【作者】 黄亮；

【导师】 余平；

【作者基本信息】 南昌大学 ， 化学工程与技术， 2025， 硕士

【摘要】 樟树籽仁油是我国独有的天然中链油脂,其中链脂肪酸含量分别为月桂酸(37.39%)、癸酸(56.83%)和辛酸(0.46%)。研究表明,长期过量摄入三月桂酸甘油酯会影响体内胆固醇的代谢并升高血液胆固醇水平。樟树籽仁油因其月桂酸含量超37%,长期食用亦可能引发类似的代谢紊乱问题。为了进一步提高樟树籽仁油的生理效应和经济价值,本论文在第二章至第四章中分别以Lipozyme RM IM脂肪酶为生物酶催化剂,以辛酸、癸酸为酰基供体与樟树籽仁油反应,调整其中链脂肪酸组成(降低月桂酸含量);并探究不同酰基供体在反应动力学中的差异;以不同摩尔比制备了不同月桂酸含量的樟树籽仁油。另一方面,工业油酸中的油酸和亚油酸因性质相近导致分离困难,常规方法较难实现高纯油酸的制备,这也制约了油酸在食品、医药等领域的应用。在第五章中本论文以尿素包合法分离纯化工业油酸,以达成结构相似的脂肪酸绿色分离。主要研究结果如下:(1)以月桂酸含量为评价指标,优化低月桂酸樟树籽仁油制备工艺。筛选确定Lipozyme RM IM脂肪酶为催化反应的最佳用酶。癸酸反应体系最佳技术条件为:底物摩尔比10∶1,反应时间6 h,反应温度50℃,加酶量6 wt%,所得产品的中链脂肪酸含量为11.40%月桂酸、85.72%癸酸和0.24%辛酸;辛酸反应体系最佳技术条件为:底物摩尔比6∶1,反应温度50℃,反应时间6 h,加酶量4wt%,所得产品的中链脂肪酸含量为16.34%月桂酸、54.53%癸酸和25.81%辛酸。两种酰基供体反应所得产品的理化性质均符合植物油国家标准(GB 2716-2018)。(2)对比辛酸和癸酸分别作为酰基供体的反应动力学。基于反应温度与反应初速度之间的关系,分别以酰基供体增量(辛酸体系:22.88 k J/mol,癸酸体系:45.18 k J/mol)和月桂酸减量(辛酸体系:44.46 k J/mol,癸酸体系:51.36 k J/mol)所表示的反应活化能中,辛酸体系的反应活化能均小于癸酸体系,表明以辛酸为酰基供体时克服的能垒更低,更易发生反应。基于底物浓度与反应初速度之间的关系,可知辛酸体系和癸酸体系的酰基交换反应分别符合单底物竞争抑制和双底物竞争抑制的Ping-Pong Bi-Bi机制,拟合确定CCSKO的米氏常数(辛酸体系:1.59 mmol/L,癸酸体系:0.091 mmol/L)均远小于酰基供体的米氏常数(辛酸体系:626.01 mmol/L,癸酸体系:10.18 mmol/L),表明Lipozyme RM IM脂肪酶对CCSKO具有更高的亲和力。(3)辛酸和癸酸分别以不同摩尔比(脂肪酸∶樟树籽仁油,1∶1～12∶1)制备不同月桂酸含量的樟树籽仁油,采用高效液相色谱和差示量热扫描仪测定其甘油三酯组成与热力学性质变化。经不同酰基供体交换后,辛酸体系中甘油三酯增加了两种新的构型(CCCa和CCLa/CCa Ca);与樟树籽仁油相比,其熔融和结晶温度均显著降低。癸酸体系中的甘油三酯构型无变化,但随着摩尔比的增加,Ca Ca Ca(ECN=30)构型成为其主要组成;熔融和结晶温度在摩尔比(1∶1～5∶1)下有小幅度的下降,增加摩尔比后逐渐与樟树籽仁油的熔融和结晶温度接近。(4)以油酸的纯度与得率为评价指标,采用尿素包合法纯化工业油酸,通过单因素实验优化得到最佳纯化工艺条件为:尿素∶脂肪酸为3∶1(w/w)、95%乙醇∶尿素为4∶1(v/w)、结晶温度为10℃、结晶时间为6 h。在该条件下,油酸纯度为89.78%,得率为91.31%。本文优化的工艺过程不同于传统的解包合方式,采取更为绿色的解包合过程,既实现尿素的回收利用,又不影响分离效果。更多还原

【Abstract】 Cinnamomum camphora seed kernel oil(CCSKO)is a unique natural medium-chain oil in China,which contains lauric acid(37.39%),capric acid(56.83%),and caprylic acid(0.46%).Studies have shown that long-term excessive intake of glyceryl trilaurate may disrupt cholesterol metabolism and elevate blood cholesterol levels.Given that the lauric acid content of CCSKO exceeds 37%,prolonged consumption could lead to analogous metabolic dysregulation.To further enhance the physiological effects and economic value of Cinnamomum camphora seed kernel oil(CCSKO),this study employed Lipozyme RM IM lipase as a biocatalyst in Chapters 2 to 4.Caprylic acid and capric acid were utilized as acyl donors to react with CCSKO,adjusting its medium-chain fatty acid composition(reducing lauric acid content).Additionally,the differences in reaction kinetics between these acyl donors were investigated.CCSKO with varying lauric acid contents was prepared using different molar ratios.On the other hand,conventional methods struggle to separate oleic acid and linoleic acid in industrial oleic acid due to their structural similarity,limiting the production of high-purity oleic acid.This challenge hinders the broader application of oleic acid in food,pharmaceutical,and related industries.In Chapter 5,urea inclusion was used to separate and purify industrial oleic acid to achieve green separation of fatty acids with similar structure.The main research results are as follows:(1)Optimized the preparation process of low lauric acid content CCSKO with lauric acid content as the evaluation index.Lipozyme RM IM lipase was identified as the optimal catalyst for this reaction.For the capric acid reaction system,optimal conditions included:substrate molar ratio 10∶1(capric acid to CCSKO),reaction time6 h,reaction temperature 50℃,and enzyme load 6 wt%.Under these conditions,the content of medium-chain fatty acids was 11.40%lauric acid,85.72%capric acid,and0.24%caprylic acid.For the caprylic acid reaction system,optimal parameters included:substrate molar ratio 6∶1(caprylic acid to CCSKO),reaction temperature 50℃,reaction time 6 h,and enzyme load 4 wt%.Under these conditions,the content of medium-chain fatty acids was 16.34%lauric acid,54.53%capric acid,and 25.81%caprylic acid.The physicochemical properties of the modified oils from both reactions complied with China’s national vegetable oil standards(GB 2716-2018).(2)A comparative analysis of reaction kinetics was conducted between caprylic acid and capric acid as acyl donors.Based on the relationship between the temperature of the reaction and initial reaction velocity.Activation energies were calculated based on the increase in acyl donor content(22.88 k J/mol for caprylic acid and 45.18 k J/mol for capric acid)and the reduction in lauric acid content(44.46 k J/mol for caprylic acid and 51.36 k J/mol for capric acid).The caprylic acid system exhibited lower activation energy compared to the capric acid system.The results of activation energy indicate that the caprylic acid as the acyl donor overcomes a lower energy barrier and is more prone to reaction.Based on the relationship between substrate concentration and initial reaction velocity.It can be seen that the acyl exchange reaction of caprylic acid system and capric acid system conforms to the Ping-Pong Bi-Bi mechanism of single-substrate competition inhibition and double-substrate competition inhibition,respectively.The Michaelis-Menten constant of CCSKO(caprylic acid system:1.59 mmol/L,capric acid system:0.091 mmol/L)was much smaller than that of acyl donor(caprylic acid system:626.01 mmol/L,capric acid system:10.18 mmol/L).This indicates that Lipozyme RM IM lipase exhibits higher affinity toward CCSKO than toward the acyl donors.(3)CCSKO with varying lauric acid contents was prepared using different molar ratios of caprylic acid and capric acid(fatty acid:CCSKO,1∶1～12∶1).The triglyceride composition and thermodynamic properties were analyzed via high-performance liquid chromatography(HPLC)and differential scanning calorimetry(DSC).After acyl donor exchange,two new triglyceride configurations(CCCa and CCLa/CCa Ca)emerged in the caprylic acid system.Compared to unmodified CCSKO,the melting and crystallization temperatures of the modified oil were significantly reduced.In the capric acid system,the triglyceride configurations remained unchanged.However,with increasing molar ratios,Ca Ca Ca(ECN=30)became the predominant component.The melting and crystallization temperatures exhibited a slight decrease at molar ratios of1∶1～5∶1 but gradually approached those of unmodified CCSKO at higher molar ratios.(4)Using oleic acid purity and yield as evaluation criteria,industrial oleic acid was purified via the urea inclusion.Through single-factor experimental optimization,the optimal purification conditions were determined as follows:urea-to-fatty acid ratio of 3∶1(w/w),95%ethanol-to-urea ratio of 4∶1(v/w),crystallization temperature of10℃,and crystallization time of 6 hours.Under these conditions,the purity of oleic acid reached 89.78%with a yield of 91.31%.Unlike traditional decomplexation methods,the optimized process adopted a greener decomplexation approach,enabling efficient urea recycling while maintaining separation efficiency.更多还原