look

Look at the transparency, pure vegetable oil is transparent, and the transparency will be reduced due to the mixing of alkaline grease, wax and impurities in the production process;

Look at the color, pure oil is colorless, oil will have color because the pigment in oil is dissolved in oil during production; Look at the sediment, its main component is impurities.

smell

Each oil has its own unique smell. You can put a drop or two of oil on your palm, rub your hands together and smell it carefully while it is hot.

Odd oil indicates that there is a problem with the quality, and it is likely to be smelly waste oil; You can't buy it if it smells of mineral oil.

taste

Take a drop of oil with chopsticks and taste it carefully.

Oil with sour taste is unqualified, oil with bitter taste has been rancid, and oil with peculiar smell may be "gutter oil"