Comparison of Microwave-Assisted Hydrodistillation and Hydrodistillation Methods for the Analysis of Volatile Secondary Metabolites

Abstract

Microwave-assisted hydrodistillation (MWHD) and hydrodistillation (HD) were carried out for the analysis of volatile components in whole and ground fruits of Anethum graveolens. L. (dill seed) and Coriandrum sativum. L. (coriander seed). Fruits were distilled using a microwave oven modified to fit a Clevenger apparatus. The effect of microwave energy on the yield and composition of the essential oil was investigated against the classical hydrodistillation. Essential oils of all samples were analyzed by GC-FID and gas chromatography-mass spectrometry (GC-MS). In the whole dillseed oil, the amounts of cis.-isodihydrocarvone (from 7.5% to 10.9%) and carvone (from 45.7% to 69.3%) were increased by microwave energy while limonene (from 17.7% to 4.7%), myristicin (from 8.7% to 5.7%) and dill apiole (from 14.1% to 6.1%) were decreased. Grinding of the material also increased the amounts of main components except for myristicin and dill apiole. A decrease in the linalool content of the coriander oil (from 80.0% to 75.5%) was observed in the microwave-assisted hydrodistilled ground fruits. Microwave-assisted distillation appeared to increase the amounts of fatty acids, for example, tetradecanoic acid (from 2.8% to 8.8%) and hexadecanoic acid (from 1.9% to 6.0%) in coriander oil.     

绿茶中茶多酚的复合酶-微波法提取工艺研究

目的 采用复合酶-微波法从绿茶中提取茶多酚。方法 通过单因素试验法和正交试验法确定复合酶-微波法提取茶多酚的最佳工艺,同时比较复合酶-微波法、复合酶法、索氏法和微波法对提取效果的影响。结果 优化得到提取茶多酚的最佳工艺为：在50 ℃条件下用纤维素酶和果胶酶前处理40 min,微波辐射8 min,微波功率500 W,料液比1∶30,25%乙醇溶液作为萃取剂。结论 验证试验表明,最佳工艺可行;从提取时间和提取效率来看,复合酶-微波法提取茶多酚比复合酶法、索氏法和微波法耗时少、提取效率高。     

木豆叶中黄酮微波提取工艺研究

目的 选取适合提取木豆叶中黄酮的方法,并优化提取工艺参数。方法 以木豆叶中荭草苷、木犀草素和总黄酮的提取率及提取物抗氧化活性为指标,将微波辅助提取与热回流、超声波及浸泡提取方法相比较,并采用中心组合设计对影响荭草苷和木犀草素提取效果的微波辅助提取工艺参数进行了优化。结果 通过比较确定微波辅助提取法较为适合木豆叶中黄酮的提取;优化得到荭草苷和木犀草素最佳微波提取工艺参数为：木豆叶粒径为50目,乙醇体积分数为80%,料液比1∶20,提取温度60 ℃,提取次数4次,提取时间10 min,微波功率500 W;荭草苷和木犀草素的提取率分别为（4.42±0.01）、（0.10±0.01）mg/g。结论 采用微波辅助提取木豆叶中的黄酮具有提取时间短、提取率高、产物抗氧化效果好的特点,优化的工艺参数具有可行性和实际应用价值。     

微波辅助提取雪莲果低聚糖的工艺研究

目的 确立雪莲果低聚糖的微波辅助提取工艺.方法 采用微波辅助提取雪莲果中的低聚糖,以雪莲果低聚糖提取率为考察指标,以提取温度、提取时间、料液比、微波功率、微波时间、解析剂比为考察因素进行正交试验,优化最佳提取工艺条件.结果 最佳提取工艺条件为:提取温度80℃,提取时间60min,液料比50:1,微波功率700W,微波时...     

木瓜齐墩果酸微波辅助提取工艺优化

目的:优选木瓜中齐墩果酸的微波辅助提取工艺.方法:以齐墩果酸得率为指标,选择乙醇体积分数、微波功率、粒径大小为自变量,采用响应面法分析各自变量及其交互作用对齐墩果酸得率的影响;采用HPLC测定齐墩果酸含量.结果:最佳提取工艺为乙醇体积分数83％,微波功率229 W,粒径0.18 mm,此工艺条件下,齐墩果酸提取率6.33％,与理论预测值6.46％基本吻合.结论:该优选工艺简便可行,对木瓜中齐墩果酸提取条件优化有一定参考价值.     

Optimization of the microwave-assisted extraction conditions of tea polyphenols from green tea

Green tea, a popular drink with beneficial health properties, is a rich source of polyphenols that have a wealth of physiological activities. The purpose of the present study was to develop a microwave-assisted extraction (MAE) of green tea polyphenols. MAE of tea phenols from green tea was investigated through orthogonal array design. The content of total phenols in tea infusions was determined using UV/vis spectrophotometric methods. Four factors (microwave intensity, microwave irradiate time, microwave irradiate number of times and tea/water ratio) have a substantial impact on the extraction. The extraction conditions of tea polyphenols are optimized, and the order of importance that influenced the extraction rate was found to be: microwave radiate time>microwave intensity>tea/water ratio>radiate number of times, and the optimal performance of extraction was obtained under microwave intensity 600 W, microwave radiate time 3 min and microwave radiate number of times once with tea/water ratio 1:20.MAE offers important advantages over conventional methods, such as shorter extraction times, substantial savings of energy and a reduced environmental burden.     

微波法与超声波法比较研究铁棒锤的挥发油

目的研究铁棒锤微波和超声波2种不同提取方法提取挥发油成分的异同。方法采用微波辅助提取法和超声波辅助提取法提取铁棒锤中的挥发油。采用GC-MS结合计算机检索对所得挥发油成分进行分析和鉴定,用峰面积归一法测定各组分的相对含量。结果分别用2种方法从铁棒锤中提取挥发油,鉴定出30和33种化合物。结论 2种不同方法提取铁棒锤挥发油化学组成成分差异性较大,部分挥发油成分还具有毒性,这些挥发油成分是否是铁棒锤毒性成分的组成部分,还有待进一步研究。     

Investigation on Crystallization and Magnetic Properties of (Nd,Pr, Ce)2Fe14B/α-Fe Nanocomposite Magnets by Microwave Annealing Treatment

In the present work, the structures and magnetic properties of (Nd, Pr, Ce) ₂Fe₁₄B/α-Fe nanocomposite magnets were thoroughly investigated. The microwave annealing was applied to achieve a uniform heating effect and uniform grains. Microwave annealing is more favorable to obtain α-Fe phase than conventional annealing, which leads to the enhanced coercivity of hysteresis loops. The coercivity of nanocomposite magnets was 245 kA/m after annealing at 2000 W for 10 min.     

Microwave-assisted hydrolysis of lutein and zeaxanthin esters in marigold (Tagetes erecta L.)

Saponification of lutein and zeaxanthin was performed by microwave-assisted hydrolysis (MAH) and analysed by ultra performance liquid chromatography. The optimal condition of MAH was studied, and the degradation or isomerization of lutein and zeaxanthin were estimated under MAH. The concentrations of lutein and zeaxanthin in 20 marigold samples were assessed by saponification using traditional heater and MAH, the regression coefficient of lutein obtained by two methods was 0.9688 and that of zeaxanthin was 0.9527. The limit of detection for lutein and zeaxanthin was 0.05 and 0.1 μg/ml, respectively, and the limit of quantification for lutein and zeaxanthin was 0.05 mg/100 g and 0.1 mg/100 g, respectively.     

EDTA络合提取-GFAAS法测定藿香正气丸中的铝离子残留

建立了免消化处理的乙二胺四乙酸二钠(EDTA)络合提取,结合GFAAS法测定藿香正气丸中的铝离子残留.对样品前处理方法进行了系统研究,采用EDTA对样品中铝离子进行络合提取,对萃取溶剂pH,浓度,体积,微波萃取温度,时间,石墨炉升温程序进行了优化考察,并与微波消解法测定结果比较.结果表明,0.1g样品加入0.05 mol·L-1 EDTA溶液20 mL(PH 3.5),以150℃微波萃取10 min,进一步在257.4 nm检测波长及优化的石墨炉升温程序下进行GFAAS的测定.方法的检测限为2.37 μg·L-1,定量限为7.89 μg·L-1,精密度RSD小于2.3％,平均回收率为96.9％～ 101％.该法简单、快速、准确,可用于快速检测中成药中的铝离子残留.