Article

Alkylpyridiniums. 2. Isolation and Quantification in Roasted and Ground Coffees

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  • Nestlé Research
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Abstract

Recent model studies on trigonelline decomposition have identified nonvolatile alkylpyridiniums as major reaction products under certain physicochemical conditions. The quaternary base 1-methylpyridinium was isolated from roasted and ground coffee and purified by ion exchange and thin-layer chromatography. The compound was characterized by nuclear magnetic resonance spectroscopy ((1)H, (13)C) and mass spectrometry techniques. A liquid chromatography-electrospray ionization tandem mass spectrometry method was developed to quantify the alkaloid in coffee by isotope dilution mass spectrometry. The formation of alkylpyridiniums is positively correlated to the roasting degree in arabica coffee, and highest levels of 1-methylpyridinium, reaching up to 0.25% on a per weight basis, were found in dark roasted coffee beans. Analyses of coffee extracts also showed the presence of dimethylpyridinium, at concentrations ranging from 5 to 25 mg/kg. This is the first report on the isolation and quantification of alkylpyridiniums in coffee. These compounds, described here in detail for the first time, may have an impact on the flavor/aroma profile of coffee directly (e.g., bitterness), or indirectly as precursors, and potentially open new avenues in the flavor/aroma modulation of coffee.

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... Synthetic d 3trigonelline hydroiodide, d 3 -NMP iodide, and NMP iodide were synthesized as reported earlier. 7,8,26 Determination of Roast Color. The determination of the roast color was done with a Color Tester LFM 1 Dr Lange type using an OG 539 yellow light filter and a photocell analyzing the diffuse light reflected from a sample of ground roast coffee. ...
... N-Methylpyridinium has been reported as the major reaction product of trigonelline during coffee bean roasting with yields of up to ∼18% (relative to 1). 8 Our data show that coffee roasting in authentic industry scale leads to substantial formation of 2 with yields up to approximately 50% (based on trigonelline) in espresso style roasting (color ∼50 scale parts), exceeding laboratory scale roasting (cf. Figure 2). Within the investigated color range the concentration of NMP approximated a linear function of the color with R 2 between 0.5424 and 0.8133 (cf. ...
Article
Quantitative analysis of the bioactives trigonelline (1), N-methylpyridinium (2), caffeine (3) and caffeoyl quinic acids (4) in a large set of roasted Arabica (total sample size n=113) and Robusta coffees (total sample size n=38) revealed that the concentration of 1 and 4 significantly correlated with the roasting color (P<0.001, two tailed) while 2 significantly correlated inversely with the color (P<0.001, two tailed). As dark roasted coffees were rich in N-methylpyridinium while light roasted coffees were rich in trigonellin and caffeoyl quinic acids, manufacturing of roast coffees rich in all four bioactives would therefore necessitate blending of two or even more coffees of different roasting colors. Additional experiments on the migration rates during coffee brewing showed that all four bioactives were nearly quantitatively extracted in the brew (>90%) when a water volume/coffee powder ratio of >16 was used.
... In addition to extracts from light, medium and dark roasts, selected constituents (Fig. 1) were included in the experiments to clarify their impact on the antioxidant effectiveness of the respective coffee brews. The phenolics 5-CQA (the major CQA isomer), CA, catechol (CAT) and 1,2,4-trihydroxy- benzene (THB) were studied in comparison to TRIG, NMP ion and as minor degradation products of TRIG N-methyl-2-methylpyridinium (NM-2MP) and N-methyl-3- methylpyridinium (NM-3MP), which have also been identified in roasted coffee [12, 13]. We investigated the direct radical scavenging capacity of coffee extracts/compounds, using oxygen radical absorbing capacity (ORAC) and trolox equivalent antioxidant capacity (TEAC) assay [14]. ...
... 5-CQA, TRIG hydrochloride, 1,2,4-trihydroxybenzene, CAT, menadione (Md), tert-butylhydroperoxide (TBH), Trolox s (6-hydroxy-2,5,7,8-tetrametylchroman-2-carboxylic acid), 2,2 0 -azinobis-(3-ethylbenzothiazonline-6-sulfonic acid) (ABTS), a, a 0 -azodiisobutyramidine dihydrochloride, catalase , RIPA buffer and protease inhibitor cocktail were obtained from Sigma-Aldrich (Deisenhofen, Germany). The iodide salts of NMP, d 3 -NMP, NM-2MP and NM-3MP were prepared following literature protocols [12, 13] (Boettler et al., submitted). d 6 -CAT and d 3 -TRIG hydroiodide for quantitative purposes were available from former studies [17]. ...
Article
Epidemiological studies suggest that coffee can reduce the risk of degenerative diseases such as diabetes type 2, cardiovascular disease and cancer. These beneficial effects have partly been attributed to the antioxidant activity of coffee. We determined composition and antioxidant potential of differentially roasted coffee extracts and investigated the impact of selected original constituents and roast products. Parameters studied were direct antioxidant activity (trolox equivalent antioxidant capacity/oxygen radical absorbing capacity), cellular reactive oxygen species (ROS) level, DNA damage and protein expression of NAD(P)H: quinone oxidoreductase, γ-glutamylcysteine ligase and glutathione reductase in HT-29/Caco-2 cells at 24-h incubation. All extracts showed distinct direct antioxidant activity: medium roasts>light roast AB1 (caffeoylquinic acid (CQA)-rich Arabica Brazil extract); dark roast AB2 (N-methylpyridinium (NMP)-rich Arabica Brazil extract), and diminished t-butylhydroperoxide-induced ROS level in HT-29 cells (AB2>medium roasts>AB1). NAD(P)H:quinone oxidoreductase 1 expression and γ-glutamylcysteine ligase expression were distinctly induced by AB1 and 5-CQA, but not by AB2 and NMP. 5-CQA and caffeic acid exhibited highest trolox equivalent antioxidant capacity/oxygen radical absorbing capacity values (5-CQA: 1.3/3.5 mM and caffeic acid: 1.3/3.9 mM trolox); ROS level was distinctly diminished by 5-CQA (≥3 μM), catechol (30 μM) and trigonelline (≥30 μM), whereas menadione-induced DNA damage in Caco-2 cells was reduced by NMP compounds (1-30 μM). The results emphasize that both original constituents and roast products contribute to the cellular antioxidant effectiveness of coffee.
... Its quality is typically evaluated by professional cuppers trained to assess subjective contributors to flavor and aroma. Quality may also be monitored via a more objective evaluation, particularly through the content of compounds known as coffee taste descriptors, namely, caffeine (1), trigonelline (2), nicotinic acid (3), N-methylpyridinium ion (4), 5-monocaffeoylquinic acid (5-CQA) (5), and 5-hydroxymethyl furfural (6) (1)(2)(3)(4). Compounds 2-4 are also key markers in the roasting process (4,5). ...
... Quality may also be monitored via a more objective evaluation, particularly through the content of compounds known as coffee taste descriptors, namely, caffeine (1), trigonelline (2), nicotinic acid (3), N-methylpyridinium ion (4), 5-monocaffeoylquinic acid (5-CQA) (5), and 5-hydroxymethyl furfural (6) (1)(2)(3)(4). Compounds 2-4 are also key markers in the roasting process (4,5). ...
Article
Full-text available
Nicotinic acid, N-methylpyridinium ion, and trigonelline are well studied nutritional biomarkers present in coffee, and they are indicators of thermal decomposition during roasting. However, no method is yet available for their simultaneous determination. This paper describes a rapid and validated HPLC-diode array detector method for the simultaneous quantitation of caffeine, trigonelline, nicotinic acid, N-methylpyridinium ion, 5-caffeoylquinic acid, and 5-hydroxymethyl furfural that is applicable to three coffee matrixes: green, roasted, and instant. Baseline separation among all compounds was achieved in 30 min using a phenyl-hexyl RP column (250 × 4.6 mm, 5 μm particle size), 0.3% aqueous formic buffer (pH 2.4)–methanol mobile phase at a flow rate of 1 mL/min, and a column temperature at 30°C. The method showed good linear correlation (r2 > 0.9985), precision (less than 3.9%), sensitivity (LOD = 0.023–0.237 μg/mL; LOQ = 0.069–0.711 μg/mL), and recovery (84–102%) for all compounds. This simplified method is amenable for a more complete routine evaluation of coffee in industry.
... Compounds 1,4-dimethylpyridinium (1,4-DMP) and 1-methylpyridinium (1-MP) are the products of thermal decomposition of trigonelline under conditions encountered during coffee roasting. Recently they have become a subject of great interest because of theirs potential endothelial and vasoprotective activity (Stadler et al., 2002;Natella et al., 2008;Buscemi et al., 2009). This activity may be the result of structural similarity to 1-methylnicothinamide (MNA), and its antithrombotic, anti-inflammatory and vasoprotective action is a consequence of its stimulation of endothelium to produce prostacyclin (PGI 2 ) in the COX 2 -dependent mechanism (Chlopicki et al., 2007). ...
... An example of such a substance is 1,4-DMP with proven antioxidant, hepatoprotective and vasoprotective activity (Somoza et al., 2003). The pharmacokinetic profile of this compound is, however, unknown and there is no available method to quantify 1,4-DMP in biological matrices such as plasma or tissue homogenates, since the methods that have been published so far deal only with determination of 1,4-DMP in coffee beverage or in roasted and ground coffees (Stadler et al., 2002;Somoza et al., 2003). The aim of this work was to develop and validate method to quantify 1,4-DMP in rat plasma for the purpose of pharmacokinetic studies. ...
... lg/g fresh weight) and Fabaceae (166-8004 lg/g fresh weight) (Corol et al., 2012;Matsui, Yin, Yamanaka, Iwasaki, & Ashihara, 2007). More importantly, trigonelline is known to be the second most abundant alkaloid in coffee (Rubiaceae) after caffeine (Stadler, Varga, Milo, et al., 2002). Based on the data available in the scientific literature, contents of trigonelline in coffee beans range from 7.7 to 14.8 mg/g dry weight for Coffea arabica, and 5.2 to 15.5 mg/g dry weight for C. canephora (Campa et al., 2004;Koshiro, Zheng, Wang, Nagai, & Ashihara, 2006;Lang, Yagar, Eggers, & Hofmann, 2008;Matsui et al., 2007;Perrone, Donangelo, & Farah, 2008;Stennert & Maier, 1994). ...
... The compound detected at the latest retention time ( Recently, Servillo and coworkers investigated the stability of PipBet in Robusta green beans, heated for different times at 190°C and 210°C (Servillo et al., 2016). They report that PipBet is heat stable at 210°C in coffee, so possibly other reaction mechanisms contribute to stabilizing the molecule, or reversible Nmethylation reactions may be occurring with other alkyl donors present in coffee Stadler, Varga, Milo, et al., 2002). ...
Article
This study describes, for the first time, the role of pipecolic acid betaine and pipecolic acid, naturally present in some foods, in the formation of the plant growth regulator N,N-dimethylpiperidinium (mepiquat) under dry thermal conditions. The formation of mepiquat and intermediate compounds was investigated in model systems using high performance liquid chromatography-quadrupole/ time-of-flight mass spectrometry. Mepiquat is released with a yield of up to 0.66 mol% after thermal treatment (> 150 °C) of pipecolic acid betaine. Similar conversion rates are attained with the congener piperidine-2-carboxylic acid (DL-pipecolic acid), albeit in the presence of alkylating agents, such as choline, glycine betaine or trigonelline, that are fairly widespread in food crops. These new pathways to mepiquat indicate that the occurrence of low levels of this thermally induced compound is probably more widespread in processed foods than initially suspected (see Part 2 of this study on the occurrence of mepiquat in selected foodstuffs).
... In den letzten Jahren standen vor allem die physiologisch aktiven Abbauprodukte NMP (2) und Nicotinsäure (5) sowie deren Bildung im Fokus von Veröffentlichungen (Stadler, et al. 2002b, Perrone, et al. 2008b, Lang, et al. 2008 ...
Thesis
Mit Hilfe von Stabilisotopenmarkierungsexperimenten wurden bisher unbekannte Bitterstoffe in Röstkaffee lokalisiert und identifiziert. Auf Basis von in-bean Carbon Module Labelling Approaches (CAMOLA) und Carbon Bond Labelling Approaches (CABOLA), mittels hochauflösender Massenspektrometrie sowie ein- sowie zweidimensionaler Kernresonanzspektroskopie, konnten die Strukturen und Bildungswege von neuartigen Bitterstoffen in Röstkaffee in aufgeklärt werden. Zusammen mit der Entwicklung geeigneter Stabilisotopenverdünnungsanalysen mittels LC-MS/MS konnten quantitative Studien angestellt werden, um die Reaktionswege und die Bildungskinetik von bekannten, aber auch bis dato unbekannten Bitterstoffen, in unterschiedlichen Röstgraden von Kaffee zu bestimmen.
... In an ''in-vivo'' study performed with rats, it was observed that feeding rats with coffee brew resulted in an increase of the total antioxidant capacity of the plasma (Somoza et al., 2003). A major contributor to the antioxidant activity was identified as N-methylpyridinium, a recently discovered alkaloid that is present in roasted coffee at concentrations of up to 0.25% on a dry weight basis (Stadler et al., 2002). Moreover, coffee consumption has been associated with reduced incidences of several types of cancer (Leitzmann et al., 2002;Tavani & La Vecchia, 2000), Parkinson's disease (Ascherio et al., 2001), liver cirrhosis (Tverdal & Skurtveit, 2003) and type 2 diabetes (Van Dam & Feskens, 2002). ...
Article
Due to the recognized toxicity of acrylamide, intensive efforts have been made to reduce the concentration of this undesired Maillard by-product in food. This work reports the results obtained from a series of experiments aimed at determining the concentration of acrylamide and the in vitro radical scavenging capacity in the same roasted and ground coffee samples, as it is well established that a significant part of the antioxidant activity in coffee is linked to the melanoidins, which are also considered as Maillard reaction products (MRPs). The radical scavenging capacity was measured using electroparamagnetic resonance (EPR). Coffee samples from the Robusta and Arabica varieties were roasted at 236 °C over different time periods to obtain very light, light, medium and dark roast. Color analyses were performed on all samples. Increasing the roasting degree led to a decrease in acrylamide concentration as well as radical scavenging capacity. The results of this work indicate that any mitigation efforts must also take into account the potential loss of desired food constituents and consequently changes to the risk/benefit characteristics of foods.
... During roasting trigonelline, which comprises $1% of the dry weight of the green bean is degraded substantially being converted to nicotinic acid (aka vitamin B3 and niacin) and several pyridine derivatives including 1-methylpyridinium and 1,2-dimethylpyridinium (Fig. 5). [48][49][50] Coffee has been reported to provide 1-3 mg of nicotinic acid per cup contributing to 6-18% of the recommended dietary allowance of 16 mg per day for adult men. 7 ...
Article
This review provides details on the phytochemicals in green coffee beans and the changes that occur during roasting. Key compounds in the coffee beverage, produced from the ground, roasted beans, are volatile constituents responsible for the unique aroma, the alkaloids caffeine and trigonelline, chlorogenic acids, the diterpenes cafestol and kahweol, and melanoidins, which are Maillard reaction products. The fate of these compounds in the body following consumption of coffee is discussed along with evidence of the mechanisms by which they may impact on health. Finally, epidemiological findings linking coffee consumption to potential health benefits including prevention of several chronic and degenerative diseases, such as cancer, cardiovascular disorders, diabetes, and Parkinson's disease, are evaluated.
... The caffeine level was in the range of conventional ground coffee [17]. The high concentration of roast products such as NMP (1.10 mg/g) is in the upper range of dark roasts [18], whereas the concentration of CQAs (10.18 mg/g) is in the range expected in medium roasted coffee. These compounds have previously been shown to be extracted practically quantitatively ([90 %) during brewing at the selected ratio of water volume to coffee weight of [16 [19]. ...
Article
Full-text available
Coffee consumption has been reported to decrease oxidative damage in peripheral white blood cells (WBC). However, effects on the level of spontaneous DNA strand breaks, a well established marker of health risk, have not been specifically reported yet. We analyzed the impact of consuming a dark roast coffee blend on the level of spontaneous DNA strand breaks. Healthy men (n = 84) were randomized to consume daily for 4 weeks either 750 ml of fresh coffee brew or 750 ml of water, subsequent to a run in washout phase of 4 weeks. The study coffee was a blend providing high amounts of both caffeoylquinic acids (10.18 ± 0.33 mg/g) and the roast product N-methylpyridinium (1.10 ± 0.05 mg/g). Before and after the coffee/water consumption phase, spontaneous strand breaks were determined by comet assay. At baseline, both groups exhibited a similar level of spontaneous DNA strand breaks. In the intervention phase, spontaneous DNA strand breaks slightly increased in the control (water only) group whereas they significantly decreased in the coffee group, leading to a 27 % difference within both arms (p = 0.0002). Food frequency questionnaires indicated no differences in the overall diet between groups, and mean body weight during the intervention phases remained stable. The consumption of the study coffee substantially lowered the level of spontaneous DNA strand breaks in WBC. We conclude that regular coffee consumption contributes to DNA integrity.
... mg kg -1 ) (Koshiro et al. 2006;Lang et al. 2008) and Coffea canephora (5.2-15.5 mg kg -1 ) (Campa et al. 2004;Koshiro et al. 2006), plays a pivotal role in the transfer of N-methyl substituents to available nucleophiles. In fact, trigonelline has been identified in earlier studies as a good methyl group donor in thermally driven methyl displacement reactions leading to alkylated pyridines Stadler, Varga, Milo, et al. 2002). ...
Article
Full-text available
This study is the first to examine the role of choline and glycine betaine, naturally present in some foods in particular in cereal grains, to generate N,N-dimethylpiperidinium (mepiquat) under Maillard conditions via transmethylation reactions involving the nucleophile piperidine. The formation of mepiquat and its intermediates piperidine - formed by cyclization of free lysine in the presence of reducing sugars - and N-methylpiperidine were monitored over time (240°C, up to 180 min) using high resolution mass spectrometry in a model system comprised of a ternary mixture of lysine/fructose/alkylating agent (choline or betaine). The reaction yield was compared to data recently determined for trigonelline, a known methylation agent present naturally in coffee beans. The role of choline and glycine betaine in nucleophilic displacement reactions was further supported by experiments carried out with stable isotope-labeled precursors ((13)C- and deuterium-labeled). The results unequivocally demonstrated that the piperidine ring of mepiquat originates from the carbon chain of lysine, and that either choline or glycine betaine furnishes the N-methyl groups. The kinetics of formation of the corresponding demethylated products of both choline and glycine betaine, N,N-demethyl-2-aminoethanol and N,N-dimethylglycine, respectively, were also determined using high resolution mass spectrometry.
... Thermal degradation of chlorogenic acids will result on phenolic substances that contribute to bitterness. A major contributor to the antioxidant activity was identified as N-Methylpyridinium, which was recently discovered alkaloid that is present in roasted coffee at concentrations of up to 0.25% on a dry weight basis (Stadler, 2002). Coffee is frequently recommended as a stimulant to prevent hypertension. ...
Article
Full-text available
Vietnam Robusta Coffee was roasted at different roasting degree and roasting temperature and 9 element concentrations (K, Mg, Ca, Na, Fe, Cu, Mn, Zn and Pb) of roasted coffee were analyzed by Flame atomic absorption method (FAAS) in this study. The results showed that the concentrations were ranged in 1447.97 ~ 1342.10 (mg/100g), 768.22 ~ 1259.44 (μg/g),10.35 ~ 13.15 (μg/g), and 17.38 ~ 20.97 (μg/g) for element of K, Ca, Cu and Mn in green and roasted coffee beans, respectively. All determined elements were the smallest value in green coffee, then increased with increasing roasting level and reached the highest value in Spain roast (roasting temperature of 250°C). Mg concentration ranged in 682.70 ~ 3647.73 (μg/g); Fe concentration ranged in 37.20 ~ 53.44 (μg/g); Zn concentration ranged in 5.97 ~ 6.89 (μg/g) and Pb concentration ranged in 2.18 ~ 15.04 (μg/100g). Concentrations of all determined elements didn’t change with the increased roasting process.
... This result indicates that one major prerequisitein addition to relatively high temperatureis the availability of an adequately large pool of quaternary ammonium compounds such as trigonelline to furnish the N-methylated congeners (Stadler et al. 2002a). Coffee is a product that meets these requirements (Stadler et al. 2002b). ...
Article
Previous work in model systems has demonstrated that mepiquat can be formed under typical roasting conditions from the amino acid lysine via the Maillard reaction and trigonelline, the latter alkaloid serving as a methyl donor. This study shows for the first time that mepiquat is formed in low mg/kg amounts during the coffee roasting process and consequently can be detected in roast and ground as well as soluble coffee up to levels of 1.4 mg/kg. Darker roast coffees contain relatively higher amounts of mepiquat versus light roasted beans, with an excellent correlation of mepiquat formation to roast colour (r2 = 0.99) in Robusta beans. A survey of 20 of the major green coffee origins (Robusta and Arabica coffees) showed the absence of mepiquat (<0.005 mg/kg). Preliminary studies indicate that mepiquat is not formed during processing (thermal treatment) in most of the cereal based foods such as pizza and ready-to-eat cereals, but was detected in barley after roasting (0.64 mg/kg). Mepiquat can therefore be considered a process-induced compound formed from natural constituents during the roasting process. Even considering a high intake of seven cups per day of soluble coffee containing 1.4 mg/kg mepiquat in the coffee powder (highest amount measured in this study), the resulting intake would exhaust only less than 0.2% of the ADI of mepiquat.
... Methyl rearrangement reactions involving trigonelline are not new and have, for example, been reported to occur in coffee (Stadler et al. 2002b). The loss of the methyl group in trigonelline was shown to be temperature dependent by the profile of nicotinic acid formation over the temperature range of 220-250°C. ...
Article
Full-text available
This preliminary study reports for the first time the formation of N,N-dimethylpiperidinium (also termed mepiquat, a plant growth regulator used widely on cereal crops) by Maillard-driven degradation of lysine under dry thermal conditions and in the presence of the naturally occurring alkaloid trigonelline. The heat treatment was carried out at 240°C, and the resulting samples were analyzed by liquid chromatography coupled to a high resolution mass spectrometer operating based upon the Orbitrap technology. Results confirmed that lysine undergoes cyclization by decarboxylative deamination in the presence of a carbonyl source (e.g. reducing sugars) to yield piperidine. Moreover, methyl rearrangement in the presence of trigonelline and under typical temperatures of roasting generates detectable amounts of mepiquat, identified by detailed mass fragmentation studies. The essential role of lysine in the formation of mepiquat was confirmed in a model system using (13)C6-lysine which showed the expected incorporation of five (13)C atoms into the mepiquat nitrogen heterocycle. These findings are relevant to the potential occurrence of mepiquat in roasted products such as coffee and cereals.
... A major contributor to the antioxidant activity was identified as N-Methylpyridinium, a recently discovered alkaloid that is present in roasted coffee in concentrations of up to 0.25 % on a dry weight basis (Stadler et al., 2002). Moreover, coffee consumption has been associated with reduced incidences of several types of cancer (Leitzmann et al., 2007); Tavani and La-Vecchia, 2000), liver Cirrhosis (Tverdal and Skurtveit, 2003) and type 2 diabetes (Van Dam and Feskens, 2002). ...
... The analysis of the cytosolic enzymes of the lymphocytes after coffee consumption showed an increased activity of superoxide dismutase (?38%), whereas glutathione peroxidase remained unchanged. One of the active principles in coffee brews acting as key antioxidants might be N-methylpyridinium, a decarboxylation product that is generated during coffee bean roasting (Fig. 2; Stadler et al. 2002). In rats, Somoza et al. (2003) demonstrated an increase in total antioxidant capacity and alpha-tocopherol concentrations in the plasma of rats fed on coffee or N-methylpyridinium for 10 days. ...
Article
Full-text available
Melanoidins are the final products of the Maillard reaction. The main dietary sources of melanoidins are coffee, bread crust, bakery products, black beer and cocoa. Although the chemical structures of melanoidins are widely unknown, data from gravimetric techniques allow to roughly estimate a daily intake in the order of 10 g with a Western diet. Melanoidins contribute to the sensorial properties, modulating texture and flavour of foods. Growing evidence also suggests that melanoidins have health beneficial properties, such as chemopreventive, antioxidant and antimicrobial activities, and the ability to chelate different minerals. In the gastrointestinal tract, melanoidins behave not only as antioxidants, but also as dietary fibre by promoting the growth of bifidobacteria. This array of biological activities suggests the need for analytical techniques to identify the melanoidin structures and to control their formation during thermal food processing.
... The most common alkaloid in green coffee is caffeine (1%-4%), whose concentration strongly depends on variety and growing conditions, followed by trigonelline (~0.8%) [113][114][115]. Trigonelline is partially degraded during coffee roasting, forming N-methylpyridinium ions by decarboxylation and nicotinic acid by demethylation [116][117][118]. ...
Article
Full-text available
The coffee plant Coffea spp. offers much more than the well-known drink made from the roasted coffee bean. During its cultivation and production, a wide variety of by-products are accrued, most of which are currently unused, thermally recycled, or used as animal feed. The aim of this review is to provide an overview of novel coffee products in the food sector and their current legal classification in the European Union (EU). For this purpose, we have reviewed the literature on the composition and safety of coffee flowers, leaves, pulp, husk, parchment, green coffee, silver skin, and spent coffee grounds. Some of these products have a history of consumption in Europe (green coffee), while others have already been used as traditional food in non-EU-member countries (coffee leaves, notification currently pending), or an application for authorization as novel food has already been submitted (husks, flour from spent coffee grounds). For the other products, toxicity and/or safety data appear to be lacking, necessitating further studies to fulfill the requirements of novel food applications.
... However, other chemical reactions induced by roasting have recently begun to attract attention. For example, the flavour active compound 1-methylpyridine, found in relatively high quantities in roasted coffee, is proposed to be a roasting induced break-down product of the alkaloid trigonelline in green coffee [15,16]. Similarly, b-damascenone, a very potent and volatile aroma compound found in both low levels in green coffee [1718] and at higher levels in roasted coffee [18] is thought to be formed primarily by heat/chemical induced degradation of one or more carotenoids [18,19]. ...
Article
Roasted coffee contains a complex array of volatile organic compounds (VOCs) which make an important contribution to the characteristic flavour and aroma of the final beverage. It is thought that a few of the potent coffee aroma components, such as "beta-damascenone", could be derived from carotenoid precursors. In order to further investigate the potential link between carotenoids and coffee aroma profiles, we have measured the carotenoid content in developing coffee grain. The data obtained confirms the presence of lutein in the grain, and additionally shows that the immature coffee grain also contains significant amounts of beta-carotene, alpha-carotene, violaxanthin, and neoxanthin. Complimentary quantitative gene expression analysis revealed that all the carotenoid biosynthetic genes examined are expressed in the grain, and that the transcript levels are gene and stage dependent. Furthermore, consistent with the reduction of the carotenoid levels at the last stage of grain development (mature-red), most of the transcript levels were also found to be lower at the final developmental stage. Quantitative expression analysis of the carotenoid genes was also carried out for the developing pericarp tissue of the coffee cherries. Again, all the genes examined were expressed, and in most cases, the highest transcript levels were detected around the large green-yellow stages, a period when carotenoid synthesis is probably greatest.
... Substantial levels of NA are formed by increasing time and temperature of coffee roasting. [9][10][11] After ingestion, NAM is methylated in the liver, to N 1 -methylnicotinamide (NMNAM) by nicotinamide N-methyltransferase and then oxidized to N 1 -methyl-2-pyridone-5-carboxamide (2-Py) and N 1 -4-pyridone-5-carboxamide. [12,13] The major urinary metabolites of niacin are NMNAM and 2-Py, accounting for 20 -35 % and 45 -60%, respectively, of all niacin metabolites. [14,15] The European Food Safety Authority (EFSA) has recommended the determination of urinary metabolites, namely NMNAM and 2-Py, as a way of measuring an individual's niacin intake. ...
Article
Full-text available
Scope: Coffee is a major natural source of niacin in the human diet, as it is formed during coffee roasting from the alkaloid trigonelline. The intention of our study was to monitor the urinary excretion of niacin metabolites after coffee consumption under controlled diet. Methods and results: We performed a four-day human intervention study on the excretion of major niacin metabolites in the urine of volunteers after ingestion of 500 mL regular coffee containing 34.8 μmol nicotinic acid (NA) and 0.58 μmol nicotinamide (NAM). In addition to NA and NAM, the metabolites N1-methylnicotinamide (NMNAM), N1-methyl-2-pyridone-5-carboxamide (2-Py), and nicotinuric acid (NUA) were identified and quantified in the collected urine samples by stable isotope dilution analysis (SIVA) using HPLC-ESI-MS/MS. Rapid urinary excretion was observed for the main metabolites (NA, NAM, NMNAM, and 2-Py), with tmaxvalues within the first hour after ingestion. NUA appeared in traces even more rapid. In sum, 972 nmol/h of NA, NAM, NMNAM, and 2-Py were excreted within 12 h after coffee consumption, corresponding to 6 % of the ingested NA and NAM. Conclusion: The results indicate regular coffee consumption to be a source of niacin in human diet. This article is protected by copyright. All rights reserved.
... Compounds exhibiting neuroprotective effects have been suggested to alter the course of metabolic events subsequently reducing occurrence of stroke, convulsions, or trauma (Mancini, Wang, and Weaver 2018). Roasted coffee also contains high amounts of N-methylpyridinium (Stadler et al. 2002), a potent activator of Nrf2nuclear translocation and subsequent antioxidant response elements-dependent gene transcription in human colon carcinoma cells (Boettler et al. 2011). Indeed, subsequent human trials corroborated modulated Nrf2-transcription after consumption of a coffee with high amounts of N-methylpyridinium (74 mg/L). ...
Article
The purpose of food processing today is to make food safer, more nutritious and tastier, and to increase storage life. Consumers have a lack of trust in the way food is produced, formulated and processed, particularly with possible contaminants or chemical residues from production. Food manufacturers are not seen as being highly trusted sources. This may partly result from manufacturers’ reluctance to share all information and to protect intellectual property via patents and thus maintain a competitive edge. There is a need to inform the consumer better about what operations the involved ingredients are subjected to and why. Various ways of food processing are reviewed. New food processing technologies face challenges when introduced and factors influencing consumers’ and other stakeholders’ acceptance should be part of decision-making process when adopting new technologies. Consumers’ perception of risks is not the same as the risk assessment made by experts. A few specific cases are being discussed to further highlight the multiplicity of factors that may contribute to the development of a certain consumer perception about a product or a class of products. This is also linked to the emergence of certain terminologies that are associated with an increasingly negative perception of the processing of foods. We recommend more transparency on food formulation and food processing to restore consumer trust, which enables to take the advantage of the benefits different processing methods offer. Food manufacturers must make an effort to let consumers know how their food is being processed within the walls of the factory and highlight the benefits vis-à-vis preparing foods in a domestic environment.
... CGA undergoes numerous transformations in vivo, resulting in the formation of derivatives that might be not as effective as the parent compound [118]. Trigonelline is degraded into N-methylpyridinium during roasting [119], leading to relatively low concentrations in the coffee beverage. Interestingly, strong antioxidant effects of N-methylpyridinium and a lyophilized de-caffeinated coffee brew have been described by Somoza et al. [120] following a 10day administration to rats. ...
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The manuscript reviews beneficial aspects of food processing with main focus on cooking/heat treatment, including other food-processing techniques (e.g. fermentation). Benefits of thermal processing include inactivation of food-borne pathogens, natural toxins or other detrimental constituents, prolongation of shelf-life, improved digestibility and bioavailability of nutrients, improved palatability, taste, texture and flavour and enhanced functional properties, including augmented antioxidants and other defense reactivity or increased antimicrobial effectiveness. Thermal processing can bring some unintentional undesired consequences, such as losses of certain nutrients, formation of toxic compounds (acrylamide, furan or acrolein), or of compounds with negative effects on flavour perception, texture or colour. Heat treatment of foods needs to be optimized in order to promote beneficial effects and to counteract, to the best possible, undesired effects. This may be achieved more effectively/sustainably by consistent fine-tuning of technological processes rather than within ordinary household cooking conditions. The most important identified points for further study are information on processed foods to be considered in epidemiological work, databases should be built to estimate the intake of compounds from processed foods, translation of in-vitro results to in-vivo relevance for human health should be worked on, thermal and non-thermal processes should be optimized by application of kinetic principles.
... Other precursors of flavor and aroma in coffee are secondary metabolites, such as alkaloids (caffeine and trigoneline ) and phenylpropanoid chlorogenic acid (CGA). These three components, together with sucrose, seem to be the main factors influencing coffee quality, because sucrose and trigoneline enhance coffee quality, while CGA and caffeine confer bitter taste [7,107,130131132133. The comparison between the two coffee species showed that C. arabica has more trigoneline and sucrose, and C. canephora contains more CGA and caffeine [131]. ...
Article
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Coffee is one of the world's most important crops; it is consumed worldwide and plays a significant role in the economy of producing countries. Coffea arabica and C. canephora are responsible for 70 and 30% of commercial production, respectively. C. arabica is an allotetraploid from a recent hybridization of the diploid species, C. canephora and C. eugenioides. C. arabica has lower genetic diversity and results in a higher quality beverage than C. canephora. Research initiatives have been launched to produce genomic and transcriptomic data about Coffea spp. as a strategy to improve breeding efficiency. Assembling the expressed sequence tags (ESTs) of C. arabica and C. canephora produced by the Brazilian Coffee Genome Project and the Nestlé-Cornell Consortium revealed 32,007 clusters of C. arabica and 16,665 clusters of C. canephora. We detected different GC3 profiles between these species that are related to their genome structure and mating system. BLAST analysis revealed similarities between coffee and grape (Vitis vinifera) genes. Using KA/KS analysis, we identified coffee genes under purifying and positive selection. Protein domain and gene ontology analyses suggested differences between Coffea spp. data, mainly in relation to complex sugar synthases and nucleotide binding proteins. OrthoMCL was used to identify specific and prevalent coffee protein families when compared to five other plant species. Among the interesting families annotated are new cystatins, glycine-rich proteins and RALF-like peptides. Hierarchical clustering was used to independently group C. arabica and C. canephora expression clusters according to expression data extracted from EST libraries, resulting in the identification of differentially expressed genes. Based on these results, we emphasize gene annotation and discuss plant defenses, abiotic stress and cup quality-related functional categories. We present the first comprehensive genome-wide transcript profile study of C. arabica and C. canephora, which can be freely assessed by the scientific community at http://www.lge.ibi.unicamp.br/coffea. Our data reveal the presence of species-specific/prevalent genes in coffee that may help to explain particular characteristics of these two crops. The identification of differentially expressed transcripts offers a starting point for the correlation between gene expression profiles and Coffea spp. developmental traits, providing valuable insights for coffee breeding and biotechnology, especially concerning sugar metabolism and stress tolerance.
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Trigonelline and sucrose are two coffee aroma precursors. Contents of these compounds are higher in Coffea arabica than in Coffea canephora green beans and this could be the main explanation for consumers' preference for C. arabica coffee. This is the first evaluation of sucrose and trigonelline contents involving 14 species and six new taxa not yet botanically characterised. Trigonelline and sucrose contents varied between species from 0.39% to 1.77% dry matter basis (dmb) and from 3.8% to 10.7% dmb, respectively. C. canephora could be improved through both compounds by crosses with Coffea eugenioides.
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The present study describes stress degradation studies on a biomarker, trigonelline following the International Conference on Harmonization (ICH) guidelines under different stress conditions and establishment of a stability‐indicating HPTLC assay method. Analysis of trigonelline was performed on TLC aluminium plates precoated with silica gel 60F‐254 and mobile phase consisting of n‐propanol‐methanol‐water (4:1:4 v/v/v). Spectrodensitometric scanning was carried out in absorbance mode at 269 nm for trigonelline (Rf=0.46±0.02). Trigonelline was subjected to acid and alkali hydrolysis, oxidation, dry heat, wet heat treatment, and photodegradation. Statistical analysis proves that the developed HPTLC method is reproducible and selective. As the method could effectively separate the drug from its degradation products, it can be employed as a stability‐indicating one. Moreover, the method was utilized to investigate the kinetics of the acidic and alkaline degradation processes at different temperatures and to study degradation in constant ionic strength buffer solutions within the pH range 1–11.
Article
The in vitro radical scavenging capacity of the roasted and ground coffee is generally known as well as the published results of lowering the incidence of various diseases by regular intake of coffee. The antioxidant capacity of coffee is based mainly on the phenols, but during the roasting phenols are degraded and new products with antioxidant capacity are formed. A major contributor to the antioxidant activity was identified as N-methylpyridinium, which is formed during the roasting by degradation of trigonelline, the degradation is about 50% of trigonelline content and the concentration of N-methylpyridinium in roasted coffee is up to 0.25% on a dry weight basis. These literature data were verified within the processing plant experiment, during the usual roasting procedure of Robusta coffee the fol - lowing parameters were analysed: humidity, water activity, total antioxidant capacity, total phenols, chlorogenic acid and trigonelline content, and colour ( L*, a*, b*). The changes of the evaluated parameters were correlated to each other. During the roasting the total antioxidant capacity (TAC) decreased to about one half of original level in the beginning stages of roasting, another decrease continued during the storage of roasted coffee at about 10% within the year. The degradation of trigonelline, neither the content of chlorogenic acid or total phenols did not correlate with TAC in samples during the roasting and storage.
Article
Oxidative cellular stress initiates Nrf2 translocation into the nucleus, thus inducing antioxidant response element (ARE)-mediated expression of Phase II enzymes involved in detoxification and antioxidant defence. We investigated whether coffee extracts (CEs) of different proveniences and selected constituents have an impact on the Nrf2/ARE pathway in human colon carcinoma cells (HT29). Assessed as increased nuclear Nrf2 protein, Nrf2 nuclear translocation was modulated by different CEs as observed by Western blot analysis. In addition to the known Nrf2 activator 5-O-caffeoylquinic acid (CGA), pyridinium derivatives like the N-methylpyridinium ion (NMP) were identified as potent activators of Nrf2 nuclear translocation and ARE-dependent gene expression of selected antioxidative Phase II enzymes in HT29. Thereby, the substitution pattern at the pyridinium core structure determined the impact on Nrf2-signalling. In contrast, trigonelline was found to interfere with Nrf2 activation, effectively suppressing the NMP-mediated induction of Nrf2/ARE-dependent gene expression. In conclusion, several coffee constituents, partly already present in the raw material as well as those generated during the roasting process, contribute to the Nrf2-translocating properties of consumer-relevant coffee. A fine tuning in the degradation/formation of activating and deactivating constituents of the Nrf2/ARE pathway during the roasting process appears to be critical for the chemopreventive properties of the final coffee product.
Chapter
IntroductionHarvesting coffee beans, roasting and blendingPhytochemicals in coffeeBioavailability of coffee chlorogenic acids in humansConclusions References
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A nanoreactor of poly(N-isopropylacrylamide)-grafted Pd nanoparticle (Pd@PNIPAM) is proposed for the Suzuki reaction performed in the sole solvent of water. The Pd@PNIPAM nanoparticle has a core of Pd nanoparticle and a corona of poly(N-isopropylacrylamide) brushes. The Pd@PNIPAM nanoparticle can act as a nanoreactor for the Suzuki reaction since the grafted poly(N-isopropylacrylamide) brushes provide a nanoenvironment for guest molecules. Both hydrophilic and hydrophobic reactants can be enriched in the nanoreactor of Pd@PNIPAM, and therefore the Suzuki reaction within the nanoreactor is performed in water at room temperature or above the phase-transition temperature of the corona-forming brushes of poly(N-isopropylacrylamide). Besides, the nanoreactor of Pd@PNIPAM can be recycled due to the reversible phase-transition of the poly(N-isopropylacrylamide) brushes.
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Maillard reaction products (MRPs) and advanced glycation end-products (AGEs) correspond to modified protein derivatives that are initially generated by non-enzymatic glycation between amino acids and reducing sugars in heat-treated foods and in vivo, respectively. Because lung tissue highly expresses the receptor for advanced glycation end-products (RAGE), we studied the impact of MRP/AGE-rich foods like bread crust (BC) and coffee extract (CE) on the proliferation and cell death induction using lung epithelial (H358) cells. Here, we showed that CE impairs the proliferation and viability of H358 cells at much higher extent than BC does. Particularly cell death induced by CE showed a concentration-dependent shift from apoptotic to necrotic features as estimated by caspase activation, phosphatidylserine exposure, leakage of the outer membrane, mitochondrial dysfunction and stress kinase activation. Moreover, CE at higher dose triggered the generation of reactive oxygen species thereby mediating caspase inhibition. Non-toxic concentrations of both foods only impaired the proliferation associated with an increased amount of cells in the S/G2 phase of the cell cycle, which did not depend on the over-expression of RAGE. From our data we conclude that MRP/AGE-rich foods mediate antiproliferative effects at moderate concentrations that might be important in physiological conditions like cancer prevention but contributes to cell death at higher levels in vitro.
Article
NMR has become a valuable tool in the study of a wide variety of structural and compositional aspects of food chemistry and food analysis. P NMR spectroscopy has been an invaluable tool in the analysis of foods and the study of the factors affecting food quality. P NMR spectra of intact muscle with or without deuterium locking have been used with great success, obtained either by utilizing large bore magnets or horizontal MRI scanners. Foodstuff such as in milk, where phosphorus appears in the form of phospholipids, elaborate experimental procedures have been developed in order to acquire high resolution P NMR spectra. P NMR has been used to measure the phospholipid content of Greek extra-virgin olive oil, identifying PA, PI, and the hydrolyzed lyso analogues, LPA and LPI as the most abundant PLs. The P-tagging NMR methodology has also been applied to study the effect of thermal stressing on saturated and unsaturated seed oils.
Chapter
IntroductionDietary phytochemicalsVegetablesFruitsHerbs and spicesCerealsNutsAlgaeBeveragesDatabases
Article
A sensitive and specific liquid chromatography electrospray ionization-mass spectrometry method for determination of 1,4-dimethylpyridinium (1,4-DMP) in rat plasma has been developed and validated. Chromatography was performed on an Aquasil C(18) analytical column (4.6 × 150 mm, 5 µm, Thermo Scientific, Rockford, IL, USA) with isocratic elution using a mobile phase containing acetonitrile and water with an addition of 0.1% of formic acid. Detection was achieved by an Applied Biosystems MDS Sciex (Concord, Ontario, Canada) API 2000 triple quadrupole mass spectrometer. Electrospray ionization was used for ion production. The limit of detection in the single ion monitoring mode was found to be 10 ng/mL. The limit of quantification was 50 ng/mL. The precision and accuracy for both within-day and between-day determination of 1,4-dimethylpyridinium was 2.4-7.56 and 90.93-111.48%. The results of this analytical method validation allow pharmacokinetic studies to be carried out in rats. The method was used for the pilot study of the pharmacokinetic behavior of 1,4-DMP in rats after intravenous administration. Copyright © 2012 John Wiley & Sons, Ltd.
Chapter
Coffee brew presents a rich source of bioactive compounds known to be powerful antioxidants. The present paper gives an overview of these antioxidants. Coffee provides a high content of chlorogenic acids and caffeine, as well as a significant content of nicotinic acid, trigonelline, tocopherols, cafestol, kahweol, and heterocyclic compounds. The quality of coffee used for the preparation of a beverage is related to the chemical composition of the roasted beans, which is affected by the chemical composition of the green beans and post-harvest processing conditions (drying, storage, roasting, and grinding). Although phenolic antioxidants, naturally occurring in coffee, are degraded during the roasting process, the antioxidant properties of roasted coffee can be maintained, or even enhanced, by the formation of compounds with antioxidant activity, such as Maillard reaction products.Because of their significant antioxidant properties, coffee by-products can also be used as functional ingredients or additives in the food industry.
Article
N-Methylpyridinium (NMP) is a thermal degradation product of trigonelline formed upon coffee roasting and hypothesized to exert several health benefits in humans. Since for trigonelline evidence for hypoglycemic effects exists, we examined whether NMP also affects mechanisms of glucose utilization and cellular energy formation. For this purpose, the impact of trigonelline and NMP on respiratory activity, extracellular acidification, cellular adenosine nucleotides, energy supply from fatty acids and glucose as well as thermogenesis in HepG2 cells was analyzed. A 24 hour incubation with nanomolar concentrations of NMP enhanced oxygen consumption rates, resulting in increased ATP levels. Glucose was identified as the prevalent energy substrate as its uptake was augmented up to 18.1% ± 7.44% by NMP at 0.09 μM, whereas the uptake of fatty acids decreased upon NMP treatment. Cellular glucose uptake was also stimulated by trigonelline administration; however, a shift to the anaerobic energy production pathway was monitored. Both pyridine derivatives induced thermogenesis, although trigonelline presumably promoted proton leaks, while NMP increased the concentration of the uncoupling protein-2. We provide evidence that both compounds appear to stimulate cellular energy metabolism in HepG2 cells. Human intervention studies are warranted to ensure these effects in vivo.
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Helquats are novel helical dications combining features of two privileged classes of compounds - helicenes and viologens. This review discusses the origin and current status of helquat chemistry focusing on three- and fourstep synthetic routes. Driving forces in this freshly opened territory are the prospects of versatile applications inspired by chemistries of both viologens and helicenes. These novel chemical compounds are readily accessible.
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The formation of 6-(hydroxymethyl)pyridin-3-ol by ring expansion of 5-(hydroxymethy)furfural (HMF) in the presence of ammonia-producing compounds was studied to determine routes of formation of pyridin-3-ols in foods. 6-(Hydroxymethyl)pyridin-3-ol was produced from HMF in model systems, mostly at neutral pH values, as a function of reaction times and temperature, and with an activation energy (Ea) of 74  3 kJ/mol, which was higher than that of HMF disappearance (43  4 kJ/mol). A reaction pathway is proposed, which is general for the formation of pyridin-3-ols from 2-oxofurans. Thus, it explains the conversions of furfural into pyridin-3-ol and of 2-acetylfuran into 2-methylpyridin-3-ol, which were also studied. When honey and sugarcane honey were heated, they produced different pyridin-3-ols, although 6-(hydroxymethyl)pyridin-3-ol was the pyridine-3-ol produced to the highest extent. Obtained results suggest that formation of pyridin-3-ols in foods is unavoidable when 2-oxofurans are submitted to thermal heating and ammonia (or ammonia-producing compounds) is present.
Chapter
The concentration of caffeine in green coffee beans varies between 0.9‐1.3 and 1.5‐2.5% dry matter for arabica and robusta coffees, respectively. The caffeine content of beans is not markedly reduced by roasting, although losses, presumably due to sublimation, may occur if the heating process is carried out at higher temperatures. Caffeine consumption increases metabolic rate, energy expenditure, lipid oxidation, and lipolytic and thermogenic activities, and so has potential as an aid in weight loss and reducing the overall risk of developing metabolic syndrome. Like caffeine, there are reports of both positive and negative effects of theobromine on human health. The metabolic step is the demethylation of caffeine leading to paraxanthine, theobromine, and theophylline. A number of species, including dogs, horses, and the New Zealand kea, have very limited capacity to metabolize theobromine, which tends to accumulate and becomes toxic with potentially fatal consequences. Several studies have investigated the bioavailability of trigonelline in humans and animals.
Article
The acceptance of many foods is related to traditional cooking practices, which create taste and texture and are important to digestibility, preservation, and the reduction of foodborne illnesses. A wide range of compounds are formed during the cooking of foods, a number of these have been shown to lead to adverse effects in classical toxicological models and are known as food processing contaminants (FPC). It is essential that the presence and effects of such compounds alone and in combination within the diet are understood such that proportionate risk management measures can be developed, while taking a holistic view across the whole value chain. Furan and alkylfurans (principally 2‐ and 3‐methylfuran) are highly volatile FPC, which are formed in a wide range of foods at low amounts. The focus of research to‐date has been on those foods, which have been identified to be most consequential in terms of being sources of exposure, namely jarred and canned foods for infants and young children (meals and drinks) and coffee (roast and ground, soluble). This report presents (i) new industry data on the occurrence of furan and methylfurans in selected food categories following previous coffee studies, (ii) the most salient parameters that impact furan formation, and (iii) aspects of importance for the risk assessment.
Article
Roasting of Coffea arabica L. seeds gives rise to chemical reactions that produce more than 800 compounds, some being responsible for the desired organoleptic properties for which the beverage called “coffee” is known. In the industry, the “roasting profile”, i.e. the times and temperatures applied, is key to influence the composition of roasted coffee beans and the flavour of the beverage made from them. The impact of roasting on the chemical composition of coffee has been the subject of numerous studies, including by NMR spectroscopy. However, the roasting equipment and profiles applied in these studies are often far from real industrial conditions. In this work, the effect of two critical technological parameters of the roasting process namely the "development time" (the period of time after the "first crack", a characteristic noise due to seed disruption) and the final roasting temperature on coffee extracts were investigated. Seeds were roasted at pilot scale according to 13 industrial roasting profiles and extracted in D2O. The extracts were analysed by ¹H NMR experiments. The NMR spectra were compared using (i) quantitative analysis of main signals by successive orders of magnitude and (ii) chemometric tools (PCA, PLS and S‐OPLS). This allowed to identify compounds which may serve as markers of roasting and showed that changes in chemical composition can be detected even for slight change in final temperature (~1°C) or in total roasting time (~ 25 s).
Chapter
Since the discovery of acrylamide in food in 2002, the food industry has explored numerous strategies for reducing levels. Key aspects of this mitigation work are summarized in the FoodDrinkEurope (FDE) ‘Acrylamide Toolbox.’ The food industry has achieved reductions in several product categories, but no clear solutions are yet available for certain categories such as coffee. Monochloropropane-1,2-diol and glycidyl esters have also raised much attention, present mainly in refined edible vegetable oils and are generated during the oil deodorization process. This article summarizes the key mitigation measures to lower chloro- and glycidyl esters during refined palm oil production and addresses the efforts required to further improve the quality and safety of refined vegetable oils.
Article
Introduction Alzheimer's disease Coffee Caffeine Phenolics Other coffee constituents Conclusions References
Article
Coffee consumption sometimes is associated with symptoms of stomach discomfort. This work aimed to elucidate whether two coffee beverages, containing similar amounts of caffeine, but differing in their concentrations of (β) N-alkanoyl-5-hydroxytryptamides (C5HTs), chlorogenic acids (CGAs), trigonelline, and N-methylpyridinium (N-MP) have different effects on gastric acid secretion in healthy volunteers. The intragastric pH after administration of bicarbonate with/without 200 mL of a coffee beverage prepared from a market blend or dark roast blend was analyzed in nine healthy volunteers. Coffee beverages were analyzed for their contents of C5HT, N-MP, trigonelline, CGAs, and caffeine using HPLC-DAD and HPLC-MS/MS. Chemical analysis revealed higher concentrations of N-MP for the dark brown blend (87 mg/L) compared to the market blend coffee (29 mg/L), whereas concentrations of C5HT (0.012 versus 0.343 mg/L), CGAs (323 versus 1126 mg/L), and trigonelline (119 versus 343 mg/L) were lower, and caffeine concentrations were similar (607 versus 674 mg/mL). Gastric acid secretion was less effectively stimulated after administration of the dark roast blend coffee compared to the market blend. Future studies are warranted to verify whether a high ratio of N-MP to C5HT and CGAs is beneficial for reducing coffee-associated gastric acid secretion.
Article
Introduction Food Processing and Major Benefits Conclusions and Future Research Needs References
Article
Chemistry of coffee, under the heading of biodiversity, covers both general and new aspects of interest: the challenge of an expanding cultivation of coffee; the rise and threat of species; coffee components developing in the fruit, at postharvest treatment, via the roasting process, in the preparation of the beverage; and, finally, the beverage's effects on humans.
Article
Iodide contrast sensitization to direct irradiation of charge transfer salts incurs carboxylic acid release via visible light absorption. The photochemical reduction of N-methyl-4-pyridinium iodide esters to release carboxylic acids is examined using (1)H NMR analysis. Photolysis reactions are carried out under mild, biphasic solvent conditions using a household LED lamp. Carboxylic acid release is reported in high yields, and the viability of this method for synthetic chemistry is demonstrated through a macroscale reaction.
Article
This review evaluates coffee constituents in order to determine their influence on the inflammation process. Coffee is a common beverage that contains multiple substances that impact inflammatory markers. The caffeine, chlorogenic acid (CGA), cafestol, trigonelline, and kahweol found in coffee are thought to have significant potential as antioxidants and free radical scavengers. Experimental animal studies indicated reduction of tumour necrosis factor alpha (TNF-α), interleukin-1B (IL-1B), and monocyte chemoattractant protein-1 (MCP-1) with coffee consumption. Human studies presented mixed results. At this point, coffee shows some promise against the inflammatory response. More research with controlled, double-blinded studies in humans must be conducted before practitioners advise patients to utilize the beverage as a prophylaxis against inflammation.
Article
As the most consumed beverage in the world, the material basis of the sensory quality for roasted coffee beans has always received much attention. The objective of the present study was to clarify the physical morphology changes, main chemical ingredients and cupping scores of arabica coffee beans of different roasting degrees, by scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) and sensory analysis, respectively. Statistical analysis of the data by multivariate analysis demonstrated that trigonelline, sugars, malate, quinic acids, γ-butyro-lactone and acetate have the potential to be new roasting markers. Additionally, in all the sensory indicators, body and acidity were found to be susceptible to roasting degree. Basing on cluster heatmap and sensory molecular network, the complex relationships between sensory indicators and ingredients were discussed. The results of partial least squares regression (PLSR) showed that the content of the main coffee ingredients can be used to predict the body score.
Article
The paper reports on the development of an accurate hydrophilic liquid interaction chromatography tandem mass spectrometry (HILIC-MS/MS) based stable isotope dilution analysis for the simultaneous quantitation of the food-derived bioactive pyridines trigonelline, nicotinic acid, nicotinamide, and N-methylpyridinium, as well as their key metabolites nicotinamide-N-oxide, N-methylnicotinamide, N-methyl-2-pyridone-5-carboxamide, N-methyl-4-pyridone-5-carboxamide, and N-methyl-2-pyridone-5-carboxylic acid in human plasma and urine. Precision of the stable isotope dilution analysis (SIDA) was 1.9% and 11.9% relative standard deviation (n = 6), and accuracy was between 92.4% and 113.0%. The lower limit of quantitation (LLOQ) was 50 fmol (10 pmol/mL) injected onto the column for all analytes with the exception of N-methyl-2-pyridone-5-carboxylic acid and N-methyl-2-pyridone-5-carboxamide, for which an LLOQ of 100 fmol (20 pmol/mL) was found. The method was applied to monitor the plasma appearance and urinary excretion and to determine pharmacokinetic parameters of the bioactive pyridines as well as their metabolites in a clinical human intervention study with healthy volunteers (six women, seven men) after oral administration of 350 mL of a standard coffee beverage. Trigonelline plasma levels increased from 160 nmol/L to maximum concentrations of 5479 (males) or 6547 nmol/L (females), and N-methylpyridinium plasma levels raised from virtually complete absence to maximum values of 777 (females) or 804 nmol/L (males) within 2-3 and 1-2 h after coffee consumption, respectively. The high plasma levels of N-methylpyridinium found after coffee consumption clearly demonstrate for the first time that this cation is entering the vascular system, which is the prerequisite for biological in vivo effects claimed for that compound. In contrast, the coffee intervention did not significantly influence the plasma concentrations of N-methyl-2-pyridone-5-carboxamide and N-methyl-4-pyridone-5-carboxamide, the major niacin metabolites. Within 8 h after coffee intervention, an urinary excretion of 57.4 +/- 6.9% of trigonelline and 69.1 +/- 6.2% of N-methylpyridinium was found for the male volunteers, whereas females excreted slightly less with 46.2 +/- 7.4% and 61.9 +/- 12.2% of these pyridines.
Article
By means of gas chromatography/mass spectrometry following preseparation by free flow field step electrophoresis 38 acids have been identified and quantified in coffee. Of these, 18 acids were identified for the first time and 5 others quantified for the first time in coffee. As a rule, the contents of the acids increase slightly on steam treatment and strongly on roasting. Exceptions are acids generated from other acids or trigonelline, which are formed on roasting only. On average, the contents of a steam treated roasted coffee sample were lower than the contents of a corresponding untreated sample. Nevertheless, a distinction of the two groups of coffees is not possible. In addition to the analysis of some coffee samples of known origin, the acids contents of 6 commercial blends of medium roast, of one espresso blend and of one instant coffee were determined.
Article
The method of Kwasny for the chemical determination of the organic roasting loss of coffee by analysing trigonelline and niacin has been examined. For this purpose a new gas chromatographic method for nicotinic acid has been worked out. In contrast to Kwasny, the contents of nicotinamide have not been determined. Data from two roasting series published by Trugo and Macrae have been included. The values for 13 Arabicas of different degrees of roast and of three provenances, as well as five samples of Uganda Robusta correspond fairly well with the results of Kwasny, but two samples of India Robusta do not. Therefore the method of Kwasny seems to be valid in general, but it is necessary to be aware that there are exceptions.
The method of Kwasny for the chemical determination of the organic roasting loss of coffee by analysing trigonelline and niacin has been examined. For this purpose a new gas Chromatographic method for nicotinic acid has been worked out. In contrast to Kwasny, the contents of nicotinamide have not been determined. Data from two roasting series published by Trugo and Macrae have been included. The values for 13 Arabicas of different degrees of roast and of three provenances, as well as five samples of Uganda Robusta correspond fairly well with the results of Kwasny, but two samples of India Robusta do not. Therefore the method of Kwasny seems to be valid in general, but it is necessary to be aware that there are exceptions.
Article
By gas chromatography/mass spectrometry twenty-three basic heterocyclic compounds have been identified in an extract from roasted barley. Several other such compounds have been identified tentatively. The classes of compounds include pyridines, pyrazines, thiazoles and oxazoles. Such compounds appear to contribute to the flavour of beer brewed with grists containing roasted barley.
Article
Flavour precursors from water-soluble green coffee low molecular weight (B) and high molecular weight (C) fractions were investigated and the volatiles formed during roasting were identified by high resolution gas chromatography/mass spectrometry (HRGC/MS). Roasting promoted extensive degradation of trigonelline, sucrose and amino acids in fraction (B) and of arabinogalactan in fraction (C). The analyses of the roasted isolated fractions showed that furans are not only formed by sucrose degradation but also by arabinogalactan pyrolysis. Also, pyrazines appear to be mainly formed by pyrolysis of hydroxy amino acids from fraction (C). The results also showed that pyridine found in roasted coffee is not exclusively formed by trigonelline degradation but also by protein pyrolysis.
Article
Recent successful applications of NMR spectroscopy and imaging in food science prompted the authors to use these new techniques for the analysis of espresso coffee. The target of this work was to identify an experimental procedure to obtain maximum information from high-resolution 1H spectra. Only the espresso coffee was considered as the true food, since it includes all aromatic substances responsible for the coffee aroma and taste. A big effort was made in order to select an easy, quick and non-degrading procedure to analyse the espresso cup content, preventing arti®cial or natural degradation effects with a particular care in the measurement of labile and volatile components. The procedure was tested on two arabica and one robusta samples; each sample was prepared with three roasting degrees to follow the chemical changes due to the roasting process. Moreover, one water extract was prepared also from ground green coffees. As a comparison, each coffee extract was prepared both with a standard `espresso coffee machine' and with a `mocha' as used in the domestic setting. Signi®cant differences among the three samples were observed.Moreover, for all samples, as a function of the roasting degree, a clear trend in the chemical composition was observed.
Article
Natural melanoidin in alcohol distillery effluent and synthetic melanoidin, which was prepared from glucose and glycine, showed similar elemental (CHON) compositions, spectroscopic properties and electrophoretic mobilities at various pH values. Optimal flocculation induced by FeCl3, AlCl3 or polyferric hydroxysulfate was obtained at a trivalent cation concentration of 0.04 M; excess flocculant caused color intensification of distillery effluents. Based on the electrical charge properties of melanoidins, a model is proposed for their flocculation and deflocculation induced by inorganic ions.
Article
The volatile compounds formed in headspace from heated corn oil alone or from corn oil with glycine were collected by a simultaneous purging and solvent extraction apparatus. Aroma components were isolated and identified by gas chromatography and gas chromatography/mass spectrometry. Among 123 gas chromatographic peaks recorded from the samples, 71 compounds were positively identified: 18 aldehydes, 15 heterocyclic compounds, 13 hydrocarbons, 11 ketones, 4 alcohols, 3 esters, and 7 miscellaneous compounds. Total amounts of aldehydes formed in the headspace, particularly unsaturated aldehydes, decreased drastically with the addition of glycine. On the other hand, the number of volatiles formed from corn oil with glycine was significantly greater than from corn oil alone, suggesting that aldehydes formed from corn oil underwent secondary reactions with glycine.
Article
The ultraviolet spectra of aqueous solutions of Methylpyridinium iodide have been examined, and Hantzsch's statement that these do not obey Beer's law has been confirmed. Quantitative optical measurements indicate that a new species is present, which is formulated as the product of addition of iodide ion to the pyridinium ring at the 2-position.
Article
Recent successful applications of NMR spectroscopy and imaging in food science prompted the authors to use these new techniques for the analysis of espresso coffee. The target of this work was to identify an experimental procedure to obtain maximum information from high-resolution 1H spectra. Only the espresso coffee was considered as the true food, since it includes all aromatic substances responsible for the coffee aroma and taste. A big effort was made in order to select an easy, quick and non-degrading procedure to analyse the espresso cup content, preventing artificial or natural degradation effects with a particular care in the measurement of labile and volatile components. The procedure was tested on two arabica and one robusta samples; each sample was prepared with three roasting degrees to follow the chemical changes due to the roasting process. Moreover, one water extract was prepared also from ground green coffees. As a comparison, each coffee extract was prepared both with a standard ‘espresso coffee machine’ and with a ‘mocha’ as used in the domestic setting. Significant differences among the three samples were observed. Moreover, for all samples, as a function of the roasting degree, a clear trend in the chemical composition was observed. © 1999 Society of Chemical Industry
Article
Aroma volatiles of fresh cooked ground beef subjected to varying degrees of heating were adsorbed on to Tenax TA, and the desorbed aromas analysed sensorially-and chemically. Cooked meaty character, when present, was being sampled on to the Tenax and desorbed from it under the analytical conditions used. Several of the components identified by combined capillary gas chromatography-mass spectrometry have not been reported previously from heated beef. Data is presented to support the generalization that the higher the degree of heating, the greater the concentrations of aliphatic aldehydes (especially Strecker aldehydes), benzenoids, aliphatic polysulphides, heterocyclic compounds and lipid-derived volatiles, whilst smaller contributions to the isolates arise from aliphatic ketones and alcohols (of non-lipid origin) and aliphatic mono-sulphur components. By sensory analysis, eight odour qualities were frequently used during gas chromatographic odour port assessment, namely buttery, caramel, burnt, green, fragrant, oily/fatty, nutty and meaty. Components associated with the former seven qualities are aroma modifiers whereas compounds contributing meaty quality are character impact compounds, e.g. 2-methyl-3-(methylthio)furan and 3-methylcyclopentanone. Additionally, several unsaturated alicyclic ketones were present which resemble the cyclohexenones previously known to be significant in meat aroma.
Article
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].Die Ergebnisse zahlreicher Bestimmungen von Trigonellin in Roh-, Rstkaffees und Kaffee-Extrakten werden mitgeteilt. In blichen Kaffeearten und Rstgraden wurden hnliche Werte gefunden, wie sie sich in den meisten Literaturstellen finden, inCoffea dewevrei var.excelsa undC. stenophylla aber niedrigere als in der einzigen anderen Publikation darber. Dmpfen vermindert die Gehalte minimal. Kurzzeitrstung kann zu hheren Werten bei demselben organischen Rstverlust fhren, doch wurde dies bei Handelsprodukten nicht beobachtet. Bei der industriellen Extraktion von Rstkaffee wird nicht alles Trigonellin extrahiert; der Prozentsatz ist von der Extraktionsausbeute abhngig.
Article
Quaternary ammonium bases were isolated from nerve axoplasm of the squid Dosidicus gigas, and partial identification was achieved. One of the bases appears to be tetramethylammonium ion (“tetramine”), and reasons are given to believe that another base is a quaternary pyridinium compound. closely related to N-methylpyridinium ion. Though the nature of the two other constituents is still unknown, it can be said that probably neither one of them has a free carboxyl group.The total concentration of these basic constituents of axoplasm is about 0.1% of the dialyzable solutes.
Article
1. The quaternization of [14C]pyridine by metabolic N-methylation in vivo has been investigated in eight species by determination of the urinary excretion product, N-methylpyridinium. 2. All eight species N-methylated pyridine, but the extent to which this occurred was species-dependent; methylation was extensive (20-40% dose) in the cat, guinea-pig, gerbil, rabbit and hamster,but was low (5-12% dose) in rat, mouse and two human volunteers. The low N-methylation in the rat was not enhanced by DL-methionine supplementation. 3. In the rat and guinea-pig, the pattern of N-methylation was similar when the [14C]pyridine was given by the oral and intraperitoneal routes. In both species the reaction was dose-dependent. 4. N-Methylpyridinium excretion was found to be a valid parameter of the N-methylation of pyridine in vivo, since rats and guinea-pigs eliminated this compound in the urine unchanged following its intraperitoneal administration. 5. The pharmacological and toxicological implications of the biological quaternization of azaheterocycles are discussed.
Article
Hep G2 cells, an established cell line derived from a human hepatoma, have retained a number of hepatocytic phase I and II reactions. The influence of picolines (2-, 3- and 4-methylpyridine), related compounds and some classical enzyme inducers on specific glutathione transferase (GST) activity and its subunit composition in Hep G2 cells was investigated. Increased GST activity was observed for rifamycin, phenobarbital, pyrazine and the picolines, of which the 4-isomer was the strongest inducer. The GST subunits were analysed by HPLC. GSTP1, GSTM1a, GSTA1 and GSTA2 were present in control Hep G2 cells. GSTM1a disappeared or was strongly reduced under the influence of the test chemicals. All GST increases were due to augmented GSTA1 expression. Thus, picolines stimulate GST activity in Hep G2 cells by influencing the class alpha GSTA1.
Article
Pyridine derivatives are widely used solvents and precursors for the synthesis of chemicals of industrial importance. Oxidized metabolites have been implicated in the observed toxicity of pyridines and are known to induce drug-metabolizing enzymes in rat liver. In this study the three isomeric picoline (methylpyridine) N-oxides, as major oxidized metabolites of 2-, 3- and 4-picoline, were evaluated as inducers of cytochrome P450 (CYP) enzymes in rat liver. After a single dose of 100 mg/kg 24 h before sacrifice the 3- and 4-isomers were effective inducers of microsomal substrate oxidations associated with the phenobarbital-inducible CYPs 2B; upregulation of CYP2B protein was confirmed by immunoblotting. In contrast, the 2-isomer did not increase CYP2B protein or activity in rat liver but CYP2E1 protein expression was upregulated by the isomers to 160-200% of control. The three chemicals increased aniline 4-hydroxylation activity in rat liver, which is consistent with induction of CYPs 2B or 2E1 and 4-nitrophenol 2-hydroxylation activity was increased in microsomal fractions from 3- and 4-picoline N-oxide-treated rats. The activities of several other CYPs were also determined and CYP1A-dependent 7-ethylresorufin O-deethylation was increased (to approximately 6- and 2-fold of control) by the 3- and 4-isomer, respectively, whereas the activity of CYP3A-mediated androstenedione 6beta-hydroxylation was decreased by the agents--most notably by the 2-isomer. During NADPH-supported oxidation of CCl4, lipid peroxidation was increased in microsomes from 3- and 4-picoline N-oxide-pretreated rats and was modulated in vitro by the CYP2B inhibitor orphenadrine, but not by the CYP2E1 inhibitor 4-methylpyrazole. These findings establish that particular isomers of picoline N-oxide rapidly upregulate CYP2B or, to a lesser extent, CYP2E1 and implicate CYP2B in the enhanced lipid peroxidation observed in microsomes from rats treated with 3- and 4-picoline N-oxides. Such induction process may contribute to the hepatotoxicity of pyridines by enhancing the capacity for microsomal lipid peroxidation.
Article
Determination of the color intensity of heated mixtures of L-alanine and carbohydrate degradation products revealed furan-2-carboxaldehyde and glycolaldehyde as by far the most effective color precursors. EPR studies demonstrated that furan-2-carboxaldehyde generated colored compounds exclusively via ionic mechanisms, whereas glycolaldehyde led to color development accompanied by intense radical formation. In agreement with literature data, these radicals were also detected in heated mixtures of L-alanine and pentoses or hexoses, respectively, and were identified as 1,4-dialkylpyrazinium radical cations by EPR as well as LC/MS measurements. Studies on the mechanisms of radical formation revealed that under the reaction conditions applied, glyoxal is formed as an early product in hexose/L-alanine mixtures prior to radical formation. Reductones then initiate radical formation upon reduction of glyoxal and/or glyoxal imines, formed upon reaction with the amino acid, into glycolaldehyde, which was found as the most effective radical precursor. LC/MS measurements gave evidence that these pyrazinium radicals cations are not stable but are easily transformed into hydroxylated 1,4-dialkyl-1, 4-dihydropyrazines upon oxidation and hydrolysis of intermediate diquarternary pyrazinium ions. Besides other types of color precursors, these intermediates might be involved in the formation of colored compounds in the Maillard reaction.
Article
We compared pyridine and five of its metabolites in terms of (i) in vivo induction of CYP1A1 expression in the lung, kidney, and liver in the rat and (ii) in vitro binding to, and activation of, the aryl hydrocarbon receptor (AhR) in cytosol from rat liver or Hepa1c1c7 cells. Following a single 2.5 mmol/kg ip dose of either pyridine, 2-hydroxpyridine, 3-hydroxypyridine, 4-hydroxypyridine, N-methylpyridinium, or pyridine N-oxide, CYP1A1 activity (ethoxyresorufin O-deethylase), protein level (as determined by Western blotting), and mRNA level (as determined by Northern blotting) were induced by pyridine, N-methylpyridinium, and pyridine N-oxide in the lung, kidney, and liver. The induction by N-methylpyridinium or pyridine N-oxide was comparable to or greater than that by pyridine in some tissues. 2-Hydroxypyridine and 3-hydroxypyridine caused tissue-specific induction or repression of CYP1A1, whereas 4-hydroxypyridine had no effect on the expression of the enzyme. Pyridine and its metabolites elicited weak activation of the aryl hydrocarbon receptor in a gel retardation assay in cytosol from rat liver but not Hepa 1c1c7 cells. However, the receptor activation did not parallel the in vivo CYP1A1 induction by the pyridine compounds, none of which inhibited binding of ¿(3)H2,3,7, 8-tetrachlorodibenzo-p-dioxin to AhR in a competitive assay in rat liver cytosol. The findings are consistent with a role of pyridine metabolites in CYP1A1 induction by pyridine but do not clearly identify the role of aryl hydrocarbon receptor in the induction mechanism.
Article
Five proline-based diketopiperazines were identified in water extracts of roasted coffee proteins and roasted coffee itself. These are cyclo(pro-ile), cyclo(pro-leu), cyclo(pro-phe), cyclo(pro-pro), and cyclo(pro-val). The isolation included gel chromatography and solvent (CHCl(3)) extraction; in the case of roasted coffee brews, polyamide column chromatography was also used. The identification was achieved by LC-ESI-MS and -MS/MS by comparison of the retention time and the fragmentation pattern with reference compounds. As a second method GC-EI-MS was used. By both methods the presence of diketopiperazines in roasted coffee was unambiguously verified.
Article
Trigonelline is a well-known precursor of flavor/aroma compounds in coffee and undergoes significant degradation during roasting. This study investigates the major nonvolatile products that are procured after trigonelline has been subjected to mild pyrolysis conditions (220-250 degrees C) under atmospheric pressure. Various salt forms of trigonelline were also prepared and the thermally produced nonvolatiles analyzed by thin layer chromatography, liquid chromatography-electrospray ionization tandem mass spectrometry, and (1)H and (13)C nuclear magnetic resonance. Results revealed the decarboxylated derivative 1-methylpyridinium as a major product of certain salts, the formation of which is positively correlated to temperature from 220 to 245 degrees C. Moreover, trigonelline hydrochloride afforded far greater amounts of 1-methylpyridinium compared to the monohydrate over the temperature range studied. Investigations into other potential quaternary amine products of trigonelline also indicate nucleophilic substitution reactions that lead to dialkylpyridiniums, albeit at concentration levels approximately 100-fold lower than those recorded for 1-methylpyridinium.
Food contaminant trace analysis: the pivotal role of liquid chromatography-mass spectrometry (LC-MS) tech-niques
  • R H Stadler
Stadler, R. H. Food contaminant trace analysis: the pivotal role of liquid chromatography-mass spectrometry (LC-MS) tech-niques. New Food 2000, 3, 32-37.
Influence, sur l'amertume d'un café-boisson, de quelques paramètres d'extraction. Proceed-ings of the 8th International Scientific Colloquium on Coffee
  • A Voiley
  • F Sauvageot
  • D Durand
Voiley, A.; Sauvageot, F.; Durand, D. Influence, sur l'amertume d'un café-boisson, de quelques paramètres d'extraction. Proceed-ings of the 8th International Scientific Colloquium on Coffee, Abidjan, 1977; Association Scientifique Internationale du Café: Paris, France, 1979; pp 251-259.
Untersuchungen über den Bittergeschmack von Röstkaffee. Zusammenhänge zwischen Struktur und Bittergeschmack bei einigen einfachen organischen Verbindungen
  • W C Chen
Chen, W.-C. Untersuchungen u ¨ber den Bittergeschmack von Rö. Zusammenhä zwischen Struktur und Bitterge-schmack bei einigen einfachen organischen Verbindungen. Ph.D.
Analysis of acids in coffee by capillary electrophoresis. ASIC, 16th Collo-quium
  • M Weers
  • H Balzer
  • O Bradbury
  • G Vitzthum
Weers, M.; Balzer, H.; Bradbury, O.; Vitzthum, G. Analysis of acids in coffee by capillary electrophoresis. ASIC, 16th Collo-quium, Kyoto, Japan; 1995; pp 218-223.
Schilter B.; Cavin, C.; Tritscher, A.; Constable, A. Coffee: Recent DeVelopments. Health and Safety Considerations
  • G Debry
  • Coffee
Debry, G. Coffee and Health; Libbey Eurotext: Paris, France, 1994. (24) Schilter B.; Cavin, C.; Tritscher, A.; Constable, A. Coffee: Recent DeVelopments. Health and Safety Considerations; Clarke, R. J., Vitzthum, O. G., Eds.; Blackwell Science: London, U.K., 2001; Chapter 8, pp 165-183.
Health benefits of coffee Received for review
  • B Schilter
  • D Holzhaeuser
  • C Cavin
  • Stadler
Schilter, B.; Holzhaeuser, D.; Cavin, C. Health benefits of coffee. Proceedings 2001 ASIC Meeting; ASIC: Paris, France, 2001; in press. Received for review September 24, 2001. Revised manuscript received November 26, 2001. Accepted November 26, 2001. JF011235C 1206 J. Agric. Food Chem., Vol. 50, No. 5, 2002 Stadler et al.
  • Hughes E. B.