"Active cooling", a path to a crispier crust?
I do most of my bread-baking in a convection oven. I have been pleased with the flavor and textures but have been frustrated by my lack of consistency in obtaining crispy crusts when desired especially with baguettes. I have tried the method of "declining oven, door ajar" but this has not consistently helped. After following some recent threads here on the subject, I decided to try something new. So far, in very preliminary testing, I have been quite pleased with the results and wanted to share them with the community.
I am calling the process "active cooling" and quite simply it involves, at the end of the bake, leaving the loaf in the convection oven at the final baking temperature with the convection fan still turned on, opening the oven door about halfway, and letting the loaf cool for five minutes or so in the oven, at which point it could be removed for cooling on a rack. What I found was that, if the crust was hard at the end of the normal bake, it would stay that way during the active cooling and for multiple hours afterwards. Despite the extra time in the oven during the active cooling, there was no significant further darkening of the crust (as would be expected with merely prolonging the baking time) and the crumb stayed as moist as ever.
My theory on why this works is mostly speculation based on a few observations. I noticed that when my baguettes were removed from the oven for cooling on the rack, they would lose 2-3% of their weight over the next hour, most likely representing water loss. From what I have read here, it is this water migration from inside to outside that causes the crust softening. When doing the active cooling, I measured the weight change over the five minutes of active cooling minute by minute. Here is one of my loaves (Loaf was baked at 450° for 15 minutes. 15 min marks the start of the active cooling. Results are loaf weight in grams. Formula is Hamelman's Baguette with poolish):
@20 min=267.8g. Take out of oven for passive cooling.
After 1.5 hours more out of oven =265.6g
It seems like the total water loss of ~7gm is virtually the same as with rack cooling but that the active cooling speeds up the process markedly, possibly in a wicking-type process. Maybe, this moving water thru the crust more rapidly diminishes the softening action.
I realize that all this is based on very limited observations as I have tried this with only two very different baguette formulas but the results were so striking that I wanted to pass it along. I also realize there are many variables in the process including optimal active cooling temps, length of cooling time, applicability to different formulas and ingredients that need to be worked out. I would be very interested in fellow tfl'ers' thoughts on the process as well as their experiences if they try it with their own ovens.