by Spider » Thu Oct 11, 2012 5:19 pm
It just doesn't make any sense to "always do this", or "never do that", as different situations call for different tools and applications.
Olive oil has its uses, as defined by its composition and physical properties. Same goes for whatever else.
There are very good reasons olive oil is not a good frying oil...chief among them that it is very unrefined stuff, and when you expose it to high temperatures all the impurities start breaking down and giving off funky odors and flavors. Fill up a fryer with EVOO...and it doesn't take long at all before it gets completely nasty. Don't believe me? Try it. (This is not to say in a gourmet application it can't be done, but it is simply impractical real world)
More refined fats have fewer impurities, higher smoke points, and simply last MUCH longer under the punishing conditions in a fryer, and that is why they are used. To say nothing of the cost.
As for the frying process itself, its merely a matter of balancing pressures. The pressure of steam being forced out of the food by conduction of heat overcomes the pressure of the oil trying to penetrate the food. As long as you've got enough heat to keep the steam pressure up, the oil can't penetrate all those groovy little tunnels the steam digs on its way out. Once the food has lost enough moisture that the pressure drops, then the oil starts seeping in, and you get greasy food.
Basically:
If the temperature is too low to cook the food before the moisture gets too low, or worse, not generate enough steam to begin with, you have greasy food.
If the temperature is too high to allow the food time to cook through before blasting all the moisture out, then you have greasy food.
Its the reason proper fries can actually be cooked twice at two different temps and not wind up greasy in the least. Prof is absolutely correct about the amount of oil it takes to cook something properly. If the food is coming out all soggy with grease...you did something wrong, and its certainly not the fault of whatever oil you chose.