Search

The Italian espresso coffee is a very popular drink worldwide. Roasting of coffee grains represents a key step in the development of the beverage characteristics and aroma. A coffee blend (80% Coffea arabica and 20% canephora) of a well-known Italian coffee firm underwent 3 roasting conditions (standard with end temperature of 216 °C, below standard with end temperature of 206 °C and over standard with end temperature of 223 °C) to study the effects of processing conditions on the chemical composition of the coffee powder and on the chemical and sensory characteristics of the espresso beverage. Proximate composition, polar and semi-polar metabolome (amino acids and aliphatic acids), chlorogenic acids, and volatile organic compounds were determined in the powder and beverage by means of standard methods, HPLC-ESI(±)-HRMS, HPLC–PDA/ESI–MS and HS-SPME/GC–MS respectively. Changes induced in the powder and beverage by roasting conditions are described with heatmaps and correlation networks between polar metabolites and sensory characteristics of the espresso beverage are reported. The concentration of chlorogenic acids is inversely proportional to the roasting temperature and the lower is the roasting temperature, the higher is the acid taste in the espresso. Some volatile organic compounds might be analytical markers of the strength of the roasting process. Cream and body of drink are increased as roasting temperature increases. [ABSTRACT FROM AUTHOR]

This work presents in vitro and in vivo aroma release analysis of three espresso coffees carried out by PTR-ToF-MS headspace and nosespace analysis, respectively. The products were C. arabica coffees prepared using an espresso coffee machine: a low-caffeine C. arabica var. laurina light roast, a low-caffeine C. arabica var. laurina dark roast, and a single-origin coffee from Ethiopia which were roasted to a medium roast degree. Headspace analysis allowed for discrimination between coffees with a prediction accuracy of 92% or higher. Relevant discriminating compounds were related to the roasting degree and varietal compounds. Coffee nosespace consisted of 35 mass peaks overall. Despite this relatively low number of detected peaks, coffee discrimination was still possible with ≥93% accuracy. The compounds most relevant to the discrimination were those related to the roasting degree. Major differences—both qualitative and quantitative—were found between headspace and nosespace profiles. [ABSTRACT FROM AUTHOR]

This paper assesses a custom single-type electronic nose (eNose) applied to differentiate the complex aromas generated by the caffeinated and decaffeinated versions of one encapsulated espresso coffee mixture type. The eNose used is composed of 16 single-type (identical) metal–oxide semiconductor (MOX) gas sensors based on microelectromechanical system (MEMS). This eNose proposal takes advantage of the small but inherent sensing variability of MOX gas sensors in order to provide a multisensorial description of volatiles or aromas. Results have shown that the information provided with this eNose processed using LDA is able to successfully discriminate the complex aromas of one caffeinated and decaffeinated encapsulated espresso coffee type. [ABSTRACT FROM AUTHOR]

The instrumental equipment of an espresso coffee machine has a remarkable influence on the extraction of the espresso coffee (EC). This study aims to evaluate the effect of different perforated disc heights and filter baskets, two fundamental parts of the espresso coffee machine, on EC carbohydrates content and composition. Four different heights (4–7 mm) of perforated discs and two different filter baskets were used to prepare Italian style EC and evaluate the feasibility of lowering the amount of ground coffee while keeping the same quality of the standard Italian espresso. Arabica and Robusta coffee beans, with 12 and 14 g of roasted coffee powder, were used to prepare 40 mL of EC, split in two cups. The content of total solids, high molecular weight material and polysaccharides, such as galactomannans (GM) and arabinogalactans (AG), were compared. The results show that the increase of the height of perforated disc affected the extraction of the polysaccharides content in the cup, with a decrease of GM and AG. As a conclusion, the configuration of perforated disc height and the filter used was shown to modulate the chemical profile of EC brew, with impact on espresso coffee cup quality. [ABSTRACT FROM AUTHOR]

This work presents in vitro and in vivo aroma release analysis of three espresso coffees carried out by PTR-ToF-MS headspace and nosespace analysis, respectively. The products were C. arabica coffees prepared using an espresso coffee machine: a low-caffeine C. arabica var. laurina light roast, a low-caffeine C. arabica var. laurina dark roast, and a single-origin coffee from Ethiopia which were roasted to a medium roast degree. Headspace analysis allowed for discrimination between coffees with a prediction accuracy of 92% or higher. Relevant discriminating compounds were related to the roasting degree and varietal compounds. Coffee nosespace consisted of 35 mass peaks overall. Despite this relatively low number of detected peaks, coffee discrimination was still possible with ≥93% accuracy. The compounds most relevant to the discrimination were those related to the roasting degree. Major differences—both qualitative and quantitative—were found between headspace and nosespace profiles.

This paper assesses a custom single-type electronic nose (eNose) applied to differentiate the complex aromas generated by the caffeinated and decaffeinated versions of one encapsulated espresso coffee mixture type. The eNose used is composed of 16 single-type (identical) metal–oxide semiconductor (MOX) gas sensors based on microelectromechanical system (MEMS). This eNose proposal takes advantage of the small but inherent sensing variability of MOX gas sensors in order to provide a multisensorial description of volatiles or aromas. Results have shown that the information provided with this eNose processed using LDA is able to successfully discriminate the complex aromas of one caffeinated and decaffeinated encapsulated espresso coffee type.

This study aims to assess for the first time the content of phytosterols (PS) in espresso coffee (EC) to deepen the knowledge about the phytochemicals and health potentials of coffee brews. PS were extracted by hot saponification from 14 EC samples produced with coffee originating from 13 coffee-producing countries. PS were identified and quantified by high-performance liquid chromatography (HPLC) after derivatization. Among the detected PS, β-sitosterol (4.1–18.2 mg/L) was the most abundant followed by stigmasterol (1.1–4.9 mg/L), campesterol (0.9–4.7 mg/L), and cycloartenol (0.3–2.0 mg/L). Total PS fraction ranged from 6.5 mg/L to 30.0 mg/L with an average level of 15.7 ± 5.8 mg/L. Therefore, a standard cup of EC (25 mL) could provide 0.4 ± 0.1 mg of PS. [ABSTRACT FROM AUTHOR]

Lignans are a class of polyphenols considered to be phytoestrogens because of their oestrogenic/antiestrogenic activities and their plant origin. Few works have reported on the content of lignans in ground coffee, and most of them analysed a small number of samples. Hence, our aim was to quantify the content of three lignans, secoisolariciresinol, lariciresinol and matairesinol, in ground coffee by using high-performance liquid chromatography tandem mass spectrometry. Evaluation of acidic hydrolysis, methanolic extractions, and enzymatic digestions as extraction methods indicated that enzymatic digestion with Taka-diastase 2% was the best. When this method was applied to 30 different ground coffees, we found that SECO was the highest concentration lignan (84.4-257.8 μg kg-1), followed by LARI (26.1-91.5 μg kg-1). Moreover, comparison of lignan extraction yield in espresso coffee and ground coffee showed that these molecules seem to be completely extracted during espresso coffee percolation, since the extraction yield average was 95.2%. [ABSTRACT FROM AUTHOR]

Furfural is a toxic compound that can be found in a wide variety of everyday food and beverages, notably espresso coffee. Given the toxicity of furfural, exposure could lead to liver and skin cancer. Recently, graphene oxide (GO) has been used for application in Solid Phase Micro-Extraction (SPME) due to its large surface area and wide variety of oxygenated functional groups, which makes it an excellent support for the adsorption of different organic compounds. Therefore, in this work a thermally reduced graphene oxide coating (rGOC) was synthetized for the micro-extraction of furfural in espresso coffee. This rGOC was able to absorb the furfural from espresso coffee despite having thickness of around only 1.9 μm. An analysis and optimization of extraction conditions of the furfural in the espresso coffee was carried out and then applied to the quantification of furfural. The furfural was quantified using a Gas Chromatograph coupled to a Mass Spectrometer (GC–MS). The concentration of furfural found was 2.1724 ± 0.0837 mg/L using rGOC whereas with commercial DVB/CAR/PDMS fiber was 2.0766 ± 0.0444 mg/L. The present work attempts to expand the applications of GO in SPME through the analysis of furfural in complex matrix foodstuffs such as espresso coffee. The application of rGOC, as presented in this article, has the advantage of being easy to prepare, requires a low quantity of material and together with its low cost, such application can easily be used instead of commercial fibers. [ABSTRACT FROM AUTHOR]

Acidity is an important parameter in coffee, contributing to aroma and flavor, imparting fruity notes, and improving the gloss of the coffee, making the beverage more interesting. In this study, two analytical methods were proposed to quantify the content of nine organic acids, caffeine, phenolic acids, and four chlorogenic acids in espresso coffee using an HPLC-DAD instrument. In addition, a new solid-phase extraction (SPE) sample clean-up procedure for organic acids has been optimized. The newly developed analytical methods were characterized by satisfactory recovery levels of sample clean-up procedure (41.798.6%) and good resolution of all peaks in both chromatography separations. In addition, the investigated validation parameters implied good repeatability, sensitivity and linearity. These methods were applied to espresso samples with three different roasting degrees (light, medium, and dark) of the same coffee variety (100% Arabica) to study the effects of the roasting process on the content of caffeine, organic and chlorogenic acids. The caffeine content was relatively stable to heat. The concentration of chlorogenic acids decreased due to roasting while the total organic acid content increased, with the formation of acetic and lactic acids in medium and dark roasting. Therefore, these new approaches can be considered as reference methods for the determination of carboxylic acids in coffee. [Display omitted] • A new SPE purification has been developed for organic acids quantification in coffee. • New HPLC-DAD method for carboxylic acids quantification in coffee. • Influence of roasting degree has been evaluated on EC chemical composition. • Oxalic, quinic, lactic and acetic acid concentration increased with roasting degree. [ABSTRACT FROM AUTHOR]

Single-dose coffee capsules have revolutionized the coffee market, fueling espresso coffee popularity and offering access to a wide selection of coffee blends. Nevertheless, scarce information related to coffee powder and brew’s combined volatile characterization is available. In this study, it is hypothesized that coffee brew aroma characteristics can be predicted based on coffee powder’s volatile composition. For this, headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry detection (GC × GC-ToFMS) was used. The data were combined via chemometric tools to characterize in depth the volatile composition of eight blends of capsule-coffee powder and respective espresso brews, simulating the consumer’s perception. A total of 390 volatile compounds were putatively identified, 100 reported for the first time in roasted coffee or brews. Although the same chemical families were determined among the coffee powders and espresso brews, a different volatile profile was determined for each matrix. The Pearson correlation of coffee powders and respective brews allowed to identify 15 volatile compounds, mainly terpenic and esters recognized by their pleasant notes, with a strong relationship between the amounts present in both matrices. These compounds can be key markers to predict the volatile aroma potential of an espresso brew when analyzing the coffee powder.

This study aims to assess for the first time the content of phytosterols (PS) in espresso coffee (EC) to deepen the knowledge about the phytochemicals and health potentials of coffee brews. PS were extracted by hot saponification from 14 EC samples produced with coffee originating from 13 coffee-producing countries. PS were identified and quantified by high-performance liquid chromatography (HPLC) after derivatization. Among the detected PS, β-sitosterol (4.1–18.2 mg/L) was the most abundant followed by stigmasterol (1.1–4.9 mg/L), campesterol (0.9–4.7 mg/L), and cycloartenol (0.3–2.0 mg/L). Total PS fraction ranged from 6.5 mg/L to 30.0 mg/L with an average level of 15.7 ± 5.8 mg/L. Therefore, a standard cup of EC (25 mL) could provide 0.4 ± 0.1 mg of PS.

Espresso coffee (EC) is a common coffee preparation technique that nowadays is broadly widespread all over the globe. Its popularity is in part attributed to the intense aroma and pleasant flavor. Many researchers have studied and reviewed the aroma of the coffee, but there is a lack of specific review focused on EC aroma profile even if it is intensively investigated. Thus, the objective of the current review was to summarize the aroma profile of EC and how different preparation variables can affect EC flavor. Moreover, a collection of diverse analytical procedures for volatile analysis was also reported. The findings of this survey showed that the volatile fraction of EC is extremely complex, but just some compounds are responsible for the characteristic aroma of the coffee, such as some aldehyde, ketones, furanones, furans, sulfur compounds, pyrazines, etc. In addition, during preparation, some variables, e.g., temperature and pressure of water, granulometry of the coffee particle, and brew ratio, can also modify the aroma profile of this beverage, and therefore its quality. A better understanding of the aroma fraction of EC and how the preparation variables should be adjusted according to desired EC would assist coffee workers in obtaining a higher quality product.

Coffee extraction is a complex mass transfer process that takes place between hot water and ground coffee beans when the water passes through a bed of coffee grounds. In this study, a general set of macroscopic governing equations for coffee extraction was derived using the volume averaging theory. Moreover, lumped parameter analytical solutions for the extraction of drip coffee, espresso coffee, and immersion-brewed coffee (e.g., siphon coffee) were obtained by integrating the macroscopic governing equations. A dimensionless number associated with controllable parameters in the coffee brewing techniques, namely the flow rate of hot water, the amount of coffee grounds, and the size of the ground coffee particles, is proposed based on the appropriate normalization of the derived equations. It was found that when brewing an espresso coffee, this dimensionless number is sufficiently high so that the extraction depends on the flow rate of hot water and the amount of beans. In contrast, drip coffee extraction can be controlled by this dimensionless number. A set of exhaustive experiments brewing each considered type of coffee was conducted to examine the validity of the proposed models. It was found that the present analytical solutions agree well with experimental data, indicating that the proposed models can be used to accurately predict coffee extraction. • The 3D coffee extraction model was derived based on volume averaging theory. • Analytical solutions were proposed for drip, espresso and immersed coffee. • Experiments were conducted to examine validity of the proposed models. • It was found that the presented models can predict each coffee extraction. [ABSTRACT FROM AUTHOR]

Several factors have led to an increase in the consumption of sweeteners in substitution of sucrose. Studies on the behavior and the sensory properties of sweeteners are relevant, once they provide knowledge about both the adequate sweetener concentration with a sweetness equivalence to a sucrose‐sweetened product and the possible sensory changes of the product. The addition of stevia with different rebaudioside A concentrations and sucralose to traditional and decaffeinated espresso coffee was studied, using the just‐about‐right scale and magnitude estimation method, to determine the ideal sweetness and the acceptance of the samples. The effect of the intensity of sensory attributes sweet taste, bitter taste, coffee flavor, and body in the acceptance was evaluated by penalty analysis. Decaffeinated presented proportionally lower sucrose concentration and sweetness equivalence than the traditional samples. Stevia concentrations were similar, despite the different rebaudioside A concentrations, for both traditional and decaffeinated samples, and rebaudioside A levels from stevia in espresso have no differences in sweetness intensity. Sucralose was the most intense sweetener in espresso. Although no differences were observed in the acceptance test in relation to appearance, aroma, and texture among the samples, the internal preference map showed segmentation of consumers with respect to the acceptability. This segmentation is more related to the type of sample than the added sweetener. Penalty analysis demonstrated that the most penalizing sensory characteristics were "coffee flavor" and "sweet," leading to a significant decrease in the acceptability of the samples. Practical Application: Conclusions obtained are important source of knowledge for the coffee industry, in the development and manufacture of beverages with coffee. The present findings can help to understand the behavior and the sensory properties of sweeteners. They provide knowledge about sensory perception of sweet and bitter tastes, and the factors that influence this perception and the sensory profile of the samples, once the behavior of sweeteners varies according to the product to which they are added. [ABSTRACT FROM AUTHOR]

Coffee beverages may be obtained using several extraction methods, among which espresso coffee (EC) represents now a worldwide adopted system. Recent advances in coffee grinding equipment allow today to achieve a detailed control of granulometric distribution, and the grinding process is an essential step of coffee production cycle both for the aromatic profile composition and for the chemical properties of the beverage (Severini, 2015). The comminution process consists of the breaking down particles into smaller fragments; as well-known, its main objective is to increase the overall particle surface area exposed to water leading to a more efficient extraction of soluble substances (Illy, 2005a). Basically, the coffee brewing process includes two steps: a washing phase concerning the snapshot dissolution of free solubles at the particle surface followed by diffusion phase of solubles within the porous particles (Spiro 1992, Baggenstoss 2008). The variability in particle size distribution on the quality of EC has been studied by various authors. Severini et al. has tackled the influence of the grinding level on the aromatic profiles and chemical attributes (percolation time, caffeine content, pH and titratable acidity) as a consequence of changes in the microstructural properties of the coffee cake. Generally speaking such results would imply that the final effect in terms of aromatic compounds extraction follows a monotonic law respect to granulometric size. This result is true in an average sense but it cannot be given for granted for any aromatic compounds if we refine the resolution of granulometric class. The reasons for which some aromatic compounds do not follow the supposed trend (the lower the grain size, the higher the aromatic compound content) can be most probably related to the internal distribution of precursors and to the different non-isotropic roasting grade of the bean, where the external part undergoes to an increased thermal load. This will change at the same time the kinetics and formation of aromatic compounds, and the mechanical properties as well, strictly correlated to the way the bean is crashed during the grinding phase and consequently to the granulometric distribution of different parts of the coffee bean. Results presented in this work allow to correlate choices in terms of granulometric distribution to characteristics aromatic compounds, in order to enhance specific flavors in espresso coffee. Unlabelled Image • Espresso coffee aromatic profile is strongly affected by granulometric distribution of grinded coffee. • Some aromatic compounds show non-monotonic correlation with comminution size. • Anisotropic thermal load during roasting can correlate anisotropic mechanical properties and final products distribution. • Espresso coffee can be designed in an "a priori" mode enhancing specific flavors by picking up specific granulometric class. [ABSTRACT FROM AUTHOR]

Highlights • Qualitative models of coffee quality using the data FTIR spectra and sensory analysis were developed. • Models predicting attribute of coffee quality from FTIR spectra were also developed. • The models for aroma, flavor, aftertaste and acidity showed very consistent. • Coffee sensory analysis and spectroscopy techniques are promising to classify coffee by its sensory profile. Abstract Coffee cup quality, determined by the sensory attributes evaluated by professional tasters, is a decisive factor for evaluating coffee, with the "Specialty Coffee Association of America" (SCAA) classification being nowadays considered the most suitable. P anels of trained coffee tasters are used by the industry to describe and evaluate beverage quality, but those evaluations can be subjective and time demanding. Recent studies have demonstrated the potential of spectroscopy-based methods for establishing parameters of quality in the analysis of food products, including coffee. Thus, the aim of this study was to evaluate the potential of ATR-FTIR and chemometrics to discriminate espresso coffees with different sensory characteristics reported by a panel of coffee tasters. The results showed good consistency among coffee tasters. PLS-DA models based on spectroscopic data were able to classify samples according to sensory attributes, confirming the potential of FTIR and chemometrics in coffee quality evaluation. [ABSTRACT FROM AUTHOR]

Coffee brews have High Molecular Weight (HMW) compounds with described immunostimulatory activity, namely polysaccharides and melanoidins. Melanoidins are formed during roasting and are modified during brews technological processing. In addition, brews have Low Molecular Weight (LMW) compounds, namely free chlorogenic acids and caffeine, with well-known anti-inflammatory properties. However, this study shows that both espresso and instant coffee brews did not present immunostimulatory neither anti-inflammatory in vitro activities. It is possible that the simultaneous existence of compounds with antagonistic effects can mitigate their individual effects. To test this hypothesis, an ultrafiltration separation process was applied, studying the behavior of coffee brews’ HMW on retention of LMW compounds. Several ultrafiltration sequential cycles were required to separate retentates from LMW compounds, suggesting their retention. This effect was higher in instant coffee, attributed to its initial higher carbohydrate content when compared to espresso. Separation of HMW and LMW compounds boosted their immunostimulatory (6.2–7.8 µM nitrites) and anti-inflammatory (LPS induced nitrite production decrease by 36–31%) in vitro activities, respectively. As coffee anti-inflammatory compounds are expected to be first absorbed during digestion, a potential in vivo fractionation of LMW and HMW compounds can promote health relevant effects after coffee intake.

Coffee capsules market is on the rise as it allows access to a wide selection of coffee, differing in taste and brand. However, few data about the chemical characterization of the capsule-brewed coffee aroma are available. In this work, an untargeted approach using headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography−mass spectrometry (GC-MS) and combined to chemometrics was performed to study and compare aroma profile from 65 capsule-brewed espresso coffees (ECs) commercialized by five of the most representative brands in Italy. Volatile profiles obtained from ECs were subjected to multivariate statistical analysis, which generally did not show a significant variability among coffees belonging to the same brand, except for those modified after the addition of specific flavor additives or aromatic substances (such as caramel, chocolate, etc.). Similarities may be related to the starting coffee brew or the processing method, which is likely the same for each individual brand. Additionally, partial least squares discriminant analysis (PLS-DA) showed that capsules from a specific brand contain the highest concentration of pyrazines, thus characterized by an intense and characteristic aroma, and a stronger note than those from the other brands. This study supports that the chemical analysis in conjunction with chemometric tools is a useful approach for assessing flavor quality, even if the need remains to identify volatile markers of high-quality beverages.

Abstract: Lignans are polyphenolic compounds that are considered phytoestrogens for their plant origins, and they possess different biological activities. Three different extraction methods, ie, “dilute and shoot”, acidic hydrolysis, and enzymatic digestion, have been compared for extracting lignans (secoisolariciresinol (SECO), matairesinol (MAT), and lariciresinol (LARI)) from espresso coffee (EC) by using high‐performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS). The best recovery values (SECO: 97%, LARI: 98%, and MAT: 93%) were obtained by using enzymatic hydrolysis with Clara‐Diastase at 10% (w/v), keeping the sample at 37°C for 3 hours. For this reason, this method has been chosen and then applied to quantify lignans in 9 different EC samples from 5 different geographical origins (Brazil, Colombia, El Salvador, Ethiopia, and India). Secoisolariciresinol and LARI were found in all EC samples from 27.9 to 52.0 μg L−1 and from 5.3 to 27.8 μg L−1 respectively, contrary to MAT that it was not possible to detect it in each type of coffee. This method confirms the high specificity and sensitivity of MS/MS system for detecting bioactives in complex matrix such as coffee. [ABSTRACT FROM AUTHOR]

Electronic senses were applied in order to evaluate the effect of brewing temperature on the sensorial properties of espresso coffees (ECs) produced by a bar machine of the latest generation able to work with constant, increasing and decreasing water temperature profiles. The obtained ECs were analyzed by e-nose, e-tongue and e-eye to depict their aroma and taste fingerprint and to evaluate the visual characteristics of foam. Physicochemical analyses were carried out to determine the extraction rate of typical EC components and to evaluate their antioxidant activity. The electronic devices coupled with multivariate statistical analysis demonstrated a good ability to discriminate and characterize coffee samples on the basis of their sensorial properties in relation to the brewing temperature. According to these results, electronic senses can be applied to assess the influence of the percolation parameters on the sensory attributes of ECs, thus resulting useful tools for the optimization of processing conditions. [ABSTRACT FROM AUTHOR]

The Italian espresso coffee is the most aromatic coffee brew. Among the several variables affecting the physicochemical and sensorial attributes of the beverage, the use of different types of coffee filter holders was never studied. Electronic nose is a useful technique for the control of food and beverages because it combines the advantages of both instrumental and sensorial analyses. In this work, the influence of two filter holders, 1-cup or 2-cups, on the main chemical attributes and global aromatic profile of the espresso coffee samples, obtained in different extraction conditions, was studied. Any significant differences were not observed in the overall aromatic profile of espresso coffee brews by using the two types of filter holders, whereas the pH, titratable acidity, total solids and caffeine content were greatly affected by the type of filter holder. [ABSTRACT FROM AUTHOR]

Single-dose coffee capsule system is a technology used to prepare espresso coffee which offers consumers the possibility to choose among several blends. However, the characterization of espresso coffees extracted with these systems, namely regarding polysaccharides structures and melanoidin content, is scarce. In order to define a carbohydrate and melanoidin composition pattern for single-dose espresso coffee base blends, a range of 6 commercial espresso coffee blends was studied. In addition, a decaffeinated blend and a blend supplemented with plant natural extracts were also included. The base blends showed galactomannans as the predominant polysaccharides over arabinogalactans, on the contrary of the decaffeinated blend. The blend supplemented with natural plant extracts showed glucose-rich polysaccharides. The labelled intensity of coffee single-dose seems to be related with the unknown brown compounds of melanoidins, present in the high molecular weight material of the brews. A pattern could be obtained for single-dose espresso coffee base blends, presenting an average per cup of 1.21 g of total solids and 242 mg of soluble dietary fibre, constituted by 62 mg of galactomannans and 48 mg of arabinogalactans, and 123 mg of melanoidins. On average, 46% of espresso coffee low molecular weight compounds are adsorbed to the high molecular weight material, evidencing the importance of the adsorption/desorption phenomena for the properties of coffee dietary fibre. [ABSTRACT FROM AUTHOR]

BACKGROUND To improve the quality of espresso coffee, the variables under the control of the barista, such as grinding grade, coffee quantity and pressure applied to the coffee cake, as well as their variance, are of great importance. A nonlinear mixed effect modeling was used to obtain information on the changes in chemical attributes of espresso coffee ( EC) as a function of the variability of extraction conditions. RESULTS During extraction, the changes in volume were well described by a logistic model, whereas the chemical attributes were better fit by a first-order kinetic. The major source of information was contained in the grinding grade, which accounted for 87-96% of the variance of the experimental data. The variability of the grinding produced changes in caffeine content in the range of 80.03 mg and 130.36 mg when using a constant grinding grade of 6.5. CONCLUSION The variability in volume and chemical attributes of EC is large. Grinding had the most important effect as the variability in particle size distribution observed for each grinding level had a profound effect on the quality of EC. Standardization of grinding would be of crucial importance for obtaining all espresso coffees with a high quality. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The formation and stabilization of crema on espresso coffee are areas that have been well studied during the last 2 decades. In contrast, the contribution of the sensory perception of crema in the coffee consumption experience has not received a lot of attention. Crema being a key visual differentiator between espresso coffees, it may influence the overall sensory and hedonic experiences through the process of assimilation or contrast of visually induced expectations. The objective of this research was therefore to investigate the role of the expectation generated by crema visual cues on actual sensory and hedonic espresso coffee consumption experience. The study was designed to measure the impact of absence, presence and amount of crema on expectation for espresso coffee in liking, quality, overall taste intensity, bitterness and smoothness. Four espresso coffees with different amounts of crema were rated on each characteristic by espresso coffee consumers in three evaluation conditions: visual condition (expectation induced by crema visual cues), in-mouth condition (espresso coffee tasting while participants were blindfolded), full condition (standard tasting). The aim of this procedure was to quantify the respective contribution of crema visual cues and in-mouth espresso coffee tasting to the overall espresso coffee experience. Results showed that espresso coffee without crema was expected to be moderately liked, low in quality and weakly smooth as compared to espresso coffee with crema. Such expectations negatively impacted hedonic and sensory in-mouth experience through assimilation effect. Change in crema amount also impacted consumers' expectation which in turn modulated hedonic and sensory experience for espresso coffee. For the first time, this study highlighted the key role of crema visual cues on espresso coffee consumption experience. [ABSTRACT FROM AUTHOR]

Coffee is one of the most popular hot drinks in the world; it may be prepared by several methods, but the most common forms are boiled (brew) and pressurized (espresso). Analytical studies on the substances responsible for the pleasant aroma of roasted coffee have been carried out for more than 100 years. Brew coffee and espresso coffee (EC) have a different and peculiar aroma profile, demonstrating the importance of the brewing process on the final product sensorial quality. Concerning bioactive compounds, the extraction mechanism plays a crucial role. The differences in the composition of coffee brew in chlorogenic acids and caffeine content is the result of the different procedures of coffee preparation. The aim of the present review is to detail how the brewing process affects coffee aroma and composition. [ABSTRACT FROM AUTHOR]

The efficient substitution of sucrose by a sweetener in beverages requires the application of some sensory techniques. First, one must determine the concentrations of the sweeteners under study, equivalent in sweetness to the ideal sucrose concentration. In addition, it is fundamental to determine which is most similar to sucrose. The objectives of this study were to determine the ideal sweetness for espresso coffee and the equivalent concentrations in sweetness of different sweeteners, as well as characterise the time-intensity profile of each sweetener in relation to sweetness. The sweeteners evaluated were sucralose, aspartame, neotame, a cyclamate/saccharin mixture (2:1) and stevia. The sucrose concentration considered ideal by consumers was 12.5% (w/v), and the equivalent concentrations of the sweeteners were 0.0159% for sucralose, 0.0549% for aspartame, 0.0016% for neotame, 0.0359% for the cyclamate/saccharin mixture and 0.0998% for stevia. The time-intensity analysis indicated that possibly the sweeteners neotame, aspartame and sucralose would be the best substitutes for sucrose. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the effect of preparation conditions of espresso coffee (EC) on the diterpenes profile. ECs were prepared from roasted and ground (R&G) Arabica coffee and analyzed for the content of cafestol and kahweol by liquid-liquid extraction followed by HPLC-DAD, as well as their lipid content. The main variables in the present study were as follows: the water quantity, the amount of coffee, the particle size, the percolation time, the water temperature and pressure. Average cafestol, kahweol and lipid content of R&G Arabica coffee were 467 ± 20 mg/100 g, 638 ± 33 mg/100 g and 15.1 ± 0.1 g/100 g, respectively. Although all parameters influenced the diterpenes content of ECs (21 samples), the particle size and water quantity were the most significant ones. It was possible to reduce the total diterpenes from 58.8 ± 0.7 mg/L (2.3 mg/40 mL) to 30.7 ± 0.8 mg/L (1.2 mg/40 mL) by varying the brewing conditions. The average extraction yield of diterpenes and lipids was in the range of 1.5-2.5 and 7.0-9.0 %, respectively. Regarding total cafestol and kahweol, very fine particles seem to be more desirable for the production of highly concentrated brew (2.3 mg/40 mL) with cafestol and kahweol extraction yields of 2.8 and 2.9 %, respectively, than other studied ECs. On the other hand, samples brewed at 70 °C exhibited lower diterpenes content (1.2 mg/40 mL) and diterpenes extraction efficiency (1.4 %) with respect to all other considered parameters. This study clearly shows that parameters for coffee brew preparation may be changed to modify the diterpenes content of ECs according to the desired purpose. [ABSTRACT FROM AUTHOR]

In an espresso-style extraction hot water (90 ± 5 °C) is driven through a coffee packed bed by a pressure gradient to extract soluble material from the coffee matrix. Permeability is a key parameter affecting extraction as it determines the flow rate through the bed and hence brewing and residence time. This may alter bed-to-cup mass transfer and therefore impact brew quality. In this work a methodology that will allow estimation of the permeability of coffee packed beds in steady-state was developed. Fitting measured flow rate – pressure drop data to Darcy’s law resulted in permeability values in the range of 10 −13 –10 −14 m 2 . Disagreement between the experimental and theoretical permeability, as estimated from dry measurements of particle size distribution and Kozeny–Carman equation, was found. Bed consolidation may have a larger effect on the packing structure than the mere decrease in bed bulk porosity. The Kozeny–Carman equation, corrected with a porosity-dependent tortuosity according to a power law, gave a good fit of the data. [ABSTRACT FROM AUTHOR]

Coffee melanoidins have attracted interest as a result of its potential health benefits. This investigation aims to elucidate the extraction behavior of melanoidins and their populations during the preparation of portioned espresso coffee and its relationship with the antioxidant activity of the coffee brew. Filter-paper pods, FAP capsule, and clone capsule containing light roasted coffee have been investigated. An accumulative fractionation approach has applied to model the extraction kinetics of melanoidins, melanoidin populations, browning, chlorogenic acids (CGA), and antioxidant activity. Melanoidins were very efficiently extracted in clone capsules since less than 9 s was necessary to extract the 50% of the melanoidin content as compared with pods and FAP capsules, and the kinetic of extraction is slower than CGA. The extraction profile of melanoidins and browning fitted better with the antioxidant capacity than CGA and total solids profile. Melanoidin populations were obtained according to ethanol solubility. Total melanoidin content and the ratio between melanoidin populations did not change during extraction volume for espresso coffee. Melanoidin populations soluble at 75% ethanol showed the highest antioxidant activity. However, melanoidins with higher antioxidant activity are extracted at higher volumes. This investigation could make possible the adjustment of the technological requirements of espresso coffeemakers to produce an espresso coffee with high levels of beneficial compounds. [ABSTRACT FROM AUTHOR]

Abstract: Plasticizer residues in espresso coffee made from three capsule typologies, pods and moka pots were determined by GC–MS. The plasticizer migration from the coffee powder into espresso coffee as a result of brewing was evaluated. Among 27 investigated plasticizers, only DMP, DiBP, and DEHP were found in all analyzed samples. DEA and DEHS were found in capsules made from polystyrene with lid of aluminum and a heat seal layer of polyethylene. DEHA residues were determined in moka pots, in pods and in capsules made from polypropylene and in polypropylene with a micro-perforated film of low-density polyethylene lids. The migration assessment showed that DMP amounts were significantly higher in all capsule types, pods and moka pots, probably due to transfer from the plastic components of coffee machines, capsules and rubber sealing rings. In comparison with current values proposed by European agencies for food safety, the daily intake of plasticizers from espresso coffee was very low. [Copyright &y& Elsevier]