Ooooooh, fire brick. Very nice.
Those should work beautifully for pizza. What's the thickness of your current stone? 1/2"? 3/4"? If it's 1/2, then you should see a pretty dramatic improvement. If it's 3/4... it won't be a huge difference, but you will see an improvement. I was just brushing up on the technical specs of fire brick vs baking stones tonight. Baking stones tend to have better conductivity, but fire brick has all that beautiful thermal mass.
Because of it's lower conductivity, fire brick will take longer to pre-heat, but once it's pre-heated, it will hold it's heat for a while (it should resolve your recovery concerns). Although an hour and a half might be a little overkill for a 3/4" stone, I'm certain you're going to need it for the brick. How concerned are you by large utility bills?
The first time you bake with the brick, you might want to go with 1 hour 45, see how it goes, and then dial it back.
550 is the absolute highest your oven will go, right?
Low alumina firebrick (the kind you have) tends to be fairly gritty and rough, so I like to hit up the baking side with a little coarse sandpaper. After I do that, I wash them vigorously with clean water, let them dry, arrange them in the oven and then bring them up to temp extremely slowly. Bakingstone.com has a pretty good guide for curing new stones.
Are all those bricks yours? If you have enough, you definitely want to go with two shelves (hearth and ceiling). You might have to play around with the height of the ceiling, but I would go with 10-12". Make sure you're comfortable launching and retrieving pies in whatever vertical space you create, though. Arrange the stones so that they are flush with each other and flat. I used folded up aluminum foil to prop up some bricks that were a bit low. A level helps. Keep an eye on your oven shelf and make sure the weight isn't stressing it/making it sag. I don't think you'll have a problem with one layer, but it's still something to be aware of. A fire brick deck can add up in weight.
I had to cut my bricks in order to form them into a 16" deck (to fit my 17" deep oven). Since I didn't have equipment myself, I had the store where I bought the bricks cut them for me. It cost more for the cutting than it did for the bricks. Hopefully your oven will be a little more accommodating.
According to Professor Raymond Calvel, in his book The Taste of Bread, at page 57:
"...in the final analysis the pH is related to the level of residual sugars present in the patons just before baking. These residual sugars are the remainder of those that fed dough fermentation, and they fulfill important functions during the baking process. The level at which they are present plays an important role in determining the extent of oven spring during the first moments of baking. They also contribute to the Maillard reaction and caramelization phenomenon that produce crust coloration.
Generally a below-average pH coincides with a lack of residual sugars, which translates into a deficiency in oven spring. This problem is evidenced by a slight decrease in loaf volume and in the end by a lack of crust coloration accompanied by excessive crust thickness. The bread will also exhibit a significant lack of aroma, the crust will have less taste, and the crumb will be slightly less flavorful."
Peter, I could be wrong about this, but I've always perceived there to be two different processes running synchronously yet somewhat independently in dough- yeast activity and amylase activity. The amylase activity seems to do it's thing the moment water enters the picture, and, (I think) continues to do it's thing somewhat consistently through changes in temperature (ie refrigeration). The yeast, on the other, slows down as the temperature drops. That's the beauty of cold fermentation- you're handicapping the yeast while the amylase is creating all that delicious and maillard friendly sugar.
Acid, specifically carbonic acid, is a byproduct of yeast activity. In theory, I would think one could do a fairly warm fast ferment that produces a dough with the same pH as a dough cold/slow fermented for a far longer time, but, because of all that amylase activity during the cold ferment, the residual sugar would greater. Same pH different levels of sugar.
Maybe. I feel very confident talking thermodynamics, and, to an extent rheology, but microbiology and enzymes, not so much. For a product with such few ingredients (bread) it's mind boggling how complicated it is.
Regarding amylase, your post in another thread about autolyses really opened my eyes. I was, up until today, in the erroneous autolyse includes yeast camp. I'm not sure where I picked that up. Since an autolyse is just flour and water, might that give the amalyse activity a bit of a head start?