Identification: Once "gutter oil" enters the market, consumers must learn to identify it through their senses. According to experience, edible vegetable oils can generally be identified by looking, smelling, tasting, listening, and asking questions.

Take a look. Look at the transparency. Pure vegetable oil is transparent. During the production process, the transparency will decrease due to the mixing of alkali, wax, impurities, etc.; look at the color. Pure oil is colorless. During the production process, due to the pigments in the oil, the transparency will decrease. Oil will take on color only when it is dissolved in oil; looking at the sediment, its main component is impurities. Color contrast

Second smell. Each oil has its own unique smell. You can put one or two drops of oil on your palms, rub your hands together, and smell the scent carefully when it feels hot. Oil with a peculiar smell indicates that there is a problem with the quality. The smelly oil is probably gutter oil; if it smells like mineral oil, you should not buy it.

Three tastes. Use chopsticks to take a drop of oil and taste it carefully. Oil with a sour taste is an unqualified product, oil with a burnt and bitter taste has gone rancid, and oil with a peculiar smell may be "gutter oil".

Four cans: Take one or two drops of oil at the bottom of the oil layer, apply it on flammable paper, light it and listen to the sound. A product that burns normally and makes no sound is a qualified product; a product that burns abnormally and makes a "squeaking" sound indicates that the moisture content exceeds the standard, and is an unqualified product; a "cracking" explosion sound is made when burning, indicating that the water content of the oil seriously exceeds the standard, and may It is an adulterated product and must not be purchased.

Five questions: Ask the merchant about the purchase channel, and if necessary, ask for purchase invoices or check the sampling test report of the local food hygiene supervision department.

Gutter oil can also be detected quickly and accurately through the following method: utilizing the relationship between metal ion concentration and conductivity, the amount of metal ions in the oil can be determined by detecting the conductivity of the oil. Many experiments have shown that the conductivity of Kushui oil is 5 to 7 times that of first-grade edible oil, so Kushui oil can be accurately identified.