At first glance. Look at the transparency, pure vegetable oil is transparent, and the transparency will decrease due to the mixing of alkali grease, wax and impurities in the production process; Look at the color, pure oil is colorless, in the production process, because the pigment in the oil is dissolved in the oil, the oil will be colored; Look at the sediment, its main component is impurities.

second smell. Each oil has its own unique smell. You can drop a drop or two of oil on your palm, rub your hands together, and smell it carefully when you are hot. Oil with odor indicates that there is a problem with the quality, and it is likely to be waste oil with odor; If there is a smell of mineral oil, you can't buy it.

three tastes. Take a drop of oil with chopsticks and taste it carefully. The oil with sour taste is unqualified, the oil with bitter taste has been rancid, and the oil with peculiar smell may be "waste oil".

four listening: take one or two drops of oil from the bottom of the oil layer, spread it on flammable paper, light it and listen to its sound. The products with normal combustion and no noise are qualified products; If the combustion is abnormal and makes a "squeaky" sound, the water content exceeds the standard and it is an unqualified product; When burning, it makes a "crackling" explosion, indicating that the water content of the oil is seriously exceeding the standard, and it may be an adulterated product, so it is absolutely impossible to buy it.

five questions: ask the merchants about the purchase channels, and if necessary, ask for the purchase invoice or check the sampling inspection report of the local food hygiene supervision department.

personally, I think the third point is the quickest way, which is also a long-term process, sometimes it is really difficult to distinguish, be a conscientious person in life!