One of the really useful perks of developing your understanding of sourdough fermentation is the ability to convert yeasted (whether fresh yeast, active or instant dry yeast) recipes into a sourdough version.

I find this useful for two main reasons; the first being that I now have a handful of ‘go-to’ options for using up extra sourdough starter from baking with, or feeding my sourdough starter, and the second being that the long, slow fermentation of the sourdough process makes a significant change to the digestibility and available nutrients of foods with gluten-containing grains in them.

Despite there being a plethora of information out there on the internet for various sourdough breads, the information is a lot thinner in other areas of baking. Once you understand a few key elements of how a sourdough culture behaves in different doughs and different scenarios, you can adapt any baked recipe to include sourdough fermentation!

Lesson #1 – TIME

When converting a recipe from yeasted to sourdough, you are always going to be significantly increasing the average time that a recipe will take to complete from initial mixing to final baking.

Whereas most yeasted recipes will call for a main fermentation (or bulk fermentation) time of around 30-60 minutes, a bulk fermentation in a sourdough dough is much more commonly in the range of 3-4 hours for a regular bread without sugars or fats (known as enriched breads), and can extend anywhere up to 6-8 hours for enriched versions (e.g. brioche).

Just remember that although more time is involved, it is not necessarily your active time. You’ll still be able to go about your life while the fermentation happens in the background! You’ll just learn to move more with the flows and rhythm of sourdough and most people find this to actually be an enjoyable thing as it forces them to slow down and remain more in the moment.

Lesson #2 – QUANTITY

Packaged yeast is like a huge spring-trap loaded up with ready-to-go yeast cells lying in wait for some flour and water to fire it into action. The moment they meet, activity begins at quite a rapid rate and within 30 minutes you could have a super bubbly dough with only a couple of grams of yeast. The quantity required to kick off a dough is very low, and you’ll often see formulas for breads such as pizza where it calls for making a poolish in advance by adding sometimes as little as 1 gram of dried yeast to 1 kilogram of flour – a measly 0.1% of yeast to flour ratio!

Contrast this with sourdough where the most common percentage used would be in the range of 15-25% of total flour. The activity which begins is more like an old car gently starting off at the traffic lights, gradually building up momentum over time. Despite using such a larger percentage, sourdough still can take 3-4 hours for bulk fermentation to complete compared to perhaps 30-60 minutes for the yeasted equivalent.

Lesson #3 – HANDLING

An act that has no place in the world of sourdough baking is a term I hear a lot in yeasted bread recipes: “punch the dough down”. Please don’t ever ‘punch down’ your poor vulnerable sourdough doughs down to deflate them (unless maaaaybe you’re making sourdough pita or another very flat flatbread, and even then a gentle rolling out with a pin is more friendly than beating the living daylights out of it!).

When I am making sourdough breads I approach the process as if I only have one chance to insert as much air into my dough as I can. While the dough is fermenting it is filling up with gas and in general I want to keep as much of this in as possible. Unlike in yeasted breads where the yeast activity is so super-charged that we need to keep de-gassing (or ‘punching down’) in order to not end up with a giant air bubble, in sourdough breads we want to retain most of the gases being developed. This obviously doesn’t apply in some scenarios such as pastas or flatbreads, but these can be gently deflated in the final stages of shaping in a much kinder way!

Lesson #4 – FATS & SUGARS

Just like when you eat a big/heavy meal and might feel a bit sleepy or sluggish afterwards, sourdough doughs become slow and sluggish when lots of sugar and/or fat is added to them too!

If you are converting a yeasted dough with sugars and/or fats in them, you will generally want to make two KEY adjustments to increase your likelihood of success:

1. Increase the % of sourdough starter used – more starter means more yeast cells and the more you’ve got in there (up to a point) the better chance of fermentation being sufficiently achieved. Consider using at least 30% of a ripe/mature sourdough starter when including sugars and/or fats in your dough.

• Convert a portion of your sourdough starter to a ‘sweet starter’ – this basically involves temporarily making a breakaway sourdough starter you will use in your dough. To this ‘rebel starter’ you will add your regular flour and water combination, but also incorporate sugar at a ratio of 28% sugar to total flour (so if you feed the starter 50 grams of flour you will also give it 14 grams of sugar). This feed is done as the final feed before using the sourdough starter in your dough, and really helps the cells in the starter adjust to the massive hit of sugar and fat in the dough by making it more osmotolerant (able to withstand osmosis).

Conclusion

Once you’ve gained some experience and confidence in making some different sourdough-fermented breads you’ll start to realise the options are limitless and you’ll be hunting around for recipes to upgrade your grain-based goods by fermenting them with a sourdough starter (and perhaps even adding in some more wholegrain flours – but we’ll get to that!).

Part of my goal on this blog is to share these recipes with you as I have a real interest in taking recipes that have been established as if they can/should only be made with rapid rising yeast, and convert them to a sourdough format, often with additional health improvements from fresh wholegrain flours, or substitutions to include more spelt flour (helpful for IBS sufferers and those with wheat sensitivity).

SUMMARY

Key adjustments to make when converting from yeasted to sourdough:

1. Ferment significantly LONGER – generally 3 to 4 times as long as you would with yeast.
2. Use MORE – generally ignore the yeast amount called for in the recipe and instead use your bakers % by looking at the total amount of flour called for, and multiplying that by 20% to arrive at how much starter to use.
3. Be GENTLE – no punching, kicking or headlocks please.
4. Adjust for SUGARS & FATS – Use even more starter if the dough contains sugar and/or fats and consider converting your starter to a sweet starter for better fermentation.

Shout out if you have any questions or want to run an idea for a converted recipe by me – I always love to discuss baking experiments!