'Deep-frying' is a
cooking method whereby food is submerged in hot oil or
fat. This is normally performed with a
deep fryer or
chip pan; industrially, a
pressure fryer or
vacuum fryer may be used.
Deep frying is classified as a dry cooking method because no water is used. And due to the high temperature involved and the high heat conduction of oil, it cooks food extremely fast.
Technique
If performed properly, deep-frying does not make food excessively greasy because the
moisture in the food repels the oil: The hot oil heats the
water within the food,
steaming it from the inside out, oil cannot go against the direction of this powerful flow. As long as the oil is hot enough and the food is not immersed in the oil for too long, oil penetration will be confined to the outer surface. However, if the food is cooked in the oil for too long, too much of the water will be lost and the oil will begin to penetrate the food. The correct frying
temperature depends on the thickness and type of food, but in most cases it lies between 175 and 190°
C (345–375°
F)
Some fried foods are given a coating of
batter or
breading prior to frying. The effect of these is that the outside of the food becomes crispy and browned while the inside becomes tender, moist, and steamed. Some foods, such as
potatoes or whole, skin-on
poultry, produce a natural coating and do not require breading or battering.
Oil deterioration
Overheating or over-using the frying oil, or undue exposure to air while hot, leads to formation of
oxidation products,
polymers and other deleterious, unintended or even toxic compounds such as
acrylamide (from in
starchy foods). Researchers in many countries have found that of the three major market sectors, the most abused frying oils were (in order from the worst) those in the catering, domestic and industrial sectors. Deep-frying under vacuum helps to significantly reduce the acrylamide formation, however this process is so far not widely used in the food industry due to the high investment volume involved.
Some useful tests and indicators of excessive oil deterioration are the following:
★ Sensory: Darkening, smoke, foaming, thickening.
★ Laboratory:
Acidity (FFA),
anisidine value,
viscosity, total
polar compounds, polymeric
triglycerides.
Instruments that read the total polar compounds, currently the best single gauge of how deep fried an object is, are available with sufficient accuracy for restaurant and industry use.
Disadvantages
Deep frying produces large amounts of
waste oil, which must be properly disposed.
Deep fry
shortenings contain
trans fat.
See also
★
French fried potatoes
References
External links
★
Christian Science Monitor: Backstory: If you can think of it, he can deep-fry it
★
Deep Fryer Recipes