Commonly speaking, gutter oil can be divided into the following categories: First, gutter oil in the narrow sense, that is, the greasy float in the sewer or hotels, restaurants, leftovers, leftovers (commonly known as slop) after a simple processing, refining of the oil; second, low-quality pork, pig entrails, pig skin processing and refining of the output of the oil; third, the number of times used for deep-fried food oil more than the prescribed requirements, and then be reused Thirdly, the oil used for deep-fried food has been reused after being used more than the required number of times, or the oil has been reused after adding some new oil to it.
Harm: Junk oil is a non-edible oil of extremely poor quality, extremely unhygienic, with peroxide value, acid value and moisture seriously exceeding the standard. It contains toxins that flow into rivers and streams can cause nutrient enrichment of water bodies, and once consumed, it can destroy white blood cells and the mucous membranes of the digestive tract, cause food poisoning, and even cause cancer. One of the "vegetable oils" is frying oil, which is used repeatedly for a long time at high temperature, and in contact with oxygen in the air, hydrolysis, oxidation, polymerization and other complex reactions occur, resulting in an increase in the viscosity of the oil, deepening of the color, peroxide value, and the production of volatiles and aldehydes, ketones, lactones, and other irritating odor substances, which have carcinogenic effects. "Swill oil" in the main hazardous substances ----- aflatoxin toxicity is arsenic 100 times.
Identification: "gutter oil" once into the market, consumers should learn to sensory identification. According to experience, edible vegetable oils are generally seen, smelled, tasted, listened to, asked five aspects can be identified.
A look. Look at the transparency, pure vegetable oil is transparent, in the production process due to the mixing of alkali fats, waxes, impurities, etc., transparency will decline; look at the color, pure oil is colorless, in the production process due to the pigment in the oil dissolved in oil, oil will be colored; look at the precipitate, whose main component is impurities.
The second smell. Each kind of oil has its own unique odor. You can drop one or two drops of oil on the palm of your hand, rub your hands together, and carefully smell its odor when it is hot. There is an odor of oil, indicating that the quality of the problem, there is a foul smell is likely to be gutter oil; if there is the smell of mineral oil can not buy.
Three tastes. Use chopsticks to take a drop of oil, carefully taste its flavor. Taste with sour oil is substandard products, there is a burnt bitter taste of oil has been rancidity, there is a strange smell of oil may be "gutter oil".
Four listen: take a drop or two of oil at the bottom of the oil layer, apply it to a piece of flammable paper, ignite it and listen to the sound. Burning normal no sound is a qualified product; burning abnormal and issued a "squeak" sound, water exceeds the standard, is a substandard product; burning issued a "crackle" explosion, indicating that the water content of the oil is seriously exceeded, and may be adulterated products, absolutely not! Purchase.
Five questions: ask the merchant's purchase channel, if necessary, ask for purchase invoices or check the local food hygiene supervision department sampling test report.
Many merchants buy gutter oil because it is cheap and profit-driven!