast, begin by removing it from the jar. A sort of crust will have formed on the outside, which should be discarded. Weigh out 50g of the soft interior and discard the rest. Combine the 50g of yeast with 50g of flour and 25ml of water. Knead into a dough as before, place back into a clean jar (we recommend cleaning the jar with water and no soap), cover with cheesecloth and place in a warm location.
Repeat this feeding process every two days for the next two weeks.
After two weeks, begin feeding the dough every day for a further two weeks. At this point, your yeast should be ready to use for baking. Don't worry if it takes more or less time, though! Many factors can change the speed of this natural process. A good sign is when the dough rapidly grows after feeding. If it doubles in size 4-5 hours after being fed, your yeast is very strong!
Once your yeast has fully developed, you're not going to want to continue feeding it every day! At this point, you can keep it in the fridge and, because the low temperature slows the fermentation process, you can feed it every three days. For example, you can feed it on Monday, Thursday, Sunday, Wednesday, etc.
To cook with the yeast, be sure to follow the specific guidelines in a given recipe for taking the yeast out of the fridge and re-feeding it prior to baking!
Tips & Troubleshooting
If you have a fruit bowl, try placing your yeast jar close by! The fruit actually produces bacteria that will help the yeast to grow.
The smell of the yeast should be sour but not revolting (think plain yogurt). If your yeast becomes too acidic, try soaking the 50g to be fed in a mixture made with 1/2 liter of water and 1 tbsp of sugar for 30 minutes prior to feeding. Reweigh it and discard yeast until you arrive at 50g again. Proceed with feeding as usual.