【作者】 战宇；

【导师】 宁正祥；

【作者基本信息】 华南理工大学 ， 食品科学， 2003， 博士

【摘要】 民以食为天,食以加工保藏为先。食品工业的核心技术之一是食品的防腐保鲜。研究广谱、高效、低毒的食品防腐保鲜剂,对促进食品工业的发展具有重要的意义与实用价值。食品防腐剂构效关系的研究发现,富马酸二甲酯分子中含有的二个等价的α,β-不饱和羰基结构,是一个非常有效的抗菌活性功能域,但因富马酸二甲酯潜在的皮肤过敏毒性而禁止使用。研究如何利用富马酸分子中的高效抗菌母体结构而又不产生毒副作用,具有重要意义。本论文以反丁烯二酸为母体,利用桂醇基作为远离抗菌活性中心的疏水性残基增强抗微生物代谢性,与甲醇经酯化反应合成出一种新的食品防腐剂-丁烯二酸桂醇甲酯。论文同时对丁烯二酸桂醇甲酯的抑菌活性及在荔枝常温保鲜中的应用效果进行了研究。丁烯二酸桂醇甲酯的合成路线为:首先以顺丁烯二酸酐与肉桂醇反应生成顺丁烯二酸桂醇单酯,经转型反应后再进行甲酯化制取丁烯二酸桂醇甲酯。桂醇甲酯的最佳合成工艺条件为:以摩尔质量比为1:2 的马来酸酐与肉桂醇在95℃醇解2~4h 制取顺丁烯二酸肉桂醇单酯,加入复合转型催化剂在85℃~90℃下反应2.5~3.0h 转型后,添加6 倍摩尔质量的甲醇,以3% 1.25:1 的BF3 和HCl 混合液作为酯化催化剂,90℃恒温反应4h 合成。酯化反应体系中的水分含量是制约合成产率的主要因素之一。实验通过流加硫酸来除去反应中生成的水分。除水剂硫酸的总用量为3%,在酯化反应进行0.5h~3.0h 之间流加,桂醇甲酯的合成产率随硫酸流加次数的增多而增大。当硫酸流加次数达到7 次时,桂醇甲酯的合成产率可达87.6%。转型产物丁烯二酸桂醇单酯难溶于水,易溶于有机溶剂中。经甲酯化反应后,丁烯二酸桂醇甲酯在水中的溶解度增大。实验还发现,随桂醇单酯甲酯化反应的进行,晶体形态由针形簇状逐渐转变为片状并聚集成块。桂醇甲酯的最大紫外吸收波长为218nm。合成产物经高压液相色谱分析,气相色谱-质谱检测表明其组成为富马酸二甲酯、丁烯二酸桂醇甲酯和丁烯二酸二桂醇酯。对合成产物采用溶剂法重结晶后,丁烯二酸桂醇甲酯的含量可达到90%以上。对丁烯二酸桂醇甲酯抑菌特性的研究结果表明:桂醇甲酯的抑菌活性不受环境酸碱条件的影响,在不适于微生物生长的pH 条件下,能够协同环境对微生物的生长发挥更有效的抑制作用;当使用浓度增大至0.075%以上时,桂醇甲酯的更多还原

【Abstract】 Food is very important to the people. In the production of food, it is crucial that proper measures are taken to ensure the safety and stability of the product during its whole shelf life. So it is a hot issue in food science to develop high-performance, broad-spectrum and low toxicity preservatives. The relationship between structure and antimicrobial activity of preservatives showed that dimethyl fumarate (DMF) is an effective preservative containing two α,β-unsaturated carbonyl, but it is banned to be used in food because of its skin allergy. It is significant to study how use the effective group of α,β-unsaturated carbonyl and has no poisonous side effect. In the dissertation a new preservative -cinnamyl methyl fumarate (CMF) was designed and synthesized which has two α,β-unsaturated carbonyl as base group, cinnamyl as hydrophobicity group to increase its antimicrobial activity. Its antimicrobial activity and the effect in litchi fresh-keeping were also studied. In order to synthesize CMF, the following route was adopted: maleic anhydride react with cinnamyl alcohol to produce cinnamyl maleate, then isomerized and esterified. The optimum technology condition to synthesize CMF as following: maleic anhydride and cinnamyl alcohol (molar ratio 1:2) react under 95℃for 2~4h before the isomerization catalysts were added. Then the mixture maintained at 85℃~90℃for 2.5~3.0h before methol (molar ratio 1:6), 3% 1:1 HCl and BF3 mixture were added. Then react under 90℃for 4h. Content of water is one of the main factors to restrict the synthesis rate. The experiment adopted adding sulphuric acid to remove the water during esterification. The amount of sulphuric acid is 3%, adding at 0.5h~3.0h during esterification. The synthesis rate of CMF increased with adding times of sulphuric acid. When adding times reach seven, the synthesis rate of CMF increase to 87.6%. The cinnamyl fumarate is difficult to dissolve in water, and easy to dissolve in organic solvent. The solubility of CMF increases in water. It is also found that during esterification the crystal form change from a cluster of needle to lamellar crystal in bulk. The largest ultraviolet absorption wavelength of CMF is 218nm. The high pressure liquid chromatogram, gaseous phase chromatogram -mass spectrum were used to analysis the constitute of the material. The result showed that there are dimethyl fumarate, cinnamyl methyl fumarate and dicinnamyl fumarate in it. After purification, the contents of CMF can reach more than 90%. The experiment of CMF antimicrobial activity shows that: antimicrobial activity of CMF doesn’t influence by the pH of environment. Under low pH, CMF can coordination with the environment to restrain the growth of the microorganism more effectively. When increase the concentration of CMF to 0.075%, the antimicrobial effect doesn’t remarkably change with the increase of concentration. Changes of temperatures can’t influence the antimicrobial activity of CMF. The minimal inhibitory concentration of CMF is lower than that of the food preservatives-potassium sorbate, sodium benzoate and hydroxybenzoate by 4~10 times. CMF is stability, difficult to sublimation. It overcomes the shortage of DMF, and hopeful to become a new food additive. 0.05%CMF can inhibit the growth of Peronophythora litchi Chen. Filming with 1%CMF, 10% critic acid and 10% membranes material, litchi can store under25~ 35℃(relative humidity 80%~90%) for 12days. From the results of SEM, we could find that fresh-keeping treatment could from a layer of manmade wax, that could keep the integrality of real pericarp of litchi, prolong its fresh period.更多还原