One of the things my wife does is "pre-heat" the oven. It is a gas oven. I have issues with this.
My first issues is that the gas/air and radiant heat in the oven surely takes literally seconds to be "at temperature". Yes, the metal tray/rods the food goes on will take more time, but they are small, and actually way less mass than the "baking tray" on which items will be placed and which are not pre-heated.
The only way I could really test this would be temperature probes and tests, but I really do not see the logic of pre-heat on a gas oven of more than like 60 seconds.
My second issue, which applies more so if the first is wrong, is why not put the damn food in the oven during the "pre-heat". Not doing does clearly waste energy. Yes, the time calculation for cooking may need to allow for a short period of lower heat at the start, but overall it will be less than pre-heating an oven whilst the food is simply sitting at room temperature just waiting.
Two reasons I can think of for this. Firstly, the heating time varies per oven, so you'd have to customise the recipe for your oven even more than usual. Secondly, some recipes (sponge cakes for example) are really sensitive to excess temperature variation. So waiting until the thermostatic cycle settles and thermal mass is heated is necessary if you don't want your cake to collapse.
ReplyDeleteFor regular cooking (roast veg, casseroles etc).I often stick the food in straight away as you suggest.
Gadget up! Meater probe shows my current oven is up to temp rapidly, whereas a pal's cheap gas oven takes ages to get to the specified temp and then overshoots a lot. Yours is probably good enough to use from almost 'on' but plenty are underpowered or mis-calibrated.
DeleteI dont see why the type of fuel matters? You typically pre heat electric ovens to remove a variable - the amount of time it takes to get to temperature - from the cooking process. The oven dumps 2-3kw of energy into the oven cavity and reaches temperature in about 10-15 minutes. A gas oven dumps about 2-3kw of energy in the form of a gas flame into the oven cavity which will then heat up at the same rate, all other things being even? Unless you have some magical oven which can dump massive amounts of energy in during the initial phase?!
ReplyDeleteMy issue is surely it is the hot gas/air that cooks in a gas oven. Well the rate that is heated is surely quite quick. I mean heating all the metalwork will take much longer, but is that the main source of cooking? Maybe it is. I know it is not as direct as cooking over the flame of a camp fire, but surely a similar principle - you don't have to wait for a campfire to pre-heat (pre-heat what, the whole forrest?) - if there is a flame it is flaming hot.
DeleteWith the oven pre heated you are cooking using radiant heat from all around the food ie the oven sides, top and bottom etc. That won't happen with a cold oven. I know from my dad doing it for about a year that trying to cook pizza in an oven that is warming up from cold is a disaster, you get soggy pizza and if you leave it in long enough for the base to cook properly the toppings burn. Wood fired pizza ovens don't cook from the flame, they cook from the radiant heat of the entire brick pizza oven being very hot and radiating at the pizza in all directions.
ReplyDeleteI happen to own a gas (bottled propane) fan oven & and an oven thermometer. Fourteen minutes ago, I ignited the oven. Only now is the thermometer rreading 170°C. Without the fan operating, it would take much longer. TBH, I hate the thing & am refurb’ing an electric Bosch combo/microwave fan oven as I have many years of experience of using this type,, best of ovens IMHO. I haven’t really got into the physics of it, observation & results only.
ReplyDeleteIt could be worse! My oven is electric. My wife insists on setting it to a higher temperature than she actually wants so that it "heats up faster" then turning it down. She does the same with the climate control in the car. It drives me nuts.
ReplyDeleteTotally, and drives me nuts too.
Delete