Take a look: look at transparency and color. The color is dark, turbid, and there is sediment. It may be gutter oil that is easy to solidify at low temperature. The first detection trick is to pour a little oil on the popsicle, and the oil will soon solidify and adhere to the popsicle, which is probably made of waste oil. The second trick is to pour a little oil on the glass. If the oil flows slowly, there may be a problem.

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. It's probably the gutter oil that smells bad and smells faint.

Third taste: take a drop of oil with chopsticks and taste it carefully. The oil with peculiar smell may be gutter oil, the cooking oil containing gutter oil is not fragrant, and the residual oil residue is black charcoal.

Listen 4: Take one or two drops of oil from the bottom of the oil layer, smear them on flammable paper, light them and listen to their sound. 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 is possible to adulterate the product, so it is absolutely impossible to buy it.

Five Questions: Ask the merchants about the purchase channels, ask for purchase invoices or check the sampling inspection reports of local food hygiene supervision departments if necessary.

Physical and chemical inspection of waste oil