I'm doing some computer work for a local engineering firm that specializes in heating ad AC systems. They design and sell a lot of steam boilers and are very familiar with the industry and the sub specialty of bakery's. I noticed a client name that I recognized as a old name in the community that is a well known bakery and asked what they were doing. I was surprised to find they were working on the steam system for a large commercial tunnel oven.
According to my friend, the steaming method used in these ovens is a closely guarded secret or at least not well known. The oven they are installing is an Italian model and they don't provide any information what so ever regarding steam. Nothing about sizing of nozzles or flow rates or length of the steam blast is part of the information from the manufacturer. Apparently this is a common situation they run into often.
The interesting thing I learned that will be of interest to Fresh Loafers is that they purposefully make a wet steam. I have noticed when using my hand held steam generator that the first few seconds of the output, when the pressure is highest, the steam is quite dry. Gradually as the pressure goes down it begins to spray a mist of wet steam and it seems like it is spritzing a little water along with the steam. I read somewhere that the benefit of using a steam generator was that it does produce a dry steam which is beneficial to the process. Now I'm questioning that belief.
If the point of steaming is to moisten the surface of the dough to aid in gelatinization of the surface so the spring will be more effective and give the surface a nice shiny surface, well then a moist steaming would be better I would think. My friend says he has installed many of these and that's the way they all are, at the insistence of the baker.
So, what does this mean to us? The procedure that Hamelman suggests is adding water to the pan in a quantity that is more than what will be boiled away in 10 or so minutes, then removing the pan to stop the steam effect. This sounds to me like it would produce a wetter atmosphere than a smaller amount that would be gone in a few minutes or my usual 10 seconds of high pressure dry steam. I'm thinking that releasing the dry steam from the steam generator and using the wet secondary steam would produce a better result. I have been doing the opposite.
I hope I'm not the only one that finds this interesting. The subtleties of the first few minutes in the oven can have quite a dramatic effect on the bread.