Coffee Oil Extraction Methods: A Review.

Green and roasted coffee oils are products rich in bioactive compounds, such as linoleic acid and the diterpenes cafestol and kahweol, being a potential ingredient for food and cosmetic industries. An overview of oil extraction techniques most applied for coffee beans and their influence on the oil composition is presented. Both green and roasted coffee oil extractions are highlighted. Pressing, Soxhlet, microwave, and supercritical fluid extraction were the most used techniques used for coffee oil extraction. Conventional Soxhlet is most used on a lab scale, while pressing is most used in industry. Supercritical fluid extraction has also been evaluated mainly due to the environmental approach. One of the highlighted activities in Brazilian agribusiness is the industrialization of oils due to their increasing use in the formulation of cosmetics, pharmaceuticals, and foods. Green coffee oil (raw bean) has desirable bioactive compounds, increasing the interest of private companies and research institutions in its extraction process to preserve the properties contained in the oils.

The impact of altering the concentration of coffee constituents on their anticancer effect on oral squamous cell carcinoma cell line - in vitro study.

Introduction: Oral squamous cell carcinoma (OSCC) is one of the most common malignancies of the head and neck, which attracts much attention because of its increasing incidence and poor outcome. Coffee is one of the most popular beverages that are globally consumed. It consists of several phytochemical constituents, such as polyphenols, caffeine, and chlorogenic acid (CGA). Those constituents account for the potential effects on several diseases, including cancer. It has been reported that coffee exerts significant cytotoxicity against OSCC via inhibition of epidermal growth factor receptor tyrosine kinase (EGFR-TK) and up-regulation of apoptotic proteins, such as caspase-3 and caspase-9. The current study aims to measure the concentration of caffeine and CGA in 3 different types of coffee extracts, unroasted green coffee (GC), medium-roasted coffee (MRC), and decaffeinated coffee. Material and methods: The cytotoxic effect against OSCC-25 cell lines was evaluated and correlated with the concentration of constituents in each extract. The mechanisms of cytotoxicity were also studied by assessing the effect of each extract on caspase-3 and caspase-9 levels, in addition to the inhibitory effect on EGFR-TK. Results: It was found that the caffeine concentration was higher in MRC than in GC because of the roasting process. However, the concentration of caspase-3 and -9 and the inhibitory effect on EGFR-TK were much higher in GC than MRC-treated cells because of the higher concentration of CGA. Conclusions: Decaffeinated coffee exerts lower cytotoxic effects because it was totally deprived of caffeine and CGA during the decaffeination process.

Electronic Prediction of Chemical Contaminants in Aroma of Brewed Roasted Coffee and Quantification of Acrylamide Levels.

The aim of this research was to apply an electronic device as indirect predictive technology to evaluate toxic chemical compounds in roasted espresso coffee. Fresh coffee beans were subjected to different thermal treatments and analyzed to determine volatile organic compounds, content of acrylamide and 5-hydroxymethylfurfural, sensory characteristics and electronic nose data. In total, 70 different volatile compounds were detected and grouped into 15 chemical families. The greatest percentage of these compounds were furans, pyrazines, pyridines and aldehydes. The positive aroma detected had the intensity of coffee odor and a roasted aroma, whereas the negative aroma was related to a burnt smell. A linear relationship between the toxic substances and the sensory defect was established. A high sensory defect implied a lower content of acrylamide and a higher content of 5-hydroxymethylfurfural. Finally, electronic signals were also correlated with the sensory defect. This relationship allowed us to predict the presence of these contaminants in the roasted coffee beverage with an indirect method by using this electronic device. Thus, this device may be useful to indirectly evaluate the chemical contaminants in coffee beverages according to their sensory characteristics.

Consumption of Roasted Coffee Leads to Conjugated Metabolites of Atractyligenin in Human Plasma.

Roasted coffee contains atractyligenin-2-O-ß-d-glucoside and 3'-O-ß-d-glucosyl-2'-O-isovaleryl-2-O-ß-d-glucosylatractyligenin, which are ingested with the brew. Known metabolites are atractyligenin, atractyligenin-19-O-ß-d-glucuronide (M1), 2ß-hydroxy-15-oxoatractylan-4α-carboxy-19-O-ß-d-glucuronide (M2), and 2ß-hydroxy-15-oxoatractylan-4α-carboxylic acid-2-O-ß-d-glucuronide (M3), but the appearance and pharmacokinetic properties are unknown. Therefore, first time-resolved quantitative data of atractyligenin glycosides and their metabolites in plasma samples from a pilot human intervention study (n = 10) were acquired. None of the compounds were found in the control samples and before coffee consumption (t = 0 h). After coffee, neither of the atractyligenin glycosides appeared in the plasma, but the aglycone atractyligenin and the conjugated metabolite M1 reached an estimated cmax of 41.9 ± 12.5 and 25.1 ± 4.9 nM, respectively, after 1 h. M2 and M3 were not quantifiable until their concentration enormously increased ≥4 h after coffee consumption, reaching an estimated cmax of 2.5 ± 1.9 and 55.0 ± 57.7 nM at t = 10 h. The data suggest that metabolites of atractyligenin could be exploited to indicate coffee consumption.

Detection of the 5-hydroxymethylfurfural content in roasted coffee using machine learning based on near-infrared spectroscopy.

Since 5-hydroxymethylfurfural (5-HMF) is carcinogenic to humans, its detection in foods is essential. This study performed near-infrared (NIR) spectroscopy (11998-4000 cm-1) to determine the 5-HMF content in roasted coffee. The random forest (RF) was used to extract important wavenumbers, after which three machine learning models (ordinary least square (OLS), support vector machine (SVM), and RF) were established for the prediction. RF obtained the best prediction results (Rc2 = 0.98 and Rp2 = 0.92) compared with OLS and SVM and effectively extracted the important wavenumbers (11667 cm-1, 11666 cm-1, 10905 cm-1, 7096 cm-1, 7095 cm-1, 7094 cm-1, 7093 cm-1, 7092 cm-1, 5054 cm-1, 5026 cm-1, 5025 cm-1, and 5024 cm-1). The results demonstrated that machine learning models based on NIR spectroscopy could provide a non-destructive approach for determining 5-HMF content in roasted coffee.

Integrated effect of yeast inoculation and roasting process conditions on the neo formed contaminants and bioactive compounds of Colombian roasted coffee (Coffea arábica).

The rational design of methodologies to control the neoformed compounds occurrence (NFCs), such as acrylamide and hydroxymethylfurfural (HMF) in roasted coffee, must consider the preservation of the bioactive compounds contained in this beverage. The aim of this work was to evaluate the integrated effect of yeast inoculation during the fermentation stage and the modification of roasting parameters on the final concentrations of NFCs and bioactive compounds of roasted coffee. A completely randomized factorial design was used to evaluate the effect of yeast inoculation (with and without inoculation), roasting temperature (150, 180 and 210 °C) and roast degree (medium, dark) on the (i) physicochemical characteristics (volume change, mass loss, water activity, non-enzymatic browning index, antioxidant capacity, total polyphenols, chlorogenic acid and caffeine) as well as HMF and acrylamide levels of roasted coffee. Response variables were analyzed separately by ANOVA and clustering of treatments was explored by PCA. Yeast inoculation did not significantly (p > 0.05) affect volume change, mass loss, antioxidant capacity, total polyphenols content, and caffeine contents. The interaction of evaluated factors significantly decreased (p < 0.05) the acrylamide and HMF contents of roasted coffee (43 % and 56.0 %, respectively). Based on PCA grouping the best treatments were medium roast at 210 °C (inoculated and uninoculated) and at 180 °C (inoculated). Under these conditions it is possible to produce a roasted coffee mitigated in neo formed contaminants that present the physicochemical properties of original product.

Specialty and high-quality coffee: discrimination through elemental characterization via ICP-OES, ICP-MS, and ICP-MS/MS of origin, species, and variety.

BACKGROUND: This study aimed to establish the elemental profiling and origin combined with the genetic asset of coffee samples collected from major coffee-producing countries. A total of 76 samples were analysed for 41 elements using inductively coupled plasma-optical emission spectroscopy (ICP-OES), inductively coupled plasma-mass spectrometry (ICP-MS), and inductively coupled plasma-triple quadrupole mass spectrometry (ICP-MS/MS). The mineral composition of the silver skin detachment during the roasting process was also evaluated to verify the loss of minerals during roasting, differences in composition with beans, and between species. RESULTS: Application of linear discriminant analysis provided models with an accuracy of 93.3% for continents, 97.8% for countries of cultivation, and 100% for species. Discrimination between Arabica, Canephora coffee, and Eugenoides, and different varieties of Arabica species were identified in both models with calcium (Ca), barium (Ba), cadmium (Cd), rubidium (Rb), and strontium (Sr) as significant discriminant elements. Rb, Sr, sulphur (S), and thulium (Tm) were significant discriminant elements in both models for geographical distinction at different scales. Most of the elements had significantly higher values in silver skin than those in roasted coffee at different magnitudes, with exceptions of P and Rb. CONCLUSION: In summary, determination of mineral elements, processed by multivariate statistical analysis, was demonstrated to be discriminant for different coffee species. Linear discriminant analysis of the elemental analysis of samples from the seven major producing countries provided a reliable prediction model. Elemental analysis of major and minor elements is relatively easy and can be used together with other traceability systems and sensory evaluations to authenticate the origin of roasted coffee, different species, and varieties. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The challenge of o-phenylphenol detection in coffee: How "OPP-conjugates" hide their presence in green and roasted samples.

o-Phenylphenol (OPP) is not a commonly used pesticide in the coffee production chain. Although it has only been detected in roasted coffee, it is unlikely that OPP can be formed during roasting. Its acidic nature may lead to the formation of conjugates with natural matrix components. The objective of this study is to optimize an analytical method to discover how these conjugates may mask the presence of OPP in coffee. Sample extraction with hexane followed by basic hydrolysis and then a QuEChERS method allows the presence of OPP to be quantitatively detected via UPLC-MS/MS. The optimized method was applied to the same Arabica coffee (Brazil), and the quantification of comparable amounts of OPP was observed in both green and roasted samples (34.8 vs 32.2 µg/kg). The optimized procedure detected twice the amount of OPP in roasted samples, compared to the QuEChERS method, suggesting that roasting causes the partial hydrolysis of OPP conjugates.

Evaluation of the Olfactory Quality of Roasted Coffee Beans Using a Digital Nose.

The roasting process is one of the critical points to obtain a product of the highest quality with certain sensorial properties including the aroma of coffee. Samples of coffee beans were roasted at different thermal treatment intensities with the aim of obtaining aromatic compounds detected with an electronic device. Sensory analysis, volatile compound profiling, and electronic nose analysis were carried out. Through principal component analysis (95.8% of the total variance of the data was explained by PC1 and PC2) and partial least squares discriminant analysis (the sum of the diagonal elements gave a hit rate of 94%), it could be demonstrated that the E-nose is able to discriminate roasted coffee beans subjected to different thermal treatments. Aromatic profiling was carried out by a testing panel and volatile compounds (VOCs) for the discrimination of roasted coffee samples. Alcohols, aromatics, esters, ketones and furanone were found in higher proportions in samples at the lowest thermal treatment. The VOCs with positive attributes were 1-(4-nitrophenyl)-3-phenylamino-propenone, carboxylic acids, 2-methoxy-4-vinylphenol, and 2-phenylethyl alcohol, while the compounds with negative ones were 2-methyl-furan, 2,5-dimethyl-pyridine, 2-methyl-butanal, and 2-furfurylthiol. The PLS model allows for the quantification of the positive and negative aromas (RCV2 = 0.92) of roasted coffee by using the E-nose. Therefore, the E-nose, that is, an inexpensive and nondestructive instrument, could be a chemometric tool able to discriminate between different qualities of coffee during processing.

Identification and Quantitation of Reaction Products from Chlorogenic Acid, Caffeic Acid, and Their Thermal Degradation Products with Odor-Active Thiols in Coffee Beverages.

A holistic ultraperformance liquid chromatography (UPLC)-time of flight (TOF)-mass spectrometry-based approach was used to screen for storage-induced reaction products consisting of the volatile key coffee thiols methanethiol, 2-furfurylthiol, 2-methyl-3-furanthiol, 3-mercapto-3-methylbutanol, and 3-mercapto-2-butanone and low-molecular weight phenolic constituents of coffee beverages including chlorogenic acid, caffeic acid, and their thermal degradation products hydroxyhydroquinone, catechol, and 4-ethylcatechol. Multiple marker compounds could be detected in thiol-enriched coffee brews after UPLC-TOF-MS profiling and statistical data analysis. Subsequently, marker compounds were synthesized and structurally characterized via high-resolution mass spectrometry and 1D- and 2D-NMR experiments. Quantification of these reaction products in fresh and stored coffee beverages was realized in native coffee and after stir bar sorptive extraction with liquid desorption by means of UHPLC-MS/MS. The quantitative data revealed the biggest influence of storage time on the formation of reaction products between hydroxyhydroquinone and methanethiol and 2-furfurylthiol, while other reaction products were only slightly affected by storage and thus most likely formed during the roasting process.

Assessment of ochratoxin A exposure risk from the consumption of coffee beans in Phnom Penh, Cambodia.

This survey aimed to determine OTA contamination in roasted coffee samples commercialised in Phnom Penh, Cambodia and to assess the potential health risk from OTA exposure. Forty locally grown and imported coffee samples were collected and analysed. Analytical validation methods were fully performed. In 3 of 40 samples (7.5%), the results showed detectable levels of OTA, ranging from 0.19 to 1.12 µg kg-1, with an overall average of 0.26 µg kg-1 and an average over the LOQ (n = 3) at 0.81 µg kg-1. OTA estimated daily intake (EDI) of both values were 0.05 (overall average) and 0.17 ng/kg bw/day (the worst-case scenario) with the calculated risk of OTA exposure expressed as a Hazard Quotient at 0.003 and 0.01, respectively. This result could imply a low health risk to Cambodian coffee consumers.

Discovery of novel coffee diterpenoids with inhibitions on Cav3.1 low voltage-gated Ca2+ channel.

Seven new (1-4, 6-8) diterpenoids with rare skeletons and seven known ones (9, 12, 17, 18 and 23-25) were isolated from roasted beans of Coffea arabica L. Together with previously obtained diterpenoids, a total of 26 molecules (1-25, 4a) were evaluated their activities on Cav3.1 low voltage-gated Ca2+ channel. Compounds 1, 3, 6, 7, 12, 13, 17, 19 and 24 exhibited noticeable Cav3.1 inhibitions (41.2%-96.1%) at 10 µM. The IC50 values of 1, 6, 7, 12, 13, 17 and 24 are 2.9, 2.3, 0.68, 14.8, 11.6, 6.1 and 6.8 µM, respectively. The ring moiety at C-18 and C-19, and esterification of OH-17 with long-chain fatty acids seem important for their activities. Further studies indicated that 1 and cafestol may act on different binding sits with the Cav3.1 blocker Z944, which is in clinical trial. Significantly, the present study initially shows that coffee diterpenoids are potential natural resources for Cav3.1 inhibitors.

Determination of Acrylamide in Selected Foods from the Romanian Market.

Several processed food products may contain toxic compounds considered risk factors for human health. Known for its possible carcinogenic effects, acrylamide is an organic compound periodically analyzed by the entities responsible for consumer safety. Knowing the acrylamide content of food offers the possibility of implementing corrective measures when needed, targeted at lowering its level. The aim of the paper was to screen for the presence of acrylamide in four products consumed almost daily in Romania and calculate acrylamide exposure by consuming one serving. Expressed in µg/kg coffee has the highest average acrylamide content (199), followed by potato chips (134), pretzels (120), and bread (14). Results regarding the acrylamide content in one serving showed the highest levels of acrylamide in pretzels (10.20 µg/serving), followed by potato chips (4.00 µg/serving), coffee (2.20 µg/cup), and bread (0.40 µg/slice). The calculation of the acrylamide content for one serving of the studied products will facilitate the following studies on the dietary acrylamide intake of the Romanian population, studies which, to our knowledge, have not been performed so far.

Multi-element determination of essential and toxic metals in green and roasted coffee beans: A comparative study among different origins using ICP-MS.

The aim of this study is to compare the elemental composition among different coffee varieties consumed in Jordan. Levels of different metallic elements in coffee samples; green and roasted coffee beans from five origins; Brazil, Ethiopia, Kenya, Columbia, and India, collected from the Jordanian market were investigated. Twenty-two elements, including essential and toxic elements such as potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), aluminum (Al), manganese (Mn), copper (Cu), barium (Ba), strontium (Sr), zinc (Zn), chromium (Cr), lead (Pb), nickel (Ni), vanadium (V), cobalt (Co), gallium (Ga), uranium (U), cadmium (Cd), silver (Ag), lithium (Li), indium (In), bismuth (Bi), thorium (Th), and thallium (Ti), were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The detected heavy metals and their intake per 1 cup of coffee did not largely contribute to the recommended daily intake (RDI) and tolerable upper limit of daily intake (TULD) in an adult with an average body weight of 80 kg. The ICP-MS versus flame atomic absorption spectrometry (FAAS) results were linearly fitted, and the correlation coefficients (R2 > 0.95) were better than 0.95 for the three checked elements. No significant difference between the results of the two techniques was observed (p > 0.05). The ANOVA results indicated the presence of a significant difference between the levels of Cr, Co, and Zn in green and roasted coffee beans. The results of this study indicated that the coffee consumed in Jordan did not contain toxic levels of heavy elements and is safe for consumption according to health organizations.

Determination of ochratoxin A in coffee by ELISA method and its relationship with the physical, physicochemical and microbiological properties / Determinación de ocratoxina A en café mediante método ELISA y su relación con las propiedades físicas, fisicoquímicas y microbiológicas

Background: Coffee is one of the most consumed beverages in the world; however, it may contain toxic compounds such as ochratoxin A (OTA). Objectives: Determine the OTA's presence in different types of coffee, intended for beverage preparation and marketed in Colombia through the application of the enzyme-linked immunosorbent assay (ELISA) and analyze its relationship with the physical, physicochemical and microbiological properties. Methods: 8 samples of coffee commercialized in the Colombian market were selected, in which the OTA content was determined by applying the ELISA method. Likewise, a microbiological analysis was performed, and physicochemical properties were determined, such as moisture content, aw, percentage total dissolved solids (%TDS), and extraction yield (%EY). Physical properties such as free-flow densities, compacted bulk densities (CBD), porosity, average particle size (ASP), and color. The data were treated with multivariate analysis using Principal Component Analysis (PCA) and Cluster Analysis (CA) to quantitatively investigate the relationships between the coffee samples concerning their physical, physicochemical properties, and OTA content. LSD test was applied with a significance level of 95 % and Pearson correlation test. Results:All the samples had OTA content, but only 2 exceeded the limits allowed by the regulations, with a maximum value of 15.449 µg/Kg, which represents 31.449 % of the tolerable daily intake according to the parameters defined by Joint FAO/WHO Expert Committee on Food Additives (JECFA). According to the PCA and CA, the samples were grouped harmonically according to the type of coffee associated with its commercial presentation and industrial process, OTA content, and ASP. OTA content was significantly and positively correlated (p< 0.05) with %EY, %TDS, ASP, porosity, CBD and moisture. Conclusions: The coffees marketed in Colombia showed a variable range of OTA, where soluble coffees had higher OTA contents than roasted coffees, and 25 % of the coffees analyzed do not meet the levels defined by Colombian regulations. The OTA content in coffee is related to properties that define the ability to extract solutes from coffee

Antecedentes: El café es una de las bebidas más consumidas en el mundo, sin embargo, puede contener compuestos tóxicos como la ocratoxina A (OTA). Objetivos: Determinar la presencia de OTA en diferentes tipos de café destinados a la preparación de bebida y comercializados en Colombia mediante la aplicación del ensayo inmunoabsorbente ligado a enzimas (ELISA) y analizar su relación con las propiedades físicas, fisicoquímicas y microbiológicas. Métodos: Se seleccionaron 8 muestras de café comercializado en el mercado colombiano, en las cuales se determinó el contenido de OTA mediante la aplicación del método ELISA. Así mismo se realizó análisis microbiológico y se determinaron propiedades fisicoquímicas como contenido de humedad, aw, porcentaje de sólidos disueltos totales (%TDS) y rendimiento de extracción (%EY); y propiedades físicas como densidad por caída libre, densidad compactada (CBD), porosidad, tamaño promedio de partícula (ASP) y color. Los datos fueron tratados con análisis multivariado empleando análisis de componentes principales (PCA) y análisis de conglomerados (CA) para investigar cuantitativamente las relaciones entre las muestras de café con respecto a sus propiedades físicas, fisicoquímicas y contenido de OTA. Se aplicó prueba LSD con un nivel de significación del 95 % y prueba de correlación de Pearson. Resultados: Todas las muestras presentaron contenido de OTA, pero solo 2 sobrepasaron los límites permitidos por la normatividad, con un valor máximo de 15.449 µg/Kg, el cual representa un 31.449 % de la ingesta diaria tolerable según los parámetros definidos por el Comité Mixto FAO/OMS de Expertos en Aditivos Alimentarios (JECFA). De acuerdo al PCA y CA, las muestras se agruparon armónicamente de acuerdo al tipo de café asociado a su presentación comercial y proceso industrial, contenido de OTA y ASP; el contenido de OTA se correlacionó significativa y positivamente (p < 0.05) con el %EY, %TDS, ASP, porosidad, CBD y humedad. Conclusión: Los cafés comercializados en Colombia presentan un rango variable de OTA, en donde los cafés solubles presentan contenidos de OTA mayores que los cafés tostados y el 25 % de los cafés analizados no cumplen con niveles definidos por la normatividad colombiana. El contenido de OTA en el café está relacionado con propiedades que definen la capacidad de extracción de solutos del café

Identification and Quantitation of Reaction Products from Quinic Acid, Quinic Acid Lactone, and Chlorogenic Acid with Strecker Aldehydes in Roasted Coffee.

To gain comprehensive insight into the interactions of key coffee odorants, like the Strecker aldehydes, acetaldehyde, propanal, methylpropanal, 2- and 3-methylbutanal, and methional, and the nonvolatile fraction of coffee, an untargeted metabolomics approach was applied. Ultra performance liquid chromatography (UPLC)-time of flight (TOF)-mass spectrometry (ESI-) profiling followed by statistical data analysis revealed a marker substance for a coffee beverage spiked with acetaldehyde with an accurate mass of 217.0703 [M - H]-. This compound could be identified as a reaction product of quinic acid (QA) and acetaldehyde linked by acetalization at the cis-diol function of QA. Consequently, the acetalization of aldehydes, QA, 5-O-caffeoyl quinic acid (CQA), and quinic acid γ-lactone (QAL) was investigated by means of model reactions, followed by synthesis, isolation, and structure elucidation via UPLC-TOF-MS and 1D and 2D NMR techniques. UHPLC-MS/MSMRM screening and the quantification of aldehyde adducts in coffee beverages revealed the presence of QA/acetaldehyde, -/propanal, -/methylpropanal, and -/methional reaction products and CQA/acetaldehyde, -/propanal, -/methylpropanal, -/2- and 3-methylbutanal, and -/methional and QAL/acetaldehyde adducts for the first time, in concentrations of 12-270 µg/L for QA/aldehydes, 5-225 µg/L for CQA/aldehydes, and 62-173 µg/L for QAL/acetaldehyde. The sensory characterization of the identified compounds showed bitter taste recognition thresholds of 48-297 µmol/L for CQA adducts and 658 µmol/L for QAL/acetaldehyde, while the QA adducts showed no bitter taste (<2000 µmol/L).

Impacts of quaker beans over sensory characteristics and volatile composition of specialty natural coffees.

The objective of this study was to evaluate the volatile composition and the sensory effect of the presence of Quaker beans in natural specialty coffee beverage and, consequently, to confront the requirement of the Specialty Coffee Association regarding the total absence of Quaker beans in a natural specialty coffee batch. Sensory analysis and volatile composition were performed for three different colorations of Quaker beans, added separately to natural specialty coffee samples at seven different concentrations. Beans with color equal to or above Agtron 82.8 negatively affected the sensory characteristics of natural specialty coffee only from the presence of 7 Quaker beans in one cup (65 beans). Through the analysis of volatile composition, volatile compounds formed during roasting were identified in Quaker beans from precursors present in raw immature beans. Therefore, the color and sensory characteristics of Quaker are a consequence of the chemical composition of an immature bean.

Characterization of Arabica and Robusta volatile coffees composition by reverse carrier gas headspace gas chromatography-mass spectrometry based on a statistical approach.

Nineteen samples of Arabica and 14 of Robusta coming from various plantation were analysed by dynamic headspace capillary gas chromatography-mass spectrometry to characterize the volatile fraction of green and roasted samples and the relationships of the same species with geographical origin. As concerns green beans, Arabica species appear characterized by high content of n-hexanol, furfural and amylformate, while Robusta species by greater content of ethylpyrazine, dimethylsulfone and 2-heptanone. Four variables, 4-methyl-2,3-dihydrofuran, n-hexanol, limonene and nonanal, appear involved in the characterization of the geographical origin of the analysed samples. The volatile fraction of the roasted Arabica samples, appear characterized by high content of pyridine, diacetyl, propylformate, acetone and 2,3-pentanedione, while Robusta samples by high content of methylbutyrate, 2,3-dimethylpyrazine and 3-hexanone. Considering geographical origin of the analysed samples, four compounds appear involved, in particular 2-butanone, methylbutyrate, methanol and ethylformate. Very accurate (error rate lower than 5%) rules to classify samples as Arabica or Robusta according to their compounds profile were developed.

Effect of roasting degree of coffee beans on sensory evaluation: Research from the perspective of major chemical ingredients.

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.

Degradation of benzopyrene and acrylamide in roasted coffee beans by corona discharge plasma jet (CDPJ) and its effects on biochemical and sensory properties.

This study was aimed to reduce the concentrations of benzopyrene (BaP) and acrylamide (ACR) in roasted coffee beans by corona discharge plasma jet (CDPJ). The initial concentrations of BaP and ACR in roasted beans were decreased by 53.6% and 32.0%, respectively, following CDPJ (powered by 20 kV DC/1.5 A) treatment for 60 min. The levels of total solid, total acid, chlorogenic acid, caffeine, trigonelline, and pH were insignificantly changed upon CDPJ treatment compared to controls. However, the concentration of total phenolic content and Agtron color values were altered significantly. The treatment of beans did not alter descriptive sensory properties of the corresponding coffee brews, except aroma and aftertaste characteristics. As the treatment time increased from 15 to 60 min, scores for aroma profiles in PCA plot were shifted from right to left, although overlapping was observed between 15- and 30-min-treated samples. Additionally, none of the treated samples were discriminated from the control by electronic tongue.