肉桂中肉桂醛及肉桂酸的微波辅助萃取及HPLC测定

利用聚焦式微波辅助萃取系统,结合HPLC分析,对肉桂 中的肉桂醛和肉桂酸进行微波萃取分离和分析,并比较 了水及乙醇等溶剂作为萃取溶剂的效果。研究发现,极性 强的溶剂,如水、乙醇容易吸收微波,温升较快,而石油醚 和正己烷等极性较弱的溶剂,对微波的吸收较弱,温升较 慢。比较极性溶剂在微波场温升效应得,无水乙醇≥80％ 乙醇>纯水>0.1NNaOH>0.1NHCl。以乙醇为溶剂进行肉 桂醛的微波萃取,得率为2.37％,以水为溶剂的萃取得率 为2.04％;溶剂之间的差别不大。而对肉桂酸的微波萃取, 以乙醇为溶剂的萃取得率为0.96％,以水为溶剂的萃取得 率为2.91％,溶剂之间的微波萃取效果差别较大。      

高速逆流色谱纯化元宝枫神经酸的研究

将元宝枫翅果脱去果皮,获得元宝枫种仁,处理粉碎,采用液压榨油机方式制取元宝枫原油,通过CO_2超临界萃取技术,获得元宝枫精油。以正庚烷、乙腈为基本两相,选择氯仿、醋酸乙酯调节系统极性,组成2种三元溶剂体系;以正己烷、水为基本两相,选择乙醇调节系统极性,组成第3种三元溶剂体系。以上述3种溶剂体系进行精油的高速逆流色谱纯化。结果表明,高速逆流色谱纯化效果最好的溶剂系统是正己烷、乙醇和水组成的三元溶剂系统,为弱极性溶剂系统;高速逆流色谱纯化效果的最佳参数:流动相流速为3.5 m L/min,转速为850 rad,正己烷、乙醇、水的比例为6:5:1.5;纯化元宝枫神经酸的纯度为18.05%,得到了理想的纯化效果。     

六堡茶中咖啡因加速溶剂萃取(ASE)的工艺研究

本研究探讨了加速溶剂萃取(ASE)法提取六堡茶中咖啡因。采用快速溶剂萃取仪提取六堡茶中咖啡因,以乙醇为萃取溶剂,利用单因素试验考察乙醇浓度对提取率的影响,设置仪器压力为10MPa,选择萃取温度、萃取时间、循环次数等影响咖啡因得率的因素进行L_9(3~4)正交试验,以咖啡因得率为主要指标,考察ASE法最佳提取条件并与微波辅助提取法进行比较。结果显示ASE法提取六堡茶中咖啡因的最优化条件是以无水乙醇为溶剂,在温度120℃条件下静态萃取3次,每次10min;经ASE法提取,咖啡因的平均得率为20.374mg/g,其提取物经过C18固相萃取小柱处理不仅能除去六堡茶提取液中的大部分杂质,而且对咖啡因的含量几乎没有影响,经微波辅助法提取,咖啡因的平均得率为17.028mg/g。说明ASE法提取六堡茶中咖啡因,其提取率高于微波辅助提取法,且能保证提取物的质量。     

超临界CO2、微波和超声波辅助提取光皮树子油工艺研究

本文通过超临界CO2提取光皮树子油的均匀设计实验和微波和超声波诱导提取光皮树子油的正交实验比较,考察影响提取的主要因素,寻求最佳萃取工艺。超临界CO2萃取最佳工艺条件为：萃取压力37MPa,萃取温度300C,CO2流量30kg／h和时间80min,得率16．34％;微波萃取最佳工艺条件为：溶剂为石油醚,物料与溶剂比例1：3,辐射时间7min,辐射功率720w,得率8．12％。超声波萃取最佳工艺条件为：物料与溶剂比例1：7,溶剂为正已烷,浸泡时间18h,得率7．75％。结果表明超临界CO2萃取光皮树子油品质最好,而且萃取也最高,质量最稳定。     

微波法萃取玉米黄色素的工艺

采用微波萃取技术提取玉米黄色素,研究微波控制条件对玉米黄色素提取率的影响,并在单因素试验的基础上进行正交试验.研究结果表明,玉米黄色素的最大吸收波长为448nm,微波萃取玉米黄色素的最佳工艺条件为以50％乙醇为提取溶剂,微波功率450W、料液比为1:12(g:mL)、微波作用时间80s、萃取2次.     

微波法萃取春砂仁中低极性油树脂的研究

以低极性的乙醚作溶剂，比较微波-溶剂萃取法与单纯有机溶剂萃取法提取春砂仁中低级性油树脂的提取率，并对微波法中溶剂用量、萃取温度、萃取时问等3个因素进行了筛选，表明微波萃取法所取得的产率比有机溶剂法高14．3％；其最佳提取率对应的溶剂与砂卜粉的比例（固液比）为1：5，萃取温度为45℃，萃取时间为180s，产率达3．2％。本文还采用了同相微萃取（SPME）顶夺取样方法，通过GC／MS分析并比较了萃取物中的主要有效成分，说明微波萃取法不仪提取率较高，且具有一定的选择性。     

超声波—微波协同萃取姜辣素的工艺研究

研究超声波-微波协同萃取姜辣素的工艺条件。以生姜粉为材料,通过单因素和正交试验探讨超声波-微波协同萃取姜辣素的工艺条件中溶剂种类、乙醇浓度、微波功率、微波处理时间、料液比及超声波等因素对萃取效果的影响。最佳工艺条件：70％乙醇为溶剂;料液比1：12．5（W：V）;超声波250W微波协同处理60s,姜辣素的提取率达到1．843％,处理后物料经70℃热回流提取2h,姜辣素的提取率可达到3．262％,是直接热回流提取2h的1．5倍。     

超声-微波协同辅助萃取茶皂素

采用超声-微波协同辅助萃取脱脂油茶籽粕中的茶皂素.在单因素试验的基础上,固定超声波功率50 W,萃取次数2次,以乙醇体积分数、料液比、微波功率和萃取时间为影响因素,茶皂素得率为指标,正交试验进行优化,最终确定的茶皂素萃取工艺条件为:乙醇体积分数50％,料液比1∶10,微波功率600W,超声波功率50 W,萃取时间150 s,萃取次数2次.在此条件下,茶皂素得率为(17.43±0.13)％,纯度为67.12％.     

超声波-微波协同萃取紫草总色素及紫草素的制备

以新疆紫草为原料,乙醇作萃取剂,考察了超声波-微波协同萃取紫草总色素的工艺条件.并采用Cu2络合纯化方法将萃取所得的总色素水解制备成了紫草素.在超声波功率内置为50W的仪器条件下,采用分光光度法测定提取液吸光度的方法考察了萃取剂浓度,料液比,微波功率、提取时间对色素提取效果的影响.通过单因素实验和L9(34)正交实验确定了萃取紫草总色素的优化工艺条件为:乙醇浓度90％,料液比1:12,微波功率70W,提取时间7min.在此优化条件下紫草素及其衍生物的得率可达5.36％.总色素经Cu2络合纯化水解为紫草素的得率为29.25％.这是一种实验室中简单、快速、高收率的由天然紫草分离制备紫草素的有效方法.     

微波和超临界CO2萃取杜仲籽油工艺研究

通过微波萃取和超临界CO2萃取杜仲籽油的正交试验,考察影响萃取效果的主要因素,寻求最佳萃取工艺条件。微波萃取最佳工艺条件为:以环己烷为萃取剂,原料粉碎度40目,溶剂与物料质量比值为5.0,微波功率700W,每次微波辐射时间50s,微波累计辐射8次,在此条件下油脂得率为27.07%。超临界CO2萃取的最佳工艺条件为:萃取压力35MPa、萃取温度45℃、萃取时间70min、分离温度30℃、CO2流量25～30kg/h,原料粉碎度40目,在此条件下油脂得率27.76%。并比较不同提取方法对油脂得率和油脂品质的影响。结果表明,微波萃取所需时间最短,油脂得率较高;超临界CO2萃取所得杜仲籽油的品质最优,是提取优质杜仲籽油的首选方法。     

几种肉桂酸衍生物与肉桂酸的抑菌作用比较研究

用滤纸片法比较9种肉桂酸衍生物与肉桂酸的抑菌作用。试验结果表明,各衍生物对供试菌均有不同程度的抑菌作用,与肉桂酸相比较,这9种衍生物的抗菌谱均变窄,但较多种类对供试菌出现抑菌作用的浓度较肉桂酸低。     

Enzymatic formation of styrene during wheat beer fermentation is dependent on pitching rate and cinnamic acid content

Styrene is formed by the thermal decarboxylation of cinnamic acid during wort boiling or by enzymatic decarboxylation during fermentation. The enzymatic reaction processes simultaneously to the decarboxylation of ferulic‐ and p‐cumaric acid to clove‐like 4‐vinylguaiacol and phenolic 4‐vinylphenol by the same PAD1 and FDC1 decarboxylase enzymes. However, the formation of styrene occurs much faster within the first hours of fermentation. In addition, the conversion of cinnamic acid starts immediately after pitching without an adaption of yeast on the new medium. Only after 120 min does the level of transposition decrease. Moreover, high cinnamic acid content in pitching wort, in combination with an open fermentation management, causes faster and higher styrene formation during this period. In contrast to the formation of 4‐vinylguaiacol, a correlation between pitching rate and styrene formation during open fermentation could be shown. The resulting time interval between styrene and 4‐vinylguaiacol formation provides scope for minimization strategies for styrene, while maintaining the typical wheat beer flavours. Copyright © 2012 The Institute of Brewing & Distilling     

Efficient synthesis of hydroxystyrenes via biocatalytic decarboxylation/deacetylation of substituted cinnamic acids by newly isolated Pantoea agglomerans strains

BACKGROUND: Decarboxylation of substituted cinnamic acids is a predominantly followed pathway for obtaining hydroxystyrenes—one of the most extensively explored bioactive compounds in the food and flavor industry (e.g. FEMA GRAS approved 4‐vinylguaiacol). For this, mild and green strategies providing good yields with high product selectivity are needed. RESULTS: Two newly isolated bacterial strains, i.e. Pantoea agglomerans KJLPB4 and P. agglomerans KJPB2, are reported for mild and effective decarboxylation of substituted cinnamic acids into corresponding hydroxystyrenes. Key operational parameters for the process, such as incubation temperature, incubation time, substrate concentration and effect of co‐solvent, were optimized using ferulic acid as a model substrate. With strain KJLPB4, 1.51 g L^?1 4‐vinyl guaiacol (98% yield) was selectively obtained from 2 g L^?1 ferulic acid at 28 °C after 48 h incubation. However, KJPB2 provided vanillic acid in 85% yield after 72 h following the oxidative decarboxylation pathway. In addition, KJLPB4 was effectively exploited for the deacetylation of acetylated α‐phenylcinnamic acids, providing corresponding compounds in 65–95% yields. CONCLUSION: Two newly isolated microbial strains are reported for the mild and selective decarboxylation of substituted cinnamic acids into hydroxystyrenes. Preparative‐scale synthesis of vinyl guaiacol and utilization of renewable feedstock (ferulic acid extracted from maize bran) have been demonstrated to enhance the practical utility of the process. Copyright © 2011 Society of Chemical Industry     

Inhibition of browning by antibrowning agents and phenolic acids or cinnamic acid in the glucose–lysine model

The effects of antibrowning agents and phenolic acids or cinnamic acid on the inhibition of browning were investigated with a glucose–lysine model. Six antibrowning agents (cysteine, glutathione, sodium sulfite, pentasodium tripolyphosphate, citric acid and oxalic acid) and four phenolic acids (ferulic, hydroxybenzoic, syringic and vanillic acids) were used. In order to investigate the antibrowning capacity of these agents, model solutions containing glucose, lysine and an antibrowning agent were heated at 50 °C in the presence of FeCl₂, before being stored in nitrogen or air at 4 °C or 30 °C. Browning was accelerated to some degree during storage in air at 30 °C. In the case of storage at 4 °C, however, no browning was detected in nitrogen after four weeks. Citric acid was the most efficient antibrowning agent during storage in air at 30 °C and inhibited browning to 36% after four weeks. However, its antibrowning capacity was increased by 8–15% in the presence of any of the phenolic acids or cinnamic acid, essentially independently of concentration in the range 10 µM to 10 mM or the type of phenolic acid. Copyright © 2005 Society of Chemical Industry     

Antibacterial activity and mechanism of cinnamic acid and chlorogenic acid against Alicyclobacillus acidoterrestris vegetative cells in apple juice

The aim of this study was to investigate the antibacterial activity and mechanism of cinnamic acid and chlorogenic acid against Alicyclobacillus acidoterrestris. Minimum inhibitory concentrations of cinnamic acid and chlorogenic acid were 0.375 and 2.0 mg mL⁻¹, and the minimum bactericidal concentrations were 0.50 and 4.0 mg mL⁻¹, respectively. The apple juice ingredients had little influence on the inactivation of A. acidoterrestris. After treatment with cinnamic acid and chlorogenic acid, the morphology of A. acidoterrestris cells were severely destroyed; the leakage of nucleic acids and proteins increased significantly. SDS-PAGE investigation of bacterial proteins proved that the loss of soluble proteins was obvious as well. These results demonstrated that cinnamic acid and chlorogenic acid exerted their antibacterial activity mainly by an action mode of membrane disruption. This study provides an alternative method for the control of A. acidoterrestris-related spoilage in the fruit juice/beverage industry.     

Determination of lignin in the presence of ester-bound substituted cinnamic acids by a modified acetyl bromide procedure

The lignin content of plant materials can be determined spectro-scopically but the presence of ester-bound substituted cinnamic acids in the cell walls of some plant families, particularly the Gramineae, gives elevated values. Pre-treatment with either pyrrolidine : pyridine or 0-5 m sodium methoxide selectively removes the ester-bound acids leaving intact the true lignin. The treatments have been applied to cellulose powder, immature perennial ryegrass stems, oat straw and forage rape stems. The pyrrolidine : pyridine treatment removes a slightly higher proportion of these non-lignin components but the sodium methoxide treatment appears to cause less damage than the heterocyclic bases to other cell wall constituents and is preferred if the residues are to be used for other purposes.     

Transformation of substituted cinnamic acids using l-cysteine metal complexes in aqueous media

4-Hydroxycinnamic, 4-methoxycinnamic, ferulic and cinnamic acids were both non-oxidatively and oxidatively decarboxylated in alkaline aqueous media in the presence of l-cysteine–Fe(II) and l-cysteine–Co(II) heterogeneous catalysts using hydrogen peroxide or molecular oxygen. GC/MS analysis of diethylether extracts of reaction mixtures confirmed that the addition of hydrogen peroxide resulted predominantly in oxidative decarboxylation of substituted cinnamic acids, producing the corresponding carbonyl compounds (4-hydroxybenzaldehyde, 4-methoxybenzaldehyde, vanillin, benzaldehyde). On the other hand, saturation of this heterogeneous reaction system with molecular oxygen led to the formation of a variety of products, probably via peroxoacid anions or peroxoradical intermediates, e.g., ferulic acid was transformed to vinylguaiacol and vanillin with yields of 22% and 0.7%, respectively.     

酸性离子交换树脂催化制备1（3）-对甲氧基肉桂酸甘油一酯

研究了在离子交换树脂催化作用下,对甲氧基肉桂酸与甘油酯化反应得到具有较好亲水性的对甲氧基肉桂酸甘油一酯,并对反应条件进行优化。然后对产物进行紫外光谱扫描、液相色谱分析与~1H NMR核磁共振检测。结果表明:在反应温度130℃、对甲氧基肉桂酸与甘油摩尔比1∶10、催化剂amberlyst~15-离子交换树脂用量(基于对甲氧基肉桂酸质量)20%、反应时间3 h条件下,对甲氧基肉桂酸甘油一酯产率最高,可达69.63%,对甲氧基肉桂酸的转化率为91.91%。产物在280~320 nm波段吸收效果很好。经柱层析分离后,产物纯度在99.2%以上。经~1H NMR核磁共振检测,确定了1(3)-对甲氧基肉桂酸甘油一酯的分子结构。     

L-抗坏血酸肉桂酸酯的合成及其抗氧化活性研究

以L-抗坏血酸和肉桂酸为原料,采用酰氯法合成得到了L-抗坏血酸肉桂酸酯。用分光光度法研究了酯化产物的稳定性、清除羟自由基(?OH)和二苯代苦味肼基自由基(DPPH?)的能力,并与Vc和常用的油溶性抗氧化剂叔丁基对苯二酚(TBHQ)进行比较,结果表明：新合成的L-抗坏血酸肉桂酸酯与Vc相比,稳定性得以明显改善,其清除DPPH?的EC50值为63.96 μmol/L,清除能力与Vc相当,清除?OH的EC50值为7.84 mmol/L,在浓度较高时优于TBHQ。