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17 pages, 661 KiB  
Article
An Ultrasonication-Assisted Green Process for Simultaneous Production of a Bioactive Compound-Rich Extract and a Multifunctional Fibrous Ingredient from Spent Coffee Grounds
by Jaquellyne B. M. D. Silva, Mayara T. P. Paiva, Henrique F. Fuzinato, Nathalia Silvestre, Marta T. Benassi and Suzana Mali
Molecules 2025, 30(15), 3117; https://doi.org/10.3390/molecules30153117 - 25 Jul 2025
Viewed by 259
Abstract
Spent coffee grounds (SCGs) are lignocellulosic residues generated from producing espresso or soluble coffee and have no commercial value. This study aimed to develop a new single-step process for extracting bioactive compounds from SCGs based on ultrasonication in an aqueous medium and simultaneously [...] Read more.
Spent coffee grounds (SCGs) are lignocellulosic residues generated from producing espresso or soluble coffee and have no commercial value. This study aimed to develop a new single-step process for extracting bioactive compounds from SCGs based on ultrasonication in an aqueous medium and simultaneously recovering the residual solid fraction, resulting in the integral utilization of the residue. This process resulted in a liquid aqueous extract (LAE) rich in bioactive compounds (caffeine: 400.1 mg/100 g; polyphenols: 800.4 mg GAE/100 g; melanoidins: 2100.2 mg/100 g) and, simultaneously, a solid multifunctional ingredient from modified spent coffee grounds (MSCGs) rich in bioactive compounds and dietary fibers (73.0 g/100 g). The liquid extract can be used as a natural ingredient for drinks or to isolate caffeine, while the solid matrix can be used to produce functional foods. This technique proved to be a promising eco-friendly alternative for the simultaneous production of two different materials from SCGs, maximizing resource efficiency, with some advantages, including short time, simplicity, and cost-effectiveness; using water as a solvent; and requiring no further purification processing. Full article
(This article belongs to the Section Green Chemistry)
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19 pages, 5003 KiB  
Article
Coffees Brewed from Standard Capsules Help to Compare Different Aroma Fingerprinting Technologies—A Comparison of an Electronic Tongue and Electronic Noses
by Biborka Gillay, Zoltan Gillay, Zoltan Kovacs, Viktoria Eles, Tamas Toth, Haruna Gado Yakubu, Iyas Aldib and George Bazar
Chemosensors 2025, 13(7), 261; https://doi.org/10.3390/chemosensors13070261 - 18 Jul 2025
Viewed by 741
Abstract
With the development of various new types of instrumental aroma sensing technologies, there is a need for methodologies that help developers and users evaluate the performance of the different devices. This study introduces a simple method that uses standard coffee beverages, reproducible worldwide, [...] Read more.
With the development of various new types of instrumental aroma sensing technologies, there is a need for methodologies that help developers and users evaluate the performance of the different devices. This study introduces a simple method that uses standard coffee beverages, reproducible worldwide, thus allowing users to compare aroma sensing devices and technologies globally. Eight different variations of commercial coffee capsules were used to brew espresso coffees (40 mL), consisting of either Arabica coffee or a blend of Robusta and Arabica coffee, covering a wide range of sensory attributes. The AlphaMOS Astree electronic tongue (equipped with sensors based on chemically modified field-effect transistor technology) and the AlphaMOS Heracles NEO and the Volatile Scout3 electronic noses (both using separation technology based on gas chromatography) were used to describe the taste and odor profiles of the freshly brewed coffee samples and also to compare them to the various sensory characteristics declared on the original packaging, such as intensity, roasting, acidity, bitterness, and body. Linear discriminant analysis (LDA) results showed that these technologies were able to classify the samples similarly to the pattern of the coffees based on the human sensory characteristics. In general, the arrangement of the different coffee types in the LDA results—i.e., the similarities and dissimilarities in the types based on their taste or smell—was the same in the case of the Astree electronic tongue and the Heracles electronic nose, while slightly different arrangements were found for the Scout3 electronic nose. The results of the Astree electronic tongue and those of the Heracles electronic nose showed the taste and smell profiles of the decaffeinated coffees to be different from their caffeinated counterparts. The Heracles and Scout3 electronic noses provided high accuracies in classifying the samples based on their odor into the sensory classes presented on the coffee capsules’ packaging. Despite the technological differences in the investigated devices, the introduced coffee test could assess the similarities in the taste and odor profiling capacities of the aroma fingerprinting technologies. Since the coffee capsules used for the test can be purchased all over the world in the same quality, these coffees can be used as global standard samples during the comparison of different devices applying different measurement technologies. The test can be used to evaluate instrumentational and data analytical developments worldwide and to assess the potential of novel, cost-effective, accurate, and rapid solutions for quality assessments in the food and beverage industry. Full article
(This article belongs to the Special Issue Electronic Nose and Electronic Tongue for Substance Analysis)
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14 pages, 5810 KiB  
Article
CO2 Absorption on Cu-Doped Graphene, a DFT Study
by Juan Oseas López Fuentes, Roxana Mitzayé del Castillo Vázquez and Juan Manuel Ramirez-de-Arellano
Crystals 2025, 15(5), 460; https://doi.org/10.3390/cryst15050460 - 14 May 2025
Viewed by 1224
Abstract
We studied the interaction between a Cu-doped graphene layer and a CO2 molecule, using DFT, ab initio calculations, and the pseudopotential formalism. We used the Quantum ESPRESSO code package, with the PBE XC functional expression and the semiempirical Grimme’s DFT-D3 Van der [...] Read more.
We studied the interaction between a Cu-doped graphene layer and a CO2 molecule, using DFT, ab initio calculations, and the pseudopotential formalism. We used the Quantum ESPRESSO code package, with the PBE XC functional expression and the semiempirical Grimme’s DFT-D3 Van der Waals correction. We found that the Cu atom, being absorbed in a C vacancy on the graphene surface, has a catalytic effect on the absorption of CO2 in said surface. The Van der Waals correction calculations showed that the CO2 is physisorbed, with an adsorption energy of −0.1786 eV. Our results are congruent with previously published results. The Cu-doped graphene surface could be suitable for the development of a CO2 sensor. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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29 pages, 7563 KiB  
Article
Influence of Fluorine Doping on Rutile TiO2 Nanostructures for Visible-Light-Driven Photocatalysis: A DFT + U Study
by Fikadu Takele Geldasa and Francis Birhanu Dejene
Nanomaterials 2025, 15(9), 694; https://doi.org/10.3390/nano15090694 - 5 May 2025
Cited by 2 | Viewed by 540
Abstract
In this work, a density functional theory (DFT) with Hubbard correction (U) approaches implemented through the Quantum ESPRESSO code is utilized to investigate the effects of fluorine (F) doping on the structural, electronic, and optical properties of rutile TiO2. Rutile TiO [...] Read more.
In this work, a density functional theory (DFT) with Hubbard correction (U) approaches implemented through the Quantum ESPRESSO code is utilized to investigate the effects of fluorine (F) doping on the structural, electronic, and optical properties of rutile TiO2. Rutile TiO2 is a promising material for renewable energy production and environmental remediation, but its wide bandgap limits its application to the UV spectrum, which is narrow and expensive. To extend the absorption edge of TiO2 into the visible light range, different concentrations of F were substituted at oxygen atom sites. The structural analysis reveals that the lattice constants and bond lengths of TiO2 increased with F concentrations. Ab initio molecular dynamics simulations (AIMD) at 1000 K confirm that both pristine and F-doped rutile TiO2 maintains structural integrity, indicating excellent thermal stability essential for high-temperature photocatalytic applications. Band structure calculations show that pure rutile TiO2 has a bandgap of 3.0 eV, which increases as the F concentration rises, with the 0.25 F-doped structures exhibiting an even larger bandgap, preventing it from responding to visible light. The absorption edge of doped TiO2 shifts towards the visible region, as shown by the imaginary part of the dielectric function. This research provides valuable insights for experimentalists, helping them understand how varying F concentrations influence the properties of rutile TiO2 for photocatalytic applications. Full article
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17 pages, 2839 KiB  
Article
Combined Effect of Spent Mushroom Substrate and Agro-Industrial Residues on Pleurotus columbinus Production and Intra-Cellular Polysaccharide Synthesis
by Marianna Dedousi, Chrysavgi Gardeli, Seraphim Papanikolaou and Panagiota Diamantopoulou
BioTech 2025, 14(2), 34; https://doi.org/10.3390/biotech14020034 - 2 May 2025
Viewed by 1286
Abstract
Spent mushroom substrate (SMS), spent coffee grounds from espresso production (SCG), faba bean harvest residues (FBR), pistachio shells (PS) wheat straw (WS) (control) agro-industrial waste were combined in different ratios, with or without supplements (wheat bran, soybean flour), to create novel substrates for [...] Read more.
Spent mushroom substrate (SMS), spent coffee grounds from espresso production (SCG), faba bean harvest residues (FBR), pistachio shells (PS) wheat straw (WS) (control) agro-industrial waste were combined in different ratios, with or without supplements (wheat bran, soybean flour), to create novel substrates for Pleurotus columbinus growth. The impact of the substrates on the mycelial growth rate (Kr), biomass production, laccase, total cellulases and carbohydrate synthesis, along with the C and N consumption by P. columbinus, were examined in fully colonized substrates. The incubation period, earliness and biological efficiency (B.E.) (%) were also determined. Then, the intracellular polysaccharide (ICP) contents of the P. columbinus produced mushrooms were evaluated in the most promising substrates. P. columbinus was grown successfully in a wide range of C/N ratios of substrates and the fastest Kr (7.6 mm/d) was detected on the 70 SMS-30 FBR, without supplements, whereas substrates consisting of SCG enhanced biomass production (700.0–803.7 mg/g d.w.). SMS and PS or SCG led to the shortest incubation and earliness period of P. columbinus. The C content was reduced and the N content was substantially increased in all the colonized substrates. The 70 SMS-30 FBR and 80 SMS considerably enhanced the laccase production (up to 59,933.4 U/g d.w.) and substrates consisting of PS promoted total cellulases activities. Greater amounts of carbohydrates (3.8–17.4 mg/g d.w.) than that in the control were recorded for all the substrates. The combination of SMS and SCG or WS led to the highest B.E. values (59.3–87.1%) and ICP amounts (34.7–45.9%, w/w), regardless of the supplement addition. These findings support the effective utilization of agro-industrial waste in P. columbinus cultivation, producing high-value-added compounds and supporting mushroom growth. Full article
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10 pages, 2393 KiB  
Article
Density Functional Theory Simulations of Skaergaardite (CuPd) with a Self-Consistent Hubbard U-Correction
by Martino Napoli and Assimo Maris
Chemistry 2025, 7(2), 56; https://doi.org/10.3390/chemistry7020056 - 2 Apr 2025
Viewed by 624
Abstract
The electronic and phonon bands of Skaergaardite are investigated using density functional theory (DFT) as implemented in Quantum ESPRESSO. Skaergaardite is a copper palladium mineral (CuPd) found in the Skaergaard intrusion with a CsCl-type (B2) structure. Due to its porous structure, it presents [...] Read more.
The electronic and phonon bands of Skaergaardite are investigated using density functional theory (DFT) as implemented in Quantum ESPRESSO. Skaergaardite is a copper palladium mineral (CuPd) found in the Skaergaard intrusion with a CsCl-type (B2) structure. Due to its porous structure, it presents a large surface area available for interactions, which makes it a promising catalyst. The PBE-GGA functional with a Hubbard-like localized term (DFT+U) is combined with ultrasoft and norm-conserving pseudopotentials, and a conventional approach with a dense Monkhorst–Pack grid of k-points 12 × 12 × 12 is applied. The electronic valence bands are mainly constituted by 3d orbitals of Cu and 4d orbitals of Pd and a pseudo-gap can be recognized. With respect to DFT, DFT+U causes a general downward shift in the valence band. The acoustic and optical phonon branches are separated by a few cm−1 gap at about 150 cm−1 and show a density of state curve typical of ordered materials. These results highlight the reliability of DFT+U in studying bimetallic systems with scarce experimental benchmarks, offering insights into the behavior of Skaergaardite and its potential applications in material science such as reduction reactions and hydrogen storage. Full article
(This article belongs to the Section Chemistry of Materials)
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19 pages, 1360 KiB  
Article
Cross-Cultural Comparison of the Espresso Protocol Repeatability
by Jisoo Choi, Jeehyun Lee and Edgar Chambers
Foods 2025, 14(4), 593; https://doi.org/10.3390/foods14040593 - 11 Feb 2025
Viewed by 1223
Abstract
The Espresso Protocol (TEP) was used to assess the quality of coffee beans through espresso extraction incorporating a sensory approach. TEP includes overall quality evaluation and attribute evaluation using check-all-that-apply (CATA). This study aims to evaluate the repeatability of TEP when used by [...] Read more.
The Espresso Protocol (TEP) was used to assess the quality of coffee beans through espresso extraction incorporating a sensory approach. TEP includes overall quality evaluation and attribute evaluation using check-all-that-apply (CATA). This study aims to evaluate the repeatability of TEP when used by experts and to compare cross-cultural assessments to determine its applicability across different countries with diverse coffee cultures. Experts with over three years of experience in the coffee industry from five countries—France (n = 7), India (n = 12), Italy (n = 7), the Republic of Korea (n = 10), and the USA (n = 10)—participated in our study. The experiment was conducted in three replications using eight different single-origin coffee samples over two or three consecutive days. Cluster analysis using CATA data was performed to verify the repeatability of individual participants in the characterization of espresso samples, revealing that most participants were repeatable in their three-time evaluations. Moreover, a significant homogeneity index demonstrated a high degree of similarity in the sensory characteristics used by experts from each country, although cultural differences were observed in the terminology used to describe coffee. In conclusion, the repeatability of individual experts and the reliability of TEP were successfully demonstrated. However, some differences in sensory evaluations were noted across cultures; these were likely influenced by differences in the use of terminology, which emphasizes the need for training in the coffee lexicon. Full article
(This article belongs to the Special Issue Sensory and Consumer Testing of Novel Methods and Novel Foods)
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21 pages, 17447 KiB  
Article
Espresso Crema Analysis with f-AnoGAN
by Jintak Choi, Seungeun Lee and Kyungtae Kang
Mathematics 2025, 13(4), 547; https://doi.org/10.3390/math13040547 - 7 Feb 2025
Cited by 1 | Viewed by 916
Abstract
This study proposes a system that evaluates the quality of espresso crema in real time using the deep learning-based anomaly detection model, f-AnoGAN. The system integrates mobile devices to collect sensor data during the extraction process, enabling quick adjustments for optimal results. Using [...] Read more.
This study proposes a system that evaluates the quality of espresso crema in real time using the deep learning-based anomaly detection model, f-AnoGAN. The system integrates mobile devices to collect sensor data during the extraction process, enabling quick adjustments for optimal results. Using the GrabCut algorithm to separate crema from the background, the detection accuracy is improved. The experimental results show an increase of 0.13 in ROC-AUC in the CIFAR-10 dataset and, in crema images, ROC-AUC improved from 0.963 to 1.000 by VAE and hyperparameter optimization, achieving the classification of optimal anomalies in the image. A Pearson correlation coefficient of 0.999 confirms the effectiveness of the system. Key contributions include hyperparameter optimization, improved f-AnoGAN performance using VAE, integration of mobile devices, and improved image preprocessing. This research demonstrates the potential of AI in the management of coffee quality. Full article
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16 pages, 1226 KiB  
Article
A Comparative Elemental Analysis of Espresso Coffee from Poland and Portugal
by Pawel Konieczyński, Kinga Seroczyńska, Marek Wesolowski, Edgar Pinto, Cristina Couto, Ana Cunha, Rui Azevedo and Agostinho Almeida
Foods 2025, 14(3), 426; https://doi.org/10.3390/foods14030426 - 28 Jan 2025
Viewed by 1074
Abstract
A comparative elemental analysis of espresso coffee from Poland and Portugal was carried out. Using an ICP-MS analytical procedure, samples collected from public cafes in Poland and Portugal (n = 60 and n = 44, respectively) were studied for their macromineral and trace [...] Read more.
A comparative elemental analysis of espresso coffee from Poland and Portugal was carried out. Using an ICP-MS analytical procedure, samples collected from public cafes in Poland and Portugal (n = 60 and n = 44, respectively) were studied for their macromineral and trace element content. To evaluate the contribution of water to the final composition of the beverage, paired samples (i.e., collected from the same locations) of drinking water were also analysed. The mineral profile of the coffee espresso samples was quite similar: Mg > P > Ca > Rb > Mn > B > Zn > Cu > Sr > Ba > Ni > Pb > Cs > Mo > Sn > Cd > Sb > Tl for samples from Poland and Mg > P > Ca > Rb > B > Mn > Zn > Sr > Cu > Ni > Ba > Cs > Pb > Mo > Sn > Sb > Cd > Tl for samples from Portugal. For most of the elements, the espresso samples showed much higher levels than the water used in its preparation. The two most notable exceptions were Ca and Sr, where the elements present in the coffee came mainly from the water. The contribution of coffee espressos to the daily intake of essential elements seems to be reduced. Other non-essential elements like Ni (median = 81.0 µg/L and 86.8 µg/L for Polish and Portuguese espresso, respectively) and Pb (median = 14.3 µg/L and 4.43 µg/L, respectively) were observed in significant amounts in the coffee espresso samples analysed in this study. These elements have been shown to leach from coffee machines in other studies. More studies are necessary to confirm these results. Full article
(This article belongs to the Special Issue Trace Elements in Food: Nutritional and Safety Issues)
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15 pages, 2734 KiB  
Article
Engineering the Mechanics and Thermodynamics of Ti3AlC2, Hf3AlC2, Hf3GaC2, (ZrHf)3AlC2, and (ZrHf)4AlN3 MAX Phases via the Ab Initio Method
by Adel Bandar Alruqi
Crystals 2025, 15(1), 87; https://doi.org/10.3390/cryst15010087 - 17 Jan 2025
Cited by 1 | Viewed by 1164
Abstract
When combined with ceramics, ternary carbides, nitrides, and borides form a class of materials known as MAX phases. These materials exhibit a multilayer hexagonal structure and are very strong, damage tolerant, and thermally stable. Further, they have a low thermal expansion and exhibit [...] Read more.
When combined with ceramics, ternary carbides, nitrides, and borides form a class of materials known as MAX phases. These materials exhibit a multilayer hexagonal structure and are very strong, damage tolerant, and thermally stable. Further, they have a low thermal expansion and exhibit outstanding resistance to corrosion and oxidation. However, despite the numerous MAX phases that have been identified, the search for better MAX phases is ongoing, including the recently discovered Zr3InC2 and Hf3InC2. The properties of MAX phases are still being tailored in order to lower their ductility. This study investigated Ti3AlC2 alloyed with nitrogen, gallium, hafnium, and zirconium with the aim of achieving better mechanical and thermal performances. Density functional theory within Quantum Espresso module was used in the computations. The Perdew–Burke–Ernzerhof generalised gradient approximation functionals were utilised. (ZrHf)4AlN3 exhibited an enhanced bulk and Young’s moduli, entropy, specific heat, and melting temperature. The best thermal conductivity was observed in the case of (ZrHf)3AlC2. Further, Ti3AlC2 exhibited the highest shear modulus, Debye temperature, and electrical conductivity. These samples can thus form part of the group of MAX phases that are used in areas wherein the above properties are crucial. These include structural components in aerospace and automotive engineering applications, turbine blades, and heat exchanges. However, the samples need to be synthesised and their properties require verification. Full article
(This article belongs to the Special Issue Modern Technologies in the Manufacturing of Metal Matrix Composites)
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11 pages, 1197 KiB  
Article
Ab Initio Investigation of the Mechanics and Thermodynamics of the Cubic EuAlO3 and GdAlO3 Perovskites for Optoelectronic Applications
by Adel Bandar Alruqi and Nicholas O. Ongwen
Crystals 2024, 14(12), 1084; https://doi.org/10.3390/cryst14121084 - 16 Dec 2024
Viewed by 984
Abstract
Perovskites are currently becoming common in the field of optoelectronics, owing to their promising properties such as electrical, optical, thermoelectric, and electronic. Although mechanical and thermal properties also play a crucial part in the functioning of the optoelectronic devices, they have scarcely been [...] Read more.
Perovskites are currently becoming common in the field of optoelectronics, owing to their promising properties such as electrical, optical, thermoelectric, and electronic. Although mechanical and thermal properties also play a crucial part in the functioning of the optoelectronic devices, they have scarcely been explored. The present work performed an ab initio study of the mechanical and thermal properties of the cubic EuAlO3 and GdAlO3 perovskites for the first time using density functional theory. Quantum Espresso and Themo_pw codes were utilized by employing the generalized gradient approximation. Although the results showed that both materials have good mechanical and thermal properties that are ideal for the above–mentioned applications, EuAlO3 possessed better structural and thermal stability, bulk modulus, Poisson ratio, thermal expansion coefficient, and thermal stress; while GdAlO3 possessed better Young’s modulus and shear modulus. Moreover, the mechanical properties of the two materials turned out to be much better than those of the common materials for optoelectronic applications, while their thermal properties were comparable to that of sapphire glass. Since this study was computational, an experimental verification of the computed properties of the two materials needs to be carried out before they can be commercialized. Full article
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11 pages, 1694 KiB  
Article
Effect of Pressure on the Structural and Mechanical Properties of Cubic Silicon Carbide Reinforced with Aluminum and Magnesium
by Adel Bandar Alruqi and Nicholas O. Ongwen
Aerospace 2024, 11(12), 1026; https://doi.org/10.3390/aerospace11121026 - 16 Dec 2024
Cited by 1 | Viewed by 1148
Abstract
Ranging from the most demanding technical applications to soft, extremely ductile wrapping foil, aluminum is one of the most versatile and reasonably priced metallic materials. These are attributable to the unique blend of features that it provides, together with its alloys, owing to [...] Read more.
Ranging from the most demanding technical applications to soft, extremely ductile wrapping foil, aluminum is one of the most versatile and reasonably priced metallic materials. These are attributable to the unique blend of features that it provides, together with its alloys, owing to its lightweight, and some of its alloys have higher strengths than that of structural steel. However, it is expected that the demand for aluminum will quadruple within the next 10 years, and as a result, the aerospace industry is increasingly turning to recycled alloys to fulfill its high demand. This study uses the ab initio method, implemented in the quantum espresso code, to examine the influence of pressure on the structural and mechanical properties of cubic silicon carbide alloyed with aluminum (Al) and magnesium (Mg). The study is motivated by the aerospace industry’s growing need for sustainable materials. Some of the carbon atoms were swapped out for Al or Mg or both (co-doping) atoms in order to create the alloys. The results demonstrated that the application of pressure significantly influences both the structural and mechanical properties of the alloys, making them a promising option for the construction of environmentally friendly aircraft components. Full article
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21 pages, 1570 KiB  
Article
Effect of Temperature and Storage on Coffee’s Volatile Compound Profile and Sensory Characteristics
by Magdalena Gantner, Eliza Kostyra, Elżbieta Górska-Horczyczak and Anna Piotrowska
Foods 2024, 13(24), 3995; https://doi.org/10.3390/foods13243995 - 11 Dec 2024
Viewed by 2879
Abstract
The study investigated the effects of storage temperature, type of coffee, and brewing method on coffee’s volatile compound profile and sensory quality. Three types of coffee were included in the study: Arabica, Robusta, and their 80/20 blend. Samples were stored at 5 °C [...] Read more.
The study investigated the effects of storage temperature, type of coffee, and brewing method on coffee’s volatile compound profile and sensory quality. Three types of coffee were included in the study: Arabica, Robusta, and their 80/20 blend. Samples were stored at 5 °C and 20 °C for one month, after which the changes in the composition of volatile compounds were analysed and the sensory quality of espresso and cold brew coffee was assessed. The results showed that storing coffee at a lower temperature slows the changes in the profile of volatile compounds such as aldehydes, alcohols, pyrazines, and furans, helping preserve the desired aroma and flavour characteristics. Storage at higher temperatures resulted in greater changes in the volatile profile and sensory quality, with higher perceptions of earthy, sharp, and smoky notes and lower chocolatey and sweet notes. The brewing method also had a significant effect on the sensory quality. The espresso coffee had a higher intensity of coffee aroma, chocolate flavour, smoky aroma, and roasted notes. In contrast, cold brew coffee was perceived as sweeter, fruitier, and had more pronounced rum notes. The coffee type also significantly influenced the aroma and flavour profile. Arabica had a more harmonious and mild aromatic profile, while Robusta had a sharper aroma. The blend of Arabica and Robusta combined the characteristics of both coffees and offered a balanced aromatic profile. Full article
(This article belongs to the Special Issue Latest Research on Flavor Components and Sensory Properties of Food)
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26 pages, 1629 KiB  
Review
Quantitative Analysis of Caffeine in Roasted Coffee: A Comparison of Brewing Methods
by Iwona Mystkowska, Aleksandra Dmitrowicz and Monika Sijko-Szpańska
Appl. Sci. 2024, 14(23), 11395; https://doi.org/10.3390/app142311395 - 6 Dec 2024
Cited by 1 | Viewed by 4116
Abstract
Coffee is one of the most widely consumed beverages in the world due to its sensory and health benefits. The caffeine content, a bioactive compound of coffee, depends on many factors, including the brewing method, which is the subject of ongoing scientific research. [...] Read more.
Coffee is one of the most widely consumed beverages in the world due to its sensory and health benefits. The caffeine content, a bioactive compound of coffee, depends on many factors, including the brewing method, which is the subject of ongoing scientific research. In addition, various methods are used in studies to determine the caffeine content. However, it is worth noting that there is considerable variation in the individual analytical parameters within these methods. The aim of this study was to update the data on the effects of different brewing methods on the caffeine content of the brew and to present the current state of knowledge on techniques for the determination of this compound. A literature review was conducted, taking into account the latest studies in this field. The results showed that the caffeine content (mg/100 mL) of the brew prepared with the Cold Brew method was 48.50–179.95, Espresso—50.40–965.60, French Press—52.00–123.90, AeroPress—56.35–120.92, and Moka—128.00–539.90. These methods were characterized by different brewing parameters (time, water temperature and pressure, ratio of coffee to water), which differentiated the caffeine content. In addition, some methods were characterized by a wide range of caffeine content, suggesting that even minor variations in brewing method parameters may affect the content of this ingredient. High-performance liquid chromatography (HPLC) was the predominant method used. The detector wavelengths, along with other parameters of the HPLC method, such as gradient profiles and column temperatures, can affect the precision and accuracy of the analysis, and these differences can modify analyte retention and detection, leading to discrepancies in results. These results point to the need for studies that consider various brewing methods and a wide range of coffee types, including roast and origin, to accurately determine the effects of these factors on caffeine content determined by one precise method. Full article
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8 pages, 1844 KiB  
Proceeding Paper
Analysis of the Pyrolysis of Methane Reaction over Molten Metals for CO2-Free Hydrogen Production: An Application of DFT and Machine Learning
by Lord Ugwu, Yasser Morgan and Hussameldin Ibrahim
Eng. Proc. 2024, 76(1), 97; https://doi.org/10.3390/engproc2024076097 - 3 Dec 2024
Viewed by 1120
Abstract
The co-production of CO2 continues to remain the bane of several hydrogen production technologies, including the steam reforming of methane and the dry reforming of methane processes. Efficient utilization of abundant greenhouse gas in the form of methane provides opportunities for the [...] Read more.
The co-production of CO2 continues to remain the bane of several hydrogen production technologies, including the steam reforming of methane and the dry reforming of methane processes. Efficient utilization of abundant greenhouse gas in the form of methane provides opportunities for the design of an innovative system that will maximize the use of such a raw material in the most environmentally friendly manner. The study of the mechanism of the pyrolysis of methane reactions over molten metals provides promise for improved hydrogen yield and methane conversion with a greater turnover frequency. Catalyst electronic properties computed via Density Functional Theory using the Quantum Espresso code provided data that were built into a database. Using Bismuth as the base metal, active transition metals including Ni, Cu, Pd, Pt, Ag, and Au of different concentrations of 5, 10, 15, and 25% were placed on 96 atoms of the base metal and relaxed to obtain the optimized geometric structures for the catalytic reaction studies. The kinetics of the individual elementary steps of the pyrolysis reaction at preset temperatures over the bi-metals were calculated using the Car-Parinello (CP) method and Nudge Elastic Band (NEB) computations. The collated data of the various pyrolysis of methane reactions over the different bi-metals was used to train machine learning models for the prediction of reaction outcome, catalytic performance, and efficient operating conditions for the pyrolysis of methane over molten metals. The turnover frequency, which is determined using the transition state energies of the fundamental reaction cycles, will be used to simulate the stability of the catalyst. Full article
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