Study On Discrimination And Determination Of The Waste Cooking Oils Adulterating The Edible Oils

Nowadays, the lawbreaking thing that some people refine the waste cooking oil simply then adulterate edible oil with it sometimes happens which does harm for people's health. The edible oils which adulterated waste cooking oil were hardly discriminated by smell and seeing. It's very important to enhance the correlative departments'supervising ability and seed effective discrimination ways to ensure the quality and sanitation of edible oils.This paper analyzed and evaluated three kinds of waste cooking oil, including hogwash oil, waste edible oil and deep-frying oil, founding four ways of discriminating adulteration, the progress had been reviewed on several aspects:1. The senses characters, basic constituents, refrigeration characters, acid value, iodine value, peroxide value, refractive index and melting point were tested in this paper ,and the results were far from the range of normal edible oils'; contents of trace elements in waste cooking oil were determined with microwave digestion and inductively coupled plasma mass spectrometry, finding the contents of Fe, Pb, Cr, Zn, Mn were much higher than those in the edible oils; the volatile substances of the three kinds of waste cooking oil (≤80℃) were analyzed by GC-MS, including small molecule acid , ester, aether and alkenes, PAH, sulfid,etc, which were the reason of fulsome smell of waste cooking oil, and which was hydrolytic and oxidative product of waste cooking oil and could not be found in the edible oils.2. Made the fast test paper. When the edible oils adulterated waste cooking oil, the color of the test paper could turn yellow, while the edible oils didn't change. The color of the test paper could tell the qulity of the oil sample.3. The electrical conductivity of water phase of the waste cooking oil is higher than the water phase of the eligible edible oil. The electrical conductivity of the samples'water phase rise with increase of adulteration of the waste cooking oil. If the electrical conductivity of unknown samples was above 30μs/cm, it may contain waste cooking oil.4. Tested the content of cholesterol in waste cooking oil. When the content of cholesterol in unknown samples was above 0.05mg/g, the chromatographic peak appear clearly, while there was no cholesterol in the eligible edible oils.5. The SFC of hogwash oil, waste edible oil and three edible vegetable oils were detected with the way of nuclear magnetic resonance at 10℃and 0℃.The SFC of hogwash oil and waste edible oil were much higher than the edible vegetable oils'The SFC of edible vegetable oils increased with the increasing of adulteration quantity. Research conclusion: this method can judge whether the edible vegetable oils adulterated waste cooking oil only if there was 1% adulteration.