The Reasearch Of Methods To Discerm Catering Waste Oil

There are three major categories of catering waste oil:swill oil recycled by leftovers, long-handled frying oil and cooking oil extracted from the grease trap. At present, catering waste oil is to be quite common in the illegal use of, and every year a large number of post-refining waste oil back through the restaurant. Catering waste oil are often subject to serious pollution, can no longer be eaten. The phenomenon of rampant "Waste oil", seriously affected the balance of our waste oil management system, and is a threat to health and safety of the masses. In recent years, the state of food safety problems pays more and more attention to the "waste oil" problem, and also takes crack down on attitude. However, the lack of food inspection department a clear detection of indicators of waste oil, which to combat the illegal use of "waste oil" has caused no small obstacle. Several catering waste oil detection methods were established and assessed in order to establish a practical method of identifying catering waste oil. The relevant regulatory authorities can provide a reference work in the detection of catering waste oil.First, sensory evaluation, the basic physical and chemical indicators, conductivity of catering waste oil were determined. Nine kinds of catering waste oil were carried out initial and secondary refiningnd under laboratory conditions. Physical and chemical analysis showed that although the initial collection of catering waste oil in the sensory level, the basic physical and chemical testing, analysis and general oil conductivity has a significant difference.But after refining, the difference reduced or eliminated.It's indicating that the traditional profile detection methods can not meet the catering waste oil testing needs.Secondly, a method of detecting catering waste oil fatty acid components by gas chromatography analysis was established. Several parameters and the temperature of the gas chromatographic conditions were optimized. Using the DB-23capillary GC column for separation, hydrogen flame ionization detector FID for detection. Select heptadecanoic acid methyl ester, trans-methyl oleate, trans-linoleic acid methyl ester fatty acids as method validation material. The linear range was0.02～1.6mg/mL with the good linear relation. R2were0.9971～0.9989, the lowest detectable limits were0.003～0.005mg/mL the lowest quantitation limits were0.010～0.016mg/mL.The recoveries of seventeen carbon alkyl acid was at90.91～102.11%, RSD (n=3) were1.96～3.49%. This method meets the catering waste oil fatty acid composition analysis. The collection of catering waste oil and its refined oils, total of39oil samples were detected. The selected samples of catering waste oil fatty acid composition were similar to palm oil and soybean oil respectively. Palm oil was similar accounted for the majority, at70%. Comparative study of oil samples by the relative degree of unsaturation, short-chain fatty acids and trans fatty acids has been explored, and it's found that catering waste oil and its refined oil have ordinary differences.Then, a gas chromatography-mass spectrometry (GC-MS) detection of cholesterol in catering waste oil method was established. Temperature program of GC and MS ion source temperature and other parameters were optimized instrument settings. Using selected ion monitoring mode (SIM) scan, cholesterol peaks to ensure sufficient data collection points, increased sensitivity, lower detection limits. The method of traditional saponification process pre-treatment and laboratory-made silica gel columns pre-treatment were campared, and the silica gel column method showed a better reproducibility and higher recovery rate. The linear range of cholesterol was2～200μg/mL, R2was0.9994. The recoveries of blank samples spiked at three levels of cholesterol were89.43%-95.95%, and RSD were0.52%-2.06%. Cholesterol in all catering waste oil and its refined oil samples had been detected. The cholesterol content were ranging from3.26～387.61μg/mL. Cholesterol easily exists in the catering waste oil, and it is suitable to identify the characteristics of catering waste oil as an important reference. After that, a GC-MS analysis method combined with principal component analysis (PCA) statistical method was established. Through the difference between short-chain fatty acids fingerprints chromatogram of catering waste oil and ordinary edible oil, catering waste oil samples were identified. The method showed a good repeatability, and is satisfied for a fingerprints chromatogram analysis of requirement. By comparing the short-chain fatty acids total ion flow diagram from10kinds of catering waste oil and8kinds of edible oil,7common peaks as the common characteristic peak were determined. The relative peak areas in every sample of each common peak were measured. Using the PCA clustering analysis, it can fully distinguish the catering waste oil and common edible oil. The results were direct and precise.Finally,20blind samples of ordinary cooking oil and caterring waste oil for were test, and to evaluate of previously established methods of identification of catering waste oil. The results showed that the fatty acid content analysis method has many limitations in catering waste oil identification, and the accuracy was also low, only35%. Cholesterol indentification method has a good ability to identify catering waste oil, and the accuracy reached65%; GC-MS fingerprint identification with the PCA analysis method has a high accuracy, reaching at90%.This method limitations is small and directly perceived through the senses intuitive, which is appropriate for identifying catering waste oil.