Take a look: Look at the transparency and color. The color is dark, relatively turbid, and there is sediment. It may be gutter oil that is easy to solidify at low temperatures. The first detection tip is to pour a little oil on the popsicles. If the oil solidifies quickly and adheres to the popsicles, it is probably made of gutter oil. Tip two is to pour a little oil on the glass. If the oil flows very slowly, there may be a problem.

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 smell carefully when it feels hot. If there is a smell or a faint smell, it is probably gutter oil.

Three tastes: Use chopsticks to take a drop of oil and taste it carefully. The oil with the peculiar smell may be gutter oil. Oil containing gutter oil will not be fragrant when cooking, and the residual oil residue will be black charcoal.

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. If it burns abnormally and makes a "squeaking" sound, the moisture content exceeds the standard, and it is an unqualified product; if it makes a "cracking" explosion sound when burning, it indicates that the water content of the oil seriously exceeds the standard, and the product may be adulterated, so it must not be purchased.

Five questions: Ask the merchant about the purchase channel. If necessary, ask for the purchase invoice or check the sampling inspection report of the local food hygiene supervision department.

Physical and chemical testing of gutter oil