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PubMed2004

Laser mass spectrometry as on-line sensor for industrial process analysis: process control of coffee roasting.

The objective of the project is to develop on-line, real-time, and noninvasive process control tools of coffee roasting that help deliver a consistent and high-quality coffee aroma. The coffee roasting process was analyzed by direct injection of the roaster gas into a time-of-flight mass spectrometer and ionized either by resonance enhanced multiphoton ionization (REMPI) at 266 and 248 nm or vacuum ultraviolet single-photon ionization (VUV-SPI) at 118 nm. The VUV ionization scheme allows detecting mainly the most volatile and abundant compounds of molecular mass below 100 m/z, while REMPI ionizes mainly aromatic compounds of molecular mass larger than 100 m/z. Combining the compounds ionized by resonant and single-photon ionization, approximately 30 volatile organic compounds are monitored in real time. Time-intensity profiles of 10 important volatile coffee compounds were discussed in connection with their formation chemistry during roasting. Applying multivariate statistics (principle component analysis) on time-intensity traces of nine volatile coffee compounds, the roasting degree could be traced as a consistent path in the score plot of the two most significant principle components (including 68% of the total variance), for a range of roasting temperatures (200-250 degrees C).

Beverages↗
PubMedDate not supplied

Combined phenyl silane and immunoaffinity column cleanup with liquid chromatography for determination of ochratoxin A in roasted coffee: collaborative study.

A collaborative study was conducted to evaluate a liquid chromatography (LC) method for ochratoxin A using sequential phenyl silane and immunoaffinity column cleanup. The method was tested at 3 different levels of ochratoxin A in roasted coffee, which spanned the range of possible future European regulatory limits. The test portion was extracted with methanol and sodium bicarbonate by shaking for 30 min. The extract was filtered, centrifuged, and then cleaned up on a phenyl silane column before being eluted from the washed column with methanol-water. The eluate was diluted with phosphate-buffered saline (PBS) and applied to an ochratoxin A immunoaffinity column, which was washed with water. The ochratoxin A was eluted with methanol, the solvent was evaporated, and the residue was redissolved in injection solvent. After injection of this solution onto a reversed-phase LC apparatus, ochratoxin A was measured by fluorescence detection. Eight laboratory samples of low-level naturally contaminated roasted coffee and 2 laboratory samples of blank coffee (< 0.2 ng/g ochratoxin A at the signal-to-noise ratio of 3:1), along with ampules of ochratoxin A calibrant and spiking solutions, were sent to 15 laboratories in 13 different European countries. Test portions of the laboratory samples were spiked at levels of 4 ng/g ochratoxin A, and recoveries ranged from 65 to 97%. Based on results for spiked blank material (blind duplicates) and naturally contaminated material (blind duplicates at 3 levels), the relative standard deviation for repeatability (RSDr) ranged from 2 to 22% and the relative standard deviation for reproducibility (RSDR) ranged from 14 to 26%. The method showed acceptable within- and between-laboratory precision, as evidenced by HORRAT values, at the low level of determination for ochratoxin A in roasted coffee.

Calibration↗
PubMed1978

[Diphenols and caramel compounds in roasted coffees of different varieties. II. (author's transl)].

Eleven diphenols and seven caramel compounds were extracted from roasted coffee with pentane/ether (1 + 1), silylated with BSTFA, characterized, and semiquantified by GC-MS. Seven phenols and five caramel components were identified for the first time in roasted coffee. Robusta coffee contained the highest amounts of phenols and maltol. Arabica showed higher amounts of furaneol (2.5-dimethyl-4-hydroxy-3(2H)-furanone), isomaltol, 5-hydroxymaltol, and 5-hydroxy-5.6-dihydromaltol.

Chromatography, Gas↗
PubMed2002

Dicinnamoylquinides in roasted coffee inhibit the human adenosine transporter.

Preliminary screening of a minor, non-xanthine constituent of roasted coffee, 3,4-diferuloyl-1,5-quinolactone (DIFEQ), showed inhibition of the adenosine transporter at low micromolar concentration. DIFEQ is a neutral derivative of the chlorogenic acids, i.e. isomeric mono- and di-substituted coumaroyl-, caffeoyl-, and feruloyl-esters of quinic acid, formed in the roasting process of coffee. Displacement of the adenosine transporter antagonist [(3)H](S)-(nitrobenzyl)-6-thioinosine binding by DIFEQ in cultured U-937 cell preparations, expressing the human adenosine transporter protein (hENT1), showed a K(i) of 0.96+/-0.13 microM. Extracts of regular and decaffeinated coffee showed binding activities equivalent to 30-40 mg DIFEQ per three cups of coffee. Acute administration of a high dose of DIFEQ (100 mg/kg i.p.) reduced open field locomotion in mice for 20 min in correlation with brain levels of DIFEQ. Both 3,4-dicaffeoyl-1,5-quinide and 3,4-dicoumaroyl-1,5-quinide, two close structural analogs of DIFEQ also present in roasted coffee, showed similar affinities for the adenosine transporter, while the corresponding 3- and 4-mono caffeoyl- and feruloyl-quinides were one to two orders of magnitudes less active. This suggests that 3,4-dicinnamoyl-1,5-quinides in coffee could have the potential to raise extra-cellular adenosine levels, thereby counteracting the stimulant effect of caffeine.

Animals↗
PubMed2000

A powerful aromatic volatile thiol, 2-furanmethanethiol, exhibiting roast coffee aroma in wines made from several Vitis vinifera grape varieties.

The chemical compound 2-furanmethanethiol (2FM), with a strong roast coffee aroma, has been identified in sweet white wines made from the Petit manseng grape variety, and in certain red Bordeaux wines (made from the Merlot, Cabernet franc, and Cabernet sauvignon grape varieties). This was done by extracting specific volatile thiols using p-hydroxymercuribenzoate. The 2FM has also been found in toasted oak used in barrel-making. All the Petit manseng sweet white wines and some of the red Bordeaux wines analyzed contained between a few ng/L and several dozen ng/L of 2FM. Taking into account its very low perception threshold (0.4 ng/L in a model hydro alcoholic environment), 2FM could therefore contribute to the roast coffee aroma of certain wines.

Chromatography, Gas↗
PubMed2004

Determination of biologically active substances in roasted coffees using a diode-array HPLC system.

We studied the simultaneous quantitative analysis of biologically active substances, such as nicotinic acid, trigonelline, caffeine, qunolinic acid and tannic acid and pyrogallic acid, in several roasted coffees by an HPLC/diode-array system with a home-made sol-gel and ODS-2 columns. A simple method for simultaneous quantitative analysis of biologically active substances in the coffee brew became feasible by an HPLC/diode-array system with a sol-gel column at a single wavelength of 210 nm. The most efficient condition of the Rs value was above 1.05 when two sol-gel columns were connected. In addition, the elution behavior of nicotinic acid in brew extracted from commercially available coffee beans suggests the thermal decomposition process during roasting, and indicated the maximum value for full city roasted coffee.

Biological Factors↗
PubMed2004

In vitro and ex vivo antihydroxyl radical activity of green and roasted coffee.

The specific antiradical activity against the hydroxyl radical of the water soluble components in green and dark roasted Coffea arabica and Coffea robusta coffee samples, both in vitro by the chemical deoxiribose assay and ex vivo in a biological cellular system (IMR32 cells), were determined. All the tested coffee solutions showed remarkable antiradical activity. In the deoxiribose assay, all the tested solutions showed similar inhibitory activity (IA%) against the sugar degradation (IA values ranged from 45.2 to 46.9%). In the cell cultures, the survival increase (SI%) ranged from 197.0 to 394.0% with C. robusta roasted coffee being significantly more active than the other samples. The coffee solutions underwent dialysis (3500 Da cutoff membrane) to fraction their components. In both systems, the dialysates (MW < 3500 Da) either from green or roasted coffee, showed antiradical activity, while the only retentates (MW > 3500 Da) from the roasted coffee samples were active. The preparative gel-filtration chromatography of roasted coffee C. robusta dialysate gave three fractions active in the biological system, all containing chlorogenic acid derivatives. The most active fraction was found to be that containing the 5-O-caffeoilquinic acid, which shows a linear relation dose-response ranging from 0.02 to 0.10 mM. The results show that both green and roasted coffee possess antiradical activity, that their more active component is 5-O-caffeoyl-quinic acid, and moreover that roasting process induces high MW components (later Maillard reaction products, i.e., melanoidins), also possessing antiradical activity in coffee. These results could explain the neuroprotective effects found for coffee consumption in recent epidemiological studies.

Antioxidants↗
PubMed2003

A randomized, double-blind comparison of two different coffee-roasting processes on development of heartburn and dyspepsia in coffee-sensitive individuals.

The mechanism underlying coffee-induced heartburn and dyspepsia remains poorly understood. This has led to speculation that variations in coffee processing may be important. The primary objective of this study was to determine whether a coffee brewed with coffee beans processed using conduction roasting will result in fewer symptoms of gastroesophageal reflux and dyspepsia in coffee-sensitive individuals compared to a differently processed yet otherwise similar coffee. Thirty coffee-sensitive individuals completed this single-center, randomized, double-blind, crossover study in which the symptoms of heartburn, regurgitation and dyspepsia were assessed following coffee consumption both in the fasting state and after ingestion of a standard test meal. Consumption of both coffees resulted in heartburn, regurgitation, and dyspepsia in most individuals. No significant differences in the frequency or severity of heartburn, regurgitation, or dyspepsia were demonstrated between the two coffees either in the fasting state or after the test meal. We conclude that differences in the coffee bean roasting process do not result in marked differences in coffee-induced upper gastrointestinal symptoms.

Adult↗
PubMed2000

Discriminate analysis of roasted coffee varieties for trigonelline, nicotinic acid, and caffeine content.

Arabica and robusta roasted coffees from several geographical origins, in a total of 29 samples, were characterized for their contents in caffeine, trigonelline, and nicotinic acid by a recently developed HPLC/diode-array detector method. All samples were subjected to the same roasting procedure in order to eliminate the variations due to this process. Characterization was achieved by applying multivariate and nonparametric analysis to the chromatographic results. The two coffee varieties were clearly separated by their trigonelline and caffeine contents. Nicotinic acid could not be used as a variety discriminate factor. There was no association with the geographical origin of the samples.

Alkaloids↗
PubMed1978

[Phenols in roasted coffees of different varieties. I. (author's transl)].

Thirty phenols were isolated from roasted coffee by distillation-extraction, separated from other constituents by absorption-chromatography, and characterized by means of GC-MS. Robusta coffee contained the largest amount of phenols, followed by Arabusta (Côte d'Ivoire) and Arabica. Quantity and type of phenols depends on variety as well as on the roasting conditions.

Adsorption↗
PubMed2002

Optimization of solid-phase clean-up prior to liquid chromatographic analysis of ochratoxin A in roasted coffee.

An extraction and clean-up method for ochratoxin A (OA) in roasted coffee has been developed and the HPLC method optimized. An interfering compound with a similar retention time as OA was adsorbed by the aminopropyl (NH2) material at < or = 5% NaHCO3. Residual OA on the column was recovered by washing with the extraction solution followed with methanol. Fractions were mixed together for further clean-up with Ochratest immunoaffinity columns (IACs). Analysis by HPLC resulted in a well resolved OA peak and reduction in matrix interferences. Recoveries ranged from 72 to 84% and the detection limit was 1 ng/g.

Chromatography, High Pressure Liquid↗
PubMed2005

Stability of ochratoxin A (OTA) during processing and decaffeination in commercial roasted coffee beans.

The fate of ochratoxin A (OTA) during the processing of artificially contaminated green coffee beans, the effect of decaffeination on the production of OTA in green and roasted coffee beans, and the effect of caffeine on the growth and OTA production by Aspergillus ochraceus were studied. The data indicated that the roasting, milling and decoction (brewing and Turkish coffee making) processes caused different percentage reductions in OTA. Decaffeinated samples showed a significantly higher concentration of OTA production than the caffeinated ones. A significantly higher percentage of OTA was reduced when the decaffeination process was performed before roasting treatment. Caffeine at 1.0 and 2.0% concentrations completely prevented OTA production and completely inhibited A. ochraceus growth in YES medium after 3-21 days.

Aspergillus ochraceus↗
PubMed2003

Quinides of roasted coffee enhance insulin action in conscious rats.

Consumption of large amounts of coffee has been shown to decrease the incidence of type 2 diabetes. However, the specific compounds and mechanisms responsible for this effect are not known. The aim of this study was to determine the effects of a decaffeinated coffee extract and a synthetic quinide, representative of those found in roasted coffee, 3,4-diferuloyl-1,5-quinolactone, on insulin-stimulated glucose disposal and muscle glucose uptake. Experiments were performed on conscious rats during hyperinsulinemic, euglycemic clamps receiving gastric infusions of saline, a decaffeinated coffee extract (DECAF) (220 mg/kg), or 3,4-diferuloyl-1,5-quinide (DIFEQ) (110 mg/kg). Following treatment, rats received an intravenous bolus of deoxy-[2-3H] glucose to assess muscle glucose uptake (Rg, micromol x 100 g(-1) x min(-1)). Glucose infusions [mg/(kg x min)] required to maintain euglycemia during the tracer period were higher with DIFEQ (14.6 +/- 0.7) than with saline (10.8 +/- 0.7) and DECAF (11.5 +/- 1.1). Despite increased glucose requirements, Rg in skeletal (soleus, gastrocnemius, superficial vastus lateralis) and cardiac muscle were unchanged. DECAF or DIFEQ did not affect heart rate, blood pressure, plasma nonesterified fatty acids or liver aminotransferase activity. These results demonstrate that DIFEQ increases whole-body glucose disposal independently of skeletal muscle Rg.

Animals↗
PubMed2003

Real-time monitoring of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting by resonant laser ionization time-of-flight mass spectrometry.

The formation of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting was monitored in real-time, using resonance enhanced multiphoton ionization and time-of-flight mass spectrometry. A model is proposed, based on two connected reaction channels. One channel, termed the "low activation energy" channel, consists of ester hydrolysis of 5-FQA followed by decarboxylation of the ferulic acid to form 4-vinylguaiacol, and finally polymerization at the vinyl group to form partly insoluble polymers (coffee melanoidins). The second "high activation energy" channel opens up once the beans have reached higher temperatures. It leads to formation of guaiacol, via oxidation of 4-vinylguaiacol, and subsequently to phenol and other phenolic VOCs. This work aims at developing strategies to modify the composition of coffee flavor compounds based on the time-temperature history during roasting.

Coffea↗
PubMed2000

Fourier transform infrared determination of caffeine in roasted coffee samples.

A new procedure has been developed for the FT-IR determination of caffeine in roasted coffee samples. The method involves wetting the coffee samples with a 0.25 M aqueous NH3 solution, extracting the caffeine with CHCl3, and measuring absorbance at 1,659 cm(-1) using a baseline established between 1,900 and 830 cm(-1). The procedure proposed is fast, only requiring a total extraction time of 16 min for each sample, and provides a drastic reduction of the organic solvent consumed, from the 200 mL diethyl ether and 50 mL CHCl3, required for each sample by the reference chromatographic UV-spectrometric determination to only 5 mL CHCl3. The method provides a limit of detection of the order of 3 mg L(-1) caffeine and a relative standard deviation of 0.4% for 3 independent analyses of a sample containing 18.6%mg/g caffeine. The accuracy of the FT-IR procedure was evaluated from recovery experiments on spiked samples providing values from 94.4 to 100.1% and from the comparison of results found for a series of commercial samples, by both FT-IR and the official reference procedure.

Ammonia↗
PubMed2004

Comprehensive multidimensional GC for the characterization of roasted coffee beans.

The present investigation is based on the separation of one of the most complex food matrices: the roasted coffee bean volatile fraction. Analysis of the two main species of coffee (Arabica/Robusta) was achieved through an effective and simple sampling procedure, headspace solid-phase microextraction (SPME), and the unprecedented resolving power of comprehensive gas chromatography (GC x GC). The combination of these two techniques proved to be a powerful tool for the extraction and separation of coffee volatiles. In fact, thousands of compounds that play various roles in the constitution of coffee aroma profile were resolved in the 2-D contour plot, each occupying a specific position pinpointed by two retention time coordinates. The potential use of this method for the assessment of coffee quality and the detection of commercial fraud is discussed. The potential of GC x GC for identification and classification of unknowns was also demonstrated, as the formation of characteristic patterns for structurally related compounds was observed in the bidimensional chromatogram. Moreover, reproducibility results were supported by the use of an autosampler for SPME applications that allowed any inaccuracy arising from manual handling to be avoided.

Journal Article↗