【作者】 文冬梅；

【导师】 赵谋明； 赵强忠；

【作者基本信息】 华南理工大学 ， 粮食、油脂及植物蛋白工程， 2013， 硕士

【摘要】 我国是烟草种植大国，每年均有大量的烟末、烟梗等下脚料不能用于卷烟工业生产，将这部分副产物重新利用，制备烟用香精是烟末高值化利用的理想途径。本文利用已成熟的酶解技术对烟末进行酶解，以此为基液，添加合适的氨基酸、糖类和反应介质，通过美拉德生香技术制备烟用香精，同时对烟用香精的热力学特性和裂解产物进行了研究。分析了烟末酶解液的氨基酸和肽段组成，烟末蛋白中含有19种氨基酸，其中天冬氨酸、谷氨酸及脯氨酸含量较高，三者之和占烟末总氨基酸的40.80%；肽的分子量分布表明：大于10000Da的肽仅有1.11%，1000～5000Da占56.97%，小于1000Da的肽为35.35%。以烟末酶解液为基液，分别添加苯丙氨酸、甘氨酸、丙氨酸、天冬氨酸、亮氨酸进行美拉德反应，结果表明：甘氨酸的评吸得分最高，达到83分，确定甘氨酸为反应氮源。对评吸得分为高、中、低的美拉德反应液，进行反应前后氨基酸降解率的研究以及气质分析，结果表明：空白样、甘氨酸、亮氨酸、丙氨酸中各氨基酸在热反应前后变化不同，体系中天冬氨酸、异亮氨酸和脯氨酸在反应后含量增加，说明存在着肽的降解作用；经过高温加热后的空白样风味物质总数由原来的48种，增加到76种，增加的种类以酮类、呋喃类和以吡嗪为代表的含氮化合物为主。利用GC分析了烟末酶解液中的单糖种类，检测到了5种单糖，分别为鼠李糖、阿拉伯糖、甘露糖、葡萄糖和半乳糖。在以甘氨酸为反应氮源的基础上，分别添加木糖、葡萄糖、蔗糖、麦芽糖、果糖，结果表明：木糖评吸得分最高为83，蔗糖的评吸得分最低为78.5，选出木糖为反应碳源，GC-MS结果表明：木糖的反应活性最高，产生了6种其它两种糖没有的呋喃类物质。最后确定最佳碳氮比为2:1并优化出丙二醇作为最佳反应介质。利用响应面对美拉德反应工艺进行了优化，确定最佳反应pH值为6.72，时间为3.52h，温度为102.88℃，验证实验表明预测值与实验值无显著性差异，表明此法可靠、可行。对烟用香精的热力学特性研究表明：TG-DTG曲线显示样品存在较多的失重区间，主要热失重区在100-329℃，失重率达57.55%；从DSC图可以看出样品存在两个明显的吸热峰，峰值分别为162.89℃和209.22℃，对应的焓变为347.1J/g和17.44J/g。裂解实验表明：250℃时检测到了6种物质，550℃时检测到了42种物质，850℃时检测到了31种物质。裂解产物中以酮类、芳香烃类及吡啶和吡咯类化合物居多，吡咯类化合物对卷烟香气具有重要作用。更多还原

【Abstract】 Our country is a big planter of tobacco and there is plenty of tobacco powder and stemcan·t be used in cigarette industry. If these by-products can be reused, it·s a rational way thatwe turn these by-products into tobacco essence. In this paper, Mature enzyme technology wasused to hydrolyze tobacco powder. Different amino acids, saccharides and reaction mediumswere added into the enzymatic hydrolysate preparing tobacco essence through Maillardreaction. Meanwhile, the property of thermodynamic and the product of Py-GC/MS werestudied. The amino acid and peptide of enzymatic hydrolysate were analyzed. It demonstratedthat the tobacco powder has19kinds of amino acids and the content of Asp, Glu, Pro wererelatively high which accounted for40.80%of the total amino acids. The outcome of peptidemolecular weight distribution demonstrated that peptide over than10000Da accounted for1.11%, between1000Da and5000Da accounted for56.97%and less than1000Da accountedfor35.35%.Different amino acids such as Phe, Asp, Gly, Ala, Leu were respectively added into theenzymatic hydrolysate conducting Maillard reaction. It turned out that the score of Gly is thehighest reached83, so Gly is selected as the nitrogen source. Studied the degradation rate ofamino acid and analyzed the GC-MS before and after Maillard reaction with high, middle andlow score. It turned out that blank, Gly, Leu and Ala had different degradation rate before andafter reaction. Asp, Leu and Pro increased after reaction which suggested the degradation ofpeptide. The flavor components of blank increased from48to76after high temperaturewhich comprised of ketone, furan and nitrogen compounds represented by pyrazineThe type of monosaccharide of enzymatic hydrolysate was detected by GC. It had5kinds of monosaccharide, rhamnose, arabinose, mannose, glucose and galactose, respectively.Xylose, glucose, sucrose, maltose and fructose were respectively added into the enzymatichydrolysate which containing Gly. It turned out that the score of xylose is highest reached83and the score of sucrose is the lowest reached78.5. Xylose was selected as the carbon source.The outcome of GC-MS demonstrated that xylose had the highest activity which produced6kinds of furans. At last the optimal C/N was2:1and selected propylene glycol as the optimalreaction medium The process of Maillard reaction was optimized by response surface. It determined that pH is6.72,the time is3.52h and the temperature is102.88℃. Theconfirmatory experiment had no significant difference with the predicted value whichindicated the method is reliable. The outcome of thermodynamic property of tobacco essencedemonstrated that it had many weightlessness intervals from the curve of TG-DTG. The mainweightlessness interval was between100℃and329℃which the weightlessness ratereached57.55%. It can be seen that the simple had two obviously endothermic peak from thecurve of DSC, which is162℃and209.22℃corresponding ΔH is347.1J and17.44J. Theoutcome of Py-GC/MS demonstrated that it detected6kinds of component at250℃,42kindsat550℃and31kinds at850℃. The components of Py-GC/MS had majority of ketone,aromatic hydrocarbons, pyridine and pyrrole compounds and Pyrrole compounds plays animportant role in tobacco aroma.更多还原