【作者】 徐存吉；

【导师】 陈彦；

【作者基本信息】 安徽大学 ， 生物化学与分子生物学， 2013， 硕士

【摘要】 反式脂肪酸(Tans fatty acids, TFA)是不饱和脂肪酸的反式异构体,主要存在于氢化植物油、精炼植物油以及反刍动物脂肪中。但近年来,反式脂肪酸与人类的健康的关系引起社会的高度重视,如何减少反式脂肪酸的产生与限制其使用已成为国际关注的话题与研究的热点。酯化反应,是通过改变甘油三酯的结构来改善油脂性质的方法,因其不改变油脂固有的脂肪酸的组成,能保持天然脂肪酸营养价值的特点,为油脂改性与低反式脂肪酸功能食品的制备提供了理论依据,在今后油脂开发与应用领域有着广阔的前景。目的：1、优化乙醇钠催化酯化反应的条件与改善传统后处理方法,降低反应条件,提高产品得率；2、探讨酯化反应对油脂的性质的影响,说明酯化反应不引起反式脂肪酸的生成；3、将利用酯化反应制备熔点范围为30-38℃,亚油酸含量高、成本低且不含反式脂肪酸的多种酯化黄油产品,提高产品的营养价值,扩大产品的应用范围；方法：1、以棕榈硬脂与大豆油为原料,乙醇钠为催化剂,分别考察反应温度、反应时间以及催化剂用量对混合油熔点降低程度的影响,再采用响应面Box-Benknken Design设计实验,以熔点变化为依据,优化酯化反应的实验条件；2、采用体积分数为0-50%的乙醇水溶液分别对终止反应后的产品进行洗脱处理,比较不同洗脱方法的产品得率、溶液使用量以及反应前后油脂性质,选取乙醇水溶液后处理的最佳体积分数；3、将价格低廉的棕榈硬脂与富含多不饱和脂肪酸——亚油酸的大豆油按按1∶9-9∶1比例混合,比较分析反应前不同比例的混合油性质的变化以及反应后相同比例的混合油的性质变化,通过熔点测定确定反应后熔点范围为30-38℃时混合油的比例；4、利用椰子油富含对人体有益的功效成分——中／短碳链饱和脂肪酸的优点,将其与棕榈硬脂与大豆油分别按5∶4∶1、4∶4∶2、3∶4∶4比例混合反应,分析反应前后油脂中性质变化；5、利用气相色谱-质谱联用(GC-MS)、ABB油脂分析仪、高效液相色谱(HPLC)—蒸发光散射检测器、核磁共振分析仪、差示量热扫描仪分别对反应前后油脂的脂肪酸组成、碘值、甘油三酯组成、固体脂肪含量以及熔融曲线变化进行分析。结果1、响应面优化达到反应平衡点的最佳条件为：反应温度：79.1℃,反应时间：15.6min,催化剂量：0.45%,熔点下降程度达到23.45%；2、用体积分数为50%乙醇水溶液洗脱处理时,产品得率最高,洗脱次数与洗脱溶液的体积最少,洗脱后的乙醇可回收,减少了环境的污染,同时利用乙醇水溶液洗脱不改变油脂的性质；3、棕榈硬脂与大豆油比例在6∶4-3∶7时,反应后所形成的酯化黄油熔点范围在30℃-38℃,亚油酸含量在25%-40%之间；4、棕榈硬脂、大豆油与椰子油的比例为5∶4∶1、4∶4∶2、3∶4∶4时,酯化黄油的熔点在30。C—38℃,亚油酸比例为25%,油酸含量约为20%-25%,中／短碳链饱和脂肪酸含量为6%-20%;5、混合油组分比例的不同,其性质将发生相应的改变；但酯交换反应后,混合油中的熔点、甘油三酯成分、固脂含量、DSC熔化曲线均发生明显变化,但油脂中的脂肪酸组成与碘值没有发生明显改变,说明酯化反应不会引起脂肪酸的结构与饱和度的改变,即不产生反式脂肪酸；结论酯化反应是油脂改性的重要的手段,采用酯化反应制备各种酯化黄油,尽管反应前后甘油三酯结构组成、固脂含量、融化曲线均发生明显变化,但是脂肪酸组成不变,不发生脂肪酸异构化,无反式脂肪酸生成,因此,酯化反应将是油脂加工与功能性油脂制备领域的重要的发展方向。更多还原

【Abstract】 Trans fatty acids (TFA) were unsaturated fatty acid isomers, which mainly present in ruminant animal fats, refined and hydrogenated oils. They have been applied in all kinds of food and used as function solid fats. While the relationship between trans-fatty acids and human health has been caused high attaches by social in recent years, How to reduce and restrict the production of trans-fatty acids have become an international hotspot and focus issue. The molecular rearrangement technique was a method to improve grease properties by changing the structure of triglycerides, As it couldn’t change the fatty acid composition of fats and would maintain the nutritional value of the natural fatty acids, which could provided a theoretical basis for the preparation of low trans fatty acid products, it will have broader prospects on future oil development and application areas.Objective11、 To reduce the reaction conditions and improve product yield by optimizing rearrangement reaction conditions and improving the traditional post-processing method;2、 To investigate the effect of molecular rearrangement on the properties of blends oil, especially to verify the molecular rearrangement wouldn’t cause the formation of trans fatty acids;3、 To preparation a variety of esterification butter which melting point range30℃to38℃, have high-linoleic acids but low cost and low-trans fatty acids with molecular rearrangement reaction, it would improve the nutritional value of the product and expand the range of application.Methods1、 The effect of reaction temperature, reaction time and amount of catalyst on the depression rate of melting point were investigated detected by using the palm stearin and soybean oil blends, sodium ethoxide as a catalyst. Then the optimal conditions of the molecular rearrangement reaction were optimized by the Box-Benknken response surface Design according to the change of melting point. 2、 The products after the reaction were treated with different volume fractions of ethanol solution range0to50%, respectively. The aqueous solution of ethanol optimum volume fraction of the post-processing were selected by comparing the yield and the amount of solution used in different treatments, and their properties before and after the reaction:3、 The low-price palm stearin and rich-polyunsaturated fatty acids soybean oil were blended at a ratio rang1:9to9:1, the qualitative change of different combinations of raw oil before reaction and the same proportion of blends oils before and after reaction were compared, the proportion of raw materials were selected ultimately according to the melting point determination which range of30-38℃after reaction.4、 According to the coconut oil have rich middle/short chain saturated fatty acids which have beneficial effect on the human health, It would mix with Palm stearinand soybean oil and coconut oil mixed at proportion of5:4:1,4:4:2,3:4:4, respectively, then analysed their properties change before and after reaction.5、The fatty acid composition, iodine value, triglyceride composition, solid fat content and melting curve were analysed by Chromatography-Mass spectrometry (GC-MS), ABB oil analyzer, High performance liquid chromatography (HPLC)-evaporative light scattering detector, nuclear magnetic resonance analyzer and Differential calorimeter scanner respectively.Results(1) The optimization conditions were achieve by response surface, when there were0.45%catalyst, at79.1℃for15.6min, The melting point would drop of23.45%.(2) When the product was treated with ethanol elution which volume fraction was50%, It would have the highest yield but the least amount of solution, at the same time, using these aqueous solution of ethanol elution could reduce the environment pollution as ethanol can be recycled at last, It don’t change the nature of the oil especially there were not trans fatty acids production.(3) When the proportion of palm stearin and soybean oil were6:4to3:7, the melting points of esterification reaction were range30℃to38℃, the content of linoleic acid were25%-40%; (4) When the proportion of the palm stearin, soybean oil and coconut oil were5:4:1,4:4:2,3:4:4, the melting point of esterification butter in30℃～38℃， the linoleic acid content was25%, oleic acid content was about20%～20%, linolenic acid was2%, the medium/short carbon chain saturated fatty acid content was6%～20%;(5) The nature of the mixed oil would change when the ratio of oils were different; After transesterification reaction, the melting point, triglyceride composition, solid fat content, DSC melting curve changed significantly, but the acid composition of and iodine value were same before and after reaction, there did not cause fatty acid structure and saturation changes, in other words, it wouldn’t produce trans fatty acids.ConclusionsMolecular rearrangement was an important means in oil modification, The results showed that when using molecular rearrangement to prepare esterification butter, the triglyceride composition, solid fat content, DSC melting curve had obvious changed, but the fatty acid composition was constant, importantly the fatty acids isomerization didn’t occur, there was not trans fatty acids in esterification butter. Therefore, molecular rearrangement would have more important development direction in oil processing and functional oils preparation.更多还原