Got some amazing research on sourdough starters for you that I really need to share. A fellow Dutch baking geek (Jan-Pieter) and follower of my YouTube channel has done extensive testing with two of his sourdough starters (bread flour starter vs. whole wheat starter).

He looked at the questions of: How much should your sourdough starter increase in size before you use it? Some people claim their starter triples, quadruples in size - is that really required? And what about the feeding ratio of your starter? Furthermore - what about the flour that you are using? There are some really cool implications and I wanted to share them with you.

TLGLDR (Too long, get lost, didn’t read 🤣) - A whole wheat starter reaches its peak performance faster than a bread flour based starter. The peak is individually dependant on the flour that you are feeding. Measure your own personal peak, you can start using your starter already before you reach the peak. You need to find a balance between slow and fast fermentation.

Let’s first have a look at all purpose starter:

Next up a whole wheat starter, fed in advance for several days only with whole what flour:

Going back to the all purpose starter - growth checkmarks:

Same for the whole wheat starter:

Why does your dough increase in size and then collapses?

The peak of your starter depends on the flour that you are feeding. To understand this - we need to have a closer look at what’s happening behind the scenes. Your flour contains enzymes and a very important one is called “Amylase”. Amylase is activated the moment your flour comes into contact with water. Amylase starts breaking down complex sugar molecules into easily digestible sugars. This is because the seed needs the sugar for starting the germination process. Your tiny sourdough army consisting of billions of yeast and bacteria love this. They enter a crazy munchymode with the sugar now being available. They start producing CO2, ethanol, lactic and acetic acid.

Interesting thought by the way - if you were to ferment your dough without oxygen, you might only be producing alcohol. Just like when you make beer, oxygen will make your yeast produce acidic components as well. That’s why you always make sure that your beer ferments without oxygen. Great idea for an experiment 🤣. Okay, back on topic 🤣. Another enzyme is present “Protease”. Protease loves gluten, especially chopping it down into pieces. That’s why a long fermented dough might subjectively feel more digestible than a short fermented dough (research needed). The protease and lactic plus acetic acid are the main factors for your dough to collapse in size at some point.

Just test yourself, a plain yeast based dough can increase in size much more than a sourdough based dough. That’s because a yeast based dough doesn’t contain as much lactic and acetic acid. Ultimately the inflated gluten can no longer hold its structure and will then collapse. Your peak has been reached.

Importance of the peak

Now how important is the peak height really? I don’t think it is. I challenge you to try the following: Simply try stirring your starter for 5 minutes instead of just 1. You will see that you will have a higher peak, rather than doubling, it might be tripling. That’s because you developed your starter’s gluten network more. Has this positively influenced your starter’s performance? Nope.

What about the peak of your starter? Yes - that’s another story. You should measure your individual peak. You can influence when it happens by adjusting the feeding rain of your starter, just like Peter suggested. A 1:1:1 ratio would be 40 grams of starter, 40 grams of water and 40 grams of flour for instance. A 1:5:5 ratio would be 40 grams of starter, 200 grams of water and 200 grams of flour. In the 1:1:1 mixture you start the fermentation with more bacteria and yeast in comparison to the 1:5:5 ratio. This means - your sourdough dough will ferment faster. However - you also introduce more long prefermented flour in the final dough mix. Taste wise - that’s a good thing, however, you also introduce more lactic and acetic acid. This means, that your dough’s properties when handling might worsen faster in comparison to when you have used a starter that was fed at a higher ratio: 1:5:5 or 1:10:10. Your main dough will ferment faster though with a 1:1:1 ratio as you introduce more yeast and bacterial colonies. At the same time however, your flour might not have broken down properly as the amylase didn’t have enough time yet to split up the sugars in your dough.

A slower fermentation with the 1:5:5 starter will compensate for that by requiring longer to ferment overall, but then also fermenting long enough for the amylase to do its job properly. The fix for a 1:1:1 starter is typically to do a longer autolyse (just mixing flour and water in advance). In my experiments I could not notice a major difference in an autolysed dough and a non autolysed dough when my fermentation times were at 10-12 hours with my 1:5:5 starter. What I like about the 1:5:5 / higher feeding ratios is that you have more room for error. With a 1:1:1 starter your fermentation you will reach the peak of the curve very fast. Your main fermentation is also quicker. With the 1:5:5 starter you are delaying your peak a little bit, the curve is not as steep as the research by Jan-Pieter has shown.

Generally speaking - I would use a feeding ratio that works for you in your environment. In summer I would ready my starter over night at a 1:20:20 ratio. That way I could go to bed and have a ready starter in the morning. Now in winter times, I sometimes go for a 1:3:3 ratio because my overall fermentation process is slower.

Use your starter before the peak

Now looking back at the peak. I’d say its safe to use your starter before it reached its peak. Your starter will continue to replicate and grow inside of your main dough. However - your overall fermentation is not going to be as quick. At some point your protease has broken down your gluten too much and your dough will lose its properties for oven spring. But at the same time, you need time or else the amylase hasn’t broken down the sugars enough for your starter. You need to find a balance. If you are using your starter past its peak - you might run into the issue of introducing too much acetic and lactic acid into your main dough, having negative properties. So as far as I can see and based on the experiments I conducted, use your starter earlier rather than too late.

Whole wheat vs. all purpose/bread flour starter

Now why does a whole wheat starter reach its peak faster compared to a bread flour starter? The bran and other parts of your seed contain nutrients that are required for your sourdough starter. This means a whole wheat starter has better conditions to replicate initially. However - you also don’t have as much gluten inside and thus your starter can’t be inflated as much compared to a bread flour starter. Furthermore a bread flour starter in comparison has more sugar available after the amylase created it. Imagine rocket fuel being created. Now what’s better? I guess it depends on what you are trying to bake 🤣. Plus as explained before a fast fermentation is not necessarily better.

Thanks again Jan-Pieter. You rock!