What is bulk fermentation?

Bulk fermentation (also sometimes known as primary fermentation) is the first fermentation of all your ingredients at once. The bulk ferment can be as long or as short as you like, depending on the amount of starter or pre-ferment in the recipe, and your schedule.

For scheduling purposes, bulk fermentation and proofing can be looked at as all part of the same process: if you’ll be away from the kitchen and need a longer proofing time, do less bulk fermentation. If you need proofing time to be minimal, then you can get away with bulk fermenting for longer.

How to tell when your dough has had enough bulk fermentation

One way to tell whether a dough has fermented sufficiently is to take a small piece of it as soon as it’s mixed and place it in a small glass jar. Pack it down to remove any air that’s in there and keep it close to your main dough. While the main dough ferments, you can check every now and then on the glass jar and look at the sides of the jar. If you like, you can place a rubber band around the original level of the dough in the jar, to see how much it has risen.
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Lower hydration doughs will have less bubbles, high hydration doughs more. The rubber band will show you how much it has risen. Rising to around 1 1⁄2 times its size is a good amount of fermentation to aim for with a 100% whole wheat bread.

Other ways to look at whether dough has fermented are to do with the smell of it, the feel of it, and whether it looks to have risen.

Get used to smelling your dough throughout the fermentation process – at first it will smell like raw flour, and later on it will develop the smells of sourdough bacteria and yeasts. Poke at your dough while it ferments and feel the resistance of it against your finger. At first it won’t feel like it has any air in it, later on it will feel soft and pillowy. Observe the size of the dough when it first starts fermenting, and then you may notice when it has grown significantly.

If you are fermenting in cooler-than-ideal temperatures, your dough might not appear to rise much at all. Rely on your sense of smell, also give it as much time as possible, and try to move it to a warm place if it seems to be taking way too long. There are some tricks you can use to help get better fermentation in cold kitchens, I go into far more detail about working with cold (and hot) room temperatures in my book.

Some bakers put a small piece of dough in a bowl of water, and if it floats, it’s ready. In practise, it’s really difficult to get a piece of dough without deflating it, and 100% whole grain doughs usually sink anyway, so I don’t think this is a reliable way to assess fermentation.

When doughs made mostly from wheat have successfully bulk fermented, they will have risen and become rounded at the top. This is most noticeable if you are using a mixing bowl with just enough capacity for the finished dough (ie. 2 litres (quarts) of bowl space for every 1kg (2 pounds) of dough) – if there’s a tea towel draped over the top, it will rise and you’ll see the rounded outline of the dough.

If you are working with a larger bowl, look to the edges of the dough – does the surface of the dough round upwards at the edges? Does it appear to have expanded? Does it feel like it is full of air when poked?

Overfermentation, underfermentation, and making a sourdough schedule that works for you

Once the dough has bulk fermented, there is a window of time before it becomes overfermented. There will be a longer window in cooler temperatures, a shorter one when it is hot.

When dough is overfermented, it will no longer appear domed on the top, but flat and collapsed. It will be sticky and difficult to shape.

If I’m having a busy day and am not around to check on the dough often, I will often shape and proof the dough when it is slightly underfermented and proof it for longer, rather than risking overfermentation during the bulk ferment.

There’s a balance to be found between underfermenting, where maximum flavour will not have developed, but it will be easier to shape and get a nice colour when baked, and overfermenting, which can have lots of flavour (sometimes too much sourness for some tastes), not enough caramelisation, and it is trickier to shape.

I prefer to err on the side of “not fermented enough” rather than overfermented when it comes to bulk fermentation. Overfermented dough is difficult to shape. Slightly underfermented dough is easy to shape, and can simply be proofed for a bit longer.

Making bread is something that has to work with my life, and not the other way around. By seeing bulk fermentation, proofing, and oven spring as three parts of a whole fermentation, it makes it easier to fit sourdough into my schedule, and to make quick decisions about whether to shape the dough early or not.

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May your sourdough be perfectly fermented. Floury regards,

Kate

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