In a nutshell:
Pan frying means cooking food in a hot pan with the bottom lightly coated with oil.
Shallow frying means cooking food in oil with a depth that reaches about half of the thickness of the food with the food touching the bottom of the pan all throughout.
Deep frying means cooking food in oil deep enough to cover it to allow the food to float in the oil.
The photo above shows salmon fillets being pan fried.
When the bottom of the pan is smeared with butter before pouring in pancake batter, that’s pan frying too.
The next three photos below illustrate shallow frying.
Thin slices of chicken breast fillet are breaded and shallow fried to make fried breaded escalopes (a.k.a. chicken schnitzel or milanesa).
Shredded corn and zucchini are mixed with egg, bread crumbs and herbs, formed into patties and shallow fried to make vegan corn and zucchini cakes.
Dough filled with chopped scallions are rolled flat and shallow fried to make the Chinese snack called green onion (scallion) pancakes.
Because only the bottom half of the food touches the oil, in shallow frying, the food needs to be flipped over for even cooking.
Then, there’s deep frying.
Fried chicken is deep fried.
French fries are deep fried.
Spring rolls are deep fried.
If you try to cook chicken legs in an inch of oil, or cook fries in a lightly oiled pan, or if you shallow fry spring rolls, you’re looking at a kitchen disaster.
What is it that makes the amount of oil significant?
Obviously, the amount of oil has nothing to do with the kind of food being cooking. Meat, for instance, can be pan fried (as in the case of bacon), shallow fried or deep fried. Same thing with seafood, dough, vegetables…
The significance lies in the result sought to be achieved. While getting the food cooked through is the ultimate result desired, the characteristics of the fried food is determined by the amount of oil used during the frying.
In pan frying, very little oil is used because the intention is merely sear the food and/or to add flavor (as when a little butter is melted in the pan when cooking pancakes) or to keep the food from sticking on the pan.
In shallow frying, creating a crisp and browned crust is often the desired result.
In deep frying, a crisp and browned crust and a thoroughly cooked but still moist interior is the goal.
If creating a crisp and browned crust is the result desired in shallow frying and deep frying, why not just deep fry and ensure even browning? Try making that zucchini and corn patties in the photo above and deep frying them instead of shallow frying. See if the patties don’t crumble in the oil. In short, it is the recipe that dictates whether the food should be shallow fried or deep fried.
The relation between temperature and the amount of oil
Frying always requires a high cooking temperature which can be anywhere from 350F to 375F depending on the smoking point of the oil used. I’ve written about that before in the second part of the ultimate fried chicken series.
Whether pan frying, shallow frying or deep frying, it is important for the oil to reach the required temperature before adding the food to the pan. That is what makes the difference between greasy and non-greasy fried food. And that brings me to the next obvious topic.
Is deep fried food greasier than shallow-fried food?
No. NO — unless the oil wasn’t hot enough when the food was dropped in.
In deep frying, it is only the surface of the food that gets in contact with the oil. If the temperature of the oil is correct, and if the correct temperature is maintained throughout the frying process, the interior portion of the food cooks in steam generated by the heat of the oil.
What steam? All foods contain water in varying amounts. Subject water to heat and it turns into steam.
When food is fried in oil that isn’t hot enough, that water leaks into the oil. The effect is boiling food in a mixture of water and oil. And that what makes fried food soggy and greasy. The food gets longer too cook (because of the low temperature) and it absorbs oil that it normally wouldn’t if the oil were hot enough.