美拉德反应时间对烟草花蕾发酵液挥发性香味成分的影响

为研究不同美拉德反应时间对烟草花蕾发酵液挥发性香味成分的影响,烟草花蕾经高活性产香酵母发酵后,通过时间调控优化美拉德反应制备烟用香料,并对此香料进行主成分分析以及加香评吸。结果表明:经同时蒸馏萃取提取,美拉德反应8 h样品香味物质有45种,反应12 h样品香味物质有38种,反应16 h样品香味物质有45种,反应20 h样品香味物质有42种,主要包括醇、醛、酸、酯、酮、呋喃和吡啶等。烟草花蕾发酵液经不同美拉德反应时间处理后香味成分主成分分析可知,美拉德反应时间8、12、20h样品的香味成分有显著差异,美拉德反应时间16、12 h样品的香味成分无显著差异。美拉德反应时间12h的样品对空白烟进行加香评吸的效果最佳。     

山梨糖与羟脯氨酸的美拉德反应条件优化及抗氧化研究

以山梨糖和羟脯氨酸为原料,通过单因素试验和正交试验,确定了较佳的美拉德反应条件,即当反应温度为160℃,反应时间5 h,pH为8,山梨糖和羟脯氨酸摩尔比为1∶2时,美拉德反应产物的质量最好。通过测定反应产物对DPPH自由基的清除率,结果表明美拉德反应产物可以作为抗氧化剂。利用GCMS气质联用仪对反应产物进行了分离鉴定,检测到吡嗪、吡咯、吡啶等杂环化合物,这些物质是卷烟中的重要香气成分,为卷烟加香提供了一定的理论基础。     

葡萄糖与脯氨酸的美拉德反应条件优化及其产物的再造烟叶加香研究

[目的]优化美拉德反应的条件,并考察其产物在再造烟叶中的加香效果。[方法]以葡萄糖和脯氨酸为原料,优化美拉德反应的条件,并考察其产物在再造烟叶中的加香效果,并用GC-MS对产物进行分离鉴定。[结果]美拉德反应的最优条件:在沸水浴下,反应时间3 h,pH 6,糖氨摩尔比为1∶1,丙二醇占比为30%。在此条件下,美拉德反应产物的再造烟叶增香效果好。利用气-质联用仪对产物进行GC-MS分析,检测到吡咯类、酮类等化合物,这些物质是卷烟中的重要香气成分。[结论]美拉德反应产物的再造烟叶加香效果好。     

果糖与羟脯氨酸美拉德反应条件的优化

为确定果糖与羟脯氨酸进行美拉德反应的最佳条件,以美拉德反应产物在420nm下的吸光值为评价指标,通过单因素试验和正交试验,研究了反应温度、反应时间、初始pH值、外加水分、糖氨配比对果糖与羟脯氨酸美拉德反应产物质量的影响。结果表明,最佳反应条件为:反应温度160℃、反应时间3h、初始pH值8、糖氨摩尔比1∶3、外加水分0,该条件下美拉德反应产物的吸光值为0.835。对美拉德反应产物进行GC-MS分析,鉴定出15种挥发性香气成分,其主要为吡嗪、吡咯、呋喃等杂环化合物,表明果糖与羟脯氨酸的美拉德反应产物具烟草增香作用。     

烟用美拉德反应香料研究

美拉德反应产物在国内外的食用和烟用香料中占有极为重要的位置,本试验采用不同的原料在不同的反应条件下合成出14种香气较好的产物,对适合烟用的反应产物进行筛选,并运用色谱分析法鉴定出12种挥发性致香成分,卷烟加香试验表明,筛选出的反应香料能显著地增强烟香,减少杂气,改善吸味.     

废烟末与脯氨酸的卷烟增香美拉德反应条件筛选

通过四因素四水平的正交试验考察了废烟末烟膏与脯氨酸美拉德反应的最佳条件,对甘油层和三醋酸甘油酯层中反应产物卷烟加香感官评价结果表明,反应温度100℃、时间9 h、废烟末烟膏∶氨基酸3∶1、甘油在甘油-三醋酸甘油酯中用量百分比40%,对烟丝和嘴棒的加香效果都达到最佳。对最佳条件的混合反应产物进行GC/MS分析鉴定,35种产物中包括2-甲基吡嗪、2-乙酰基呋喃、2-吡咯烷酮、2-哌啶酮、1-乙酰基吡咯烷等对烟草香味有着很好修饰作用的美拉德反应产物,以及烟碱、苯乙烯、香草醛、莨菪亭、4,7,9-巨豆三烯-3-酮等加强烟草本香化合物,可以作为烟用香料用于卷烟加香。     

烤烟花蕾美拉德反应制备烟用香料的探讨

对烤烟花蕾的美拉德反应条件进行优化认为,在反应温度为110 ℃、反应时间为4 h、pH为7时得出的烤烟花蕾香料的感官评吸分数最高,评吸结果表明,卷烟的香气增加,香气的谐调性和余味得到改善,主要增加的是卷烟的焦糖香和花甜香。对最优条件下的烤烟花蕾香料进行GC MS分析,其中含有25种挥发性化合物,包括醇类4种、杂环类5种、醛类1种、有机酸类1种、酯类2种、酮类1种及烯烃烷烃类11种。     

不同加热时间处理对烟草花蕾酶解液美拉德反应产物挥发性香味成分影响

【目的】为探寻不同加热时间处理对烟草花蕾酶解液美拉德反应产物挥发性香味成分的影响。【方法】以烟草花蕾酶解液为原料,利用主成分分析和感官评吸方法进行分析。首先,在70℃的条件下分别加热烟草花蕾酶解液8、12、16和20 h,使其发生美拉德反应,制备烟用香料;然后利用同时蒸馏萃取法提取挥发性成分并进行主成分分析,最后对该香料进行评吸试验。【结果】(1)经同时蒸馏萃取提取的香味物质,美拉德反应8 h有46种,12 h时有47种,16 h时有52种,20 h时有46种,主要包括醇、醛、酸、酯、酮、呋喃和吡啶等。(2)香味成分主成分分析可知:美拉德反应时间8、16、20 h的3个样品的香味成分有显著差异;美拉德反应时间12、16 h的2个样品香味成分无显著差异。(3)感官评吸结果表明:美拉德反应时间12 h的样品加香效果最佳。【结论】对不同的美拉德反应时间的反应产物进行化学和感官评价分析,为烟草花蕾制备烟用香料提供了方法。     

鲎血水解液美拉德反应产物的挥发性成分研究

以制备鲎试剂产生的废料血浆为原料,经盐酸水解后,水解液进行美拉德反应,通过固相微萃取-气相色谱-质谱法(SPME-GC-MS)测定反应产物中的挥发性成分,分析了其呈香机理。结果表明,鲎血水解液在p H为8.0,100℃加热2 h,其美拉德反应的褐变程度最强,确定了39种挥发性成分,主要包括烃类5.13%、酮类1.47%、酸类2.64%、醛类14.08%、酯类1.24%、酚类0.84%、醇类4.33%及含氮化合物0.26%。该结果可为开发苯甲醛、食品香精及卷烟改良剂等方面提供参考。     

模式美拉德体系产物对油脂抗氧化性能的影响研究

通过建立模式美拉德体系,研究不同反应条件下美拉德产物的抗氧化性差异。试验结果表明,将3%半胱氨酸,与1%葡萄糖,0.5%盐酸硫胺素分别混合于100g的甘油中,调其pH8,温度110℃,反应1.5h,制得的美拉德反应产物,以1%的浓度加入到油脂中,对油脂的抗氧化效果最佳。     

Fractal reaction kinetics

Classical reaction kinetics has been found to be unsatisfactory when the reactants are spatially constrained on the microscopic level by either walls, phase boundaries, or force fields. Recently discovered theories of heterogeneous reaction kinetics have dramatic consequences, such as fractal orders for elementary reactions, self-ordering and self-unmixing of reactants, and rate coefficients with temporal "memories." The new theories were needed to explain the results of experiments and supercomputer simulations of reactions that were confined to low dimensions or fractal dimensions or both. Among the practical examples of "fractal-like kinetics" are chemical reactions in pores of membranes, excitation trapping in molecular aggregates, exciton fusion in composite materials, and charge recombination in colloids and clouds.     

Simplex optimization of reaction yields

The sequential simplex algorithm, an efficient optimization strategy, rapidly improved reaction yield as a function of time and temperature in the synthesis of pi-C(5)H(5)Mo(CO)(2)CSN(CH(3))(2). The work demonstrates the feasibility and efficiency of the simplex design and suggests its application and usefulness in other syntheses.     

Supracolloidal reaction kinetics of Janus spheres

Clusters in the form of aggregates of a small number of elemental units display structural, thermodynamic, and dynamic properties different from those of bulk materials. We studied the kinetic pathways of self-assembly of "Janus spheres" with hemispherical hydrophobic attraction and found key differences from those characteristic of molecular amphiphiles. Experimental visualization combined with theory and molecular dynamics simulation shows that small, kinetically favored isomers fuse, before they equilibrate, into fibrillar triple helices with at most six nearest neighbors per particle. The time scales of colloidal rearrangement combined with the directional interactions resulting from Janus geometry make this a prototypical system to elucidate, on a mechanistic level and with single-particle kinetic resolution, how chemical anisotropy and reaction kinetics coordinate to generate highly ordered structures.     

Quantum theory of chemical reaction dynamics

It is now possible to use rigorous quantum scattering theory to perform accurate calculations on the detailed state-to-state dynamics of chemical reactions in the gas phase. Calculations on simple reactions, such as H + D2 --> HD + D and F + H2 --> HF + H, compete with experiment in their accuracy. Recent advances in theory promise to extend such accurate predictions to more complicated reactions, such as OH + H2 --> H2O + H, and even to reactions of molecules on solid surfaces. New experimental techniques for probing reaction transition states, such as negative-ion photodetachment spectroscopy and pump-probe femtosecond spectroscopy, are stimulating the development of new theories.     

Laser probing of chemical reaction dynamics

Lasers are used in increasingly sophisticated ways to carry out reactions between molecules in selected vibrational, rotational, and electronic states and to probe the product states of chemical reactions. Such investigations are providing unprecedented insights into chemical reaction dynamics, the study of the detailed motions that molecules undergo in simple chemical reactions. In many cases it is possible to describe the influence that specific types of molecular excitation have on reactive events. Experiments are also being carried out to leam about chemical reactivity as a function of the alignment of reagents. There is increasing excitement concerning the potential of laser methods to interrogate the transition states of molecular reactions.