Trigonelline in coffee

The results of several determinations of trigonelline in green, roasted and instant coffees are reported. The values in normal coffee species and degrees of roast are in agreement with most literature values. InCoffea dewevrei var.excelsa andC. stenophylla lower values were found than reported in the only other publication. The differences from steamed samples were minimal. Fast roasting may result in higher values with the same organic roasting loss, but this was not observed in commercial blends. During industrial extraction of roasted coffee, trigonelline is not completely extracted. The percentage depends on the extraction yield. tween traditionally (slowly) and fast-roasted coffee have not yet been studied, at least not by using a series of samples. In the following, we present such studies. On the importance of trigonelline in coffee analysis see [1].     

Relating consumer preferences to sensory attributes of instant coffee

The sensory profiles of 11 instant coffees including pure coffees (PC), coffee blends (CB) and a chicory instant drink (CID), commercially available in South Africa, were described and quantified. These were then related to consumer preferences (n=199) for the instant coffees using preference mapping. Based on consumer preferences, four consumer groups were identified, “pure coffee lovers” (23%), “coffee blend drinkers” (30%), “general coffee drinkers” (37%) and “not serious coffee drinkers” (10%). The “pure coffee lovers” prefer the more astringent, bitter, roasted, nutty and full-bodied flavour of the pure coffee samples. The less intense coffee flavour character, but higher sweetness and root flavour, typical of chicory blended instant coffee, were attributes that were preferred by the “coffee blend lovers”. The “general coffee drinkers” seem to consume coffee out of habit and are less concerned about the specific sensory properties of the coffee.     

Assessment of green coffee bean metabolites dependent on coffee quality using a 1H NMR-based metabolomics approach

There is increasing interest in the coffee grade or quality with the rise of coffee consumption, but a classical, chemical analysis-based understanding of the coffee bean grade is still limited. We therefore report the identification of green coffee bean metabolites related to coffee bean quality using a ¹H NMR-based metabolomic analysis of well-established specialty-grade green coffee beans, in particular, of a single species (Coffea arabica). The higher levels of sucrose and the lower levels of γ-aminobutyric acid (GABA), quinic acid, choline, acetic acid and fatty acids observed in specialty or high-grade green coffee beans, compared to commercial-grade beans, were suggestive to be multiple markers for characterizing specialty green coffee bean. In particular, variations in sucrose and GABA levels between specialty and commercial coffees could be a consequence of different environmental conditions, for example, biotic or abiotc stresses, at growing regions. These results highlight an alternative method of metabolomic approach for grading green coffee bean.     

Microwave-assisted methanolysis of green coffee oil

Optimisation of a microwave-assisted methanolysis was performed to obtain cafestol and kahweol directly from green coffee oil (Coffea arabica). A two-factor (the methanolysis period and temperature), three-level, factorial experimental design (3²) was adopted. The methanolysis procedure was performed under microwave irradiation, using closed vessel and accurate fast responding internal fibre-optic temperature probe. The effects on the responses were measured by HPLC. After 3 min of microwave irradiation (hold time) at 100 °C, with 500 mg of green coffee oil, a yield higher than 99% was obtained. The yield of this reaction is 26% after 2 h when working under conventional heating. The methods described in the literature lead to long reaction times, poor yields and formation of side products. The microwave-assisted technique proved to be faster, avoided undesired side products and gave better conversion, when compared to conventional heating process.     

An investigation on the appropriateness of chocolate to match tea and coffee

The aim of this study was to provide some recommendations for selecting a befitting tea and coffee to match chocolate with different cocoa contents. Three coffee samples (chocolate flavored, vanilla flavored and unflavored coffee), four tea samples (black tea, green tea, vanilla flavored tea and citrus flavored tea) and three chocolates (30%, 70%, and 99% cocoa) were hedonically rated by eighty regular chocolate consumers. The beverages were then paired with each chocolate, and the consumers were asked to indicate the hedonic liking of the resulting pairings, and to indicate whether the chocolate or beverage flavor dominated the pairing flavor. This study showed that liking of chocolate and coffee pairings and chocolate and tea pairings significantly varied (p < 0.001) across samples. Consumers preferred pairings with 30% cocoa and 70% cocoa chocolate to pairings with 99% cocoa chocolate. Overall, coffee is significantly (p < 0.001) preferred to tea as a chocolate partner.Chocolate and beverage pairing liking was biased by the liking of the beverage tasted alone, the liking of chocolate tasted alone, beverage type, chocolate type and the level of flavor match between chocolate and tea or coffee in a given pairing. When chocolate and beverage flavor balanced out in a given pairing, chocolate and coffee/tea pairings were significantly preferred by the consumers. A significant decrease in acceptance was observed when beverage or chocolate flavor dominated the flavor of the pairing, much more so when the chocolate flavor dominated the pairing flavor. However consumers don't enjoy any preferred chocolate with any preferred tea or coffee because some flavors match better than do others. Indeed, consumers formulate their hedonic responses taking into consideration what flavors go well together more than they rely exclusively on their hedonic judgments of the chocolates, the teas, and the coffees tasted alone.     

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.     

Quinic acid lactone in coffee

Quinic acid and its lactone (quinide) have been determined in coffee by capillary gas chromatography. No quinide could be detected in 14 green coffee's. After steaming of 4 green coffee's the content of quinic acid was always higher, but no quinide had been formed. During roasting, the latter can be detected when roasting loss exceed 6.5%. It increases approximately proportionally with quinic acid and amounts to 50% of the latter at 22% roasting loss. Both constituents decrease at unusual high roasting loss. In 13 commercial blends of roast coffee 2.4-6.4 g/kg quinide and 8.7-16.6 g/kg quinic acid were present. Especially high values were found in one Espresso type blend and high values in steamed and decaffeinated coffee's. In 11 commercial coffee extracts 2.0-23.2 g/kg quinide and 24.6-36.4 g/kg quinic acid were determined. At higher extraction yield, more quinic acid and quinide is formed, but at very high extraction yield the content of quinide is diminished. During holding of coffee brews at elevated temperature, quinide is slowly hydrolysed.     

Analysis of green coffee quality using hermetic bag storage

Coffee (Coffea arabica L.) value is highly dependent on quality. However, due to high humidity in the Central Andean Ranges of Colombia, where much of the country's coffee production resides, Farmers must sell their coffee at harvest in order to mitigate quality loss due to the high moisture. Cooperatives are generally forced to store green coffee until enough volume is collected for export, making it crucial to utilize storage solutions that maintain quality over time. This study examines the efficacy of Purdue Improved Crop Storage (PICS) hermetic bags for storage of green coffee in a simulated small farm setting. PICS bags with the standard three layers (PICS3), PICS bags with two layers (PICS2), and Traditional jute sacks were studied. Quality indicators examined were moisture content, water activity, and cupping score. Analysis of coffee stored at monthly intervals over seven months suggests that both versions of PICS show promise in maintaining moisture content, water activity, and sensory scores. Furthermore, the data suggest that water activity is a better indicator of quality than the currently used moisture content and there is no statistically significant difference in performance between the two PICS treatments.     

Authentication of Italian Espresso coffee blends through the GC peak ratio between kahweol and 16-O-methylcafestol

Since the price of Arabica is currently more than twice higher than Robusta, a rapid and reliable method for the determination of the roasted coffee blend composition is fundamental for the authentication of commercial blends used for the Italian Espresso coffee. A GC-FID method based on the ratio between the integrated peak areas of kahweol (K) divided by the sum of K and 16-O-methylcafestol (16MCF) was developed. No internal/external standard was used. Moreover, the quantitation of the unsaponifiable compounds is not necessary, as well as the calculation of any response factors. The percentage of Robusta in 34 samples of coffee blends with known composition, and in 48 samples of pure varieties was used to build a cubic polynomial function with R(2)=0.998. The roasting conditions did not affect the results. Considering eight commercial blends (ranging 0-90% Robusta), no significant difference (two-tailed P=0.817) was registered between the claimed and the predicted composition.     

Changes on the levels of serotonin precursors – tryptophan and 5-hydroxytryptophan – during roasting of Arabica and Robusta coffee

The levels of free and total tryptophan and of 5-hydroxytryptophan (5-HTP) were investigated in green and roasted grains and beverages of Coffea arabica L. (Arabica) and Coffea canephora Pierre var. robusta (Robusta). Grains were light, medium and dark roasted. Free and protein tryptophan were extracted before and after hydrolysis. The levels of tryptophan and 5-HTP were quantified simultaneously by ion-pair HPLC and fluorimetric detection after derivatisation with o-phthalaldehyde. Robusta green coffee had higher total and protein tryptophan, whereas Arabica had higher free tryptophan levels. 5-HTP was not detected in the samples before and after roasting. Free tryptophan was completely degraded during roasting. Roasting significantly affected protein tryptophan. The rate of loss was smaller in Arabica compared to Robusta at every roasting degree. A beverage prepared the Brazilian way with a medium-roasted coffee provided 1.4–2.5 mg tryptophan/50 ml cup.     

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.     

Species,roasting degree and decaffeination influence the antibacterial activity of coffee against Streptococcus mutans

Coffee beverage has been associated with antibacterial activity against Streptococcus mutans, a cariogenic bacterium. This study aimed at identifying natural compounds in coffee that contribute to such activity and investigate the influence of species, roasting and decaffeination on it. Coffee chemical compounds and aqueous extracts of green and roasted regular and decaffeinated Coffea arabica and Coffea canephora beans were tested. MIC, biofilm inhibition and biofilm reduction results were correlated with the concentration of coffee compounds in the extracts. 5-Caffeoylquinic acid, trigonelline and caffeic acid solutions showed bacteriostatic activity (MIC = 0.8 mg/mL). Lighter and regular extracts showed higher inhibitory activity than darker and decaffeinated extracts, with an inverse correlation between bacterial colony-forming units and roasting degree. Only regular C. canephora extracts showed biofilm formation inhibition. The joint effect of chlorogenic acids, trigonelline and caffeine or other compounds removed by decaffeination seems to be one of the causes for coffee antibacterial activity against S. mutans.     

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.     

D-最优混料设计优化肉苁蓉速溶咖啡加工工艺

目的 结合工厂实际优化肉苁蓉速溶咖啡配方加工工艺。方法 运用模糊综合评价法结合D-最优混料设计对肉苁蓉速溶咖啡配方进行优化, 考察总粉量、加糖量、总浸粉的占比及肉苁蓉和咖啡浓缩液的质量比对感官评分的影响。建立组成成分与肉苁蓉速溶咖啡感官评价之间的回归模型, 通过JMP软件优化得到最佳的加工工艺条件。结果 肉苁蓉速溶咖啡的最佳工艺配方: 总粉量20%、加糖量25%、总浸粉55%、肉咖比1:2、2种混合浓缩液与麦芽糊精之比1:0.6; 最佳的冲调比例: 粉水比1:8。在此条件下的感官评分为96.80分, 与预测感官评分的偏差为0.23%, 不存在显著性差异(P>0.05)。结论 本研究建立的方法及模型真实有效, 可为实际生产提供参考依据。     

Profiles of volatile compounds and sensory analysis of three blends of coffee: influence of different proportions of Arabica and Robusta and influence of roasting coffee with sugar

One hundred and forty‐six volatile compounds were identified and quantified using a static headspace sampler in three blends of coffee: Arabica/Robusta 80:20 (A80:R20) natural roasted coffee, Arabica/Robusta 20:80 (A20:R80) natural roasted coffee and Arabica/Robusta 20:80 with 50% of Robusta coffee roasted with sugar (A20:R80 50% Torrefacto). The different proportion of Arabica and Robusta coffee in the blend A80:R20 versus A20:R80 influenced the amounts of 20 chemical families of volatile compounds. Aldehydes, ketones, alcohols, pyrroles, pyrazines, furans, thiazoles, thiophenes, esters, oxazoles, lactones, sulphur compounds, pyridines, alkanes, alkenes, phenolic compounds, benzenic compounds, acids, pyranones and terpenes were present in higher quantities in the sample containing 80% of Arabica coffee, whereas sulphur compounds were more abundant in the coffee with 80% of Robusta. Sensory differences were also found between the two blends of coffee in the burnt, caramel, nutty, earthy and roasty notes. Torrefacto coffee, widely consumed in Spain, is obtained by roasting coffee with sugar. Higher quantities of ketones, alcohols, pyrazines, furans, pyridines, alkanes, phenolic compounds, pyranones and terpenes were found in the blend A20:R80 50% Torrefacto coffee versus A20:R80 natural roasted coffee. These differences in the volatile fraction were perceived by our panellists in the intensities of the nutty, roasty, earthy, burnt and caramel notes. © 2002 Society of Chemical Industry     

Studies on extraction and antioxidant potential of green coffee

Green coffee conserves were prepared from the species Coffea arabica and Coffea robusta by flaking, powdering and extraction with solvent mixtures of isopropanol and water in different ratios and their antioxidant properties were investigated. The yields of conserves were highest 27% for C. arabica and 29% for C. robusta, when isopropanol and water in ratio of 60:40 was employed. The total polyphenol content was determined and found to be higher (31.7–32.2%) in these conserves. At a concentration of 200 ppm, coffee conserves from Arabica and Robusta, exhibited 92% and 88% antioxidant activity respectively in comparison to 95% for BHA. The conserves were analyzed by HPLC and three phenolic compounds could be identified. The chlorogenic acid, the major compound in the purified extracts (56 ± 10%), was isolated and characterized by ¹H and ¹³C NMR spectral data. While the caffeic acid part of the molecule was confirmed from the signals for aromatic protons and olefenic protons, the quinic acid group was evident from the signals for methine protons α to hydroxyl groups as well as for the methylene protons of the cyclohexane moiety. Similarly, ¹³C spectra showed signals for two carbonyl carbons, apart from eight signals corresponding to six aromatic and two olefenic carbons and signals for the six carbons in the cycloalkane side chain.     

Four-week coffee consumption affects energy intake,satiety regulation,body fat,and protects DNA integrity

Recent epidemiological studies suggest that coffee, one of the most widely consumed beverages worldwide, may reduce risks of degenerative diseases such as diabetes type 2, cardiovascular disease and certain types of cancer. These effects have partly been ascribed to coffee's antioxidant and body weight-reducing capacities. To explore the mechanisms involved, effects of coffee consumption on body weight/composition, food intake, satiety markers (serotonin and ghrelin) and DNA integrity were monitored in a four-week double-blind randomized crossover intervention study with 84 healthy subjects. Subjects consumed two different coffee blends (study blend, SB, and market blend, MB), with similar caffeine contents but substantially differing contents of chlorogenic acids and N-methylpyridinium. The consumption of both coffees (3 × 250 mL per day) was associated with a decrease in body fat over the whole study period (p < 0.001), which was more pronounced with SB. During intervention with MB, plasma serotonin levels increased (p < 0.001) whereas plasma ghrelin levels decreased (p < 0.001) relative to levels recorded during the preceding washout period. Consumption of both coffee blends was associated with DNA-protective effects (p < 0.001). These findings suggest that regular coffee consumption may provide health benefits in terms of reducing energy intake and body fat, regulating satiety and protecting DNA integrity.     

Quantification of 3-aminopropionamide in cocoa, coffee and cereal products

Based on recent results confirming 3-aminopropionamide (3-APA) as a very effective precursor of acrylamide in the absence of further “catalysts”, this compound was quantified for the first time in cocoa masses, cocoa beans, coffee and cereal products by LC–MS–MS after derivatisation with dansyl chloride. Cocoa masses contained >3000 μg/kg of 3-APA, but varied significantly in its concentration. For the quantification of acrylamide (AA) in cocoa and coffee, an improved isolation procedure using charcoal was developed. In various samples of unroasted and roasted cocoa beans, the concentrations of AA were by a factor of >5 lower than those of 3-APA, but the concentrations of 3-APA and AA were more closely correlated as compared to the concentrations of AA and Asparagine. Experiments on authentic cocoa beans from Ghana and Sulawesi indicated that the thermal generation of 3-APA during roasting was much more pronounced as compared to its biochemical formation. By administering fermented cocoa beans with [¹³C₄ ¹⁵N₂]-asparagine before roasting, 3-APA was confirmed as transient intermediate in AA formation during cocoa roasting. Among the cereal products analysed, in particular popcorn contained quite high amounts of 3-APA, which were also well correlated with the AA concentration. Contrary, in coffee products, 3-APA was always lower than AA.     

焙焦油莎豆粕速溶咖啡的开发及其品质分析

目的 开发焙焦油莎豆粕速溶咖啡并对其品质进行研究。方法 将制备的焙焦油莎豆粕速溶粉与咖啡速溶粉、白砂糖、脱脂奶粉进行复配,通过单因素和正交试验设计,以感官评分为指标,优化产品配方。再利用气相色谱-质谱法对咖啡品质和理化性质进行分析。最后利用微流变分析冲释稳定性,确定食用条件。结果 确定焙焦油莎豆粕速溶咖啡最佳配比为焙焦油莎豆粕速溶粉添加量35%,咖啡速溶粉添加量5%,白砂糖添加量35%,奶粉添加量30%。咖啡成品脂肪含量为0.99%,蛋白质含量为10.01%,溶解度为94.58%,酸度为22.52%,固形物含量为7.75%。咖啡中含有34种香气成分,冲释后2h内具有较好的流变学品质。结论 油莎豆粕中含有丰富的功能活性因子,本产品的成功研发强化了咖啡的功能特性,拓宽了油莎豆副产物的应用范围,提高了油莎豆副产物的应用价值。     

Intra- and interspecific mineral composition variability of commercial instant coffees and coffee substitutes: Contribution to mineral intake

The present paper reports the amount and estimated daily mineral intake of nine elements (Ca, Mg, K, Na, P, Fe, Mn, Cr and Ni) in commercial instant coffees and coffee substitutes (n = 49). Elements were quantified by high-resolution continuum source flame (HR-CS-FAAS) and graphite furnace (HR-CS-GFAAS) atomic absorption spectrometry, while phosphorous was evaluated by a standard vanadomolybdophosphoric acid colorimetric method.Instant coffees and coffee substitutes are rich in K, Mg and P (>100 mg/100 g dw), contain Na, Ca and Fe in moderate amounts (>1 mg/100 g), and trace levels of Cr and Ni. Among the samples analysed, plain instant coffees are richer in minerals (p < 0.001), except for Na and Cr. Blends of coffee substitutes (barley, malt, chicory and rye) with coffee (20–66%) present intermediate amounts, while lower quantities are found in substitutes without coffee, particularly in barley.From a nutritional point of view the results indicate that the mean ingestion of two instant beverages per day (total of 4 g instant powder), either with or without coffee, cannot be regarded as important sources of minerals to the human diet, although providing a supplementation of some minerals, particularly Mg and Mn in instant coffees. Additionally, and for authentication purposes, the correlations observed between some elements and the coffee percentage in the blends, with particular significance for Mg amounts, provides a potential tool for the estimation of coffee in substitute blends.