Coffee and Coffee-Related Product Characterization through Rapid Analytical Methodologies and Downscaled Systems

A special issue of Foods (ISSN 2304-8158). This special issue belongs to the section "Food Analytical Methods".

Deadline for manuscript submissions: closed (30 October 2024) | Viewed by 9925

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REQUIMTE/LAQV—Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
Interests: coffee analysis; volatile compound extraction and characterization; flow analysis; analytical chemistry; electrochemical detection; liquid chromatography; low-pressure chromatographic systems with amperometric detection
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1. REQUIMTE/LAQV—Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto, Portugal
2. REQUIMTE, LAQV, ICBAS, School of Medicine and Biomedical Sciences, University of Porto, Porto, Portugal
Interests: analytical chemistry; phytochemical analysis; metabolomics; liquid chromatography; mass spectrometry; animal nutrition, method development; sample preparation
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
REQUIMTE/LAQV—Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
Interests: volatile organic compounds; liquid chromatography; extraction methodologies; mass spectrometry; miniaturization; wood-based panels analysis; analytical chemistry; sample preparation
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In view of the continuous analytical developments in terms of new sample preparation approaches and/or small-sized analytical instruments of competitive sensitivity, new analytical methods for physical and chemical characterization of coffee and coffee-related products are welcome. Such approaches are of special relevance for coffee roaster facilities which, due to poor/absent laboratorial conditions for routine analysis, choose not to perform proper analytical control of raw material, process control and final product. We hereby invite you to submit original research papers, review articles or short communications based on, but not limited to, the following topics: new analytical methodologies prone to be downsized for raw, roasted and brewed coffee of low cost; analytical methodologies focusing on compounds with known/ potential bioactivity, with an organoleptic impact, of legal concern or health-related.

Dr. João Rodrigo Santos
Dr. Inês Maria Valente
Dr. Rui Miguel Ramos
Guest Editors

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Keywords

  • raw coffee, roasted coffee, brewed coffee and coffee by-products
  • coffee and coffee-related product quality assessment and characterization
  • compounds with potential bioactivity, organoleptic impact, of legal concern or health-related
  • portable, small-sized or easy-to-assemble analytical systems
  • rapid analytical methodologies for coffee and coffee-related products

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Published Papers (6 papers)

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Research

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14 pages, 3701 KiB  
Article
Smart E-Tongue Based on Polypyrrole Sensor Array as Tool for Rapid Analysis of Coffees from Different Varieties
by Alvaro Arrieta Almario, Oriana Palma Calabokis and Eisa Arrieta Barrera
Foods 2024, 13(22), 3586; https://doi.org/10.3390/foods13223586 - 10 Nov 2024
Viewed by 589
Abstract
Due to the lucrative coffee market, this product is often subject to adulteration, as inferior or non-coffee materials or varieties are mixed in, negatively affecting its quality. Traditional sensory evaluations by expert tasters and chemical analysis methods, although effective, are time-consuming, costly, and [...] Read more.
Due to the lucrative coffee market, this product is often subject to adulteration, as inferior or non-coffee materials or varieties are mixed in, negatively affecting its quality. Traditional sensory evaluations by expert tasters and chemical analysis methods, although effective, are time-consuming, costly, and require skilled personnel. The aim of this work was to evaluate the capacity of a smart electronic tongue (e-tongue) based on a polypyrrole sensor array as a tool for the rapid analysis of coffees elaborated from beans of different varieties. The smart e-tongue device was developed with a polypyrrole-based voltammetric sensor array and portable multi-potentiostat operated via smartphone. The sensor array comprised seven electrodes, each doped with distinct counterions to enhance cross-selectivity. The smart e-tongue was tested on five Arabica coffee varieties (Typica, Bourbon, Maragogype, Tabi, and Caturra). The resulting voltammetric signals were analyzed using principal component analysis assisted by neural networks (PCNN) and cluster analysis (CA), enabling clear discrimination among the coffee samples. The results demonstrate that the polypyrrole sensors can generate distinct electrochemical patterns, serving as “fingerprints” for each coffee variety. This study highlights the potential of polypyrrole-based smart e-tongues as a rapid, cost-effective, and portable alternative for coffee quality assessment and adulteration detection, with broader applications in the food and beverage industry. Full article
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14 pages, 1715 KiB  
Article
Comparison of Ultra-High-Pressure and Conventional Cold Brew Coffee at Different Roasting Degrees: Physicochemical Characteristics and Volatile and Non-Volatile Components
by Qihan Shi, Ying Xiao, Yiming Zhou, Wenxiao Tang, Feng Jiang, Xiaoli Zhou and Hongxiu Lu
Foods 2024, 13(19), 3119; https://doi.org/10.3390/foods13193119 - 29 Sep 2024
Viewed by 800
Abstract
The impact of the roasting degree on ultra-high-pressure cold brew (UHP) coffee remains unclear, although it has been found that UHP technology accelerates the extraction of cold brew (CB) coffee. Therefore, this study investigated the effects of three different degrees of roasting (light, [...] Read more.
The impact of the roasting degree on ultra-high-pressure cold brew (UHP) coffee remains unclear, although it has been found that UHP technology accelerates the extraction of cold brew (CB) coffee. Therefore, this study investigated the effects of three different degrees of roasting (light, medium, and dark) on the physicochemical characteristics, volatile and non-volatile components, and sensory evaluation of UHP coffee. Orthogonal partial least-squares-discriminant analysis (OPLS-DA) and principal component analysis (PCA) were used to assess the effects of different roasting degrees. The results showed that most physicochemical characteristics, including total dissolved solids (TDSs), extraction yield (EY), total titratable acidity (TTA), total sugars (TSs), and total phenolic content (TPC), of UHP coffee were similar to those of conventional CB coffee regardless of the degree of roasting. However, the majority of physicochemical characteristics, non-volatile components, including the antioxidant capacity (measured based on DPPH and ABTS) and melanoidin, caffeine, trigonelline, and CGA contents increased significantly with an increase in roasting degree. The sensory evaluation revealed that as the roasting degree rose, the nutty flavor, astringency, bitterness, body, and aftertaste intensities increased, while floral, fruity, and sourness attributes decreased. The HS-SPME-GC/MS analysis showed that most volatile components increased from light to dark roasting. Moreover, 15 representative differential compounds, including hazelnut pyrazine, linalool, butane-2,3-dione, and 3-methylbutanal, were identified by calculating the odor-active values (OAVs), indicating that these contributed significantly to the odor. The PCA showed that the distance between the three roasting degree samples in UHP coffee was smaller than that in CB coffee. Overall, the effect of roasting degrees on UHP coffee was less than that on CB coffee, which was consistent with the results of physicochemical characteristics, volatile components, and sensory evaluation. Full article
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28 pages, 6207 KiB  
Article
Unveiling the Nutritional Profile and Safety of Coffee Pulp as a First Step in Its Valorization Strategy
by Alicia Gil-Ramírez, Miguel Rebollo-Hernanz, Silvia Cañas, Ignacio Monedero Cobeta, Pilar Rodríguez-Rodríguez, Andrea Gila-Díaz, Vanesa Benítez, Silvia M. Arribas, Yolanda Aguilera and María A. Martín-Cabrejas
Foods 2024, 13(18), 3006; https://doi.org/10.3390/foods13183006 - 22 Sep 2024
Cited by 1 | Viewed by 1135
Abstract
The coffee pulp, a significant by-product of coffee processing, is often discarded but has potential for recycling and high-value uses. This study aimed to investigate the chemical composition of two coffee pulp ingredients, a flour (CPF) and an aqueous extract (CPE), and conducted [...] Read more.
The coffee pulp, a significant by-product of coffee processing, is often discarded but has potential for recycling and high-value uses. This study aimed to investigate the chemical composition of two coffee pulp ingredients, a flour (CPF) and an aqueous extract (CPE), and conducted acute and sub-chronic toxicity assays to determine their safety. The proximate composition revealed the high fiber content of both ingredients; the CPF mainly contained insoluble fiber, while CPE consisted exclusively of soluble pectic polysaccharides. The CPF had higher concentrations of amino acids and a better balance of essential/non-essential amino acids, whereas the CPE exhibited higher concentrations of free amino acids, ensuring higher bioavailability. Both ingredients showed elevated mineral content, while heavy-metal concentrations remained within acceptable limits. This study established the bioactive potential of the CPF and the CPE, demonstrating the high content of caffeine and gallic, protocatechuic, and 4-caffeoylquinic acids. The toxicity studies revealed that the CPF and the CPE exhibited safety when orally administered to mice. Administered doses were non-toxic, as they did not induce lethality or adverse effects in the mice or produce significant histopathological or biochemical adverse changes. This study represents a first step in valorizing the CPF and the CPE as safe novel food ingredients with health benefits for functional and nutritional foods. Full article
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15 pages, 3413 KiB  
Article
Exploring Microbial Influence on Flavor Development during Coffee Processing in Humid Subtropical Climate through Metagenetic–Metabolomics Analysis
by Alexander da Silva Vale, Cecília Marques Tenório Pereira, Juliano De Dea Lindner, Luiz Roberto Saldanha Rodrigues, Nájua Kêmil El Kadri, Maria Giovana Binder Pagnoncelli, Satinder Kaur Brar, Carlos Ricardo Soccol and Gilberto Vinícius de Melo Pereira
Foods 2024, 13(12), 1871; https://doi.org/10.3390/foods13121871 - 14 Jun 2024
Viewed by 1465
Abstract
Research into microbial interactions during coffee processing is essential for developing new methods that adapt to climate change and improve flavor, thus enhancing the resilience and quality of global coffee production. This study aimed to investigate how microbial communities interact and contribute to [...] Read more.
Research into microbial interactions during coffee processing is essential for developing new methods that adapt to climate change and improve flavor, thus enhancing the resilience and quality of global coffee production. This study aimed to investigate how microbial communities interact and contribute to flavor development in coffee processing within humid subtropical climates. Employing Illumina sequencing for microbial dynamics analysis, and high-performance liquid chromatography (HPLC) integrated with gas chromatography–mass spectrometry (GC-MS) for metabolite assessment, the study revealed intricate microbial diversity and associated metabolic activities. Throughout the fermentation process, dominant microbial species included Enterobacter, Erwinia, Kluyvera, and Pantoea from the prokaryotic group, and Fusarium, Cladosporium, Kurtzmaniella, Leptosphaerulina, Neonectria, and Penicillium from the eukaryotic group. The key metabolites identified were ethanol, and lactic, acetic, and citric acids. Notably, the bacterial community plays a crucial role in flavor development by utilizing metabolic versatility to produce esters and alcohols, while plant-derived metabolites such as caffeine and linalool remain stable throughout the fermentation process. The undirected network analysis revealed 321 interactions among microbial species and key substances during the fermentation process, with Enterobacter, Kluyvera, and Serratia showing strong connections with sugar and various volatile compounds, such as hexanal, benzaldehyde, 3-methylbenzaldehyde, 2-butenal, and 4-heptenal. These interactions, including inhibitory effects by Fusarium and Cladosporium, suggest microbial adaptability to subtropical conditions, potentially influencing fermentation and coffee quality. The sensory analysis showed that the final beverage obtained a score of 80.83 ± 0.39, being classified as a specialty coffee by the Specialty Coffee Association (SCA) metrics. Nonetheless, further enhancements in acidity, body, and aftertaste could lead to a more balanced flavor profile. The findings of this research hold substantial implications for the coffee industry in humid subtropical regions, offering potential strategies to enhance flavor quality and consistency through controlled fermentation practices. Furthermore, this study contributes to the broader understanding of how microbial ecology interplays with environmental factors to influence food and beverage fermentation, a topic of growing interest in the context of climate change and sustainable agriculture. Full article
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22 pages, 3909 KiB  
Article
Formation of Cysteine Adducts with Chlorogenic Acid in Coffee Beans
by Sorel Tchewonpi Sagu, Nina Ulbrich, Johanna Rebekka Morche, Kapil Nichani, Haydar Özpinar, Steffen Schwarz, Andrea Henze, Sascha Rohn and Harshadrai M. Rawel
Foods 2024, 13(11), 1660; https://doi.org/10.3390/foods13111660 - 25 May 2024
Cited by 2 | Viewed by 2032
Abstract
The post-harvest processing of coffee beans leads to a wide range of reactions involving proteins. The formation of crosslinks between proteins and phenolic compounds present in high concentrations of coffee beans represents one of the most challenging and still not fully characterized reactions. [...] Read more.
The post-harvest processing of coffee beans leads to a wide range of reactions involving proteins. The formation of crosslinks between proteins and phenolic compounds present in high concentrations of coffee beans represents one of the most challenging and still not fully characterized reactions. The aim of this work was to assess the presence of products from such reactions in coffee samples, focusing on the adducts between cysteine and chlorogenic acids (CQAs). For this purpose, 19 green and 15 roasted coffee samples of the Coffea arabica, Coffea canephora, and Coffea liberica varieties were selected for this study and basically characterized. Then, targeted liquid chromatography mass spectrometry (LC-MS/MS) methods were developed to assess the formation of adducts between CQA and cysteine, glutathione, and N-acetylcysteine as the amino acid and peptide models, and quantified such adducts in coffee samples. The results of the characterization showed a heterogeneous distribution of the protein content (8.7–14.6%), caffeine (0.57–2.62 g/100 g), and antioxidant capacity (2–4.5 g ascorbic acid/100 g) in Arabica, Canephora, and Liberica samples. Glutamic acid, arginine, and proline were found to be the major amino acids, while 5-CQA (38–76%), 3-CQA (4–13%), and 4-CQA (4–13%) were the most abundant CQA derivatives of all coffee varieties. The model experiments for adduct formation demonstrated that cysteine binds to CQA via thiol groups and 5-CQA initially isomerizes to 3- and 4-CQA, depending on the conditions, allowing cysteine to bind to two different sites on 3-, 4- or 5-CQA molecules, thus, forming six different Cys-CQA adducts with m/z 476. The reaction was more favored at pH 9, and the adducts proved to be stable up to 90 °C for 10 min and up to 28 days at room temperature. The relative quantification of adducts showed peak area values ranging from 1100 to 3000 in green coffee bean samples, while no adducts were detected in roasted coffee beans. Overall, this work was the first attempt to demonstrate the presence of Cys-CQA adducts in coffee beans and paves the way for further investigations of such adduct formation at the protein level. Full article
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Review

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17 pages, 1652 KiB  
Review
Coffee Oil Extraction Methods: A Review
by Raquel C. Ribeiro, Maria Fernanda S. Mota, Rodrigo M. V. Silva, Diana C. Silva, Fabio J. M. Novaes, Valdir F. da Veiga, Jr., Humberto R. Bizzo, Ricardo S. S. Teixeira and Claudia M. Rezende
Foods 2024, 13(16), 2601; https://doi.org/10.3390/foods13162601 - 20 Aug 2024
Viewed by 2725
Abstract
Green and roasted coffee oils are products rich in bioactive compounds, such as linoleic acid and the diterpenes cafestol and kahweol, being a potential ingredient for food and cosmetic industries. An overview of oil extraction techniques most applied for coffee beans and their [...] Read more.
Green and roasted coffee oils are products rich in bioactive compounds, such as linoleic acid and the diterpenes cafestol and kahweol, being a potential ingredient for food and cosmetic industries. An overview of oil extraction techniques most applied for coffee beans and their influence on the oil composition is presented. Both green and roasted coffee oil extractions are highlighted. Pressing, Soxhlet, microwave, and supercritical fluid extraction were the most used techniques used for coffee oil extraction. Conventional Soxhlet is most used on a lab scale, while pressing is most used in industry. Supercritical fluid extraction has also been evaluated mainly due to the environmental approach. One of the highlighted activities in Brazilian agribusiness is the industrialization of oils due to their increasing use in the formulation of cosmetics, pharmaceuticals, and foods. Green coffee oil (raw bean) has desirable bioactive compounds, increasing the interest of private companies and research institutions in its extraction process to preserve the properties contained in the oils. Full article
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