基于3D-EEM对不同品种咖啡液指纹图谱的研究

该文基于三维荧光分析技术（three-dimensional excitation-emission matrix,3D-EEM）对不同品种生咖啡、烘焙咖啡浸提液中 3种特征成分绿原酸（chlorogenic acid,CGA）、咖啡因（caffeine,CAF）、葫芦巴碱（trigonelline,TRI）建立荧光指纹图谱。结果表明,CGA、CAF、TRG均有特征荧光峰;不同品种生咖啡浸提液荧光峰较为散乱,主要荧光峰分布在λex/λem=（359～450）nm/（365～761）nm和λex/λem=（750～860）nm/（450～560）nm两个范围。咖啡烘焙后浸提液荧光峰与烘焙前明显发生变化,荧光峰红移至λex/λem=（380～600）nm/（450～750）nm,瑞利散射明显减弱,两条倍频峰线消失。不同品种烘焙咖啡浸提液荧光峰位移大小有差异。利用3D-EEM初探定量表明,不同品种咖啡生豆CGA含量为0.685%～1.377%,烘焙后CGA含量下降至0.057%～0.105%;咖啡生豆CAF含量为4.121%～8.372%,烘焙后下降至1.713%～2.354%;咖啡生豆TRI含量为0.075%～0.101%,烘焙后下降至0.035%～0.077%。咖啡豆烘焙后CGA、CAF和TRI含量均有下降。     

咖啡果皮茶冲泡条件研究

从冲泡温度、冲泡时间、料水比以及冲泡次数4个因素出发,以高效液相色谱(high performance liquid chromatography,HPLC)测定的绿原酸溶出量为依据,优化咖啡果皮茶的冲泡条件,并与咖啡豆进行对比分析及感官评价.研究结果表明:以冲泡温度90℃、冲泡时间9 min、料水比1:120(g/m...     

咖啡研磨工艺对咖啡风味的影响

咖啡研磨是咖啡制作工艺中的重要操作,对咖啡成品的风味和口感有极大影响。通过对研磨设备及研磨技术的介绍,系统分析了咖啡研磨工艺对咖啡风味直接或间接的影响。     

高效液相色谱法同时测定咖啡中6种绿原酸

目的建立咖啡中同时测定5-咖啡酰奎宁酸、3-咖啡酰奎宁酸、4-咖啡酰奎宁酸、3,4-二咖啡酰奎宁酸、4,5-二咖啡酰奎宁酸、3,5-二咖啡酰奎宁酸6种绿原酸的高效液相色谱(high performance liquid chromatography,HPLC)检测方法,以及测定产自云南普洱的铁皮卡品种咖啡在不同烘焙风味下的绿原酸含量规律。方法样品经纯水超声提取2次,过滤后供HPLC测定,采用甲醇(A)和0.1%磷酸(B)作为流动相进行梯度洗脱采用C18柱进行分离,光电二极管阵列(photo-diode array,PDA)检测器最终检测。结果本方法在1 h内完成了6种绿原酸的分离分析。6种绿原酸在0.10～100.0 mg/L范围内具有良好的线性,相关系数(r)≥0.999,检出限为0.05～0.10 mg/kg,定量限为0.18～0.29 mg/kg。在2000、5000、10000 mg/kg添加水平的加标回收率为96.3%～104.8%,相对标准偏差(relative standard deviation,RSD)为0.58%～2.10%之间(n=6)。在生咖啡豆中总绿原酸含量最高,意式烘焙(23 min,250℃)最低,5-咖啡酰奎宁酸、4-咖啡酰奎宁酸和4,5-二咖啡酰奎宁酸这3种绿原酸在生咖啡豆到极轻度烘焙(12 min,230℃)这个阶段,含量逐渐上升并达到含量最高,由极轻度烘焙(12 min,230℃)到意式烘焙(23min,250℃)含量逐渐降低,而3-咖啡酰奎宁酸、3,4-二咖啡酰奎宁酸和3,5-二咖啡酰奎宁酸3种绿原酸从生咖啡豆至意式烘焙(23 min,250℃)都呈下降趋势。结论该方法快速、准确、灵敏,适合测定绿原酸含量。     

HPLC法测定焙烤咖啡中咖啡因的含量

建立高效液相色谱法简便准确测定焙烤咖啡中咖啡因的含量.采用色谱分析柱(UltimateTM XB-C18,5μm,4.6×150 mm),流动相:甲醇-水(含2 mL/L乙酸),梯度洗脱,柱温30℃;流速1.0 mL/min;检测波长286 nm;咖啡因质量浓度在5～200 μg/L范围内与色谱峰面积呈良好线形关系(R2=0.9997),平均回收率有97.93%,精密度测试结果的RSD为0.14%.该方法操作简单、结果准确、重复性好.     

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。     

红外焙炒对菜籽油风味的影响机制

在不同温度（90、110、130、150、170 ℃）下红外焙炒油菜籽,经液压压榨制备菜籽油,通过油脂氧化、硫苷化合物降解反应和美拉德反应研究红外焙炒对菜籽油风味的影响机制,并与传统炒籽（170 ℃）进行比较。结果表明,红外焙炒的菜籽油较传统炒籽的菜籽油风味有显著改善,油脂味和辛辣刺激味较后者更轻,而烤香味相对更浓,同时多环芳烃种类和含量也较少。对冷榨菜籽油（由未经任何处理的油菜籽压榨制得）加热3 h,油脂热降解的标志性化合物（E,E）-2,4-庚二烯醛和（E,E）-2,4-癸二烯醛的含量分别增加3.86倍和6.28倍。随着焙炒温度的升高,红外焙炒处理的脱脂油菜籽中硫苷化合物含量从30.73 mg/kg减少至15.23 mg/kg,游离氨基酸总量从未处理的25.61 mg/100 g减少至15.82 mg/100 g,还原糖含量从7.61 mg/g减少至2.29 mg/g。红外焙炒对菜籽油风味的影响机制主要为不饱和脂肪酸降解成为中短链醛与烯醛类化合物,硫苷化合物降解生成异硫氰酸和腈类化合物,以及美拉德反应生成吡嗪、呋喃类化合物。     

焙炒咖啡中丙烯酰胺的研究现状

咖啡在高温(200~250℃)焙炒加工过程中会产生一定量潜在的致癌物质丙烯酰胺。实验研究表明,短期接触大量丙烯酰胺会对人和动物的中枢神经造成损伤,人体长期小剂量接触丙烯酰胺会表现为四肢末端麻木、无力。咖啡焙炒加工过程中产生的丙烯酰胺除了通过天门冬酰胺途径生成以外,还可以由丙烯醛途径生成。其中影响咖啡中丙烯酰胺形成的主要因素有咖啡类型、咖啡的焙炒温度和时间。本文对控制丙烯酰胺形成途径的研究进展进行了相关阐述,并对焙炒咖啡中丙烯酰胺的进一步研究提出建议。     

不同贮存方式对黄酒风味及有机酸的影响

将分别用不锈钢大罐贮存和陶坛贮存的黄酒进行对比,分析其对黄酒风味的影响,并测定了23种挥发性风味物质和7种有机酸,结果表明,不锈钢大罐贮存相比陶坛贮存的酒精度高11％,总酸高12％,同时总糖含量低19％;有机酸中乙酸相对提高了16％,乳酸低了9％;挥发性风味物质中高级醇含量比陶坛贮存高13％,总酯高33％,同时总醛和挥...     

焙炒时间对芝麻油风味及芝麻氨基酸含量的影响

本文主要研究焙炒时间对芝麻油挥发性风味成分及芝麻中氨基酸含量(以芝麻脱脂粕中氨基酸含量为依据)的影响。经过不同时间焙炒的芝麻,用水代法提油,然后采用顶空固相微萃取(HS-SPME)结合GC/MS技术,检测芝麻油中的挥发性风味成分。随着焙炒时间的延长,吡嗪类、吡咯类、吡啶和嘧啶类、含硫类、呋喃类、酚类物质的相对含量逐渐增多,醛类、醇类、烃类和环氧烃类等物质的含量逐渐减少。对芝麻脱脂粕中18种氨基酸含量的检测数据显示,随着焙炒程度加深,氨基酸含量呈总体下降趋势,其中精氨酸、丝氨酸、赖氨酸和胱氨酸的含量减少明显,这4种氨基酸对芝麻油香味的形成可能起到了重要的作用。     

仿咖啡乳饮料的研究

研究了用决明子、脱脂奶粉、大豆芽、小麦等加工咖啡味乳饮料的最佳组合及加工的最适工艺条件。试验结果表明：决明子、大豆芽烘烤,小麦炒炭,粉碎,分别以决明子2g、大豆芽1.5g、小麦0.6g的比例加入水中,在95℃下恒温浸提1h,过滤,再溶入脱脂奶粉3g,可得到色泽纯厚、苦味适中、易消化吸收、具有咖啡的口感和风味但不含咖啡因的饮料。     

咖啡主要烘焙风味物质的形成及变化规律

咖啡以其独特的风味和功能特性受到人们的喜爱。烘焙温度及烘焙时间决定了咖啡的烘焙程度,并对咖啡风味物质的产生及变化产生重要影响。咖啡主要烘焙风味物质是与咖啡风味直接相关且代表性强的香气成分,本文通过综合分析烘焙程度与咖啡主要风味物质的形成和变化规律的关系,为系统了解和掌握精品咖啡烘焙工艺提供科学参考。      

The kinetics and mechanism of caffeine infusion from coffee: The effect of roasting

Rates of extraction of caffeine into water at 80°C were measured for green and roasted Kenyan arabica coffee beans. The green beans were roasted to controlled extents in a Moda coffee roaster, ground, and sieved to a size range 0.85–1.18 mm. Certain physical properties (weight loss, colour, bean volume and infusion pH) were determined for each product. The half-time of caffeine infusion did not change significantly on light roasting but dropped by 40% on more severe treatment and by a further 30% when roasted to scorching. The activation energy also decreased on strong roasting. The kinetic parameters have been correlated with the physical properties of the coffees and with the chemical and physical changes of roasting.     

The influence of brewing method on bioactive compounds residues in spent coffee grounds of different roasting degree and geographical origin

The content of bioactive compounds in spent coffee grounds (SGC) was studied. SGC were obtained from Coffea arabica beans of different roasting degrees (light and dark) and different geographical origins (Nicaragua, Columbia and Mexico) processed using four brewing methods (mocha, filtered, drip and infusion). The highest caffeine and chlorogenic acid contents were determined in filtered spent coffee extracts. All extracts of light roasted spent coffee grounds showed lower browning index levels in comparison to that from dark roasted spent coffee grounds. Generally, the highest content of total polyphenolic compounds and highest antioxidant capacity were determined in extracts prepared in drip. In conclusion, the results obtained in this study indicate that the spent coffee grounds produced of domestic levels, especially those obtained from filter coffeemaker, could be considered as a good source of natural antioxidants.     

Study of acrylamide in coffee using an improved liquid chromatography mass spectrometry method: Investigation of colour changes and acrylamide formation in coffee during roasting

An improved analytical method for the determination of acrylamide in coffee is described using liquid chromatography coupled to mass spectrometric detection (LC-MS). A variety of instant, ground and laboratory roasted coffee samples were analysed using this method. The sample preparation entails extraction of acrylamide with methanol, purification with Carrez I and II solutions, evaporation and solvent change to water, and clean-up with an Oasis HLB solid-phase extraction (SPE) cartridge. The chromatographic conditions allowed separation of acrylamide and the remaining matrix co-extractives with accurate and precise quantification of acrylamide during MS detection in SIM mode. Recoveries for the spiking levels of 50, 100, 250 and 500 µg/kg ranged between 99 and 100% with relative standard deviations of less than 2%. The effects of roasting on the formation of acrylamide and colour development were also investigated at 150, 200 and 225°C. Change in the CIE (Commission Internationale de l'Eclairage) a* colour value was found to show a good correlation with the change in acrylamide. CIE a* and acrylamide data was fitted to a non-linear logarithmic function for the estimation of acrylamide level in coffee. Measured acrylamide levels in commercial roasted coffees compared well with the predicted acrylamide levels from the CIE a* values.     

Consumption of green coffee and the risk of chronic diseases

ABSTRACT

Green coffee contains macro nutrients such as carbohydrates, protein, fat, as well as minor components such as caffeine, trigonelin and chlorogenic acid. Phenolics, chlorogenic acids and brown pigments are sources of natural antixodants. High polypehonic materials found in green coffee and especially chlorogenic acid in it have an important place. It is considered that; green coffee has effects on body mass, blood glucose and lipid levels, blood pressure, prevention from cardiovascular diseases which is based on chlorogenic acid consisting antioxidant activity. However, many topics like toxicological effects, doses, amounts, usage in the body, advantages and disadvantages, etc. of these active molecules need to be examined. For these reasons this article was rewieved to evaluate health effects of green coffee.     

咖啡浸提条件优化研究

以水为浸提液,研究了料液比、浸提温度、浸提时间对咖啡中咖啡因和绿原酸浸提效果的影响。通过单因素实验确定了三因素对浸提效果的影响,并通过三元二次回归正交旋转组合实验确定了最佳浸提条件为:温度为92.85℃,浸提时间为11.60min,料液比为1∶15.34,实施实验得到评估指标为0.488,预测值与该值吻合良好。     

Influence of roasting and brew preparation on the ochratoxin A content in coffee infusion

A study of the effect of coffee processing in the ochratoxin A (OTA) level has been carried out from the green beans to the drinking form. The analysis of OTA has been carried out by an in-house validated HPLC method with fluorescence detection. The limits of detection were 0.04 µg/kg for green and roasted coffee, and 0.01 µg/L for coffee brew. Thirty-six green coffee samples of different origin (Colombia, Costa Rica, Brazil, Vietnam, India and Uganda) were analysed. The highest concentrations of OTA were found in Vietnamese samples - Robusta species treated by dry processing - (range 0.64-8.05 µg/kg), that also showed the highest percentage of defective beans (7.6%). These contaminated samples were roasted in a process that controlled loss of weight and color, as in the industry. A mean reduction of 66.5% was obtained, but the reduction seems to be heterogeneous. Coffee brew was prepared by the three brewing processes more utilized in Europe: moka, auto-drip and espresso. A reduction of the OTA level has been attained, being greater when using a espresso coffee maker (49.8%) than when using auto-drip (14.5%) or moka brewing (32.1%). Therefore, the method of coffee brew preparation plays a key role in the final OTA human exposure.