It is best to choose peanut oil, palm oil, etc., which contains a lot of oleic acid and is relatively stable. Even if the oil temperature exceeds 200 degrees, it will not be oxidized and smoked, while rapeseed oil, cottonseed oil, soybean oil, etc. are prone to thermal oxidation after heating, especially soybean oil, and it is also prone to bean smell.

It is best to fry for half the surface area of the oil at one time. If there is too much food, the temperature of the oil will decrease, and the frying time will be prolonged, so that the crispy feeling cannot be fried. When frying, use high fire to shape first, and then turn to low fire to fry slowly. If the oil temperature is high, the oil will oxidize and produce peculiar smell. At this time, the food can be fished out and the oil temperature will drop slightly before frying. Deep-fried foods are sometimes fried to black color or endogenous coke, probably because the oil temperature is too low.