【作者】 张丽；

【导师】 邴炜；

【作者基本信息】 吉林农业大学 ， 粮食、油脂及植物蛋白工程， 2015， 硕士

【摘要】 近些年,不法商贩通过贩卖地沟油来谋取暴利,致使大量地沟油经过简单加工、精炼后重返人们的餐桌。由于地沟油中的重金属元素、黄曲霉毒素B1和苯并芘(α)等有毒有害物质超标,严重危害了人们的身体健康。为严防地沟油流入餐饮服务环节,切实保护消费者饮食安全,迫切需要出台地沟油的处置方法和相关法律法规,其实施重点就是地沟油检测方法的建立。由于地沟油来源广泛,成分复杂,不法商贩往往把一定量的地沟油掺入合格食用油中,增加了检测难度,因此一直都没有建立起权威性的检测方法。现有的检测方法有的只能检测单一来源的地沟油;有的灵敏度不够,不能检测经过精炼的地沟油,或不能检测掺入量较少的地沟油。本论文中采用同时蒸发萃取-气相色谱-质谱法检测地沟油中的挥发性成分。优化地沟油挥发性成分提取方法,得到了最佳的地沟油前处理条件,采用气相色谱-质谱仪进一步鉴别其挥发性成分。按国标《GB 2716—2005食用植物油卫生标准》检测油样的酸价、过氧化值,得到的结论如下:1、通过对比同时蒸发萃取法与水蒸气蒸馏-有机溶剂萃取法两种前处理方法,我们发现,同时蒸发萃取法分离提取样品效果更好,通过比较三种提取试剂乙醚、石油醚、正己烷,发现乙醚的效果最好,同时我们也优化了前处理的最佳添加量和最佳蒸馏时间。2、样品前处理后,经气相色谱-质谱进一步鉴别,发现地沟油中含有大量的醛、醇、烃、酸、酯等物质,本实验结果对地沟油检测的初筛提供了一定的参考。3、本论文选用了比较有代表性的40批次不合格油的产品,其中10批次为潲水油代表,10批次为煎炸老油代表,另外20批为疑似地沟油产品。通过用气相色谱-质谱法检测发现,本实验选取的四类来源中,烧烤地摊废弃油不合格率最高,所代表的煎炸老油的特征性挥发性物质为反式烯醛类,小吃、火锅等餐饮废弃所代表的潲水油会出现咖啡因等外来物质,而集市、农贸、小作坊油没有找到特征性挥发性物质。通过以上实验和酸价和过氧化值检测结果比较,发现虽然上述标准不能作为地沟油检测的判定方法,但可以作为地沟油检测的初筛方法。本论文提供了切实合理、简单易行的地沟油前处理方法、条件以及气相色谱-质谱条件,通过大批量的实验数据分析,得到了相对可靠的实验结果,为地沟油的检验方法的确定提供了一定的参考。更多还原

【Abstract】 In recent years, many illegal traders sell waste oil to make money, resulting in a large part of the waste oil return to our dining table after processing and refining. The waste oil seriously endanger people’s health, because of its containing the heavy metal elements, aflatoxin B1 and benzo(α) and other toxic substances which exceeding the standard. To prevent waste oil into the catering services link and effective protect the food safety of consumers, an urgent need is to establish the related laws and regulations of the waste oil, and the most important key is to establish the method of pretreatment and detection of illegal cooking oil.Because the source of the waste oil is extensive, the chemical structure is complex, and criminals are mostly to sales of waste oil refining after incorporation of qualified edible oil, the waste oil is more difficult to detect. By now there are no authority authoritative detection method. The existing detection methods are not targeted, and some can only detect a single source of waste oil; some lack of sensitivity, cannot be detected after refining waste oil, or can not detect the incorporation of small amount of cooking oil. After research efforts over the past few years, at present mainly mature methods are as following: physicochemical method, the material characteristics method, thin layer chromatography, spectrometry, high performance liquid chromatography, nuclear magnetic resonance spectroscopy, microscopy and specific gene detection.In this thesis, we firstly optimized pretreatment method of the waste oil, and further identified the main group of waste oil and analyze its reaction principle by using gas chromatography- mass spectrometry. And we detected 40 batches of illegal cooking oil samples in the market using above methods, and detect and analyze the related parameters of GB 2760-2005 “Hygienic standard of edible vegetable oil” as a contrast experiment, the main conclusions are as follows:1. Through the comparison of two kinds of waste oil pretreatment method which are simultaneous distillation extraction method and evaporation of water-vapor of organic solvent extraction method, we found that effect of the fist method is better, the TIC ion analysis exhibit the good choice of separating degree and more peak fractions. By comparing three kinds of extracting reagent diethyl ether, petroleum ether, hexane, we found that diethyl ether have the best effect, which shows good separation effect and high value of the response. At the same time, we also optimized the optimum adding amount of pretreatment and the best time of distillation.2. By using gas chromatography-mass spectrometry, we further separated and identified the sample components. And we found that the waste oil contains a large number of aldehydes, alcohols, hydrocarbons, acids, esters and other substances, and the degree of oxidation of the oil is bad, the content of these substances is bigger, the experimental results provide some reference to the waste oil detection screening. From the analysis of lipid oxidation in principle, hexanal, pentanal, nonanal, octanal, heptyl aldehyde, 2-pentyl furan is an important drop product of oleic acid and linoleic acid.(E)-2-heptenal, 2, 4-nonadienal, anti-2,4-decadienal was produced in the process of oil rancidity, and the principle of producing is analyzed.3. In this thesis, we chose more representative of the 40 batch of waste oil products, of which 10 batches are representative of 10 batches of hogwash oil for deep frying oil represents, in addition the 20 batch of suspected “drainage oil” products. Detection by gas chromatography-mass spectrometry, four types of sources of this experiment selected, barbecue stall waste oil is not qualified rate is highest, the characteristic volatile compounds by the representative of the frying oil for trans olefinic aldehydes, snacks, such as Hot pot food waste by the representative of the hogwash oil will appear caffeine and other foreign substances, while the market, farmers, small workshops oil did not find the characteristic volatile substances. Through the above experimental and the detection results of the acid value and peroxide value of standard “GB 2716-2005 Hygienic standard of edible vegetable oil”, we found that although the above criteria cannot be used as a method to determine the illegal cooking oil detection method, but can be as drainage oil detection screening.This paper provides a practical and reasonable, simple and executable pretreatment methods and conditions, gas chromatography-mass spectrometry conditions of “illegal cooking oil”. By analyzing a large number of experimental data, we obtained the relatively reliable results, and provides a certain reference for determining the “illegal cooking oil”.更多还原