Preheating the oven

[snopes]

Comment: Some friends of ours are convinced that it is dangerous for the
food if you do not preheat an over before cooking. They seem to feel the
gas gets in the food, causing the food to become unhealthy.

This seems like an old wives' tale to us!

[Eddylizard]

The food is already dead. How much more unhealthy could it get? How could you imperil it even more?

[UEL]

That reminds me of a friend of my Mom's. She has her homemade recipe book full of delicious recipes. However, the timings she has for them all are for putting the food into a cold oven. So the 45 minutes to bake a pizza on her oven is really 25 minutes on a preheated one.

I bring up pizza for a specific reason. You can only eat the first one. After that, they are all burnt. And no one can seem to convince her that she is leaving them in the oven too long. She blames her husband for making the crust too thin.

She does tend to be very defensive in the kitchen, and lets no one else near the stove.

[songs78]

There is some truth to this. In preparing foods, there is a safe zone. colder than 41º F or hotter than 140º F. Bacteria will grow within then two temperature ranges. Depending on how long the oven takes to heat to 140, bacteria will grow within the food.

This is the same reason why crock pots and slow roast bbqs are discouraged by some food professionals.

[rosa who else]

If you need the "shock value" of the higher heat, say to make a crust on the food, preheating is a good thing. And if your recipe calls for precision to make it work (like a cake or souffle) you have to preheat.

But if the food is frozen, putting it in a cold oven and then allowing it to come up to temperature can be beneficial. Example: Marie Callender's pot pies are much, much better if put into a cold oven (with the piecrust edges shielded by tinfoil), the oven set for the "preheat to" temperature and left in the oven for 1 hour. The bottom crust comes out cooked and brown and crispy which makes the whole pie more delicious.

Unless you're one of those who likes the gummy undercrust as a form of comfort food ...... I used to be (blush) one of those.

[Little Galaxy]

Yup, it definitely depends on the food - some things, like tarts, can be satisfactorily baked from a cold start but cakes and the like require preheating. However I've only heard the cold-start recommendation as a way of saving energy - the implication was that you can cold-start some foods if you really want to but everything's better off being preheated. But as for not pre-heating being actually dangerous - nah!

About the concern with crockpots and unsafe temperatures - would this be more of an issue if you put in cold food? Every crockpot recipe I have advises you to brown the ingredients and then add hot liquid, so I'd imagine the temperature would remain safe.

[snapdragonfly]

Originally Posted by Little Galaxy

About the concern with crockpots and unsafe temperatures - would this be more of an issue if you put in cold food? Every crockpot recipe I have advises you to brown the ingredients and then add hot liquid, so I'd imagine the temperature would remain safe.

I think you are onto something but I think it's frozen food, not necessarily just cold, and in particular ground beef.

[Singing in the Drizzle]

Originally Posted by songs78

There is some truth to this. In preparing foods, there is a safe zone. colder than 41º F or hotter than 140º F. Bacteria will grow within then two temperature ranges. Depending on how long the oven takes to heat to 140, bacteria will grow within the food.

This is the same reason why crock pots and slow roast bbqs are discouraged by some food professionals.

This is one of those protect our ass in case some like to eat raw meat and sues things. Unless the meat is grownd up the bacteria does not grow in the meat, but on the out side. The bacteria that has grown while waiting to oven to warm up will die at 135 deg and now been made harmless. Leaving meat out of a couple of days is a different story.

[snapdragonfly]

Originally Posted by Singing in the Drizzle

The bacteria that has grown while waiting to oven to warm up will die at 135 deg and now been made harmless. Leaving meat out of a couple of days is a different story.

And I know that is true, but other than the meat starting to putrify, why is this?

[Eddylizard]

Do you mean why, if one leaves meat out and allows the bacteria to multiply, should it matter because when you cook it they're all going to die anyway?

The problem is that food poisoning is not caused by the bacteria themselves upon ingestion, but by the toxic substances that they excrete, whch are left behind in the meat after their death, and not necessarily destroyed by cooking

A piece of meat prepared in hygienic conditions and kept refrigerated will have a low level of bacterial activity, and a level of toxins too low to be an issue when it is eaten. If the meat is kept at room temperature for a few days, since the bacteria multiply more quickly as temperature rises, so the level of toxins left behind in the meat increase.

This is the reason why in the UK at least, irradiated food is banned. Current tests performed on food test for the presence of the bacteria - not the presence of the toxins. Irradiation kills the bacteria, but again the toxins are left behind. Test shows - no live bacteria, therefore the food is safe.

There was a case here about 20 years ago, where a shipment of prawns was rejected for import, because it had too high a level of one of the food poisoning bacteria (can't recall which one.) It left the country, was irradiated in Holland, then illegaly sent back to the UK, obviously disguised as a different batch. The tests for bacterial contamination came back negative, and it was allowed into the country. The scam was only discovered when people started getting sick.

Anyhow, I thought the point of the OP had nothing to do with bacterial activity, but the concept was that in a gas fuelled oven that hadn't yet warmed up, the gas would be incompletely burned, such that methane or one natural gas' other components will seep into ones food causing a poison hazard. Which is clearly preposterous.

[snapdragonfly]

Yes, Eddylizard, that was what I meant. Thanks for the 411 on that!

[queen of the caramels]

Originally Posted by Eddylizard

Anyhow, I thought the point of the OP had nothing to do with bacterial activity, but the concept was that in a gas fuelled oven that hadn't yet warmed up, the gas would be incompletely burned, such that methane or one natural gas' other components will seep into ones food causing a poison hazard. Which is clearly preposterous.

I have a propane fuelled oven( stove), the ignition bar heats up before the gas is admitted into the burners. The temp is then regulated so all the propane is completely combusted , if that makes sense.

[Singing in the Drizzle]

The quest in have with the OP and gas ovens is how is the gas burned when the cold and different that then the oven is hot?

[lynnejanet]

I never put anything into a cold oven, but that's because, when you do, it tends to brown or even burn, before it cooks through. In an electric oven, when the oven is heating up, the element comes on and stays on until the preset temperature is reached. Once it's up to temp, the element only comes on to maintain the temperature.

If something is place fairly high or low in the oven, the top or bottom can brown under the constant glow of the oven, without actually cooking.

I have never heard of putting tarts or other pastry into a cold oven. In fact, I have always been taught to do the opposite, to ensure the crust cooks but doesn't burn. Ten - fifteen minutes ar 425, and then reduce to 350.

[Eddylizard]

Originally Posted by Singing in the Drizzle

The quest in have with the OP and gas ovens is how is the gas burned when the cold and different that then the oven is hot?

Well I don't think it is burned any differently. Maybe when the burners are cold they do not optimally combust the gas, and perhaps some unburnt gas escapes. But the burners heat up very quickly, within seconds, much sooner than the oven cavity, so I really don't think think this could be a problem.

In any case, is methane infused food a health hazard?

Originally Posted by snapdragonfly

Yes, Eddylizard, that was what I meant. Thanks for the 411 on that!

Stolen Vehicle?

[TheAmazingRando]

Originally Posted by Eddylizard

Stolen Vehicle?

Maybe it's a strictly American colloquialism, 411 is basically just another way of saying "useful information."

[Eddylizard]

Originally Posted by TheAmazingRando

Maybe it's a strictly American colloquialism, 411 is basically just another way of saying "useful information."

Okay, thanks for the er 411. I've never heard that one before. I'm familiar with a lot of American colloquialisms, thanks to our increasing habit of buying TV shows from the US rather than making our own, and I try to look up any I don't know. But in this case Google (tm) was not my friend.

[landmammal]

To clarify, 411 is the number you dial for directory assistance/information which is why "411" is shorthand for "information."

[Eddylizard]

Thans again. Thick Brit signing off here for tonight.

Damn you bloody tins and your oity-toity lingo. I'm off up the apple!

[Singing in the Drizzle]

Originally Posted by Eddylizard

Well I don't think it is burned any differently. Maybe when the burners are cold they do not optimally combust the gas, and perhaps some unburnt gas escapes. But the burners heat up very quickly, within seconds, much sooner than the oven cavity, so I really don't think think this could be a problem.

In any case, is methane infused food a health hazard?



Stolen Vehicle?

I can not think of any reason they would be different as well. So why would it affect the food differently?