what's happening in the first few minutes of baking
Dear bread experts,
Being a bread baking amateur, I only have a rough idea about what's happening in the first few minutes of baking:
- internal temperature rising, but should not be able to reach the oven temperature
- yeast may die within minutes
- water in the dough begin to escape in the form of steam
- CO2 that has already been generated in the second proofing begin to rise up, and can be trapped inside a well-formed gluten network, or may otherwise just escape the dough
but I think my understanding is quite vague, especially I'm not sure if the yeast can still generate a meaningful amount of CO2 during their limited remaining life. If during this limited time, the yeast can not generate a meaningful amount of CO2, then what we are relying on to get an oven spring is the CO2 already generated in the second proofing stage. Following this logic, I think having an optimal 2nd proofing is crucial for a good oven spring, besides other factors like strong gluten network, and good surface tension...
Can someone correct my thinking? Thank you！
Cheers!
Liming
Hey Liming. Sounds like you want to start down the scientific path of bread. Awesome!!
If you feel you are ready I would recommend buying Jeffery Hamelman's book "Bread", the updated version. It will give you all the information you seek.
Cheers!
Dave
by Emily Buehler is a book I've seen mentioned numerous times Although I admit I haven't read it, based on what people have said about it, I suspect it has the info you want and more.
The book with the best descriptions I have found is "The Bread Builders" by Niel Wing and Alan Scott.
For example, they say that 25% of oven spring is due to expansion of CO2 in the cells, 20% is due to migration of CO2 in to the cells, almost 50% is due to boiling of alcohol into cells. The rest comes from steam and a little bit of additional CO2 from the yeast. And they give a detailed description of the whole baking process.
You have asked a very good bunch of questions. Here is my understanding:
In general, metabolic processes speed up as temperature rises, until the temperature is high enough to denature protein. This applies to lots of processes in bread but, especially, fermentation. So, in the early minutes of baking, fermentation rate increases. That produces CO2 and alcohol. The alcohol evaporates. The CO2 makes bubbles. If your mixing/kneading has produced a good gluten framework, the CO2 is trapped in the alveoli (air cells) of the dough. As with any gas, it expands with rising temperature, and because this is a physical effect, not a metabolic effect, it continues to expand until limited by crust formation. (That's why delaying the crust formation by starting in a humid oven helps oven spring.)
Now, water does evaporate from the loaf surface, and insofar as it is in a gaseous state, it also expands in the alveoli, contributing to oven spring.
The majority of fermentation occurs during bulk fermentation and contributes the largest part of alveolar formation. Some occurs during proofing and some more during the first part of the bake. Each stage is important for getting the best product.
So, the short answer is that there is indeed significant fermentation during the first minutes of the bake, but the bulk of fermentation occurs during bulk fermentation. And the even shorter answer is "everything is important."
Happy baking!
David
thank you all for your book recommendation and for your sharing of knowledge !
I will get one to make myself really technically equipped. :)
cheers!
liming
I think every book suggested here is a good one. Bread science does a good job with the specific questions you have.