【作者】 唐芳；

【导师】 吴卫国；

【作者基本信息】 湖南农业大学 ， 食品科学， 2011， 硕士

【摘要】 由于植物油脂的营养价值、产量以及油料分布不均等因素的影响,植物油脂的价格存在一定的差异。一些不法经营者贪图高额利润,采用高价油中掺入低价油的不法手段。这极大地损害了广大消费者的权益。为了整顿和规范食用油市场,需要采取一系列的鉴别油脂掺假的手段,便于有利地打击市售油脂掺假。本文采用GC-MS建立标准指纹图谱,并对油脂脂肪酸进行直观比较分析和相似度分析,定性地鉴别植物油脂,为植物油脂掺假模型的建立提供依据。本论文主要研究结果如下：1.采用KOH-甲醇溶液甲酯化法和H2SO4-甲醇溶液甲酯化法对植物油脂肪酸GC-MS分析甲酯化前处理的研究,通过单因素试验和正交试验考察在KOH-甲醇溶液甲酯化法和H2SO4-甲醇溶液甲酯化法中甲醇溶液的含量、振摇时间、振摇温度对油酸甲酯转化效率的影响,来确定KOH-甲醇溶液甲酯化法和H2SO4-甲醇溶液甲酯化法中甲酯化的最佳工艺。结合这两种方法衍生出酸碱结合法,比较三种方法的甲酯化程度,最终确定了甲酯化方法中最佳的方法为酸碱结合法,其油酸甲酯的转化效率为95.5%。2.采用平均矢量法和直接选取法建立七大植物油脂肪酸的标准指纹图谱,通过将菜籽油、大豆油、花生油、棉籽油以及茶籽油采用平均矢量法,棕榈油和葵花籽油采因为样品少则直接取具有代表性的指纹图谱,建立了菜籽油、大豆油、花生油、棉籽油、茶籽油、棕榈油以及葵花籽油。通过平均矢量法建立的菜籽油、大豆油、棉籽油、花生油以及茶籽油的标准指纹图谱需要与各自对应油脂的所有样品计算相似度,相似度分别大于0.998、0.976、0.997、0.998、0.996,说明平均矢量法建立的标准指纹图谱较好的反映了每种油脂间的整体性。计算所有油脂脂肪酸标准指纹图谱间的相似度,每种油脂标准指纹图谱间存在差异,说明所有标准指纹图谱较好的反映了每种油脂间的整体性差异。同时,比较七大油脂标准指纹图谱的脂肪酸组成和含量,发现花生油中含有虫蜡酸、且花生油、木焦油酸以及山榆酸较其他油脂的含量高；菜籽油中含有神经酸,且α-亚麻酸甲酯的含量较其他油脂的含量高。3.采用相似度分析法对植物掺假油识别方法的研究,将低价油以5%、15%、25%、50%等不同梯度掺入高价油中模拟油脂掺假,计算每种掺假油脂与所有标准指纹图谱间的相似度,借助油脂标准指纹图谱间的相似度,可定性地鉴别了油脂掺假。4.采用直观比较分析法对植物掺假油识别方法的研究,借助植物油脂的特征性,采用顺式油酸/顺式亚油酸甲酯和棕榈酸/硬脂酸甲酯,绘制二维图,直观比较分析定性地鉴别了油脂掺假。更多还原

【Abstract】 The price differences of Vegetable oils resulted from production,nutritional value and uneven distribution of vegetable oils. Some uncrupulous made an illegal means, mixing cheap oils into high oils to seek high profits,which greatly damaged the interests of consumers. In order to rectify and regulate the oils market, the need to take a means of identification of adulterated oils was easy to favorably against the adulteration of commercial oils.The paper established the standard fingerprint by GC-MS,and made the comparative and the similarity analyze the fatty acid of oils to qualitative identification of vegetable oils,which provie the basis to the adulteration model established of vegetable oils. The results of this paper was as follows:(1)It studied on the methylesterification pre-treatment of GC-MS analysis of fatty acid in vegetable oils by KOH-methanol solution method and H2SO4-methanol solution method.It determined the affects of the oscillations of temperature and time,the contents of methanol solution with KOH-methanol solution method and H2SO4-methanol solution method on the conversion efficiency of the oleic acid methyl ester by the single factor experiments and orthogonal test,in order to decided to the optimized condition of KOH-methanol solution method and H2SO4-methanol solution method.Combining these two methods derived from acid-alkali combination method. Compared with three methods,it was finally determinated to the best way of methylesterification reation,called acid-alkali combination method,the conversiton efficiency of the oleic acid methyl ester by which was 95.5%.(2) It was estabalished to the standard fingerprint of the seven major oils by the common pattern method and by the method to directly choose the representation of the GC-MS fingerprint. It was established to the standard fingerprint of rapeseed oils, soybean oils, cottonseed oils, peanut oils and camellia oils by the common pattern method and the standard fingerprint of palm oils and sunflower oils by the method to directly choose the representation of the fingerprint because of oil samples less.Then,it was calculated to the similarity of the standard fingerprint of rapeseed oils, soybean oils, cottonseed oils, peanut oils and camellia oils by the common pattern method and all the samples of each oils interrelated to this standard fingerprint,which determined the similarity of rapeseed oils,soybean oils, peanut oils, cottonseed oils and camellia oils larger than 0.998,0.976,0.998,0.997,0.996.It indicated that all the standard fingerprint established by common pattern methods was consistent with the whole information of the fatty acids in each oil. It caculated the similarity of the standard fingerprint by the common pattern and by the method to directly choose the representation of the GC-MS fingerprint,which found the differences between the standard fingerpring of each oil,which reflected the differeces between each oil. It indicated that all the standard fingerprint was the differences of the fatty acids in each oil. At the same time,compared with the compositon and content of fatty acids in the seven major oils,it found that peanut oils had Hexacosanoic acid,higher content of Arachidic acid and Lignoceric acid,and rapeseed oils had nervonate acid and higher content of Linolenic acid.(3) It studied on the identification method of adulterated oils by the similarity analysis.It was caculated to the similarity of each adulterated oil and all the standard fingerprint through mixing cheap oil with different ratios of 5%,15%,25%,50% into high oil simulated the adulterated oil.It can qualitatively identify the adultertion oils with the similarity between all the standard fingerprint and the similarity of adulterated oils.(4) It studied on the identification method of adulterated oils by comparative analysis. Depended on these characteristic of vegetable oils, it drew two-dimensional diagram by the cis-oleic acid methyl ester/cis-linoleic acid methyl ester, palmitic acid methyl ester/stearic acid methyl ester.By the comparative analysis of which,it qualitatively identified the adulteration of oils.更多还原