Judging catering oil is good mainly to see the transparency of the oil, good oil should be high transparency, (low transparency is generally added chemicals and so on) lighter color, (deep color is generally added pigment) no sediment (sediment oil because there are impurities so it will precipitate). Sometimes eat in the restaurant can not see the color of the oil when we have to rely on our sense of taste, bad oil eating will have an odor and pungent, the main thing is not easy to wash the bad oil, easy to paste greasy on the pot, while the good oil is more refreshing and easy to brush off, and the taste is better!