咖啡生豆多糖提取及抗氧化活性

目的:为咖啡中多糖成分的研究和天然活性多糖的开发提供基础数据。方法:研究了云南小粒咖啡生豆多糖(GBP)的水提工艺和抗氧化活性。应用响应面法对咖啡生豆多糖提取工艺进行优化;运用傅里叶变换红外光谱(FT-IR)和扫描电镜(SEM)共同鉴定和表征咖啡生豆多糖的结构特点。采用DPPH自由基、ABTS自由基清除试验和FRAP法评估咖啡生豆多糖体外抗氧化能力。结果:咖啡生豆多糖水提法的最佳工艺条件：提取温度59℃、提取时间45 min、液料比(V_水∶m_咖啡生豆)21∶1 (mL/g)、浓缩体积1/8及乙醇体积分数75%,该条件下咖啡生豆多糖得率达9.56%。多糖样品经红外光谱和电镜扫描显示咖啡生豆是表面呈不规则的孔状结构的多糖。咖啡生豆多糖对DPPH自由基、ABTS自由基清除能力分别为2.32 mg/mL(IC₅₀)、0.011 mmol Trolox/g GBP,铁还原能力为0.95 mmol Fe²⁺/g GBP。结论:咖啡生豆多糖是具有抗氧化活性的不规则孔状结构多糖,具有进一步研究和开发的价值。     

响应面法优化咖啡生豆水提绿原酸工艺研究

以越南Robusta咖啡生豆为原料,采用水提方法提取绿原酸。通过单因素实验对料水比、提取温度、p H、提取时间等提取工艺参数进行研究,并通过响应面法优化提取工艺,建立二次多项数学模型。结果表明,单因素和响应面优化咖啡生豆水提绿原酸的最优工艺参数为:料水比1∶20、提取温度为81℃,提取时间为60 min,p H为3.6,绿原酸提取得率为3.27%。      

Effect of different extraction methods on the recovery of chlorogenic acids,caffeine and Maillard reaction products in coffee beans

Water and ethanolic extracts were obtained from green and roasted (3 different roast degrees) Arabica and Robusta coffee beans. Three types of water extracts were prepared from the examined, finely ground material through: (a) brewing with boiling water, (b) boiling in water, and (c) boiling in water under elevated pressure. All these extracts were lyophilized. Two types of ethanolic extracts were derived from the examined material through (a) extraction of the finely ground coffee beans and (b) extraction of the solid residue that remained after boiling the coffee beans in water under elevated pressure. These ethanolic extracts were dried. Both water and ethanolic extracts were analyzed for concentration of potential antioxidants such as chlorogenic acids and caffeine (by HPLC) and Maillard reaction products (measurements of absorbance at 420 nm). Concentration of chlorogenic acids in Robusta extracts varied between 0.4 and 36.0 g × 100 g⁻¹ dry extract weight (db.), while in Arabica extracts it ranged from 0.1 to 22.4 g × 100 g⁻¹ db. Extracts of dark roasted Arabica contained more chlorogenic acids than those of Robusta. Concentration of caffeine, which in green and roasted coffee beans is maintained at the similar level, tended to increase in Robusta extracts with the roast degree and temperature of extraction with water, while in case of Arabica extracts there was no noticeable tendency. Caffeine concentrations varied between 0.12 and 8.41 g × 100 g⁻¹ db. and between 0.03 and 6.53 g × 100 g⁻¹ db. in Robusta and Arabica extracts, respectively. Ethanolic extracts were characterized by relatively higher caffeine concentrations and lower contents of brown pigments and chlorogenic acids as compared to water extracts. The richest in antioxidants were extracts of green Robusta coffee beans derived through boiling in water under elevated pressure.     

Simultaneous determination of chlorogenic acids in green coffee bean extracts with effective relative response factors

Chlorogenic acids contribute great to the quality of green coffee bean extracts. In this article, the qualitative and quantitative analysis of multi-components by single-marker was proposed to simultaneously determine the contents of seven chlorogenic acids (3-CQA, 4-CQA, 5-CQA, 5-FQA, 3,4-diCQA, 3,5-diCQA, and 4,5-diCQA) in 14 samples of green coffee bean extract. 5-CQA was the single-mark to calculate the contents of chlorogenic acids with relative response factors. The reliability and stability of the relative response factors of chlorogenic acids were studied. Taguchi’s method with orthogonal array of L16 was applied in design of experiment and the minitab v16 software was used to analyze the relative response factors. The fluctuation and stability of the relative response factors were determined by analysis of variance statistical approach. The impact and optimization of columns and instruments were also studied by Taguchi Analysis. The combination of Venusil MP column and WUFENG instrument was chosen to determine the chlorogenic acids. As a comparison, the quantitative analysis of multi-components by multiple standards also had been done in this article. The compared results showed that there were no great differences in the contents of chlorogenic acids determined by quantitative analysis of multi-components by multiple standards and quantitative analysis of multi-components by single-marker with relative response factors obtained in this work.     

Proximate composition and fatty acids profile of green and roasted defective coffee beans

Defective coffee beans are responsible for the depreciation of the quality of roasted coffee consumed in Brazil. The extraction of the oil of defective beans for applications in the food and pharmaceutical sectors is being considered as an alternative use for those beans. The objective of this work was to determine the composition of the fatty acid fraction of the pressed oil and the proximate composition of crude defective beans in order to provide subsidiary information for proposals of alternative uses for these beans. The amounts of oil extracted from the defective beans were smaller than the amounts extracted from healthy mature beans. The fatty acid composition of oils from defective beans was not significantly different than that from healthy mature coffee beans.     

The effect of processing on chlorogenic acid content of commercially available coffee

Chlorogenic acids (CGA) are a class of polyphenols noted for their health benefits. These compounds were identified and quantified, using LC–MS and HPLC, in commercially available coffees which varied in processing conditions. Analysis of ground and instant coffees indicated the presence of caffeoylquinic acids (CQA), feruloylquinic acids (FQA) and dicaffeoylquinic acids (diCQA) in all 18 samples tested. 5-CQA was present at the highest levels, between 25 and 30% of total CGA; subsequent relative quantities were: 4-CQA > 3-CQA > 5-FQA > 4-FQA > diCQA (sum of 3,4, 3,5 and 4,5-diCQA). CGA content varied greatly (27.33–121.25 mg/200 ml coffee brew), driven primarily by the degree of coffee bean roasting (a high amount of roasting had a detrimental effect on CGA content). These results highlight the broad range of CGA quantity in commercial coffee and demonstrate that coffee choice is important in delivering optimum CGA intake to consumers.     

Structure expansion of green coffee beans using instantaneous controlled pressure drop process

Since 1988, when the first experiments with the Instantaneous Controlled Pressure Drop (DIC) process were performed, a lot of investigations have been carried out concerning the structure expansion, processing kinetics (drying, extraction and sterilization) and the improvement of the functional and organoleptic properties of fresh and dried foods. In this study, two DIC technologies were used to expand the structure of green coffee beans. Two varieties of commercial Arabica coffee beans of different agricultural and geographical origins (Brazilian and Ethiopian) were inspected. The effect of initial moisture content (7–40% dry basis), type of heating in the DIC process (steam and microwaves), processing parameters like pressure (0.4–0.7 MPa) and heating time (20–200 s) on bean expansion were investigated. The expansion was evaluated as the ratio of the tapped density of raw beans to that of the treated material. The hydration capacity of the beans was also studied. The Response Surface Methodology was employed to optimize the processing parameters. After the steam DIC treatment, the maximum expansion ratio of the Brazilian beans (e = 1.74) was higher than that of the Ethiopian beans (e = 1.59). For Brazilian beans, the steam DIC treatment resulted in a higher value of expansion ratio than the MW DIC treatment (e = 1.39). Concerning hydration capacity, the steam DIC treatment gave values of 78.6% and 48.2% d.b. for the Ethiopian and Brazilian beans, respectively. It means almost two-fold increase in the hydration capacity using DIC treatment. The steam DIC treatment increased and accelerated in twice the weight loss of beans during roasting.

Industrial relevance

Preliminary experiments have shown that the structure expansion of green coffee beans significantly reduced the roasting time, amended the bean suitability to grinding and improved the kinetics and yield of caffeine and active compounds extraction. The industrial DIC processes can be distinguished by high quality of final products, energy saving and positive environmental impact. Due to the fragile structure of coffee beans, a batch process should be applied. Industrial plant can be designed as a tower plant with several compartments separated by guillotine valves where the material falls down by gravity force or a carrousel or a linear plant with filling, DIC treatment and discharging operations. The ABCAR DIC Process Company (La Rochelle, France) develops plants with a capacity of 50 kg/h to 8 ton/h of dry coffee beans. Despite the promising experimental results concerning microwave DIC technology, the industrial applications are so far limited to the steam DIC treatment due to technical reasons.     

Caffeine and chlorogenic acids intake from coffee brew: influence of roasting degree and brewing procedure

The influence of coffee cultivar, roasting degree and brewing procedure in the presence and transfer of caffeine and caffeoylquinic acids (CQAs) from ground roasted coffee to the brew was evaluated. Two coffee cultivars were roasted in three roasting degrees and brewed using two different procedures. Compounds were determined simultaneously by HPLC‐DAD. Caffeine levels ranged from 87.3 to 122.5 mg/100 mL for Coffea arabica cv. Catuaí Amarelo and from 123.3 to 192.0 mg/100 mL for C. canephora cv. Apoatã. The sum of CQA isomers ranged from 24.2 to 41.3 mg/100 mL for brews prepared with dark roasted coffee and from 187.7 to 295.6 mg/100 mL for light roasted ones. Brews prepared by boiling showed higher content of the compounds than the corresponding filtered ones. C. arabica cv. Catuaí Amarelo light roasted coffee brew presented the lowest caffeine/CQA ratio, regardless of the brewing procedure used, in comparison with the highest ratio of the dark boiled brews.     

Influence of environmental factors,wet processing and their interactions on the biochemical composition of green Arabica coffee beans

Although cultivation of Arabica coffee trees at high elevation is known to favourably affect the final quality of the beverage, quantitative data describing the influence of climatic conditions on the chemical composition of the seed are still lacking. Similarly, post-harvest treatments of the beans are known to affect the generation of flavour, but the chemical transformations that occur during wet processing are poorly understood. To better characterise the effects of the environment, wet processing and their possible interactions, we quantified the changes in the main chemical components of the coffee seed (lipids, chlorogenic acids, sugars and caffeine) caused by wet processing, and analysed how these changes were affected by the variations induced by the environment before harvest. Using 16 experimental plots in Reunion Island displaying broad climatic variations, we showed that chlorogenic acids and fatty acids in the seed were controlled by the mean air temperature during seed development. By contrast, total lipid, total soluble sugar, total polysaccharide and total chlorogenic acid contents were not influenced by climate. Glucose content was positively affected by altitude, while sorbitol content after wet processing depended directly on the glucose content in fresh seeds.     

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.     

Analysis of free amino acids in green coffee beans

To investigate amino acid changes in green coffee beans in the post-harvest period, amino acid concentrations were determined in green beans and after modelled drying, fermentation and storage. After the drying at alternating temperatures up to maximally 40°C, considerable changes in the concentrations of individual amino acids were identified. At the beginning of the storage period, significant changes in concentration were found to a minor extent. Under the condition of drying, it was mainly the concentration of glutamic acid that changed considerably. There was an increase in all the samples by 500 mg/kg dry matter on average, which corresponds to an increase of about 50% of the original value. In contrast, the concentration of aspartic acid in most of the samples decreased clearly due to drying. For the predominant part of the coffee samples, there was a significant increase in the hydrophobic amino acids Val, Phe, Ile and Leu. Changes of the quantities of other amino acids were non-uniform and only insignificant. Constant drying at 80°C for most of the amino acids brought about only minor concentration changes compared to those values obtained at 40°C. Modelled fermentation had no significant effect on the concentrations of the individual amino acids. After a 4-week storage of dried beans, amino acid concentrations did not change further. It is very possible that different post-harvest treatment parameters may influence the amount of aroma precursor compounds in the coffee beans.     

Influence of processing on the content of sugars in green Arabica coffee beans

Quantitative analyses of low molecular sugars in green coffees (Coffea arabica L. var. Acaià) that were processed in parallel either by the traditional wet or the traditional dry method, revealed a close correlation between the kind of post-harvest treatment and the contents of fructose and glucose. While in washed coffee beans (wet processing) only low amounts of these both hexoses were present, those in unwashed coffees (dry processing) were significantly higher. Model-processing experiments in the laboratory confirmed these findings. Moreover, a comparison with the untreated controls revealed that the low levels of both sugars are the consequence of a decrease in the case of wet processing, whereas they remained unchanged or even increased in the case of dry processing. Further minor sugars are also affected by post-harvest treatment. The amounts of galactose, arabinose and mannose show a similar arrangement as those for glucose and fructose, although their overall concentration is about 100-fold lower. Sucrose, the major low molecular sugar in green coffee beans, is not significantly affected by coffee processing. The influence of an active seed metabolism on the observed alterations of the sugar concentrations is discussed.     

Profiling the chlorogenic acids of sweet potato (Ipomoea batatas) from China

The leaves, stem and root of sweet potato cultivated in China have been analysed qualitatively for chlorogenic acids by structure-diagnostic LC–MS³. Chlorogenic acids were not detected in the root. Caffeoylquinic acids were quantitatively the major subgroup of chlorogenic acids detected in the stem and the only subgroup detected in the leaves. This subgroup was dominated by 5-caffeoylquinic acid. The stem also contained three feruloylquinic acids, 3,5- and 4,5-dicaffeoylquinic acid, and small amounts of at least four caffeoyl-feruloylquinic acids. This is the first report of feruloylquinic and caffeoyl-feruloylquinic acids from sweet potato. Two chemically unrelated and coeluting substances with the same molecular mass (M_r = 530) extracted from the Chinese sweet potato interfered with the characterisation of the caffeoyl-feruloylquinic acids. At least five caffeoyl-feruloylquinic acids were detected in the peel of sweet potato cultivated in Tanzania that lacked these interfering substances.     

Effect of packaging materials and storage time on changes of colour,phenolic content,chlorogenic acid and antioxidant activity in arabica green coffee beans (Coffea arabica L. cv. Catimor)

The conditions and storage time of green coffee beans are very important for the commercial quality of coffee. This includes factors such as light, humidity and temperature in the warehouse and also the packaging material used. The aim of this study was to evaluate the effects of type of packaging materials namely high density polyethylene (HDPE) bag and jute sack on moisture content, colour, phenolic contents, chlorogenic acids content and antioxidant activity of Arabica green coffee bean during 15 months of storage. The results show that HDPE bag can preserve the moisture content, colour and chlorogenic acid in green coffee beans (GCB) better than a jute sack during storage. No significant difference of phenolics content in green coffee beans was observed during 4 months of storage in both types of packaging. During initial 10 months of storage the antioxidant activity of GCB stored in HDPE showed higher values than that of GCB stored in jute sack. However, after 1 year of storage, the phenolics content and antioxidant activity in GCB in a jute sack were higher than in HDPE bag. The fluctuation of moisture content could lead to stress condition of green coffee bean and contributing to forming of bioactive compounds. This finding was observed and need further investigation.     

LC–MS analysis of the cis isomers of chlorogenic acids

The behaviour of cis isomers of selected mono- and di-acyl chlorogenic acids produced by UV-irradiation has been investigated by LC–MSⁿ. cis Isomers fragment identically to the more common trans isomers. cis-5-Acyl chlorogenic acids are more hydrophobic and elute later than their mono- or di-trans counterparts whereas the reverse is true for cis-3-acyl and cis-4-acyl chlorogenic acids. The cis isomers of 1,3-dicaffeoylquinic acid, the only 1-acyl chlorogenic acid investigated, are also more hydrophobic than the di-trans isomer. Coffee leaves had a proportionately greater content of cis isomers relative to trans isomers compared with coffee beans suggesting that UV-irradiation in vivo may also cause geometric isomerisation.     

Separation and characterisation of chlorogenic acid‐rich conserves from green coffee beans and their radical scavenging potential

Methanolic extract (Me₁) obtained from low‐grade green coffee beans (LCB), which is one of the major by‐products in the coffee industry, was enriched with phenolics by different methods viz., partitioning in solvents, chromatographic separation using dowex & diaion HP20 resins and precipitation by lead acetate. Separated fractions and Me₁ were analysed for total polyphenol, chlorogenic acid, caffeine and radical scavenging activity (RSA). Chlorogenic acid isomers of Me₁ and the isolated fractions were analysed by HPLC. Me₁ found to contain total polyphenol (16.60 ± 0.4%), chlorogenic acids (CGAs) (29.60 ± 0.9%), caffeine (7.52 ± 0.2%) and exhibited RSA (92.50%) at 100 ppm concentration. Precipitation method resulted significantly (P ≤ 0.05) higher phenolics (46.33 ± 0.5%) as well as CGAs (43.50 ± 0.7%). HPLC analysis indicated that the composition of 5‐Caffeoylquinic acid (5‐CQA) was more in all the isolated fractions.     

Carbon-14 biolabeling of flavanols and chlorogenic acids in Crataegus monogyna cell suspension cultures

Pure radiolabeled phenolic compounds (including catechins, procyanidins and chlorogenic acids) were obtained by administrating ¹⁴C-l-phenylalanine to Crataegus monogyna cell suspension cultures. After a simple process of purification, pure compounds with high specific activities were recovered. In the present study, we describe a suitable method for obtaining labeled phenolics, which will be useful tools for in vivo feeding trials to trace their metabolic fate when consumed by animals and for in vitro activity mechanism studies.     

Hydrocolloids from coffee: physicochemical and functional properties of an arabinogalactan–protein fraction from green beans

The arabinogalactan–protein (AGP) fraction of green coffee beans accounts for 15% of the dry bean. A procedure was developed to solubilise most of the AGP content of the beans so that its properties as a hydrocolloid could be investigated. An AGP fraction was partially purified from green arabica coffee beans, its rheological properties characterised and compared to those of some commercially important hydrocolloids, particularly acacia gum. The coffee AGP fraction dissolved readily in water to give colourless clear solutions. The polymer was a polyelectrolyte with a high molecular weight (M_w 3.78×10⁶), characterised by a narrow polydispersity index (M_w/M_n 1.3). The intrinsic viscosity was close to that of acacia gum ([η]=0.23 dL g⁻¹), but a 1 wt% solution of coffee AGP was three times more viscous than acacia gum at the same concentration. Coffee AGP showed Newtonian flow for concentrations below 6 wt%, but above this concentration the flow behaviour entered a shear-thinning regime. The coffee AGP fraction possessed interesting foaming properties providing that the biopolymer concentration was high enough to initially stabilize the interface that is created. The high molecular weight of coffee AGP combined with its globular structure conferred upon it a high ability to retain water within a foam thin film. However, the structure of the interfacial film was less effective than that of acacia gum to entrap efficiently the gas into the foam. In summary, coffee AGP shows some interesting rheological features which suggest that coffee beans could be used as an alternative source of the class of surface-active polymers which find many commercial applications.     

Effect of roasting on chlorogenic acids,caffeine and polycyclic aromatic hydrocarbons levels in two Coffea cultivars: Coffea arabica cv. Catuaí Amarelo IAC‐62 and Coffea canephora cv. Apoatã IAC‐2258

During coffee roasting process, several substances may be formed or eliminated. The influence of roasting on polycyclic aromatic hydrocarbons (PAHs), caffeoylquinic acids (CQAs) and caffeine levels was studied in Coffea arabica cv. Catuaí Amarelo IAC‐62 and Coffea canephora cv. Apoatã IAC‐2258, roasted in three roasting degrees. CQAs and caffeine were determined simultaneously by HPLC‐DAD, and PAHs by HPLC‐FLD. Caffeine levels were higher in canephora (1486–1884 mg per 100 g) than in arabica (1110–1255 mg per 100 g) and increased up to 21% at darker roasts. Summed CQA levels were higher in green coffee (4661 and 4946 mg per 100 g) and decreased at darker roasts (234 and 377 mg per 100 g), showing no difference between the coffee cultivars studied. PAH summed levels varied from 0.052 to 0.814 μg kg^?1 (arabica) and 0.108 to 0.392 μg kg^?1 (canephora). No correlation was observed between roasting degree, coffee cultivar and PAH levels. Results were also analysed using hierarchical cluster analysis and principal component analysis.