I am not certain of this (please do not take this the wrong way, I assumed the same and I am not sure either way, I am certainly not saying you are lying). I have gotten wheat grain to 145C+ in a microwave measured with a probe digital thermometer, there was still visible steam coming off them, maybe this was something else vapourising though. The grains themselves may be acting as pressure vessels, I am not sure, but I think that is the principle behind popcorn, they explode when the CO2 build up inside is enough (the CO2 forms while heating). To test further I could weigh again and again after they have passed 100C, but like I said it may be other compounds vapourising.
The only way an oven can get the grains above 212F is to evaporate 100% of the moisture from them first, then the temperature can rise.
If you cook a chicken in the oven the fat is bubbling away but it is still moist and I would be certain water is still in it.
I grew on heavily and lightly toasted grains and they worked well, the growlogs were lost here in the crash but are at the shroomery. You do have to rehydrate, with lashings of LC! resulting in extremely quick colonisation which also gives little room for contams to take hold.
You'll have to rehydrate them somehow, but toasted cereal grains get soggy when wet.
As I have mentioned a few times I think weighing is essential to calculate the moisture loss, and know how much LC to add back.
I had an idea of selling dry sterile grain before. I was thinking of people getting sackfuls of grain exposed to radiation, it cannot be too expensive seeing how lettuce and other fruit & veg are done. Grain could be pc'd and then dried in an oven. I only thought of this as to stop the excessive price of postage of prepared grains.
Another VERY DANGEROUS method is that of water that can explode in the microwave. When the gas is boiled out of a cup of water the surface tension on the liquid is strong enough to act like a lid and the water goes well past 100C, it eventually overcomes the tension and "explodes", I have used this effect in the past when microwaving LCs, it is very easily done, I have had the door blow open on a microwave.
I was thinking this could be used with submerged grain but I do not think it will work since gases will always be released in the grains.
Glass jars do interest me, I am not certain but I think they are designed so the lids will let off excess pressure, some people mentioned this already. I had safety valves for homebrewing before which blew at I think 30psi. I know champange bottles can handle over 100psi. If you were to put a sealed bottle or jar in an oven at 121C it should be at 15psi and should be able to handle the pressure. Again this is very dangerous and should be left to the experts or nutcases like my bad self!
I have microwaved autoclave bags full of grain which expanded releasing gas out of the filter. I will try this again and try and measure the temperature which should show how much pressure is being built up.
I have always thought the definition/procedure for fractional steilization was a bit, dunno the word, maybe "exact". Seems it may be overkill and that the guy who did it may not have experimented, it worked first time so fuck it, don't fix what ain't broke!
I would like different experiments and have done some myself. e.g. soak grain in hot water and leave sit for 48hrs, then oven cook until dry, soak again for 48hrs, then simply steam it. I like the drying between times since it allows for people to be more flexible, if the only time you get to use your cooker is on a monday night (when the wife is at her class!) then you can soak grains on saturday and dry them out on the monday. Wait a week and soak next saturday to germinate the remaining endospores. It may take 3 times to be sure. Some may say this takes too long, but it is not actual manhours. Soak, strain, toss in the oven for an hour at 220C to have it bone dry.