Determination of Chlorogenic Acids with Lactones in Roasted Coffee

An HPLC method has been developed which allowed the determination of mono- and dicaffeoylquinic acids (CQA and di-CQA), corresponding lactones (CQL) and feruloylquinic acids (FQA) in roasted coffee within one chromatographic run. The elution order was verified by isolation of the individual compounds by preparative HPLC, chromatography of the fractions on the analytical HPLC system, NMR spectroscopy and thermospray LC-MS. At least 15 additional minor compounds had the spectra of hydroxycinnamic acids, some of them only occurring in roasted coffee. Caffeoyltryptophan, which has been identified some time ago by another working group could also be separated with this system. The average contents in commercial roasted coffee samples (n=12) were: 3-CQA, 5·0 g kg⁻¹; 4-CQA, 6·2 g kg⁻¹; 5-CQA, 11·4 g kg⁻¹; 4-FQA, 0·7 g kg⁻¹; 5-FQA, 1·4 g kg⁻¹; 3-CQL, 2·1 g kg⁻¹; 4-CQL, 1·0 g kg⁻¹; 3,4-di-CQA, 0·7 g kg⁻¹; 3,5-di-CQA, 0·4 g kg⁻¹ and 4,5-di-CQA, 0·8 g kg⁻¹ dry matter. There were only small differences between the different brands. Two series of samples with different degrees of roast produced from the same green coffee have also been analysed. One series was steam treated before roasting (a process which is commercially used to improve digestibility). Only in the initial stages of roasting (light roast) could a difference in the contents of the acids between both series be observed. Keeping coffee brews at an elevated temperature (4 h at 80°C) reduced the amounts of CQL to 60% of the initial value. The contents of 3-CQA and 4-CQA increased, whilst that of 5-CQA decreased. The overall contents of CQA decreased.     

UPLC法测定咖啡豆中绿原酸和咖啡因的含量

建立了咖啡豆中绿原酸和咖啡因的超高效液相色谱测定方法。咖啡豆粉碎后经70%甲醇水溶液超声提取后,在Waters BEH C18(100 mm×2.1 mm,1.7μm)上以酸性乙腈水为流动相,采用紫外检测器在274 nm测定。在优化试验条件下,咖啡豆中绿原酸和咖啡因提取完全。绿原酸在88.4 mg/L~442 mg/L时峰强度与浓度成良好线性(r2=0.999 3),相对标准偏差为2.81%,平均回收率为98.24%~99.72%。咖啡因在28.8 mg/L~143 mg/L时峰强度与浓度成良好线性(r2=0.999 8),相对标准偏差为1.34%,平均回收率为98.50%~101.32%。方法准确可靠,适用于咖啡豆中绿原酸和咖啡因含量的测定。     

响应面优化水–乙醇法提取云南咖啡生豆绿原酸工艺研究

以云南卡蒂姆咖啡生豆为原料,采用水–乙醇法对9种绿原酸异构体进行提取。通过单因素实验对物料目数、液料比、水提温度、提取时间、醇浓度和醇提温度进行研究,并采用响应面设计优化水醇提取工艺。结果表明,水–乙醇法提取率（5.21%）显著高于水提法（4.29%）;醇浓度和液料比对绿原酸提取率具有显著性影响（P≤0.01）,单因素和响应面优化得到的水–乙醇法提取绿原酸的最佳工艺条件为：醇提温度60 ℃,提取时间11.67 min,物料目数60目,液料比16.07,醇浓度20.16%,绿原酸提取率为5.31%。     

绿原酸咖啡的研制及抗氧化性评价

为提高咖啡的抗氧化性,该研究将绿原酸添加到咖啡中并进行小鼠抗氧化实验,将小鼠随机分成模型组、VC组和高、中、低剂量实验组,采用D-半乳糖灌胃建立氧化应激模型。通过测定小鼠体质量、血常规和肝脏中的丙二醛（malondialdehyde,MDA）含量、超氧化物歧化酶（superoxide dismutase,SOD）活性、谷胱甘肽过氧化物酶（glutathione peroxidase,GSH-Px）活性和免疫器官指数。结果表明,组间体质量和血常规中白细胞数无显著性差异（p＞0.05）。绿原酸中剂量组血常规中红细胞血红蛋白（mean corpuscular hemoglobin,MCH）含量、中性粒细胞数（granulocyte,GRA）、胸腺指数、脾脏指数与空白组、阳性对照组相比均无显著性差异（p＞0.05）,与模型对照组、咖啡对照组相比差异显著（p＜0.05）。绿原酸中剂量组与模型对照组相比,其MCH、GRA、肝脏MDA 含量显著降低（p＜0.05）,SOD 活性、GSH-Px 活性、胸腺指数、脾脏指数显著提高（p＜0.05）,结果表明添加绿原酸的咖啡对于D-半乳糖干预所致的小鼠产生的氧化应激损伤具有一定修复作用。     

Correlation Between the Stability of Chlorogenic Acids,Antioxidant Activity and Acrylamide Content in Coffee Beans Roasted in Different Conditions

The aim of this study was to determine the effect of different roasting conditions, including temperature, humidity, and roasting air velocity on acrylamide contents in roasted Robusta coffee. In addition, acrylamide concentrations were correlated with the degradation of coffee bean polyphenols and its antioxidant activity. In the process of roasting in a quarter-technological scale apparatus used temperatures ranged from 190 to 216°C. Dry or moist air at a velocity of 0.5 or 1 m s^?1 was used. Beans were roasted to achieve optimal sensory properties. The increase of roasting air velocity regardless of its temperature resulted in the intensification of acrylamide formation. The increase of humidity of roasting air caused a reduction of acrylamide formation, but only at the highest used roasting temperature. However, the modification of roasting conditions to achieve a drop in acrylamide concentration resulted in increased degradation of polyphenols and/or deterioration of antioxidant activity. The optimal roasting parameters were: Temperature 203°C, dry air, and low velocity of roasting air. Under these conditions, the roasted beans were characterized by relatively low level of acrylamide and moderate degradation of polyphenols.     

HPLC法同时测定绿咖啡豆中绿原酸及咖啡碱含量

建立一种高效液相色谱法(HPLC),可同时定量绿咖啡豆中绿原酸和咖啡碱的含量,并分析不同成熟度绿咖啡豆中绿原酸和咖啡碱含量变化。采用Agilent ZORBAX ODS-C18色谱柱,以0.5%乙酸水-乙腈为流动相,梯度洗脱,检测波长274 nm,流速1.0 m L/min,进样量10μL,柱温35℃。结果显示,绿原酸和咖啡碱的浓度线性范围分别为5.0 mg/L~100.0 mg/L(r~2=0.999 9)和5.1 mg/L~101.6 mg/L(r~2=0.999 9),检出限分别为0.25 mg/L和0.05 mg/L,相对标准偏差分别为1.56%和1.30%,回收率范围分别为98.86%~101.11%(RSD=1.02%)和98.70%~101.19%(RSD=0.83%)。     

Multivariate Optimization of Chlorogenic Acid Extraction From Brazilian Coffee

Brazil is the largest producer and exporter of coffee in the world; the beverage is recognized as the main source of chlorogenic acids (CA), which have beneficial effects on human health. In this study, a multivariate optimization of extraction conditions was performed, aiming to maximize the extraction of chlorogenic acids isomers (3-caffeoylquinic acid (3-CQA), 4-caffeoylquinic acid (4-CQA), 5-caffeoylquinic acid (5-CQA), 3.4-dicaffeoylquinic acid (3.4-DQA), 3.5-dicaffeoylquinic acid (3.5-DQA), and 4.5-dicaffeoylquinic acid (4.5-DQA)). The optimal extraction condition was obtained using ethanol and water in the proportions of 32.4:67.6, and a 22-min extraction period, resulting in a fast, precise, accurate, and cost-effective method, with low toxic waste generation. Optimized extraction conditions were employed to investigate the CA content in different types of ground roasted coffee available on the market (traditional, extra strong, gourmet, decaffeinated, and organic). Results showed that, although these products are differentiated by their value of trade, no difference in the chlorogenic acids content was found.     

HPLC法同时测定金银花等样品中6种绿原酸异构体的含量

目的:建立HPLC法同时测定茶叶、枸杞叶、地瓜叶、咖啡、金银花中新绿原酸、绿原酸、隐绿原酸、异绿原酸B、异绿原酸A和异绿原酸C的含有量。方法:采用50%甲醇溶液为提取剂,超声波辅助提取30 min,提取液的分析采用Agilent Eclipse XDB-C18色谱柱(4.6 mm×250 mm,5μm),流动相乙腈-0.1%甲酸溶液,梯度洗脱;流速1.0 mL/min,进样量10μL,检测波长327nm,柱温30℃。结果:6种绿原酸异构体在0.50~50 mg/L范围内线性关系良好(r>0.9995),检出限1.1~1.5 mg/kg,定量限3.7~5.0 mg/kg;在不同植物样品基质中平均加样回收率93.5%~102%,RSD>3.17%。结论:该方法简便,重复性好,准确度高,可用于植物样品中绿原酸及其异构体的含量测定及产品质量控制。     

绿咖啡豆绿原酸的体外抗氧化性活性测定

通过铁离子还原法和DPPH自由基清除法测定绿咖啡豆绿原酸的体外抗氧化活性,结果显示绿咖啡豆绿原酸具有抗氧化能力和清除自由基能力。稳定性试验结果表明,温度对绿咖啡豆绿原酸的DPPH自由基清除稳定性影响不显著;光照对稳定性有一定程度影响;pH值对稳定性影响显著,且绿咖啡豆绿原酸在酸性条件下比在碱性条件下稳定。     

Determination of Organic Acids and Sucrose in Roasted Coffee by Capiillary Gas Chromatography

Capillary gas chromatography was used to obtain high resolution profiles of 27 organic acids, caffeine, and sucrose in dimethylsulfoxide extracts of roast and ground coffees in a sixty-minute analysis. A shortened procedure was also reported for the quantitative determination of S-caffeoylquinic (SCQA) and quinic (QA) acids and sucrose. Nanogram detection limits were achieved and the reproducibility of the method was under 5% relative. Major, commercial brands of caffeinated and decaffeinated coffee produced under different roasting conditions could be distinguished based on their 5-CQA and sucrose content and on the ration of QA-to-SCQA.     

忍冬叶中绿原酸提取工艺研究

利用微波炉和紫外可见分光光度计,采用单因数测定和正交实验得出忍冬叶中绿原酸最佳提取工艺：用3倍量的80％乙醇在微波输出功率为500w的条件下预处理80s,然后加25倍量的水在80℃的水浴中浸提3次,每次14min。并建立了绿原酸的紫外分光光度测定法。     

Mechanical Characterization of Individual Instant Coffee Agglomerates

Agglomerated instant coffee particles were compressed individually with a TA-XT2 Texture analyzer. Up to about 57% equilibrium relative humidity (ERH), the force-displacement curves were very jagged. The slopes of plots of highest local force peaks vs deformation were used as a measure of agglomerate stiffness. The degree of jaggedness of the original force-displacement curves, a brittleness measure, was quantified in terms of an apparent fractal dimension using two algorithms. Stiffness and brittleness were little affected by moisture at ERH levels in the range 11 to 52%. At ERH 57% both decreased sharply, indicating plasticization of the soluble material.     

Characterization of the Ruggedness of Instant Coffee Particle Shape by Natural Fractals

The ruggedness of individual instant coffee particle shapes was quantified in terms of the natural Fractal dimension of the silhouettes from their SEM micrographs. The latter was determined from the slope of the Richardson plot covering the range between about 4 - 20% of the particle's maximum length. The Fractal dimension in this range was on the order of 1.05 to 1.2.     

高效液相色谱法测定青梅花、枝、叶中绿原酸类化合物

目的：建立反相高效液相色谱法同时测定青梅非果部位(花、枝、叶)中新绿原酸(NCA)、绿原酸(CA)及隐绿原酸(CCA)3 种绿原酸异构体的含量。方法：采用高效液相色谱法梯度洗脱,使用Luna C18 色谱柱,以体积分数2% 乙酸溶液和乙腈为流动相,二极管阵列检测器在波长328nm 处进行检测。结果：该方法线性范围宽,3种绿原酸异构体的线性范围均为5～200μg/mL,NCA、CA、CCA 的检出限分别为0.21、0.16、0.29μg/mL,定量限分别为0.76、0.50、0.98μg/mL,测得青梅花、枝、叶的30% 乙醇提取物中3 种绿原酸异构体的总含量分别为(48.26 ± 0.11)、(10.82 ± 0.04)、(21.33 ± 0.08)μg/g。结论：该方法简便、快速、准确,青梅花、枝、叶是优良的绿原酸类化合物天然资源。     

多因素交互作用导致烘焙咖啡中绿原酸快速降解

研究烘焙温度、时间及基质pH值对咖啡绿原酸的影响,采用小粒生咖啡豆进行不同程度的烘焙实验,分析不同烘焙温度和时间下pH值、质量损失率、水分质量分数、新绿原酸含量、绿原酸含量、隐绿原酸含量及3种异绿原酸异构体的变化情况,并建立绿原酸降解动力学模型,采用化学反应模型验证绿原酸单体的降解情况.结果表明,烘焙咖啡中水分质量分数...     

Application of Curve Fitting and Wavelength Selection Methods for Determination of Chlorogenic Acid Concentration in Coffee Aqueous Solution by Vis/NIR Spectroscopy

Coffee is considered as a functional food due to its being rich in bioactive compounds, mainly chlorogenic acid (CGA). CGA concentration in coffee aqueous solution was investigated based on visible/near-infrared (Vis/NIR) spectroscopy in this research. To enhance the spectral difference among different samples and increase the signal to noise ratio, Lorentz function curve fitting was applied to fit raw Vis/NIR spectra of samples. Then, the fitting parameters were used to correct raw full spectra. Partial least squares (PLS) regression method was used to develop calibration models of CGA concentration. Full-spectrum models were built with raw and fitting parameter-corrected spectra, respectively. Further, wavelength selection methods, such as genetic algorithms (GAs) and success projection algorithms (SPAs), were applied to eliminate redundancy information and identify relevant information from full spectra. Calibration models based on the effective wavelengths selected by GA and SPA methods were developed. The overall results showed that LFPs a/b-corrected spectra had a better performance compared with other processing methods. Performance of the selected wavelength model was better than that of the full-spectrum model. Final results indicated that the SPAs-PLS method provided a more precise prediction model of CGA concentration with R _c of 0.913 and R _cv of 0.795.     

基于高效液相色谱法分析烘焙程度对咖啡中绿原酸含量的影响（网络首发、推荐阅读）

探究烘焙程度对10支不同产地（产地一：云南,产地二：非洲,产地三：美洲）卡蒂姆咖啡豆中7种绿原酸化合物含量影响。采用高效液相色谱法测定生豆和烘焙豆中绿原酸、新绿原酸、隐绿原酸、异绿原酸A、异绿原酸B、异绿原酸C和5-阿魏酰奎宁酸含量。经响应面法优化7种绿原酸化合物的最佳提取条件为100 mL 0.1%磷酸溶液沸水浴提取30 min,7种绿原酸化合物在2~150 mg/L质量浓度范围内,线性相关系数良好,相关系数均大于0.999 4,方法检出限0.005~0.500 mg/g,定量限0.02~2.00 mg/g,咖啡生豆中绿原酸的含量最高,其次是5-阿魏酰奎宁酸。随着烘焙程度增加,绿原酸和5-阿魏酰奎宁酸含量显著降低（P<0.05）,新绿原酸和隐绿原酸含量先升高再降低,异绿原酸A的降解速度明显高于异绿原酸B和异绿原酸C,绿原酸、5-阿魏酰奎宁酸的降解速度与其余5种绿原酸相比,较为稳定。通过对不同烘焙程度下7种绿原酸化合物含量变化的研究,可以进一步针对咖啡绿原酸功效成分进行评价,为咖啡烘焙和品质控制提供参考依据。