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Influence of extraction temperature on the final quality of espresso coffee
Journal of The Science of Food and Agriculture
Abstract
The final quality of espresso coffee (EC) depends upon certain technical conditions, such as the extraction temperature used in preparing it. The aim of this work was to investigate the effects of water temperature (88, 92, 96 and 98 °C) on the final quality of three types of EC (Arabica, Robusta Natural blend and Robusta Torrefacto blend) in order to select the optimal temperature. Volatile compound (analysed by Static headspace gas chromatography/mass spectrometry) and sensory flavour profiles were the most relevant parameters, whereas physicochemical, taste and mouthfeel parameters were not very useful for selecting the water temperature. For Arabica and Robusta Natural blend ECs, 92 °C was the optimal water temperature. For Robusta Torrefacto blend EC the overall acceptability might lead to the selection of 88 °C as the ideal water temperature, but the high percentages of key odorants related to roasty and earthy/musty flavours and the ‘not hot enough’ perception dictated the selection of 92 °C in this case as well.
© 2003 Society of Chemical Industry
... TDS, caffeine, and trigonelline concentrations in espresso were found to increase significantly with water temperature (Andueza et al., 2003). Salamanca et al. (2017) proposed an approach for tuning the taste and aroma profile of espresso coffee by using temperature gradients. ...
... espresso coffee beverage at different temperatures and flow rates was investigated by performing the experiments shown in Table 1, all of which were within the experimental range used for parameter estimation (SM Table S1). Note that these experimental conditions were selected to avoid extrapolation of the model, mimic the conditions of earlier studies for comparison (Andueza et al., 2003;Salamanca et al., 2017), and investigate the effects of gradient control compared to constant control in a practically feasible manner. Two constant temperatures and two temperature gradients (see Table 1) were selected for comparison with the temperatures used in (Andueza et al., 2003) and the gradients used in (Salamanca et al., 2017). ...
... Note that these experimental conditions were selected to avoid extrapolation of the model, mimic the conditions of earlier studies for comparison (Andueza et al., 2003;Salamanca et al., 2017), and investigate the effects of gradient control compared to constant control in a practically feasible manner. Two constant temperatures and two temperature gradients (see Table 1) were selected for comparison with the temperatures used in (Andueza et al., 2003) and the gradients used in (Salamanca et al., 2017). The measured curves T(t) and Q(t) were used for simulations (data provided in SM Figs. ...
Influencing espresso coffee quality by adjusting the extraction process parameters is a current issue in coffee
research. In previous literature, significant effects of the brewing parameters on taste have been demonstrated for
espresso, and mathematical models were developed describing extraction kinetics. However, an attempt to
include the effects of process parameters in a model for predicting the extraction kinetics of taste-relevant solutes
had been lacking.
In this study, the two-grain model, originating from the work of Melrose and Corrochano et al. (2012, 2015,
2018), and adopted by Moroney et al. (2019), was extended by equations describing the influence of water flow
rate and temperature on mass transfer. The model parameters were estimated using experimental extraction
kinetics data for total dissolved solids, caffeine, trigonelline, and chlorogenic acid from our previous study.
Model predictions were compared with experimental data, including time-varying temperature and flow rate.
The results are summarized in a control chart and a publicly available app visualizing the importance of
extraction kinetics on espresso composition.
... These compounds exhibit variable changes in concentration and sensory potency, which explains why different coffee types may have such unique and specific flavors [46]. It was reported that espresso coffee (EC) contains volatile components belonging to different chemical classes such as furans, pyrazines, aldehydes, ketones, phenolic, and sulfur compounds [37,[47][48][49]. ...
... Andueza et al. reported that water extraction temperature of ≥ 96 °C resulted in a higher pyrazine amount during the preparation of EC from arabica. Therefore, higher amounts of some pyrazines in EC are related to the higher water temperature used for the extraction [49]. Lolli et al. [37] detected 12 pyrazines in capsulesbrewed ECs from various brands sold in Italy. ...
... However, there was no consistent trend in the content of aldehydes, which could suggest a potential variability in the quality and the perceived aroma from capsule-brewed ECs, especially from different brands [37]. Several aldehydes were reported in EC, such as acetaldehyde, propanal, 2-methylpropanal, 2-methylbutanal, and 3-methylbutanal [47,49,67,68]. ...
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.
... According to the roasting conditions, sample numbers were divided into 1 to 9 (235 • C for 13 min), 10-18 (240 • C for 15 min), and 19-27 (245 • C for 17 min). The sample number was also assigned to the particle size of grounded coffee (355 µm: 1-3, 10-12, 19-21; 500 µm: 4-6, 13-15, 22-24; 710 µm: 7-9, [16][17][18][25][26][27]. The sample number assigned according to the size of the coffee bean was divided into three equal parts according to the type of water (fil-Foods 2021, 10, 1347 3 of 13 tered water: 1, 4, 7, 10, 13, 16, 19, 22, 25; tap water: 2, 5, 8, 11, 14, 17, 20, 23, 26; bottled water: 3, 6, 9, 12, 15, 18, 21, 24, 27). ...
... Trigonelline, chlorogenic acids, and lipids increased inversely with grind size. The caffeine content also increased significantly as grind size decreased [18,29]. These results suggest that different aromatic profiles of coffee can be obtained when different grind sizes are used. ...
... According to the roasting conditions, sample numbers were divided into 1 to 9 (235 • C for 13 min), 10-18 (240 • C for 15 min), and 19-27 (245 • C for 17 min). The sample number was also assigned to the particle size of grounded coffee (355 µm: 1-3, 10-12, 19-21; 500 µm: 4-6, 13-15, 22-24; 710 µm: 7-9,[16][17][18][25][26][27] ...
Volatile compounds of coffee brewed under various roasting conditions and by different brewing methods were analyzed. Green coffee beans (Coffea arabica) were roasted at 235 °C for 13 min, 240 °C for 15 min, and 245 °C for 17 min. Roasted coffee beans were ground into particles of three different sizes (710, 500, and 355 μm) and brewed by an espresso coffee machine and the cold brew method. Three types of water (filtered, tap, and bottled) were used for coffee extraction. SPME-GC-MS results indicated that increasing the roasting temperature and time increased the levels of 2,2′-methylene-bis-furan, guaiacol, and 4-ethylguaiacol (p < 0.05) and decreased the levels of furfural (p < 0.05). Grind size was inversely proportional to the measured signal of volatiles by GC-MS (p < 0.05). The measured GC/MS intensities of 2-methylpyrazine, 2,5-dimethylpyrazine, and 2-methoxy-4-vinylphenol were significantly higher in coffee brewed with filtered water (p < 0.05) than tap and bottled water. 2-Methylpyrazine, 1-methylpyrrole, and 2-acetylfuran were the most abundant components in the cold brew. Overall, roasting conditions and extraction methods were determined to be significant factors for volatile compounds in coffee. This is the first study showing the analysis of volatile compounds in coffee according to various types of water and extraction methods, such as espresso and cold brew coffee.
... Researchers found that the concentration of ketone (-C=O) and aldehyde (-CH=O) compounds in Espresso extracted at 92 °C hot water was higher than those in Espresso extracted at 88 °C hot water. [5] The finding can be explained with multiple theories. The carbonyl group in aldehyde has an O atom with high electron density to form hydrogen bond with water molecules and help it dissolve. ...
... Similarly, in another literature, Ogoshi et al. reported that a pillar [5]arenes modified with oligoethylene oxide groups (Figure 14) demonstrated LCST behavior with a transition temperature of 55 o C, as shown in Figure 15. [15] . ...
... [15] . Such pillar [5]arenes act as another example presenting temperaturesensitive behavior as AQ-1,8-3E-OCH 3 . Figure 14. ...
The solubility of a substance determines how much of it will dissolve in a particular solvent at a given temperature. For most of the organic/inorganic compounds such as glucose and sodium chloride, their solubility in water increases with temperature. However, for polymers such as poly N-isopropylacrylamide and polyethylene oxide, they show lower critical solution temperature (LCST) behaviors and their solubility decreaseswhen temperature increases. A small molecule, 1,8-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)anthracene-9,10-dione) ( AQ-1,8-3E-OCH 3 ), shows an LCST behavior that its water solution is transparent at a temperature less than 45 °C, and cloudy at a temperature above 45 °C. More importantly, the whole process is reversible.[19] The aim of this study is to explain the LCST behavior of AQ-1,8-3E-OCH 3 so that further application can be developed. After reviewing inorganic compounds, organic molecules, and polymers, The essay concluded that the hydrophilic tails ( 3E-OCH 3 ) and the hydrophobic core ( AQ ) of AQ-1,8-3E-OCH 3 endow its amphiphilic property to form micelles, thus being phase separated from water when it is heated. In the future, it is expected that AQ-1,8-3E-OCH3 can be applied for drug release. For example, drug molecules can be first surrounded in the AQ-1,8-3E-OCH 3 micelles at a higher temperature, then get released to targeted cells at a lower temperature.
... For example, the concentration for 2FMT is up to 5080 μg/kg in roasted coffee and only up to 39 μg/L in brewed coffee (Cheong et al., 2013;Semmelroch & Grosch, 1996). In terms of extraction, the amount of thiols and the sensory profile of the brewed coffee depends obviously on the amount on the initial powder, but also on this efficiency of the extraction it-self, including thiol polarity but also physical parameters of the brewing such as ratio powder/water, water temperature and pressure, contact time (Andueza et al., 2003;Andueza, Vila, Paz de Peña, & Cid, 2007;Caporaso, Genovese, Canela, Civitella, & Sacchi, 2014). ...
... In fact, the efficiency of the extraction (solid-liquid) during the brewing process is impacted by physical parameters (water temperature, pressure, time of extraction and water/coffee ratio) (Mayer et al., 2000;Semmelroch & Grosch, 1996). However, data on the content of thiols under different coffee brewing conditions are extremely scarce and only methanethiol evolution is documented (Andueza et al., 2003). Methanethiol is more abundant in espresso coffee than in other types of brewed coffee, due to the extraction pressure and the higher ratio between coffee and water. ...
... Methanethiol is more abundant in espresso coffee than in other types of brewed coffee, due to the extraction pressure and the higher ratio between coffee and water. In this type of brewed coffee, the water temperature is important for the extraction efficiency of methanethiol (Andueza et al., 2003). Although it might be possible to extrapolate methanethiol tendency on other thiols, supplementary data are needed to highlight the impact parameters of brewing process without going beyond assumptions. ...
Volatile thiols are very strong-smelling molecules that can impact the aroma of numerous beverages. Several thiols and thiol precursors have been reported previously in different plants used as raw material for beverages, some of which are fermented. We focused on thiols in beverages and their release mechanisms from precursors during processing. Volatile thiols in beverages can be classified aslow molecular weight volatile thiols (e.g. H2S, methanethiol) which impact the smell negatively, and volatile thiols with higher boiling points that contribute positively to the aroma profile. The first part of this review is devoted to volatile thiols, without considering small malodorous molecules. The second part deals with thiol precursors and the different release mechanisms induced by processing (e.g. extraction, roasting or fermentation) and by the growing methods (e.g. viticulture), which can impact on amounts of thiols and their precursors.
... Variations in brewing parameters strongly influence the extraction yield, the composition, and hence the sensory profile of the coffee beverage. 1 Besides water pressure, 2 temperature, 3 coffee/ water ratio, 4 extraction method, 5 and water quality, 6 it is known that the particle size distribution of ground roasted coffee beans is an essential variable affecting not only the diffusion of solutes into water but also the flow through the particle bed. Voilley and Simatos 7 showed that a finer coffee ground leads to a higher dissolved solids content. ...
... The relative diameter increase was determined for the diameters d 10,3 , d16,3 , d 50,3 , d 84,3 , d 90,3 , and d 99,3 which correspond to a specific quantile of the volume distribution, where the first index represents the respective quantile expressed in a percentage. This description must be distinguished from the De Brouckere mean diameter d 4,3 which defines the volume moment mean of the particle size distribution. ...
... The relative diameter increase was determined for the diameters d 10,3 , d16,3 , d 50,3 , d 84,3 , d 90,3 , and d 99,3 which correspond to a specific quantile of the volume distribution, where the first index represents the respective quantile expressed in a percentage. This description must be distinguished from the De Brouckere mean diameter d 4,3 which defines the volume moment mean of the particle size distribution. ...
BACKGROUND
In this study, the swelling behavior of roasted coffee particles in water and particularly its impact on particle diameter is examined by applying laser‐diffraction analysis and microscopy. Several potential influencing factors are investigated: initial particle size, roasting degree, and temperature. Additionally, the time dependency of swelling and particle shape is evaluated at two different temperatures.
RESULTS
We verify that particle erosion occurs – as observed by an increase of the fine particle fraction after wetting – and it is revealed that this effect is more pronounced with a rise in temperature. The total relative increase in particle size is determined as approximately 15% based on a broad range of different sized coffee grounds. It is demonstrated that the degree of swelling is independent of both the initial particle diameter and the roasting degree. The particle shape is found to be unaffected by swelling. This research reveals that swelling is initially quick, with 60–80% of the final steady‐state diameter being reached after 30 s and completed after 4 min of wetting, i.e. within the timescale of conventional coffee brewing methods.
CONCLUSION
This work provides a better understanding of the impact of wetting as part of the coffee brewing process, thus aiding the design, modeling, and optimization of coffee extraction. It clarifies the strong deviation of previous results on coffee‐particle swelling by considering particle erosion and degassing and provides a robust method for quantification. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
... Salamanca et al. confirmed that the bitterness and acidity of espresso was more pronounced at higher brewing temperatures [21]. In a study by Andueza et al., the brewing temperature was also described as the greatest influence on the quality of espresso [22]. ...
... While the statistical results of specific differences of samples were not included in the research design of triangle tests, it was observed by many tasters during the study that hotter brewed espresso may be described as stronger, more bitter, and more acidic, similar to the study of Salamanca et al. [21]. Our results were comparable to Andueza et al. [22], even though different methodologies were used. In the case of Andueza et al. [22], the espresso samples were extracted at brewing temperatures of 88 • C, 92 • C, 96 • C, and 98 • C. It was found that more solids were detectable in espresso as the temperature increased. ...
... Our results were comparable to Andueza et al. [22], even though different methodologies were used. In the case of Andueza et al. [22], the espresso samples were extracted at brewing temperatures of 88 • C, 92 • C, 96 • C, and 98 • C. It was found that more solids were detectable in espresso as the temperature increased. The tasting panel found the espresso more bitter and astringent when it was brewed at 96 • C and 98 • C [22]. ...
Very hot (>65 °C) beverages such as espresso have been evaluated by the International Agency for Research on Cancer (IARC) as probably carcinogenic to humans. For this reason, research into lowering beverage temperature without compromising its quality or taste is important. For espresso, one obvious possibility consists in lowering the brewing temperature. In two sensory trials using the ISO 4120:2004 triangle test methodology, brewing temperatures of 80 °C vs. 128 °C and 80 °C vs. 93 °C were compared. Most tasters were unable to distinguish between 80 °C and 93 °C. The results of these pilot experiments prove the possibility of decreasing the health hazards of very hot beverages by lower brewing temperatures.
... Among the identified aldehydes, acetaldehyde (1, identification corresponding Table 3) and propanal (2) have been reported to have fruity notes (Andueza, Maeztu, Pascual, et al., 2002;; propanal,2-methyl-(3), butanal,3-methyl-(4) and butanal,2methyl-(5) were suggested as responsible of the chocolate and malty odor (Sanz, Maeztu, Zapelena, Bello, & Cid, 2002;Semmelroch & Grosch, 1995); hexanal (6) has been related to fatty-green and penetrating odor while the flavor of the 2-butenal,2-methyl-(7) is described as fruity-apple, estery, benzaldehyde (Flament & Bessière-Thomas, 2002). Acetaldehyde (1), propanal,2-methyl-(3), butanal,3-methyl-(4) and 2-butenal,2-methyl-(7) were highly extracted when using F4 particle size distribution but only 2-butenal,2-methyl-(7) contributed significantly. ...
... Among the phenolic compounds identified, phenol,2-methoxy-(32) has been considered as a key odorant in coffee (López-Galilea et al., 2006). It is responsabile for phenolic (Akiyama et al., 2007;Andueza, Maeztu, Pascual, et al., 2002), burnt aroma and other aromas such as smoky, spicy, or clove-like aroma Semmelroch & Grosch, 1995). F4 particle size distribution showed higher content in phenol,2-methoxy-(32) with respect to F6, F5, F3 and F2. ...
... Nine pyrazines (55-63) have been detected in this work, formed by reactions between α-amino acids and carbohydrates 0. These volatile compounds are mainly responsible for roasted, burned, nut-like and earthy/musty odor (Andueza, Maeztu, Pascual, et al., 2002;López-Galilea et al., 2006;Maeztu, Sanz, et al., 2001;Murota, 1993) with the exception of pyrazine,2-ethyl-6-methyl-(60) that linked to fruity and flowery notes (López-Galilea et al., 2006). The pyrazine concentration was significantly abundant in the ECs prepared with F4 particle size although for pyrazine,2,5-dimethyl-(55), 2,3-dimethylpyrazine (59) and pyrazine, 2-ethyl-3-methyl-(62), the peak area is very similar to the one achieved using the coarsest particle size. ...
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.
... This increased interaction is the basis for good release of extractable solids and aroma compounds from coffee. Grinding also ruptures coffee seed tissues and cells, accelerating the release of CO 2 and volatiles which also permits easier extraction of the remaining aroma compounds (Andueza et al., 2003a(Andueza et al., , 2003b. Although the literature lacks consensus about the exact particle size required to constitute a coffee type, various authors have used screen analysis to differentiate the grinding grade of coffee into three particle sizes, depending on coffee type: coarse (1.19 mm), medium (0.84 mm), and fine (0.59 mm) (Oliveira et al., 2017). ...
... There are only very few studies in the literature which disclose the relationship between grinding and the quality characteristics of beverages. These few studies have exclusively established the relationship (individually and combined) between different grinding grades, extraction times, and the sensory and quality attributes of coffee (Andueza et al., 2003a(Andueza et al., , 2003bSevereni et al., 2015). Andueza and colleagues refined fine-ground coffee beans through sieve analysis (710, 600, 500, 400, 300, 200, and 100 μm). ...
... The extractability percentage was also higher (>24%) for A20:R80 (a blend of 20% Arabica and 80% Robusta) 50% torrefacto coffee than for A20: R80 natural coffees; however, overextractability in torrefacto coffee did not make it bitter and astringent, which may be due to the addition of extra sugar that masks those effects. Extraction yield and solids concentration also increase with a reduction in particle size up to certain a limit (Andueza et al., 2003a(Andueza et al., , 2003bOliveira et al., 2017). However, contrary outcomes are also recorded in the literature, highlighting the insignificant relationship between different grinding grades and total soluble solids (Severeni et al., 2015). ...
... This increased interaction is the basis for good release of extractable solids and aroma compounds from coffee. Grinding also ruptures coffee seed tissues and cells, accelerating the release of CO 2 and volatiles which also permits easier extraction of the remaining aroma compounds (Andueza et al., 2003a(Andueza et al., , 2003b. Although the literature lacks consensus about the exact particle size required to constitute a coffee type, various authors have used screen analysis to differentiate the grinding grade of coffee into three particle sizes, depending on coffee type: coarse (1.19 mm), medium (0.84 mm), and fine (0.59 mm) (Oliveira et al., 2017). ...
... There are only very few studies in the literature which disclose the relationship between grinding and the quality characteristics of beverages. These few studies have exclusively established the relationship (individually and combined) between different grinding grades, extraction times, and the sensory and quality attributes of coffee (Andueza et al., 2003a(Andueza et al., , 2003bSevereni et al., 2015). Andueza and colleagues refined fine-ground coffee beans through sieve analysis (710, 600, 500, 400, 300, 200, and 100 μm). ...
... The extractability percentage was also higher (>24%) for A20:R80 (a blend of 20% Arabica and 80% Robusta) 50% torrefacto coffee than for A20: R80 natural coffees; however, overextractability in torrefacto coffee did not make it bitter and astringent, which may be due to the addition of extra sugar that masks those effects. Extraction yield and solids concentration also increase with a reduction in particle size up to certain a limit (Andueza et al., 2003a(Andueza et al., , 2003bOliveira et al., 2017). However, contrary outcomes are also recorded in the literature, highlighting the insignificant relationship between different grinding grades and total soluble solids (Severeni et al., 2015). ...
... Buratti et al. [21] stated that "the espresso coffee overall quality is affected by many factors related to coffee (variety, roasting conditions and storage conditions) [22][23][24][25], to water composition [26] and to the parameters of the percolation (temperature and pressure of water, grinding grade, dose of coffee, coffee/water ratio, pressure on the upper surface of coffee cake, extraction time) [27][28][29][30]". In this first eNose application example with complex aromas, these factors will be controlled by using an encapsulated espresso ground coffee, using soft mineral water to brew the coffee, and using a new semiautomatic coffee machine in order to guarantee similar brewing conditions that do not affect the aroma of the coffee. ...
... The brewed coffee beverage is prepared from roasted and ground coffee beans harvested from coffee plants cultivated around the world. The brewing of coffee is a process that extracts the volatile compounds and soluble and insoluble compounds from the ground coffee [28]. The volatile compounds are responsible for the aroma and are composed of ketones, aldehydes, pyrazines, and many other volatiles [46]. ...
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.
... Similarly in the current study, the brewing technique with the shortest boiling time (ACM) had the highest total phenolic and antioxidant activity values. Additionally, it was declared in the literature that technical conditions such as coffee/water ratio, water temperature, and water ± ± ± μ ± ± ± μ ± ± ± pressure are substantial contributors to the extraction of bioactive compounds and volatiles in coffee brewing (Andueza et al., 2002;2003;2007). As the coffee/water ratio was the same for all Turkish coffee samples used in this study, the other parameters are expected to be effective on the total phenolic content and antioxidant activity. ...
... Ayseli et al. (2021), investigating the aroma compounds of coffee produced from beans roasted at different degrees, emphasized that especially pyrazines play an important role in the aroma of coffee and that the heat treatment applied to the formation of these compounds has a substantial effect. In another study by Andueza et al. (2003), the pyrazine content of espresso coffee was related to the brewing water temperature. The authors reported that the higher the water temperature, the higher amount of pyrazines formed. ...
Turkish-style brewed coffee, i.e., ground coffee boiled in special pots, is one of the most consumed traditional beverages in Turkey given its unique and delicate flavor. In the current study, the effects of brewing in different pots (automatic coffee machine (ACM), stainless steel pot (SSP), and copper pot in hot sand (CPS) on the pyrazines, total phenolic content, and antioxidant activity in Turkish coffee were elucidated for the first time. Pyrazine compounds were carried out by the application of gas chromatography-mass spectrometry (GC-MS). A total of nine pyrazine compounds were detected in the samples. According to the results, the samples brewed in a copper pot in hot sand had the highest amount of pyrazines followed by SSP and ACM. 2-Methylpyrazine was found in abundance in all three samples while 2,5-dimethylpyrazine and 3-ethyl-2,5-dimethylpyrazine were the other substantial compounds. In contrast with the pyrazine formation in samples, ACM had a considerable amount of total phenolics and antioxidant activity followed by SSP and CPS. This may result from the less boiling time in ACM (around 90 seconds) which prevented the degradation of phenolics to an extent.
... Es una variación del tueste convencional el cual constituye un ejemplo típico de adulteración del café y consiste en la adición de azúcar, durante el proceso de tueste, en la forma de azucares reductores (i.e., glucosa o fructuosa) o no reductores (i.e., sacarosa) a razón de ≤ 15% en base a peso seco 16,59,79,80 provocando su caramelización lo que produce la típica coloración café del sustrato y un aumento en el número de productos resultantes de la reacción Maillard (e.g., ácidos, melanoidinas, pirazinas, piridinas y furanos etc.). ...
... El proceso Torrefacto es una práctica usual en varios países del sur de Europa y Sudamérica 59,66 y es normalmente realizado a un grado de tueste más leve para evitar los malos sabores producidos por el azúcar quemada (tipo caramelo quemado) 16,59,66 ; Además el proceso es usado para encubrir las malas características organolépticas de los cafés de mala calidad o aquellos preparados a base de C. canephora (cafés robusta) 59,65,84 y para aumentar el cuerpo de la bebida resultante 79 . ...
El café es una de las bebidas más consumidas en el mundo y su popularidad no está basada en su valor nutricional o sus potenciales beneficios a la salud, si no en su sabor placentero y las propiedades estimulantes de la cafeína. Esto es respaldado por las últimas estadísticas publicadas por la Organización Internacional del Café (ICO, por sus siglas en inglés) según la cual aproximadamente 1.4 billones de tazas de café son consumidas diariamente además del hecho de que la taza de consumo global se ha duplicado en los últimos 50 años por causa de la apertura de nuevos mercados. La amplia aceptación del café está ligada a sus propiedades sensoriales las cuales a su vez están fuertemente influenciadas por una cadena de eventos que inician desde la cosecha y las practicas postcosecha (i.e., fermentación, lavado, secado, tamizado, eliminación de granos defectuosos y almacenamiento), seguidas por el tueste, molido y empacado del producto para su posterior comercialización. No obstante, existen otros factores que también afectan las propiedades organolépticas de la bebida tales como, pero no limitado a: el pH y temperatura del agua, las mezclas realizadas antes o después del tueste, la especie y/o variedad de café, las adulteraciones, la incorporación de aditivos, el método de preparación de la bebida, el tipo de recipiente en el que se sirve la infusión, entre otros. El presente artículo presenta una breve descripción de los factores que afectan la calidad de la taza relacionados con el procesamiento del grano oro del café. Sin embargo, aunque los factores ya mencionados son tomados en consideración por los catadores, para fines comerciales, la calidad del café está y siempre estará en manos del consumidor. Después de todo la mejor prueba es cuando la persona lo prueba. Palabras clave: organoléptica, perfil de tueste, endotérmica, exotérmico, ma-croscópica, microscópica, reacción Maillard, caramelización.
... Coffee drinking has been linked to human health benefits (Higdon & Frei, 2006;Nardini, Cirillo, Natella, & Scaccini, 2002), attributed to the antioxidant capacity of bioactive compounds extracted by different brewing methods from roasted and ground coffee beans (Rao & Fuller, 2018). Several different techniques have been developed for coffee brewing as a consequence of climate, culture, and consumer preferences, among other factors (Andueza et al., 2003;Derossi, Ricci, Caporizzi, Fiore, & Severini, 2018). Previous studies have reported that the coffee brewing method may affect the physicochemical, bioactive, and antioxidant profile of the final coffee beverage (Angeloni et al., 2019;Cordoba, Pataquiva, Osorio, Moreno, & Ruiz, 2019;Derossi et al., 2018). ...
... Coffee brewing is a mass transfer phenomenon where hydrosoluble compounds are extracted from coffee particles by water (Sánchez López, Wellinger, Gloess, Zimmermann, & Yeretzian, 2016). Coffee compound extraction depends on their polarity, solubility, and brewing temperature (Andueza et al., 2003;Salamanca, Fiol, González, Saez, & Villaescusa, 2017). At high temperatures, the solubility of coffee compounds increases, and the extraction yield is thus greater. ...
The aim of this work was to analyze the influence of brewing temperature and coffee particle size on the evolution of physicochemical, bioactive, and antioxidant properties of Mexican cold brew coffee (CBC). The brewing process was carried out at two extraction temperatures (10±0.5°C and 25±0.5°C) and two particle sizes: medium (MG, 0.70 1.70 mm) and fine (FG, 0.43 0.71 mm). CBC brewing showed a complex relationship between brewing temperature and coffee grind particle size. The increase in brewing temperature enhanced the extraction rate. However, the particle size conditioned the extraction equilibrium time and final CBC properties. MG accelerated the brewing extraction rates to reach equilibrium in CBC properties (~7 h for 25ºC and ~12 h for 10ºC), while FG induced slower extraction rates and prolonged extraction times (above 12 h for both temperatures). However, FG produced CBC with higher bioactive compound content, darker color, and slightly less acidity than MG. Free online copy: https://www.tandfonline.com/eprint/NUQKRHVPXJ8QPRPZSJKR/full?target=10.1080/15428052.2020.1848683
... In fact, the efficiency of the extraction (solid-liquid) during the brewing process is impacted by physical parameters (water temperature, pressure, time of extraction and water/coffee ratio) (Mayer, Czerny, & Grosch, 2000;Semmelroch & Grosch, 1996). However, data on the content of thiols under different coffee brewing conditions are extremely scarce and only methanethiol evolution is documented (Andueza, Maetzu, Pascual, Ibañez, de la Peña, & Cid, 2003). Methanethiol is more abundant in expresso coffee than in other types of brewed coffee, due to the extraction pressure and the higher ratio between coffee and water. ...
... Methanethiol is more abundant in expresso coffee than in other types of brewed coffee, due to the extraction pressure and the higher ratio between coffee and water. In this type of brewed coffee, the water temperature is important for the extraction efficiency of methanethiol (Andueza, Maetzu, Pascual, Ibañez, de la Peña, & Cid, 2003). Although it might be possible to extrapolate methanethiol tendency on other thiols, supplementary data are needed to highlight the impact parameters of brewing process without going beyond assumptions. ...
FRANÇAIS : La mise au point d’une méthode d’analyse par UPLC-MS/MS et dilution isotopique nous a permis d’identifier pour la première fois dans un moût le S-3-(hexan-1-ol)-g-glutamyl-cystéine (gGluCys-3MH). Suite à cette découverte, l’étude des inter-conversions entre les glutathionylés, dipeptides et cystéinylés S-conjugués au 3-mercaptohexan-1-ol (3MH) ou à la 4-mercapto-4-méthyl-pentan-2-one (4MMP), a permis de mettre en évidence deux nouvelles formes de précurseurs. Le suivi de l’évolution de ces différents composés au cours de fermentations alcooliques à l’échelle laboratoire a permis de clarifier leur rôle de précurseurs et d’établir les éventuels mécanismes d’inter-conversion. Par ailleurs, à travers plusieurs expérimentations viticoles et oenologiques conduites à l’échelle pilote en Languedoc et Val de Loire pendant trois années consécutives, des éléments nouveaux ont pu être apportés quant à l’impact de la maturation du raisin et son hétérogénéité, ainsi qu’à l’importance des opérations pré-fermentaires comme la macération pelliculaire ou la stabulation sur bourbes.
Mots-clés : thiols variétaux, précurseurs d’arôme, 3MH, 4MMP, vinification, dilution isotopique.
ENGLISH : The development of a method using UPLC-MS/MS and stable isotope dilution assay allowed us to identify for the first time the S-3-(hexan-1-ol)-g-glutamyl-cysteine (gGluCys-3MH) in musts. Following this discovery, the study of inter-conversions between glutathione, dipeptides and cysteine S-conjugates to 3-mercaptohexan-1-ol (3MH) or 4-mercapto-4-methyl-pentan-2-one (4MMP) highlighted two new forms of precursors. The evolution monitoring of these compounds during alcoholic fermentations at laboratory scale allowed us to clarify their role as precursors and to establish the possible inter-conversion mechanisms. In addition, through several viticultural and oenological experiments carried out at pilot scale in Languedoc and Val de Loire during three consecutive years, new elements could be highlighted about the impact of grape ripening and its heterogeneity, as well as the importance of prefermentative processes, such as skin maceration and must conservation on lees.
Keywords: varietal thiols, aroma precursors, 3MH, 4MMP, winemaking, SIDA.
... In the literature, the most studied hot extraction methods are the espresso and filtered coffee methods. Studies have been carried to evaluate the influence of the product formulation (e.g., bean botanical type, post-harvest processes, roasting degree) and brewing process variables (extraction time, flow rate, temperature, particle size distribution, and water pressure) on the physicochemical attributes and sensory profiles 5,8,9,[14][15][16] . ...
... These parameters affect the extraction speed and way of the chemical compounds present in the roasted coffee. The chemical compounds present in the coffee exhibit different chemical properties (e.g., polarity and solubility); therefore, they have different extraction kinetics 15,18 . Overall, a higher temperature increases the solubility 19 , and it affects the saturated vapour pressure of aroma compounds. ...
The effects of grinding (medium-coarse) and extraction time (14–22 h) on the physicochemical and sensorial properties of cold brew coffee produced using two types of Colombian specialty coffees (Huila and Nariño) were evaluated. Cold coffee brewed under coarse grinding and 22 h of extraction exhibited the highest values of total dissolved solids, extraction yield, pH, titratable acidity (TA), and total phenolic content. The type of coffee used mainly affected the TA and pH. All cold brew coffee samples had lower TA values than their hot counterparts. Nariño cold brew samples had higher TA values than those of Huila in all treatments evaluated. Higher scores were reported in the sensorial evaluation of cold brew coffee when prepared using the shortest time (14 h) and coarse grinding for both coffee types. These coffees were characterized by strong sweetness, fruity and floral flavours, medium bitterness and acidity, and a creamy body. Furans, pyrazines, ketones, aldehydes, pyrroles, esters, lactones, furanones, and phenols were detected as odour-active compounds. The findings of this study demonstrate that the particle size, contact time, and coffee type affect the physicochemical and sensorial characteristics of cold brew coffee, leading to cold brew coffees with different flavour profiles.
... Lowering the brewing temperature may lessen health risks while preserving flavor [18]. The ideal temperature for espresso varies according to the kind, with Arabica and Robusta Natural blends recommended at 92°C [19]. Studies have shown that the quality of espresso coffee is notably influenced by water pressure, since higher pressures result in greater extraction of Volatile Organic Compounds (VOCs) [20]. ...
The number of coffee shops in Indonesia has grown from 1,083 stalls in 2016 to over 2,937 booths in 2019, representing a threefold growth. Coffee shop establishments must provide two essential kinds of equipment: espresso machines, which use pressure, and filter machines, which employ infusion. The issue lies in the exorbitant cost and immense power requirements of semi-automatic and automated espresso machines, which necessitate the use of a manual espresso machine for commercial operations. The equipment can generate satisfactory espresso but encounters several challenges; specifically, the espresso generated is characterized by inconsistency, constantly varying in quality. This might arise due to the erratic nature of the manufacturing process. The two objectives of this study are: (1) to design an economically efficient semi-automatic espresso machine capable of producing products that meet the international quality standards set by the Specialty Coffee Association (SCA standard) and (2) to investigate the impact of critical factors such as pressure, temperature, and grind size, on the consistent quality of the resulting coffee (measured by Total Dissolved Solids (TDS) and extraction yield (EXT)). The research employs the Research and Development (RD) methodology. The research findings indicate that the optimal levels of Total Dissolved Solids (TDS) and extraction yield (EXT) may be attained by using a pressure setting of 8 bars, a temperature of 90ºC, and a grind size of 3.2 on the scale. The technique for optimizing the response resulted in Total Dissolved Solids (TDS) levels of 10.03% and extraction yield (EXT) values of 19.56%. The results have been deemed acceptable based on the criteria set by the global standards of Specialty Coffee Association (SCA).
... An automated system can easily identify differences in aroma profiles caused by unanticipated factors such as water quality [27] [28], temperature fluctuations [29], or other difficulties during the brewing process that may impact consumer perception by using low-cost sensor technologies. Electronic noses technology provides a dependable system for detecting and correcting possible errors, guaranteeing that coffee drinkers get a consistent and high-quality sensory experience [30]. ...
One of the most important aspects of coffee's sensory experience is its scent, which is affected by roasting, microbial contamination, and place of origin. Electronic noses (ENs), which provide quick and precise identification of intricate odor patterns linked to microbial activity, have become highly effective instruments for evaluating coffee odors. This study examines the most recent uses of EN technology for evaluating coffee scent and emphasizes how important it is for assuring the safety and quality of the final product. The integration of ENs with artificial neural networks (ANNs) improves their precision in fragrance profile prediction and classification. Moreover, real-time smell profile monitoring is made possible by automated systems that use ENs, which helps with quality control in the coffee manufacturing process. Beyond the coffee business, EN technology is used in many other areas, including food safety, medical diagnostics, and environmental monitoring. Through innovation in fragrance analysis and quality control, this multidisciplinary approach promotes customer confidence and product integrity across industries.
... The literature reports different trends and only minor information to track potentially overlapping effects, which this study has attempted to avoid. However, note that the differences found in this study are significantly smaller than the values reported in the literature [13,29,30]. ...
Brewing espresso coffee (EC) is considered a craft and, by some, even an art. Therefore, in this study, we systematically investigated the influence of coffee grinding, water flow rate, and temperature on the extraction kinetics of representative EC components, employing a central composite experimental design. The extraction kinetics of trigonelline, caffeine, 5-caffeoylquinic acid (5-CQA), and Total Dissolved Solids (TDS) were determined by collecting and analyzing ten consecutive fractions during the EC brewing process. From the extraction kinetics, the component masses in the cup were calculated for Ristretto, Espresso, and Espresso Lungo. The analysis of the studied parameters revealed that flow rate had the strongest effect on the component mass in the cup. The intensity of the flow rate influence was more pronounced at finer grindings and higher water temperatures. Overall, the observed influences were minor compared to changes resulting from differences in total extracted EC mass.
... However, some small variations in compounds contents have been found. For instance, preparing ECs at 9 bar with optimal particle sizes, higher contents of caffeine, chlorogenic acids and organic acids are obtained at 88 and 93.4 • C. Some authors reported that 92 • C is an ideal water temperature for Arabica and Robusta natural blends [39]. ...
Coffee is one of the most consumed beverages in the world. This has two main consequences: a high level of competitiveness among the players operating in the sector and an increasing pressure from the supply chain on the environment. These two aspects have to be supported by scientific research to foster innovation and reduce the negative impact of the coffee market on the environment. In this paper, we describe a mathematical model for espresso coffee extraction that is able to predict the chemical characterisation of the coffee in the cup. Such a model has been tested through a wide campaign of chemical laboratory analyses on espresso coffee samples extracted under different conditions. The results of such laboratory analyses are compared with the simulation results obtained using the aforementioned model. The comparison shows a close agreement between the real and in silico extractions, revealing that the model is a very promising scientific tool to take on the challenges of the coffee market.
... If the particle size is too coarse, water can flow through large channels, resulting in a low extraction yield (under-extraction). On the other hand, if the powder is too fine, the ground coffee powder cake becomes very compressed and generates a resistance to the passage of the water, that increases the contact time between water and powder and produced an over-extracted coffee [5]. ...
This study examined the influence of ground coffee granulometry and particle distribution on extraction parameters. They have been investigated the physicochemical properties, and the bioactive and volatile compound content in coffee obtained by a conventional filter method, the French Press, as a function of particle size and distribution. Some samples have been used for the extraction the directly the grinding machine, set at different grinding grade, and other samples have been seed before the usage in order to reproduce samples at different particle size class very homogeneous. The results showed that bioactive and volatile compounds are released differently in the beverages depending on the specific particle size. The results have been demonstrated that a homogeneous grind was more deficient in bioactive compounds and total dissolved solids than a classical, bimodal grind. Moreover, extraction from a very fine homogeneous grind was poorest with respect to these compounds, despite the greater surface in contact with the solvent. Conversely, bimodal grinds obtained conventional by the grinding machine, which were more heterogeneous from a granulometric point of view, were found to be richer in volatile organic and bioactive compounds. The study highlights that the grind plays a key role in producing well-extracted coffee and, therefore, in making the most of the potential inherent in the roasted bean.
... The EC machine produces a suitable pressure on roasted ground coffee beans and percolates a limited amount of hot water in a short time to give a concentrated foamy cup of coffee. This method can be affected by many factors such as water composition and other technical conditions related to the machine (Caprioli et al., 2015;Andueza et al., 2003;Navarini et al., 2001;Petracco, 2001). The EC machine contains a volumetric pump that provides a continuous flow of water (Odello & Odello, 2006) to reach the desired pressure, then forced to heat exchanger to reach the desired temperature (91-96 degrees Celcius), after that water enters the filter unit and spread equally over the coffee surface inside the filter, then coffee particles absorb the water and swell when pre-infusion to a few second take place. ...
Coffee is a popular drink that is considered one of the most consumed beverages around the world. It contains more than 1000 biologically active compounds such as caffeine, diterpene alcohols, and chlorogenic acid. The effect of coffee on health is controversial depending on the type and the amount consumed of coffee. This review was prepared to clarify the effect of different preparation methods on coffee lipids content, as well as to study the effect of consumption of coffee prepared by different methods on body lipids profile. Coffee can be prepared by several methods, but the most two popular methods are brew and espresso. Coffee lipids which are called diterpenoid alcohols (cafestol and kahweol) can influence the body’s cholesterol level. The content of coffee lipids can be altered due to the methods of coffee preparation. Cafestol remains in the beverage of coffee when hot water is directly poured onto powdered coffee, when well-milled coffee is boiled in water a few times or when the metal filter is used instead of a paper filter, like in French Press. However, to good fortune, most of them are retained by the paper filter, which substantially reduces the cholesterol-raising effects potentially associated with coffee through consuming filtered coffee. Diterpenoids in unfiltered coffee cause an elevation of total cholesterol TC and low-density lipoprotein LDL cholesterol levels, whereas lowering the high-density lipoprotein HDL cholesterol levels in the body. However, consumption of filtered coffee slightly affects serum cholesterol levels. Also, the results of other studies revealed that the roasting degree of coffee is not related to an increase in the total cholesterol and the LDL cholesterol concentrations, but can be related to an increase in HDL cholesterol level after consumption of medium roasting MR coffee.
... Finally, there is even evidence in the field that indicates that the most important aspect of extraction of chemical components from coffee beans has everything to do with the level of energy introduced during the brew as agitation (Ahmed et al., 2018). There has been specific research around the energy profile for ideal extraction using water temperature to produce the best quality of espresso and this showed that the ideal temperatures were 88 and 92 degrees Celsius respectively for Robusta and arabica bean varieties (Andueza et al., 2003). ...
There are numerous techniques and technologies used in the brewing of coffee today. This study is aimed to design an umbrella experiment to examine the impacting key factors consistent across all methods of extraction. These factors were identified as: grind size, roast type, steep time, grind to water as a mass-to-mass ratio and temperature. Samples were prepared by grinding the beans, weighing the beans and adding the appropriate amount to a rectangular glass vessel. Distilled water was used. French press was selected as the brewing technique. No agitation after the addition of grind was allowed. Water was heated to initial temperature and added to the vessel and a timer was started. Upon time completion aliquots were taken and analysed using a prism-based automatic temperature compensation (ATC) refractometer. Minitab 19.2020.1 (64-bit) was used for analysis of variance and optimisation. In the initial design of experiments, the five factors were considered at different levels. Three factors found significant in impacting %TDS (total dissolved solids) were: total steep time, grind-to-water ratio and roast type. To further refine the experiments, 2 ³ full-factorial design was conducted for these three factors. Finally, optimisation was done to determine the factor levels to produce a cup of coffee for the target %TDS of 1.26. This research found that it is best to use medium roast coffee that is ground fine with a 0.08 grind-to-water ratio, with an initial temperature of 195 Fahrenheit in a French press, and the ideal steep time is 7 min. Previous studies have focused on the extraction methods. In this study, the method of extraction has been removed as a variable. Hence, the findings are very useful for food industry.
... respectively. Limitations of the study design include that the blend samples were brewed at 100 C with 2 C error margin because it has been found in the literature that the brewing temperature has a strong influence on the sensory perception of espresso (Andueza et al., 2003;Klotz et al., 2020). ...
Fenugreek is one of the well‐known legumes, used for its antimicrobial, antioxidant, nutritional, and pharmaceutical properties. It was aimed to obtain coffee by blending microwave (600 W)‐roasted fenugreek with coffee arabica and to determine the best roasting conditions (2 and 4 min), and blending ratios (20% and 50%) for fenugreek seeds by consumer sensory analysis. A voluntary, minimal‐trained consumer panel of 80 panelists was conducted. Coffee from roasted Arabica beans (100%) was used as a control. Cronbach's alpha values of 67.2% and 90.9% were obtained for the reliability of the first and second parts of the survey, respectively. The attributes “brown” color, “burnt,” and “bitter” taste, and “astringent” texture were significantly different between samples (p < 0.05), whereas oily appearance, green color, coffee, green/vegan, fruity, sour, sweet, nutty, caramel, cacao, caffeine and creamy flavor, and viscosity sensation were statistically the same. The Tamhane T2 post hoc test showed that the color of the control sample was more brownish, whereas the 50% blend of 4 min roasted fenugreek had a more burnt, bitter, and astringent taste. Appreciation scores for taste/aroma, appearance, and mouthfeel also differed significantly between samples, whereas odor was rated as the same by panelists. This study shows that sample with 20% mixture of fenugreek roasted for 4 min at 600 W had statistically the same scores as the control sample in terms of odor, appearance, aroma, taste, and mouthfeel. These findings were also supported by physical and antioxidative quality measurements such as color, pH, moisture content, total phenolic content, and antioxidant activity.
... The espresso brewing method differs drastically from cold or hot brew methods. In addition to high water temperature, espresso extraction is performed under high pressure using finely ground coffee [105][106][107][108]. Cruz et al. noted a high variability in the chemical composition of espresso SCGs and suggested that "the brewing method itself should be the main contributing factor to the compositional variance" [54]. ...
Nanotechnology has become increasingly important in modern society, and nanoparticles are routinely used in many areas of technology, industry, and commercial products. Many species of nanoparticle (NP) are typically synthesized using toxic or hazardous chemicals, making these methods less environmentally friendly. Consequently, there has been growing interest in green synthesis methods, which avoid unnecessary exposure to toxic chemicals and reduce harmful waste. Synthesis methods which utilize food waste products are particularly attractive because they add value and a secondary use for material which would otherwise be disposed of. Here, we show that spent coffee grounds (SCGs) that have already been used once in coffee brewing can be easily used to synthesize gold and silver NPs. SCGs derived from medium and dark roasts of the same bean source were acquired after brewing coffee by hot brew, cold brew, and espresso techniques. The total antioxidant activity (TAC) and total caffeoylquinic acid (CQA) of the aqueous SCG extracts were investigated, showing that hot brew SCGs had the highest CQA and TAC levels, while espresso SCGs had the lowest. SCG extract proved effective as a reducing agent in synthesizing gold and silver NPs regardless of roast or initial brew method.
... The CCRD is used to investigate the influence of coffee-to-water ratio, temperature, stirring on caffeine concentration, soluble solids, and caffeine yield as shown in Tables 1 and 2. Previous experiments 11,13,14,19 have shown that the most effective parameters are the coffee-to-water ratio of 10%-30% and from 4 C to 24 C of the extraction temperature. The variable stirring ranged from 0 to 400 rpm since a higher stirring rate can hinder the extraction process. ...
Background
The consumption of cold brew is relatively new, and guidelines with conditions and parameters to produce cold brew are still lacking. In this study, the parameters to obtain cold brew coffee from Coffea arabica were optimized to obtain a coffee extract rich in caffeine and soluble solids. The effects of extraction time, particle size of ground coffee, extraction temperature, coffee‐to‐water ratio, stirring on caffeine yield, and soluble solids on caffeine concentrations were studied.
Results
Optimized parameters showed 45 min sufficed to perform a cold extraction at 4°C and 24°C. The parameters selected for validation were 24°C, 30% coffee‐to‐water ratio, a stirring of 400 rpm resulting in 3.98 mg/ml of extracted caffeine, 11.20 °Brix, and 93.9% of caffeine yield. The smaller particle size (595 μm) displayed the higher caffeine extraction of about 4 mg/ml.
Conclusion
This study reveals the high efficiency of cold brew extraction and its potential at the industrial scale, decreasing costs with energy and extraction time, and producing a coffee rich in caffeine and soluble solids.
... This phase influences the solubility of the chemical compounds that are involved in the definition of the beverage flavour [14]. Several variables can play a crucial role in the EC extraction, as the grinding degree originating different particle sizes of the roast and ground coffee (R&G), percolation time, cake porosity, water temperature, pressure and quality [3,7,12,[15][16][17][18][19][20]. The influence of operational tools such as the height of perforated disc and the design of filter basket on the extraction of EC has been less studied. ...
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.
... Indeed, coffee is a popular beverage with a unique sensory profile and also a complex source of hundreds of bioactive compounds, starting from green beans up to the final cup of coffee. The most studied bioactive compounds in coffee brews include caffeine, trigonelline, diterpenes, and polyphenols such as chlorogenic acids (Figure 1) [10][11][12][13][14][15]. Among all the bioactive compounds investigated in coffee-based products, few studies have explored the presence and levels of phytosterols (PS) in coffee beans and oil [16,17]. ...
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.
... The infusion that is prepared is also characterized by appropriate density and taste, as well as a sufficiently high concentration of caffeine [102]. A temperature of water below or above than mentioned, effect on coffee infusion quality [103][104][105][106][107]. Some of the new methods of brewing coffee are performed at temperatures below 25 • C and this methods require a longer extraction time [108]. ...
Coffee is one of the most popular drinks consumed in the world, also in Poland. In the literature, much attention is paid to the influence of coffee on human health, especially daily intake of caffeine, and also purchasing consumer behavior. There is a lack of research devoted to consumer choices and habits in relation to coffee consumption and brewing method. Therefore, the aim of this study is to describe the characteristics of coffee consumers and present their segmentation based on consumer choices and habits towards coffee consumption. The study was performed using the computer-assisted web interviewing (CAWI) method on a group of 1500 adults respondents in Poland reporting the consumption of coffee. We collected information about consumer choices and habits related to coffee consumption, including brewing method, place of consuming coffee, and factors determining coffee choices. Using cluster analysis, we identified three main groups of coffee consumers. There are “Neutral coffee drinkers”, “Ad hoc coffee drinkers”, and “Non-specific coffee drinkers”. The respondents in the study are not coffee gourmets; they like and consume coffee, but these are often changing choices. To conclude, it can be stated that the Polish coffee consumer prefers conventional methods of brewing coffee (like a “traditionalist”) but is open to novelties and new sensory experiences. Based on study results it is possible to know the coffee drinking habits in Poland.
... There are also different factors in the coffee brewing that may affect the aroma in the final product; some of these are water temperature and hardness, as well as the method or machine used. In the case of water temperature, if it is not hot enough (ideal: 85-95 • C), volatile aromatic compounds are not fully incorporated and released, providing a coffee that is weak and low in aromatics [9]. Regarding water hardness, Dadali et al. [10] found that coffee brewed with medium water hardness (Total dissolved solids = TDS = 141 mg L −1 ) provides a product with more aromas compared to soft (TDS = 60 mg L −1 ) and high water hardness (TDS = 424 mg L −1 ). ...
Aroma is one of the main attributes that consumers consider when appreciating and selecting a coffee; hence it is considered an important quality trait. However, the most common methods to assess aroma are based on expensive equipment or human senses through sensory evaluation, which is time-consuming and requires highly trained assessors to avoid subjectivity. Therefore, this study aimed to estimate coffee intensity and aromas using a low-cost and portable electronic nose (e-nose) and machine learning modeling. For this purpose, triplicates of nine commercial coffee samples with different intensity levels were used for this study. Two machine learning models were developed based on artificial neural networks using the data from the e-nose as inputs to i) classify the samples into low, medium, and high intensity (Model 1) and ii) to predict the relative abundance of 45 different aromas (Model 2). Results showed that it is possible to estimate the intensity of coffees with high accuracy (98%; Model 1), as well as to predict the specific aromas obtaining a high correlation coefficient (R = 0.99), and no under- or over-fitting of the models were detected. The proposed contactless, non-destructive, rapid, reliable, and low-cost method showed to be effective in evaluating volatile compounds in coffee, which is a potential technique to be applied within all stages of the production process to detect any undesirable characteristics on-time and ensure high-quality products.
... Early work by Pangborn examined coffee brewed using a stirred pour-over technique with distilled water at 65, 80, 90, and 100 °C, and found that bitterness and sourness in general increased with temperature; complementary experiments with hard and soft water at 80 and 100 °C yielded similar increases 24 . At hotter temperatures, closer to the traditional range of drip brew, an investigation of espresso coffee systematically varied the water temperature between 88 and 98 °C and found that hotter water predictably increased TDS and PE, and yielded more acrid, roasty, bitter, and sour attributes 25 . Further work on espresso determined that espressos prepared with sufficiently small temperature differences (80-93 °C) yielded imperceptible differences as assessed by triangle test performed by untrained panellists, while larger temperature differences (80-128 °C) yielded a significant number of panellists www.nature.com/scientificreports/ ...
The brew temperature is widely considered a key parameter affecting the final quality of coffee, with a temperature near 93 °C often described as optimal. In particular, drip brewers that do not achieve a minimum brew temperature of 92 °C within a prescribed time period fail their certification. There is little empirical evidence in terms of rigorous sensory descriptive analysis or consumer preference testing, however, to support any particular range of brew temperatures. In this study, we drip-brewed coffee to specific brew strengths, as measured by total dissolved solids (TDS), and extraction yields, as measured by percent extraction (PE), spanning the range of the classic Coffee Brewing Control Chart. Three separate brew temperatures of 87 °C, 90 °C, or 93 °C were tested, adjusting the grind size and overall brew time as necessary to achieve the target TDS and PE. Although the TDS and PE both significantly affected the sensory profile of the coffee, surprisingly the brew temperature had no appreciable impact. We conclude that brew temperature should be considered as only one of several parameters that affect the extraction dynamics, and that ultimately the sensory profile is governed by differences in TDS and PE rather than the brew temperature, at least over the range of temperatures tested.
... The influence of pressure has also been studied in combination with the extraction temperature, and the analysis showed that the temperature and pressure settings from domain-expert guidelines (i.e., 92 • C and 9 bar) are close to the ones needed to obtain the best quality espresso coffee [7]. The effect on quality is also studied with respect to the extraction temperature [8], water composition [9], roasting conditions [10] and also of coffee/water ratio, type of coffee and roast combined [11]. Proton-transfer-reaction time-of-flight MS (PTR-ToF-MS) is also exploited for monitoring changes in the volatile composition and PCA and hierarchical cluster analysis are applied to differentiate between coffee types [12]. ...
Coffee is among the most popular beverages in many cities all over the world, being both at the core of the busiest shops and a long-standing tradition of recreational and social value for many people. Among the many coffee variants, espresso attracts the interest of different stakeholders: from citizens consuming espresso around the city, to local business activities, coffee-machine vendors and international coffee industries. The quality of espresso is one of the most discussed and investigated issues. So far, it has been addressed by means of human experts, electronic noses, and chemical approaches. The current work, instead, proposes a data-driven approach exploiting association rule mining. We analyze a real-world dataset of espresso brewing by professional coffee-making machines, and extract all correlations among external quality-influencing variables and actual metrics determining the quality of the espresso. Thanks to the application of association rule mining, a powerful data-driven exhaustive and explainable approach, results are expressed in the form of human-readable rules combining the variables of interest, such as the grinder settings, the extraction time, and the dose amount. Novel insights from real-world coffee extractions collected on the field are presented, together with a data-driven approach, able to uncover insights into the espresso quality and its impact on both the life of consumers and the choices of coffee-making industries.
... The preparation of the infusion is very consumer-friendly without lengthy preparation. Although data about the content of caffeine and chlorogenic acids in (roast) coffee brews were published previously (Jeon et al., 2017;Rodrigues and Bragagnolo, 2013;Ranić et al., 2015;Angeloni et al., 2019;Andueza et al., 2003), very limited data for caffeine and CGA in green coffee infusion has been published yet (Stelmach et al., 2015;Jeszka-Skowron et al., 2016). Some studies report on green coffee extracts, but did not consider the preparation of an infusion by the consumer (Shan et al., 2017;Urakova et al., 2008;Naidu et al., 2008;Craig et al., 2016;Upadhyay et al., 2012). ...
Green coffee infusion is a novel and emerging food. This is the first study to report on caffeine and chlorogenic acid content in green coffee infusion as ingested by the consumer. Caffeine was determined by adapting the corresponding DIN/ISO HPLC method. Chlorogenic acids were measured by AOAC standardized photometric method. Both methods were adapted and validated for the green coffee beans and resulting infusions. Results for caffeine in green coffee infusion reached from 113 to 188 mg/L in C. arabica infusions, and from 186 to 293 mg/L in C. canephora infusions. A decaffeinated green coffee infusion sample contained 6.2 mg/L. Results of chlorogenic acid ranged from 628 to 1040 mg/L in C. arabica infusions, and from 682 and 1210 mg/L in C. canephora infusions. Decaffeinated Arabica green coffee infusion sample had a concentration of 767 mg/L. Infusions from Robusta exceeded Arabica samples by far regarding caffeine and chlorogenic acid content. Results are discussed with numerous references in detail.
... En la Figura 19, se muestran las densidades obtenidas para los tres tipos de café a diferentes perfiles de temperatura. Como se observa no hubo diferencias notables en ninguno de los cafés bajo las diferentes curvas de temperatura, situación que se corrobora con estudios realizados por Andueza et al. (2003aAndueza et al. ( , 2003bAndueza et al. ( , 2007. Masella et al. (2015), publicaron que la densidad viene afectada significativamente por la presión y no por la temperatura, lo que demuestra que los perfiles de temperatura no modifican la densidad. ...
This thesis was devoted to the analysis and evaluation of statistical methods to
assess the quality of the coffee. In this sense, a contribution to try to quantify and
qualify the coffee quality through statistical techniques addressed from Bayesian
statistics, multivariate and experimental design were given. The methods described
in each of the studies carried out, show the relationship and the differences of the
different techniques used.
In the first study, the coffee index of quality of the coffee from the department of
Valle del Cauca in Colombia was developed taking into account the organoleptic and
agronomic characteristics using Bayesian factor analysis. A database with some
missing values (missing values). containing different organoleptic tests and
agronomic aspects of the crop was used in the analysis. For the treatment of the data
it was necessary to use data imputation techniques (listwise or case deletion (CD)
Hot deck (HD) and multiple imputation (MI) of which database product chosen
multiple imputation (MI ), since this technique showed more goodness in relation to
others. Finally, it was found for the first time, coffee index of quality using a multiple
factor analysis of Bayesian character due to the nature of the data as possible and
complex parameterization. This index reflected spatially coffee crop areas that are
identified as areas that produce good quality coffee. Besides other analyzes of
interest in relation to the variety, profit, certification and others were performed.
In the second study, the quality of the espresso was determined by investigating the
effect of extraction temperature on the physicochemical properties of espresso, using
three types of Natural Robusta coffees (Type A), Natural Arabica (Type B) and
washed Arabica (Type C) and three different temperature profiles: upward extraction
temperature (88 - 93 °C), flat (90-90 ºC) and downstream (93-88 ºC) with the latest innovation machine XCELSIUS RANCILIO class 9 trademark. The experimental
design statistical tool known as the ANOVA analysis of variance of two factors (type
of coffee and temperature profile) was used. Analyses showed that the use of
temperature profiles allows modifying, modulate, enhance or reduce the organoleptic
descriptors of an espresso.
Finally, in the third study, the discriminatory elements to characterize espresso
using the three types of coffees and profiles or extraction temperature curves that
were used in the previous study were identified. The physicochemical properties
were determined and cup tests were performed through a tasting panel that yielded
organoleptic descriptors for each CE. The statistical processing using the multivariate
technique called principal component analysis (PCA) was performed to analyze and
visualize possible correlations, and to allow the identification of trends in the quality
and their relationship to physicochemical properties.
... For example, For Arabica and Robusta Natural blend (espresso coffee), 92 °C was the optimal water temperature. For Robusta Torrefacto blend (espresso coffee) the overall acceptability might lead to the selection of 88 °C as the ideal water temperature [6]. Therefore, the aim of this project is to study the appropriate brewing condition for Centella asiatica tea. ...
Centella asiatica has known as medical plant that used for treating bruises and reducing swelling. From the previous research lately, it reported that C.asiatica has properties to improve memory recognition and promote healthy skin. C.asiatica is herbal plant that available in the market, it has been developed to enhance the amount of antioxidant. Therefore, this study was aimed to determine the most effective brewing process of C.asiatica tea and study the amount of antioxidant activities. The temperature was vary with 80°C, 85°C, and 90°C and time was 2, 3, 4, and 5 minutes. The formation of consuming tea was determined by 30 target panelists. The result showed that there was no significant difference among all temperature and time that were determined. The best temperature and time for brewing is 80°C at 5 minutes because it saves energy and can extract the highest amount of antioxidant from herbal tea.
... Because hot water can extract many chemical compounds. Some volatile substances were responsible for aroma and contributed to the taste of a cup of coffee [17]. ...
Dampit coffee and Ijo coffee has unique characteristics depending on the temperature and brewing method. One of the common coffee brewing methods used is Mokapot. The study aims to determine the sensory characteristics of Dampit coffee and Ijo coffee when brewed with Mokapot method at different temperatures. The method used for characterizing their sensory attributes was RATA (Rate-All-That-Apply) method. Consumer respondents were asked to select all perceived attributes and their intensities. The result indicated that sensory characteristic of both coffees change along with different brewing temperature. It is also important to note that bitter taste tends to be constantly rated along with different brewing temperature. Meanwhile, bitter aftertaste tends to decrease as the increase of brewing temperature.
... Concerning CGA concentrations, our data confirmed the ranges reported by Moeenfard et al. 28 , with particular high amounts of 3-CQA and 5-CQA (about 1 mg/mL each) for ECs #D-49 and #D-50 (Supplementary Table 4). These 5-CQA concentrations close to 1 mg/mL, two-to five-fold higher than those recorded for most of the capsule ECs (Supplementary Table 4), were also registered by Andueza et al. 22,30 for a set of blended ECs brewed under different extraction conditions. Table 2 also shows that ECs belonging to brand C had the highest content in the sum of these phenolics, hitting an average 118.0 ± 18.5 mg/serving, while brand D coffees had the lowest values, with an average of 83.7 ± 12.8 mg/serving. ...
Coffee is one of the most popular beverages worldwide and, nowadays, one of the most practical way for its preparation is by prepacked capsules. The aim of this study was comparing the content in caffeine, trigonelline, N-methylpyridinium (NMP), niacin, and chlorogenic acids of 65 different capsule-brewed coffees, commercialised by 5 of the most representative brands in Italy. Coffees were prepared from capsules following manufacturer’s instructions and analysed with an optimized UHPLC-MS/MS method able to assess all these phytochemicals in one single run. Inter-lot and capsule variability were also studied for a subset of coffee capsules. Except for decaffeinated coffees, caffeine amount accounted between 54 and 208 mg/serving. Regular espresso coffees showed higher trigonelline, NMP, and niacin concentrations than large (lungo) and decaffeinated samples, with average serving amounts of 17.96, 1.78, and 0.66 mg, respectively. Regarding chlorogenic acids, caffeoylquinic acids were the most relevant ones (20–117 mg/serving). Feruloylquinic acids were quantified between 8 and 50 mg/serving. Coumaroylquinic acids, hydroxycinnamate dimers, caffeoylshikimic acids, and caffeoylquinic lactones were also present at lower concentrations. Multivariate analysis provided comprehensive information on the phytochemical profile of the different types of coffee, showing a great variability among coffees with some brand-related insights. This study supports the need for accurately characterizing espresso coffees while investigating the beneficial effects of coffee on human health.
Penelitian ini bertujuan untuk mengetahui pengaruh temperature, grind size dan jenis portafilter terhadap kadar total dissolved solids (TDS) dan extraction yield (EXT) dan menemukan pengaturan mesin kopi espresso sistem pneumatik yang optimal untuk mencapai kualitas terbaik. Pada penelitian ini dilaksanakan dengan menguji karakteristik kopi espresso yaitu kadar total dissolve solid (TDS) dan extraction yield (EXT) akibat pengaruh temperatur, grind size dan tipe portafilter. Desain eksperimen faktorial penuh (full factorial design of experiments - FFD) digunakan untuk mengidentifikasi variabel yang memiliki pengaruh yang signifikan pada kualitas espresso yang dihasilkan. Data penelitian diolah menggunakan analisa varian (analysis of variance - ANOVA) dengan bantuan perangkat lunak Minitab. Hasil penelitian menunjukkan bahwa temperature, grind size dan tipe portafilter secara statistik memiliki pengaruh yang signifikan dengan tingkat kepercayaan 100% dalam mempengaruhi kadar total dissolved solids (TDS). Grind size dan tipe portafilter secara statistik juga memiliki pengaruh signifikan terhadap extraction yield (EXT) dengan tingkat kepercayaan 100%. Sebaliknya, nilai p-value yang lebih tinggi untuk faktor temperatur menunjukkan bahwa faktor tersebut secara statistik tidak memiliki pengaruh signifikan terhadap extraction yield (EXT). Hasil optimasi respons untuk kadar total dissolved solids (TDS) dan extraction yield (EXT) menghasilkan niai composite desirability (D) sebesar 0,7255. Dari nilai tersebut dapat disimpulkan bahwa kondisi optimal yang ditemukan melalui plot optimasi cukup dapat diandalkan dan sesuai dengan model regresi yang telah diuji secara kredibel. Variabel yang dapat menghasilkan kadar total dissolved solids (TDS) dan extraction yield (EXT) paling optimal didapat dari pengaturan temperatur 1000C, grind size 2.8 dan penggunaan un-pressurized portafilter. Kadar total dissolved solids (TDS) dan extraction yield (EXT) yang dihasilkan dari metode respon optimasi ini masing-masing sebesar 11,5252% dan 22,348%.
Considering the great economic significance of Coffea arabica (arabica) associated with the lower production cost of C. canephora (conilon), blends of these coffees are commercially available to reduce costs and combine sensory attributes. Thus, analytical tools are required to ensure consistency between real and labeled compositions. In this sense, chromatographic methods based on volatile analysis using static headspace-gas chromatography-mass spectrometry (SHS-GC-MS) and Fourier transform infrared (FTIR) spectroscopy associated with chemometric tools were proposed for the identification and quantification of arabica and conilon blends. The peak integration from the total ion chromatogram (TIC) and extracted ion chromatogram (EIC) was compared in multivariate and univariate scenarios. The optimized partial least squares (PLS) models with uninformative variable elimination (UVE) and chromatographic data (TIC and EIC) have similar accuracy according to a randomized test, with prediction errors between 3.3% and 4.7% and Rp2 > 0.98. There was no difference between the univariate models for the TIC and EIC, but the FTIR model presented a lower performance than GC-MS. The multivariate and univariate models based on chromatographic data had similar accuracy. For the classification models, the FTIR, TIC, and EIC data presented accuracies from 96% to 100% and error rates from 0% to 5%. Multivariate and univariate analyses combined with chromatographic and spectroscopic data allow the investigation of coffee blends.
The fresh flavor of a beer brand is one of its most important quality parameters and should be retained as long as possible through shelf-life. Early stages of beer production can have significant impacts on beer flavor stability. The use of cereal adjuncts – either malted or unmalted – is now widespread practice in brewing. This laboratory mashing study investigated the impacts of incorporating common solid adjuncts (corn and rice) at increasing grist percentages (0-50%) on flavor stability indicators measured in wort. Sweet worts were analysed for metal ion levels (ICP-MS), thiol content (RP-HPLC), oxidative stability (EPR spectroscopy), staling aldehydes (HS-SPME-GC-MS), trihydroxy fatty acids (GC-FID), t-2-nonenal potential (GC-MS), color and thiobarbituric acid (TBI). Mashing conditions for each formulation were adjusted in order to achieve target FAN values. Unmalted rice or corn adjuncts significantly reduced the total metal ion content, color, TBI and staling aldehydes in sweet worts at 50% adjunct incorporation (p < 0.05), relative in each case to the respective all-malt control mash. Our findings showed that unmalted rice or corn adjunct incorporation generally improved flavor stability metrics in sweet worts when similar mashing conditions were applied, whilst increasing the length of the ‘protein stand’ in mashing to reach target FAN in general had a negative impact on flavor stability indicators – e.g., wort T150 values significantly decreased in each recipe at 25% and 35% adjunct relative to the 12.5% adjunct brew but increased again at 50% adjunct, presumably due to the prolonged proteolytic stand employed to achieve target FAN content.
Coffee contains a variety of organic acids (OAs) and chlorogenic acids (CGAs) that contribute to overall sensory properties. Large variations in preparation and measurement methodology across the literature complicate interpretation of general trends. Here, we perform a systematic review and meta-analysis of the published literature to elucidate the concentrations of OAs and CGAs in both Coffea arabica (arabica) and Coffea canephora (robusta), for both green coffee and roasted coffee at multiple roast levels. A total of 129 publications were found to report acid concentration measurements, yielding 8,634 distinct data points. Analysis of the full data set reveals several trends. First, roasted robusta has considerably more acidic compounds than arabica with 2 to 5 times as much total OAs, and much larger amounts of formic and acetic acid. As for CGAs, in both arabica and robusta 5-CQA is the major component, and progressive roasting decreases the concentration of all CGAs. The total amount of CGA present was more dependent on roast level than the type of coffee (arabica vs. robusta). Overall, this meta-analysis suggests that the increases in certain OAs with roast level might play more of a role in the sensory profile of dark roast coffees than previously suspected.
In this study, the extraction kinetics, based on total dissolved solid (TDS), at different temperatures (4, 23, 50, and 93°C) for different grind sizes (VMD = 139, 643, 1,450, 1,747 μm) were investigated. Coffee extraction proceeded in initial fast extraction stage followed by a significantly slower extraction stage, which correspond to the extraction from surfaces of broken cells and the extraction from intact coffee cells, respectively. Diffusion inside the coffee particle is a very slow process, so breaking the cells is a very efficient way to increase the mass transfer rate. In addition, the ultimate extraction yield increased with increasing brewing temperature and decreasing of particle size. The Weibull distribution, pseudo‐first order and pseudo‐second order model were fitted to the kinetics data, with high coefficients of determination (0.687–0.998), and low root mean square error (0.02–0.26%). Meanwhile, exponential equations were created to correlate the derived rate constants (1/α, k1, and k2) with brewing temperature and particle size to achieve the prediction of brewing extent (TDSt/TDSeqm) at different temperature‐particle size combinations.
Practical applications
This study investigated the kinetics of coffee extraction at different grind size and temperature conditions with the purposes to better understanding the cold and hot coffee brewing process, as well as to predict the coffee extraction. The findings in this study will have practical applications in three folds:
• Help manufacturers of coffee brew products (ready to drink or concentrate) to better design and control their coffee extraction process.
• Aid manufacturers of coffee extraction equipment and coffee brewers to improve their products
• Provide reference information for coffee store, barista, coffee enthusiast, and consumers to brewing a better cup of coffee
From its legendary discovery in Abyssinia (today Ethiopia) to becoming one of the most consumed beverages in the world, coffee has captivated the enthusiasts for centuries due to its unique aroma and taste, as well as its effects as a stimulant in enhancing mental performance (e.g., alertness, concentration, attention). This article provides a brief overview on the production and processing of coffee, focusing on the Coffea arabica and Coffea canephora var. Robusta, also known as Arabica and Robusta, respectively. Differences in chemical compositions (e.g., lipid, sucrose, trigonelline, diterpenes, caffeine, chlorogenic acids) of bean variety contribute to desirable/undesirable sensory attributes, as well as the health implications of the final brew products. Roasting of green beans, which is typically carried out at 170–230 °C for 10–15 min, causes the degradations of polysaccharides, sugars, amino acids, chlorogenic acids, and so on. Concomitantly, a myriad of aroma volatiles and complex condensed products are formed, mainly due to Maillard reaction, Strecker degradation and pyrolytic reactions. The effects of roast time–temperature profiles on a number of key physicochemical phenomena are discussed, including changes in microstructural, formation of aroma species, development of color, and generation of CO2 during roasting. Optimal storage conditions and packaging are important in delaying product staling and to mitigate CO2 degassing issues. These aspects, along with other factors that affect the shelf-life of coffee, are discussed. Finally, a brief literature review on the health implications of coffee consumption is presented, highlighting the importance of several bioactive components (e.g., caffeine, chlorogenic acids, melanoidins, trigonelline, acrylamide, and diterpenes).
In this study, the concentration of furan and 2-methylfuran in espresso coffee (EC) obtained from Arabica and Robusta coffee varieties was determined as a function of specific particle size. The particle size and coffee variety significantly influenced the level of furan and 2-methylfuran. In Arabica variety, furan and 2-methylfuran level increased with increasing particle size. Particularly, from C<200μm to C>425μm fractions, furan increased from 68.27 to 91.48 ng mL⁻¹ while 2-methylfuran from 404.31 to 634.64 ng mL⁻¹. In Robusta variety, the highest concentration of furan and 2-methylfuran occurred in ECs prepared using C300-425μm fraction showing values of 116.39 ng mL⁻¹ and 845.14 ng mL⁻¹, respectively, for furan and 2-methylfuran. On the basis of this experiment, it is possible to establish a mitigation strategy by manipulating the particle size and coffee variety in order to reduce the level of furan and 2-methylfuran in EC up to 11.4% and 18.8%, respectively.
Espresso coffee (EC) is a complex and much appreciated beverage among coffee consumers. The extraction phase of EC, a combination of physical and chemical variables in a very short time, has a direct effect on the flavour of the beverage. This research aims to optimize the extraction process of EC by decreasing the amount of ground coffee from 14g to 12g (double cup), while keeping constant the particle size of ground coffee and the physical parameters of the espresso machine, making use of the following accessories: two different filter baskets, and four different heights of perforated discs (4-7mm). Quantitative analyses on several organic acids (acetic, citric, caffeic, malic, tartaric) and caffeine, trigonelline, nicotinic and 5-caffeoylquinic acid are carried out with HPLC-VWD through a newly developed method. This combines the quantification of organic acids, obtained through HPLC-VWD, with the results of a sensory panel evaluation on the descriptive notes of EC. The outcomes will trigger and support further studies on different extraction processes, to develop more sustainable and economically affordable coffee of high quality.
Espresso machines maintain constant the extraction process of espresso coffee (EC), however, it is difficult to grind roasted coffee in homogeneous way. This research aims to investigate grinded beans at specific particle sizes in three variously designed filter baskets and to compare the concentration of bioactive compounds while decreasing the amount of ground coffee. Analyses on caffeine, trigonelline and chlorogenic acids are carried out with HPLC-VWD, while volatiles with HS-SPME/GC-MS. Extracting with smaller particles escalates the quantity of bioactive compounds. The amount of caffeine/cup increased moving from 500-1000 µm to 200-300 µm particle size, both in Arabica and Robusta for all filter baskets. Keeping constant the volume of EC at various heights of perforated disc, the amount of bioactive compounds at 12 g were only around 9% lower than at 14 g. The outcomes will support further studies on different extraction processes, to develop more sustainable and economically affordable coffee.
Very hot (> 65 °C) beverages such as espresso were evaluated by the International Agency for Research on Cancer (IARC) as probably carcinogenic to humans. For this reason, research into lowering beverage temperature without compromising its quality or taste is important. For espresso, one obvious possibility consists in lowering the brewing temperature. In two sensory trials using ISO 4120:2004 triangle test methodology, brewing temperatures of 80°C vs. 128°C and 80° vs. 93°C were compared. From the tested levels, espresso brewed at the lowest temperature had the highest acceptance. However, most tasters were unable to distinguish between 80°C and 93°C. The results of these pilot experiments proof the possibility to decrease the health hazard of very hot beverages by lower brewing temperatures.
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.
Aroma extract dilution analysis (AEDA) revealed 13 compounds as important contributors to the aroma of roasted coffee (powder): 2-methyl-3-furanthiol (I), 2-furfurylthiol (II), methional (III), 3-mercapto-3-methylbutylformate (IV), 3-isopropyl-2-methoxypyrazine (V), 2-ethyl-3,5-dimethylpyrazine (VI), 2,3-diethyl-5-methylpyrazine (VII), 3-isobutyl-2-methoxy-pyrazine (VIII), 3-hydroxy-4,5-dimethyl-2(5H)-furanone (sotolon, IX), 4-ethylguaiacol (X), 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone (XI), 4-vinylguaiacol (XII), and (E)--damascenone (XIII). A comparative AEDA of the coffee powder and brew showed in the brew an increase of III, IX, vanillin and 4-hydroxy-2,5-dimethyl-3(2H)-furanone and a decrease of I, II, IV, V, VII, and VIII.Die Aromaextrakt-Verdnnungsanalyse (AEVA) von Rstkaffee ergab 13 wichtige Geruchsstoffe: 2-Methyl-3-furanthiol (I), 2-Furfurylthiol (II), Methional (III), 3-Mercapto-3-methylbutylformiat (IV), 3-Isopropyl-2-methoxypyrazin (V), 2-Ethyl-3,5-dimethylpyrazin (VI), 2,3-Diethyl-5-methylpyrazin (VII), 3-Isobutyl-2-methoxypyrazin (VIII), 3-Hydroxy-4,5-dimethyl-2(5H)-furanon (Sotolon, IX), 4-Vinylguajacol (XII) und (E)--Damascenon (XIII). Die vergleichende AEVA von Rstkaffee und daraus hergestelltem Aufgu zeigte im Aufgu eine Zunahme von III, IX, Vanillin und 4-Hydroxy-2,5-dimethyl-3(2H)-furanon und eine Abnahme von I, II, IV, V, VII und VIII.
Understanding "what" consumers want and "why" are two of the most significant hurdles faced by any business creating products for consumers. Properly conducted sensory research experiments can provide answers to these questions and more. Sensory evaluation provides strategic information at various stages in the product lifecycle including the front end of innovation, new product development, product optimization, marketplace audits, and quality control among others. Sensory research can help identify issues that contribute to a product's success (or failure). This fourth edition draws on the author's practical experience in partnering with business associates in marketing and development teams to bring creativity and innovation to consumer driven product development in today's global business environment. The field of sensory science continues to grow and is now recognized as a strategic source of information for many Fortune 500 companies. Many scientists working in this field depend on the core textbooks such as this one to enhance their working knowledge base with practical business applications. * Appeals to sensory professionals in both in academia and business * Methods to integrate sensory descriptive information and consumer assessment * Coordinate marketing messages and imagery with the product's sensory experience.
twentytwo compounds, which had been revealed by dilution experiments as potent odorants, were quantified by stable isotope dilution assays in brews prepared fro roasted Arabica and Robusta coffees. Calculation of odor activity values (OAVs); ratio of concentration to odor threshold) indicated 2-furfurylthiol, 3-mecapto-3-methylbutyl formate, methanethiol, ß-damascenone, methylpropanal, 3-methylbutanal as the most potent odorants. However, the rankings of the OAV were different in the two coffee brews. Thextraction yields obtained during the preparation of the brews were determined for 17 odorants. Polar compounds /e.g. guaiacol, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 2,3-butanedione) were extracted with higher yields (75-100 %); nonpolar compounds (e.g. ß-damascenone, 2-isobutyl-3-methoxypyrazine) gave yields of only 10-25%. The overall odor of the models containing the odorants in the concentation levels that had been found in the two brews was clearly coffee-like. The models reproduce the differences in the odor profiles of the two brews.
Two coffees of different botanical and geographical origins were used: Brazil coffee (dry-processed Arabica) and Uganda coffee (dry-processed robusta). The samples were roasted, and the foamability and foam stability of the espresso coffee were determined as a function of the degree of roast. Espresso coffees were characterized with regard to the amount of total solids, pH, fat, protein, and carbohydrate. The polymeric carbohydrates were precipitated with ethanol solutions (55 and 75% ethanol fractions), and the component monosaccharides were quantified by gas−liquid chromatography. A principal component analysis was applied to the chemical variables. This study showed that foamability of the espresso coffee increases with degree of roast and depends on the amount of protein in the infusion. Foamability as a function of the degree of roast does not differ significantly for the two coffees. Foam stability of espresso coffee as a function of degree of roast is related to the amount of galactomannan and arabinogalactan present and seems to be independent of the origin of the coffee despite the coffees having shown a different degree of roast for maximum foam stability. The degree of roast as a technological parameter does not allow an espresso coffee with maximum foamability and foam stability to be obtained at the same time. Keywords: Espresso coffee; degree of roast; foamability; foam stability; galactomannan; arabinogalactan; multivariate analysis; principal component analysis
Chlorogenic acids (CGA) are a group of phenolic acid derivatives which are commonly found and differently distributed in higher plants. The CGA pattern can successfully be employed to characterize green and roasted coffees of different origins and qualities. This paper reports on the possibilities of characterizing green or roasted coffees by the CGA fraction through HPLC-W and principal component analysis (PCA) and comparing the results with those from sensory evaluation. The CGA fraction was prepared by submitting the Melitta extracts of green and roasted coffees to cleanup on a C-18 cartridge, and the 40/60 methanol/water fraction was then analyzed by a RP-C-18 column at 325 nm using a methanol/citrate-hydrochloric acid mobile phase in gradient elution. Examples concern the discrimination of coffees of the same quality but from different origins or plantations, discrimination of coffee blends of different compositions, and comparison with sensory evaluation.
The volatiles forming the pleasant odour arising from freshly roasted coffee beans were investigated by means of an improved headspace technique with intermediate cryo-focusing and simultaneous sniffing analysis. Shelf-life tests were carried out with whole beans in non-air tight packs and indicated that the loss of aroma freshness several days to weeks after roasting corresponded to the decrease in certain low boiling volatiles, mainly methanethiol. To validate the method, several starting parameters were investigated, specifically the influence of particle size, degree of roasting and coffee bean origin. Results reveal that this headspace technique allows an objective evaluation of the aroma freshness of whole coffee beans without exact knowledge of coffee origin, degree of roasting or starting values. In addition the method differentiates between Arabica and Robusta coffees.Die Zusammensetzung des angenehmen Aromas, das von frisch gersteten Kaffeebohnen ausgeht, wurde mit einer Headspace-Methodik unter Einschaltung eines Cryofocussierungsschrittes sowie paralleler Schnffelanalyse untersucht. Kinetische Studien mit ganzen Rstkaffeebohnen, die in nicht luftdichter Verpackung gelagert wurden, ergaben, da die lagerungsbedingte Abnahme der Aromafrische mit dem Verlust bestimmter leichtflchtiger Verbindungen insbesondere Methanthiol korreliert. Zur Validierung der Methode wurde der Einflu verschiedener Parameter z. B. Mahlgrad, Rstgrad oder Provenienz, untersucht. Die Ergebnisse legen nahe, da die entwickelte Methodik zur objektiven Beurteilung der Aromafrische ganzer Rstkaffeebohnen eingesetzt werden kann und zwar in weiten Bereichen ohne spezielle Kenntnis der Kaffee-Herkunft, des Rstgrades sowie anderer Einflugren. Darber hinaus ist eine analytisch-chemische Differenzierung zwischenArabica undRobusta-Einzelprovenienzen mglich.
The highly volatile, potent odorants of coffee samples were evaluated by gas chromatography-olfactometry of decreasing headspace samples (GCO-H). 2,3-Butanedione, 2,3-pentanedione, 3-methyl-2-butenthiol (I), methional, 2-furfurylthiol (II) and 3-mercapto-3-methylbutylformate (III) were the key odorants of both, the powders of Arabica and Robusta coffees. 2-Methyl-3-furanthiol (IV), 2,3-diethyl-5-methylpyrazine and an unknown compound were additional key odorants of the latter. An increase in the odour potencies of acetaldehyde, propanal, methylpropanal, 3-methylbutanal and dimethyltrisulphide as well as a decrease in the odour potencies of the thiols I to IV in the brews were the major differences with regard to the powders.
Equilibration time and temperature were the factors studied to choose the best conditions for analyzing volatiles in roasted ground Arabica coffee by a static headspace sampling extraction method. Three temperatures of equilibration were studied: 60, 80, and 90 degrees C. A larger quantity of volatile compounds was extracted at 90 degrees C than at 80 or 60 degrees C, although the same qualitative profile was found for each. The extraction of the volatile compounds was studied at seven different equilibration times: 30, 45, 60, 80, 100, 120, and 150 min. The best time of equilibration for headspace analysis of roasted ground Arabica coffee should be selected depending on the chemical class or compound studied. One hundred and twenty-two volatile compounds were identified, including 26 furans, 20 ketones, 20 pyrazines, 9 alcohols, 9 aldehydes, 8 esters, 6 pyrroles, 6 thiophenes, 4 sulfur compounds, 3 benzenic compounds, 2 phenolic compounds, 2 pyridines, 2 thiazoles, 1 oxazole, 1 lactone, 1 alkane, 1 alkene, and 1 acid.
Three espresso coffee (EC) samples of different botanical varieties and types of roast were prepared in standard conditions using an experimental EC prototype: Arabica coffee, Robusta Natural blend, and Robusta Torrefacto blend (a special roast by adding sugar). The ECs were characterized with regard to the physical parameters, amount of total solids, total solids on filtrate, lipids, caffeine, trigonelline, and chlorogenic acids by HPLC, and sensory descriptive analysis related to foam appearance, taste, and mouthfeel. Principal component analysis (PCA) was applied to differentiate the EC samples. Arabica and Robusta samples were separated successfully by principal component 1 (55.3% of variance) including physicochemical and sensory parameters related to foam and taste of ECs. Torrefacto and Robusta Natural EC samples were separated by principal component 2 (20.7% of total variance) including mouthfeel and other attributes of color foam. Some interesting correlations among sensory and physicochemical variables were found. A very simple discriminate function was obtained by discriminate analysis allowing the classification of each EC sample into its respective group with a success rate of 100%.
The aromas of three espresso coffee (EC) samples from different botanical varieties and types of roast (Arabica coffee, Robusta natural blend, and Robusta Torrefacto blend (special roast by adding sugar)) were studied by static headspace GC-MS and sensory flavor profile analysis. Seventy-seven compounds were identified in all of the EC samples. Among them, 13 key odorants have been quantified and correlated with their flavor notes by applying multivariate statistical methods. Some correlations have been found in the EC samples: some aldehydes with fruity flavors, diones with buttery flavors, and pyrazines with earthy/musty, roasty/burnt, and woody/papery flavors. By applying principal component analysis (PCA), Arabica and Robusta samples were separated successfully by principal component 1 (60.7% of variance), and Torrefacto and Natural Robusta EC samples were separated by principal component 2 (28.1% of total variance). With PCA, the aroma characterization of each EC sample could be observed. A very simple discriminant function using some key odorants was obtained by discriminant analysis, allowing the classification of each EC sample into its respective group with a success rate of 100%.
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