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、质量损失率随烘焙温度的升高总体分别呈降低和升高的趋势,随烘焙时间的延长分别呈降低和升高的趋势。绿原酸含量随烘焙温度升高和时间延长显著降低（P＜0.05）,相比生咖啡豆,新绿原酸、隐绿原酸含量随烘焙温度升高先升高后降低,随烘焙时间延长显著降低（P＜0.05）。新绿原酸、隐绿原酸含量与咖啡pH值和烘焙时间呈显著负相关（P＜0.05）,绿原酸含量与烘焙温度、时间呈显著负相关（P＜0.05）,与咖啡水分质量分数呈显著正相关（P＜0.05）。温度和时间的交互作用均对咖啡绿原酸类化合物降解产生高度显著影响（P＜0.001）。绿原酸3 种异构体热降解符合一级反应动力学模型。在化学反应模型中,绿原酸转化为新绿原酸和隐绿原酸两种异构体,3 种异构体质量浓度均随pH值和温度的升高显著降低（P＜0.05）,温度与pH值交互作用对绿原酸降解影响高度显著（P＜0.001）。综上,温度、时间及pH值的协同作用致使烘焙咖啡中绿原酸的快速降解。     

Chlorogenic acids—Their complex nature and routine determination in coffee beans

The chlorogenic acids complex of coffee has received a vast amount of attention since the term was first applied in 1846 to what was then thought to be a pure compund. This paper summarises the literature concerning the characterisation and measurement of the chlorogenic acids complex in coffee and coffee products. Aspects given particular attention are: (1) the nature of the chlorogenic acids complex and its confusing trivial nomenclature; (2) the behaviour of chlorogenic acids during roasting; (3) simple methods for accurate analysis of numerous samples on a routine basis.     

ABTS radical scavenging capacity in green and roasted coffee extracts

The impact of two parameters (temperature and duration) on the radical scavenging capacity of individual compounds, and total extracts found in coffee was investigated. Phenolic coffee extracts of light (200 °C), medium (225 °C) and dark (235 °C) roasted coffees in a range of 0–30 min were analyzed by an on-line RP-HLPC-ABTS^•+ decolourization assay. This study revealed a general decrease of radical scavenging capacity related to native phenolic compounds. Processing coffee beans leads to generation of up to 10 new radical scavengers. The roasting process influences not only color and taste in coffees, but also the radical scavenging capacity of coffee as well. Phenolic content in roasted coffee and green coffee is very different. Six compounds identified as caffeoylquinic acids and dicaffeoylquinic acids, endowed with radical scavenging capacity were found in green coffee, whereas depending on the roasting process, roasted coffees can present up to 16 different radical scavengers. The compounds formed during the roast are most likely chlorogenic acids derivatives, of which 4 could be clearly identified as two feruloylquinic acids and two caffeoylquinides. In longer roasting durations, these molecules are subjected to auto-degradation, thus total radical scavenging capacity in coffee decline along with roasting (duration and temperature).     

Physicochemical characteristics of Ethiopian Coffea arabica cv. Heirloom coffee extracts with various roasting conditions

This study aimed to investigate the physicochemical characteristics of Ethiopian Coffea arabica cv. Heirloom coffee extracts with various roasting conditions. Green coffee beans were roasted at four different conditions (Light-medium, Medium, Moderately dark, and Very dark) and used to extract espresso and drip coffee. Moisture content in coffee beans was decreased as the roasting degree increased. The contents of crude fat and ash were lower in the Light-medium roasted coffee beans than in green coffee beans but increased as the roasting degree increased. The values of lightness (L^*), redness (a^*), yellowness (b^*), and browning index of coffee extracts were decreased as the roasting degree increased. Total dissolved solids in espresso coffee were increased with increasing roasting degree but decreased in drip coffee. In both the extracts, the contents of reducing sugar, titratable acidity, organic acids, and chlorogenic acid were decreased, but that of caffeine was increased with the roasting degree increased.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10068-020-00865-w.     

Effect of the roasting method on the content of 5-hydroxytryptamides of carboxylic acids in roasted coffee beans

Coffee beans of Coffea liberica (robusta) variety were roasted using convection and microwave heating. For roasting we used green coffee beans of 7.5% moisture content, and beans wetted to 10% moisture content and dried to 5% moisture content. The content of 5-hydroxytryptamides of carboxylic acids C-5-HT (determined by TLC) as the index of substances irritating alimentary canal was investigated in the roasted beans, depending on the bean treatment before roasting and applied roasting method. Analytical results show that predrying of the coffee beans caused 15-30% loss of C-5-HT, depending on the applied drying conditions. The content of C-5-HT in the roasted beans depended on the roasting method and preliminary treatment of the beans prior to roasting. A higher C-5-HT loss occurred in the case of beans subjected to two-stage processing, predrying and roasting. Convection roasting caused higher degradation of C-5-HT than microwave roasting.     

Correlation between cup quality and chemical attributes of Brazilian coffee

Brazilian arabica coffee is classified for trading according to the quality of the beverage obtained after roasting and brewing. In the present study, Brazilian green and roasted coffee beans were investigated for possible correlations between cup quality and the levels of sucrose, caffeine, trigonelline and chlorogenic acids, determined by HPLC analysis. Trigonelline and 3,4-dicaffeoylquinic acid levels in green and roasted coffee correlated strongly with high quality. To a lesser extent, caffeine levels were also associated with good quality. On the other hand, the amount of defective beans, the levels of caffeoylquinic acids (predominantly 5-caffeoyilquinic acid), feruloylquinic acids, and their oxidation products were associated with poor cup quality and with the Rio-off-flavor. The fact that similar correlations between cup quality and chemical attributes were observed in green and light roasted samples – the latter used for coffee cup classification – indicates that chemical analysis of green beans may be used as an additional tool for coffee quality evaluation.     

Effect of the roasting method on the content of 5‐hydroxytryptamides of carboxylic acids in roasted coffee beans

Coffee beans of Coffea liberica (robusta) variety were roasted using convection and microwave heating. For roasting we used green coffee beans of 7.5% moisture content, and beans wetted to 10% moisture content and dried to 5% moisture content. The content of 5‐hydroxytryptamides of carboxylic acids C‐5‐HT (determined by TLC) as the index of substances irritating alimentary canal was investigated in the roasted beans, depending on the bean treatment before roasting and applied roasting method. Analytical results show that predrying of the coffee beans caused 15–30% loss of C‐5‐HT, depending on the applied drying conditions. The content of C‐5‐HT in the roasted beans depended on the roasting method and preliminary treatment of the beans prior to roasting. A higher C‐5‐HT loss occurred in the case of beans subjected to two‐stage processing, predrying and roasting. Convection roasting caused higher degradation of C‐5‐HT than microwave roasting.     

Comparative study of polyphenols and caffeine in different coffee varieties affected by the degree of roasting

The bioactive composition of coffee, as one of the most popular beverages in the world, has attracted interest as a potential source of beneficial bioactive compounds, especially polyphenols and caffeine. Since the content of these compounds is affected by the processing conditions, the objective of this study was to determine the content of polyphenolic compounds and caffeine in four different coffee varieties: Minas and Cioccolatato (Coffea arabica), and Cherry and Vietnam (Coffea canephora syn. Coffea robusta), roasted by three varying degrees (light, medium and dark). The content of the polyphenolic compounds and the antioxidant capacity of coffees were determined using UV/Vis spectrophotometric methods, while the content of chlorogenic acid derivatives was determined using HPLC analysis. The caffeine content was determined by means of two spectrophotometric methods, as well as HPLC analysis. Additionally, raw caffeine was also obtained by an isolation procedure with chloroform. Cherry coffee, a variety of C. canephora exhibited the highest overall content of total phenols (42.37 mg GAE/g), followed by Minas coffee, while Cioccolatato contained the lowest TPC (33.12 mg GAE/g). Cherry coffee also exhibited the highest content of individual classes of polyphenols (flavan-3-ols, procyanidins and tannins), while the highest content of chlorogenic acid (CQA) derivatives was determined in Minas and Cioccolatato coffees (C. arabica). The highest content of total and individual polyphenolic compounds was determined in coffees roasted in both light and medium roasting conditions, which was also observed for the content of CQA derivatives and antioxidant capacity of roasted coffees. The highest caffeine content in the coffee samples was determined by employing the HPLC analysis (0.06–2.55%). Light roasted Cherry coffee contained the highest overall content of caffeine among all coffees, which exhibited a decrease with intensified roasting.     

Antioxidant activity,polyphenols, caffeine and melanoidins in soluble coffee: The influence of processing conditions and raw material

The production of soluble coffee starts with the selection of beans and is followed by roasting, grinding, extraction and drying. Lyophilised soluble coffees extracted by various methods from light, medium and dark-roasted arabica and robusta beans were evaluated for antioxidant activity (AA) using ABTS, Folin, DPPH and FRAP techniques. Caffeine, chlorogenic acid (5-CQA) and melanoidin content was also quantified. The data were analysed by principal component analysis. The AA values derived from the various methods used were correlated. Roasting resulted in the degradation of 5-CQA and formation of melanoidins, while AA was largely unaffected by roasting. The extraction of soluble coffee more prominently affected the AA of light-roasted coffee, mainly because it favoured the extraction of 5-CQA. The larger caffeine content in robusta coffee resulted in greater AA. All of soluble coffee products studied possessed antioxidant potential, which was conferred by their concentrations of phenolic compounds, caffeine and melanoidins.     

Contribution of coffee proteins to roasted coffee volatiles in a model system

A simple roasting model using a mineral oil bath was set up to study the effects of coffee proteins on the formation of coffee volatiles during roasting. Green coffee powder was separated into four fractions, and the highest concentration of volatile compounds was observed in the roasted sample of the water extract fraction. Sugar degradation products were the dominant compounds. The addition of coffee proteins into the nonprotein water extract fraction catalysed sugar degradation and enhanced the production of selected volatiles. Higher amounts of coffee protein correlated with the concentration of pyrazines. Coffee protein also increased sucrose degradation in the roasting of sucrose with coffee protein. However, the results from colour measurements indicated that a greater amount of protein produced a lighter colour. These results demonstrated the important contribution of coffee proteins in the formation of coffee volatiles and colour.     

印尼罗布斯塔咖啡豆应用于咖啡饮料开发的研究

印度尼西亚产的罗布斯塔咖啡豆多用于咖啡饮料的工业生产。分析了不同烘焙程度对该咖啡豆香气成分的影响。以水为介质,研究了该咖啡豆烘焙度、粉碎粒度、萃取温度以及萃取料液比对咖啡萃取的影响。通过4因素3水平正交试验确定了最佳处理条件为：烘焙度L=19＋1、粉碎粒度N0．18—0n=70％＋1％＆Pan〈5％、萃取温度90℃、萃取料液比1：14。     

Comprehensive analysis of major and minor chlorogenic acids and lactones in economically relevant Brazilian coffee cultivars

Coffee is the most consumed beverage in the world and a significant source of phenolic compounds, particularly chlorogenic acids (CGA). During coffee roasting, some CGA are partially transformed into chlorogenic acid lactones (CGL). Both CGA and CGL are important compounds for flavor and potentially beneficial to human health. In the present study, using LC–MS and synthetic standards, we investigated major and minor CGA and CGL isomers in green and roasted samples of economically relevant Brazilian Coffea arabica and Coffea canephora coffee cultivars. For the first time, in addition to nineteen previously identified CGA and CGL, 1-feruloylquinic acid, 1-feruloylquinic lactone and 3,4-diferuloylquinic acid were quantified in C. arabica and C. canephora, the contents of 3- and 4-p-coumaroylquinic lactones were reported in C. canephora and 3,4-di-p-coumaroylquinic acid was identified in C. arabica. Despite their low concentrations, the implications of these findings for flavor, cup quality and the biological properties of coffee merit further investigation.     

Formation of aliphatic acids by carbohydrate degradation during roasting of coffee

 A major fraction of the acidity generated on coffee roasting can be attributed to formation of the four aliphatic acids formic, acetic, glycolic and lactic. Addition of sucrose, glucose or fructose to green coffee beans gave, compared to untreated beans, significant increases in the yields of the four acids on subsequent roasting. In addition, model studies using these three carbohydrates confirmed sucrose as the principal green bean precursor of the acids. Arabinose, erythrose and 1,6-anhydroglucose were identified as reaction products of sucrose thermal degradation and also subsequently served as precursors for acid formation. Isotopic labelling experiments indicated that known degradation pathways could be used to explain the formation of the four aliphatic acids from sucrose. Received: 7 January 2000     

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。     

Formation of 5-hydroxymethyl-2-furfural (HMF) and 5-hydroxymethyl-2-furoic acid during roasting of coffee

The formation of 5-hydroxymethyl-2-furfural (HMF) and 5-hydroxymethyl-2-furoic acid (HMFA) during roasting of coffee was studied. At 240 degrees C the maximum concentration of HMF occurs after 3 min with a quick degradation up to 10 min when most of the HMF has disappeared again. Similar to 5-hydroxymethyl-furfural, HMFA is formed in coffee but not in a model system consisting of sucrose, alanine with or without chlorogenic acid. It was shown that HMFA is produced from different precursors than HMF namely glyceraldehyde and pyruvate. The comparison of the laboratory scale roasting with industrial roasting showed that 5-hydroxymethyl-furfural decreases with a higher degree of roasting whereas HMFA did not change. In the laboratory scale experiments, the highest concentration of 5-hydroxymethyl-furfural in coffee (909 microg/g) was obtained after 3 min and the maximum concentration of HMFA after 4 min (150 microg/g). Industrially roasted coffee contained up to 350 microg/g 5-hydroxymethyl-furfural and 140 microg/g HMFA.     

Identification of chemical clusters discriminators of the roast degree in Arabica and Robusta coffee beans

To identify chemical parameters that might be used as discriminators, pH, soluble solids, caffeine, trigonelline, total caffeoylquinic acids, 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, 5-O-caffeoylquinic acid, total dicaffeoylquinic acids, 3,4-O-dicaffeoylquinic acid, 3,5-O-dicaffeoylquinic acid, 4,5-O-dicaffeoylquinic acid, total feruloylquinic acids, 3-O-feruloylquinic acid, and 5-O-feruloylquinic acid were measured in Arabica and Robusta coffees submitted to three roasting levels. It was found that the fraction of soluble solids increased with roasting level, being slightly higher in Robusta roasted coffee. The contents of caffeine did not vary significantly between roasting degrees within the Arabica and Robusta samples, respectively, revealing a considerable stability during browning. The contents of trigonelline in Arabica and Robusta coffee decreased significantly with browning intensification. Overall, the levels of chlorogenic acids remained higher in Robusta roasted coffee beans but decreased sharply with roast increase. With roasting intensification, the ratio of total caffeoylquinic acids, total dicaffeoylquinic acids, and total feruloylquinic acids varied markedly in both species, with the proportion of total caffeoylquinic acids and total feruloylquinic acids increasing significantly, whereas the opposite occurred with dicaffeoylquinic acids. One can conclude, through the application of a multivariate analysis, that these chemicals form four clusters, constituting caffeine, trigonelline, total dicaffeoylquinic acids, and total feruloylquinic acids a relevant group for T₃ roasting level discrimination, in both coffee species. Additionally, detailing discriminators for roasting intensity in Arabica coffee might be caffeine, trigonelline, 3-O-caffeoylquinic acid, and 4-O-caffeoylquinic acid, whereas in Robusta roasted coffee are trigonelline, 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, 5-O-caffeoylquinic acid, 3,4-O-dicaffeoylquinic acid, 3,5-O-dicaffeoylquinic acid, 4,5-O-dicaffeoylquinic acid, 3-O-feruloylquinic acid, and 5-O-feruloylquinic acid.     

焙炒条件对咖啡风味影响的研究

以云南产的两种咖啡豆为分析对象．研究了焙烤过程中咖啡抽提液一些成分的变化以及对咖啡香气的影响。利用高效液相色谱对在焙烤过程中葫芦巴碱、绿原酸、烟酸、咖啡因含量的变化进行分析，并对绿原酸／咖啡因比率与色度值的相关关系建立了相应的模型。     

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.     

咖啡精油超临界CO2萃取工艺优化及理化特性分析

以云南保山小粒咖啡豆为对象,根据国家标准,测定生、熟咖啡豆的营养成分,在单因素实验的基础上,以响应面优化超临界CO₂萃取咖啡精油的工艺参数;测定生、熟咖啡精油理化指标,并通过气相色谱-氢火焰离子化检测器（GC-FID）分析生、熟咖啡精油的脂肪酸组成。结果表明:经烘焙处理后,熟咖啡豆中水分、水浸出物、咖啡因、总糖、粗纤维和粗脂肪含量与生咖啡豆中的存在显著差异（P<0.05）;超临界CO₂萃取生咖啡精油的最佳工艺条件为萃取压力25 MPa,萃取温度54 ℃,萃取时间150 min,在此条件下咖啡精油萃取得率为13.98%。烘焙处理前后,咖啡精油各常规理化指标无显著差异,且均符合国家标准要求。通过GC-FID分别检测到15和16种脂肪酸,其中亚油酸、棕榈酸、硬脂酸和油酸等为主要脂肪酸,烘焙对咖啡豆脂肪酸组成影响不明显,但各脂肪酸的含量存在一定差异。烘焙对咖啡豆及咖啡精油的各项指标均有一定程度的影响,为云南地区咖啡产业发展提供科学依据。     

The influence of coffee bean maturity on the content of chlorogenic acids,caffeine and trigonelline

This paper reports changes, with coffee fruit maturity, in the coffee bean content of chlorogenic acids, caffeine and trigonelline. The major change was a sigmoidal increase in total caffeoylquinic acid essentially in parallel with the total dry matter gain, and representing between 5% and 12% thereof. The corresponding changes in the contents of several other chlorogenic acids, caffeine and trigonelline were slight on a mass per 100 beans basis.