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Gao C, Tello E, Peterson DG. Identification of compounds that enhance bitterness of coffee brew. Food Chem 2023; 415:135674. [PMID: 36868066 DOI: 10.1016/j.foodchem.2023.135674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 02/08/2023] [Accepted: 02/09/2023] [Indexed: 02/17/2023]
Abstract
The bitterness perception of coffee is a key attribute that impacts consumer acceptance. Nontargeted liquid chromatography/mass spectrometry (LC/MS) flavoromics analysis was applied to identify compounds that enhance the bitter perception of roasted coffee brew. Orthogonal partial least squares (OPLS) analysis was used to model the comprehensive chemical profiles and sensory bitter intensity ratings of fourteen coffee brews with good fit and predictivity. Five compounds that were highly predictive and positively correlated to bitter intensity were selected from the OPLS model, further isolated, and purified using preparative LC fractionation. Sensory recombination testing demonstrated that five compounds significantly enhanced the bitter perception of coffee when presented as a mixture, but not when presented individually. In addition, a set of roasting experiments revealed the five compounds were generated during the coffee roasting process.
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Affiliation(s)
- Chengyu Gao
- Department of Food Science and Technology, 317 Parker Food Science & Technology Building, The Ohio State University, 2015 Fyffe Rd., Columbus, OH 43210, United States
| | - Edisson Tello
- Department of Food Science and Technology, 317 Parker Food Science & Technology Building, The Ohio State University, 2015 Fyffe Rd., Columbus, OH 43210, United States
| | - Devin G Peterson
- Department of Food Science and Technology, 317 Parker Food Science & Technology Building, The Ohio State University, 2015 Fyffe Rd., Columbus, OH 43210, United States.
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2
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Park JB, Peters R, Novotny JA. Impact of roasting on javamide-I/-II in Arabica and Robusta coffee beans. Food Chem 2023; 412:135586. [PMID: 36739725 DOI: 10.1016/j.foodchem.2023.135586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 12/21/2022] [Accepted: 01/25/2023] [Indexed: 01/31/2023]
Abstract
Javamide-I/-II are anti-inflammatory compounds found in coffee beans. However, potential effects of roasting on javamide-I/-II in coffee beans are currently unknown. Therefore, in this paper, the effects of roasting on javamide-I/-II were investigated in Arabica and Robusta beans. Coffee beans were roasted light, medium and dark, and the amounts of javamide-I/-II in the beans were quantified by a HPLC method. The data showed the different amounts of javamide-I/-II in the beans; not detected and ≤ 3.1 mg in Arabica beans, and 0.5-3.7 mg and 1.0-13.8 mg in Robusta beans, respectively. Furthermore, the data showed that roasting process significantly reduced the amounts of javamide-I/-II in both Arabica and Robusta beans (p < 0.05). These data were also confirmed by multivariate analyses. Additionally, these differences were validated in light, medium and dark roast coffee products in the market. Altogether, roasting can have a significant impact on javamide-I/-II amounts in coffee beans.
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Affiliation(s)
- Jae B Park
- Diet, Genomics, and Immunology Laboratory, BHNRC, ARS, USDA, Beltsville, MD 20705, USA.
| | - Renee Peters
- Diet, Genomics, and Immunology Laboratory, BHNRC, ARS, USDA, Beltsville, MD 20705, USA
| | - Janet A Novotny
- Food Components and Health Laboratory, BHNRC, ARS, USDA, Beltsville, MD 20705, USA
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3
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Al-Shemmeri M, Windows-Yule K, Lopez-Quiroga E, Fryer PJ. Coffee bean particle motion in a rotating drum measured using Positron Emission Particle Tracking (PEPT). Food Res Int 2023; 163:112253. [PMID: 36596163 DOI: 10.1016/j.foodres.2022.112253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/18/2022] [Accepted: 11/26/2022] [Indexed: 12/02/2022]
Abstract
Physicochemical transformation of coffee during roasting depends on the applied time-temperature profile (i.e., rate of heat transfer), with heat transfer phenomena governed by particle dynamics. Positron Emission Particle Tracking (PEPT), a non-invasive imaging technique, was used here to characterise the granular flow of coffee in a real, pilot-scale rotating drum roaster. The experimental study established the impact of drum speed, batch size and bean density (i.e., roast degree) on the system's particle dynamics. Particle motion data revealed two distinct regions: (i) a disperse (low occupancy, high velocity) region of in-flight particles and (ii) a dense (high occupancy, low velocity) bean bed. Implications of these results for heat transfer suggest that controlling drum speed for different density coffees will provide roaster operators with a tool to modulate conductive heat transfer from the heated drum to the bean bed. These comprehensive data thus inform roasting best practices and support the development of physics-driven models coupling heat and mass transfer to particle dynamics.
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Affiliation(s)
- Mark Al-Shemmeri
- School of Chemical Engineering, University of Birmingham, B15 2TT, UK; Jacobs Douwe Egberts, R&D Offices, OX16 2QU, UK
| | - Kit Windows-Yule
- School of Chemical Engineering, University of Birmingham, B15 2TT, UK
| | | | - Peter J Fryer
- School of Chemical Engineering, University of Birmingham, B15 2TT, UK
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4
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Caporaso N, Whitworth MB, Fisk ID. Prediction of coffee aroma from single roasted coffee beans by hyperspectral imaging. Food Chem 2022; 371:131159. [PMID: 34598115 PMCID: PMC8617352 DOI: 10.1016/j.foodchem.2021.131159] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 09/10/2021] [Accepted: 09/14/2021] [Indexed: 12/11/2022]
Abstract
This paper applied hyperspectral imaging (HSI) to predict roasted coffee aroma profile. Individual roast coffee beans were analysed by HSI and aroma by GC–MS. PLS models successfully predicted volatile aroma compounds in single coffee beans. Beans were successfully segregated into two batches with different aroma profiles.
Coffee aroma is critical for consumer liking and enables price differentiation of coffee. This study applied hyperspectral imaging (1000–2500 nm) to predict volatile compounds in single roasted coffee beans, as measured by Solid Phase Micro Extraction-Gas Chromatography-Mass Spectrometry and Gas Chromatography-Olfactometry. Partial least square (PLS) regression models were built for individual volatile compounds and chemical classes. Selected key aroma compounds were predicted well enough to allow rapid screening (R2 greater than 0.7, Ratio to Performance Deviation (RPD) greater than 1.5), and improved predictions were achieved for classes of compounds - e.g. aldehydes and pyrazines (R2 ∼ 0.8, RPD ∼ 1.9). To demonstrate the approach, beans were successfully segregated by HSI into prototype batches with different levels of pyrazines (smoky) or aldehydes (sweet). This is industrially relevant as it will provide new rapid tools for quality evaluation, opportunities to understand and minimise heterogeneity during production and roasting and ultimately provide the tools to define and achieve new coffee flavour profiles.
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Affiliation(s)
- Nicola Caporaso
- Division of Food Sciences, University of Nottingham, Sutton Bonington Campus, LE12 5RD, UK
| | | | - Ian D Fisk
- Division of Food Sciences, University of Nottingham, Sutton Bonington Campus, LE12 5RD, UK; The University of Adelaide, North Terrace, Adelaide, South Australia, Australia.
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LIczbiński P, Bukowska B. Tea and coffee polyphenols and their biological properties based on the latest in vitro investigations. Ind Crops Prod 2022; 175:114265. [PMID: 34815622 PMCID: PMC8601035 DOI: 10.1016/j.indcrop.2021.114265] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/21/2021] [Accepted: 11/09/2021] [Indexed: 06/01/2023]
Abstract
Tea and coffee contain numerous polyphenolic compounds that exhibit health-promoting properties for humans, including antioxidant and neuroprotective properties, and can also take part in the treatment of covid-19 and improve fertility. This review, presents the activity of polyphenols found in different types of tea and coffee and describes the effects of tea fermentation and coffee roasting on their polyphenol composition and antioxidant properties. Polyphenol oxidase activity is reduced in the fermentation process; therefore black tea contains significantly less polyphenolic compounds compared to green and white tea. Epigallocatechin-3-gallate - a polyphenol from tea - effectively has been shown to inhibit the activity of SARS-CoV-2 as it blocked binding of coronavirus 2 to human angiotensin converting enzyme 2, decreased the expression of inflammatory factors in the blood, including tumor necrosis factor-α and interleukin-6, and significantly increased the overall fertilization efficiency in animals. Coffee roasting process influences both the content of polyphenols and the oxidative activity. The lowest levels of active compounds such as caffeine, chlorogenic acid and coffee acids are identified in roasted coffee beans. On the other hand, light coffee and green coffee show the strongest cytotoxic potential and antioxidant properties, and thus the greatest ability to decrease apoptosis by stopping the cell cycle in the S phase. Proteins, such as components of milk, can strongly bind/interact with phenolic compounds (especially, the CGAs) contain in coffee, which may explain the negative influence of milk on its antioxidant properties. Coffee polyphenols have also antiproliferative and antiesterase activities, which may be important in prevention of cancer and neurodegenerative disorders, respectively. In this review, biological properties of tea and coffee polyphenols, observed mainly in in vitro studies have been described. Based on these findings, future directions of the research works on these compounds have been suggested.
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Affiliation(s)
- Przemysław LIczbiński
- Department of Environmental Biotechnology, Lodz University of Technology, Lodz, Poland
| | - Bożena Bukowska
- Faculty of Biology and Environmental Protection, Department of Biophysics of Environmental Pollution, University of Lodz, Lodz, Poland
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Abstract
Tea and coffee contain numerous polyphenolic compounds that exhibit health-promoting properties for humans, including antioxidant and neuroprotective properties, and can also take part in the treatment of covid-19 and improve fertility. This review, presents the activity of polyphenols found in different types of tea and coffee and describes the effects of tea fermentation and coffee roasting on their polyphenol composition and antioxidant properties. Polyphenol oxidase activity is reduced in the fermentation process; therefore black tea contains significantly less polyphenolic compounds compared to green and white tea. Epigallocatechin-3-gallate - a polyphenol from tea - effectively has been shown to inhibit the activity of SARS-CoV-2 as it blocked binding of coronavirus 2 to human angiotensin converting enzyme 2, decreased the expression of inflammatory factors in the blood, including tumor necrosis factor-α and interleukin-6, and significantly increased the overall fertilization efficiency in animals. Coffee roasting process influences both the content of polyphenols and the oxidative activity. The lowest levels of active compounds such as caffeine, chlorogenic acid and coffee acids are identified in roasted coffee beans. On the other hand, light coffee and green coffee show the strongest cytotoxic potential and antioxidant properties, and thus the greatest ability to decrease apoptosis by stopping the cell cycle in the S phase. Proteins, such as components of milk, can strongly bind/interact with phenolic compounds (especially, the CGAs) contain in coffee, which may explain the negative influence of milk on its antioxidant properties. Coffee polyphenols have also antiproliferative and antiesterase activities, which may be important in prevention of cancer and neurodegenerative disorders, respectively. In this review, biological properties of tea and coffee polyphenols, observed mainly in in vitro studies have been described. Based on these findings, future directions of the research works on these compounds have been suggested.
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Affiliation(s)
- Przemysław LIczbiński
- Department of Environmental Biotechnology, Lodz University of Technology, Lodz, Poland
| | - Bożena Bukowska
- Faculty of Biology and Environmental Protection, Department of Biophysics of Environmental Pollution, University of Lodz, Lodz, Poland
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Pires FDC, Pereira RGFA, Baqueta MR, Valderrama P, Alves da Rocha R. Near-infrared spectroscopy and multivariate calibration as an alternative to the Agtron to predict roasting degrees in coffee beans and ground coffees. Food Chem 2021; 365:130471. [PMID: 34252622 DOI: 10.1016/j.foodchem.2021.130471] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 04/14/2021] [Accepted: 06/24/2021] [Indexed: 11/30/2022]
Abstract
Agtron method is widely used in the industry to determine roasting degrees in whole and ground coffee but it suffers from some inconveniences associated with unavailability of equipment, high cost, and lack of reproductive results. This study investigates the feasibility to determine roasting degrees in coffee beans and ground specialty coffees using near-infrared (NIR) spectroscopy combined with multivariate calibration based on partial least squares (PLS) regression. Representative data sets were considered to cover all Agtron roasting profiles for whole and ground coffees. Proper development of models with outlier evaluation and complete validation using parameters of merit such as accuracy, adjust, residual prediction deviation, linearity, analytical sensitivity, and limits of detection and quantification are presented to prove their performance. The results indicated that predictive chemometric models, for intact coffee beans and ground coffee, could be used in the coffee industry as an alternative to Agtron, thus digitalizing the roasting quality control.
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Affiliation(s)
| | | | - Michel Rocha Baqueta
- Universidade Tecnológica Federal do Paraná (UTFPR), Campo Mourão, PR 87301-899, Brazil
| | - Patrícia Valderrama
- Universidade Tecnológica Federal do Paraná (UTFPR), Campo Mourão, PR 87301-899, Brazil.
| | - Roney Alves da Rocha
- Engineering Department, Federal University of Lavras (UFLA), Lavras, MG 37200-000, Brazil.
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8
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Córdoba N, Moreno FL, Osorio C, Velásquez S, Ruiz Y. Chemical and sensory evaluation of cold brew coffees using different roasting profiles and brewing methods. Food Res Int 2021; 141:110141. [PMID: 33642008 DOI: 10.1016/j.foodres.2021.110141] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 01/05/2021] [Accepted: 01/05/2021] [Indexed: 11/18/2022]
Abstract
This study evaluated the effects of different roasting profiles (time/temperature) and brewing methods on the physicochemical and sensory characteristics of coffee brews. Cold brewing (dripping and immersion) and hot brewing (French press) methods were studied to understand the effects of water temperature and technical brewing method conditions on the chemical compound extraction in coffees roasted at high-temperature short time (HTST) and low-temperature long time (LTLT). The results showed that coffee beverages were clearly differentiated concerning the roasting profile when hot water was used (90 ± 3 °C) in brewing. Separation of beverages according to the water temperature used in brewing was observed. Notably, hot brewing coffees were distinguished from cold brewing (19 ± 2 °C) based on a higher titratable acidity and abundance of some furan compounds. The non-volatile extraction rate increased at higher brewing temperatures. At the same brewing temperature, dripping exhibited a higher extraction rate than immersion brewing, which suggests that the coffee extraction process is affected by the design and operation of the cold brewing system. Coffee beverages brewed with HTST and cold dripping displayed the highest value in total dissolved solids (TDS), extraction yield, as well as the highest caffeine, trigonelline, 4- and 5-caffeoylquinic acids (CQAs) contents. Regardless of the roasting profile, coffees brewed by cold dripping were perceived with more bitter and roasted flavors. In contrast, cold immersion and hot coffee beverages showed remarkable sweetness, nutty, caramel, and malt attributes. In turn, these attributes showed an inverse correlation with caffeine concentration, trigonelline, CQAs, and TDS. The findings of this study demonstrate that volatile and non-volatile compounds present in roasted coffee depend on time-temperature roasting conditions; in turn, their presence in the resulting beverages are related to the extraction of the operational conditions of coffee brewing methods.
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Affiliation(s)
- Nancy Córdoba
- Doctoral Program in Biosciences, Faculty of Engineering, Universidad de La Sabana, Campus Universitario Puente del Común, Km. 7 Autopista Norte, Bogotá 25001, Colombia
| | - Fabian L Moreno
- Grupo de Investigación en Procesos Agroindustriales, Universidad de La Sabana, Campus Universitario Puente del Común, Km. 7 Autopista Norte, Bogotá 25001, Colombia
| | - Coralia Osorio
- Departamento de Química, Universidad Nacional de Colombia-Sede Bogotá, AA 14490 Bogotá, Colombia
| | - Sebastián Velásquez
- Research & Development Department, Industria Colombiana de Café, Medellín, Antioquia, Colombia
| | - Yolanda Ruiz
- Grupo de Investigación en Procesos Agroindustriales, Universidad de La Sabana, Campus Universitario Puente del Común, Km. 7 Autopista Norte, Bogotá 25001, Colombia.
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Wang C, Sun J, Lassabliere B, Yu B, Liu SQ. Coffee flavour modification through controlled fermentation of green coffee beans by Saccharomyces cerevisiae and Pichia kluyveri: Part II. Mixed cultures with or without lactic acid bacteria. Food Res Int 2020; 136:109452. [PMID: 32846547 DOI: 10.1016/j.foodres.2020.109452] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 06/13/2020] [Accepted: 06/14/2020] [Indexed: 10/24/2022]
Abstract
This study attempted to achieve coffee flavour biotransformation through controlled fermentation of sterilsed green coffee beans with a coculture of Saccharomyces cerevisiae and Pichia kluyveri (FYco) and a sequential inoculation of Lc. lactis subsp. cremoris and the yeast coculture (FLYco). Isoamyl acetate, 2-phenylethyl acetate, and ethyl octanoate were produced by 5.76, 1.35 and 0.54 mg/kg, respectively, in FYco fermented green coffee beans. Compared to the green coffee bean fermented by the yeast monocultures in previous study, FYco led to a 1.2- and 4.1-times elevation in production of isoamyl acetate and 2-phenylethyl acetate, respectively. FLYco further increased acetate ester production by more than 2 times relative to FYco. The esters produced in FYco and FLYco partially survived the roasting process and imparted the roasted coffees with considerable fruity and winey aromas. The lactic acid fermentation in FLYco increased the acidity in green coffee beans, which promoted the formation of caramel-smelling furfurals and preservation of acidity and sweetness in the roasted coffees. Apart from the mere additions of flavour modification from individual strains, the proper combination of multiple strains can result in synergistic effects that enhanced the modulating activities of individual strains and further enhance flavour complexity of the resulted coffee.
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Affiliation(s)
- Chenhui Wang
- Department of Food Science and Technology, National University of Singapore, Science Drive 2, Singapore 117546, Singapore
| | - Jingcan Sun
- Mane SEA PTE LTD, Biopolis Drive 3, 138623, Singapore
| | | | - Bin Yu
- Mane SEA PTE LTD, Biopolis Drive 3, 138623, Singapore
| | - Shao Quan Liu
- Department of Food Science and Technology, National University of Singapore, Science Drive 2, Singapore 117546, Singapore; National University of Singapore (Suzhou) Research Institute, No. 377 Linquan Street, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China.
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Bilge G. Investigating the effects of geographical origin, roasting degree, particle size and brewing method on the physicochemical and spectral properties of Arabica coffee by PCA analysis. J Food Sci Technol 2020; 57:3345-3354. [PMID: 32728282 DOI: 10.1007/s13197-020-04367-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 10/24/2022]
Abstract
Effects of geographical origin of Coffee Arabica beans (Brazil, Colombia and Peru), roasting degree, particle size and different brewing methods (French press, chemex and cold brew) on physicochemical and spectral properties of coffee samples were investigated in this study. Analyses of pH, total phenolic content (TPC) and total antioxidant activity (TA), UV and fluorescence spectroscopy measurements were performed. Principal component analysis (PCA) was used to obtain the most effective parameters on chemical changes. Results indicated that the increase of roasting degree caused decrements in the intensities of UV-spectra because of the degradation of trigonelline and chlorogenic acid molecules while counterpart trend was observed in the fluorescence spectra due to formation of fluorescence Maillard reaction products (MRP) during roasting. French press and cold brew methods caused similar TPC (1873.33-3818.33 and 2648.88-3824.44 μg/mL gallic acid equivalent, respectively) and TA (0.18-0.32 and 0.16-0.27 μmol/mL Trolox equivalent, respectively) values whereas chemex method showed different physicochemical properties (TPC: 1008.88-3543.88 μg/mL gallic acid equivalent and TA: 0.08-0.26 μmol/mL Trolox equivalent). Roasting degree and brewing method-compared to other parameters-were the most discriminating factors on the basis of UV spectra and fluorescence spectra of coffee brew samples, respectively. All roasting degrees could be distinguished with the rate of 71.42% on PC1 and 23.45% on PC2 of total variance according to UV-spectra while chemex and French press-cold brew methods could be differentiated with the rate of 97.24% on PC1 and 1.79% on PC2 of total variance based on fluorescence spectra on PCA score graphs.
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Affiliation(s)
- Gonca Bilge
- Department of Food Engineering, Konya Food and Agriculture University, 42080 Konya, Turkey
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Xu JL, Kim TJ, Kim JK, Choi Y. Simultaneous roasting and extraction of green coffee beans by pressurized liquid extraction. Food Chem 2019; 281:261-8. [PMID: 30658756 DOI: 10.1016/j.foodchem.2018.12.061] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 12/08/2018] [Accepted: 12/11/2018] [Indexed: 11/22/2022]
Abstract
Green coffee extracted by pressurized liquid extraction (PLE) was found to undergo a roasting process similar to traditional roasting. Liquid chromatography-tandem mass spectrometry was used to investigate the chlorogenic acid (CGA) composition and profiling changes by PLE under different extraction conditions and showed almost identical generation and degradation of CGAs occurring during traditional coffee roasting. Compared with the traditional extraction of roasted coffee, optimized PLE coffee showed three- and two-fold higher antioxidant activity and total CGA contents, respectively. Composition diversity and the content of volatile compounds in PLE coffee were found to increase as the PLE temperature increased but were lower than those of traditionally roasted coffee. The sensory attributes of PLE coffee were also evaluated to have be associated with a profile change in the volatile compounds and non-volatile CGA compounds.
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Caporaso N, Whitworth MB, Cui C, Fisk ID. Variability of single bean coffee volatile compounds of Arabica and robusta roasted coffees analysed by SPME-GC-MS. Food Res Int 2018; 108:628-40. [PMID: 29735099 DOI: 10.1016/j.foodres.2018.03.077] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/21/2018] [Accepted: 03/28/2018] [Indexed: 11/22/2022]
Abstract
We report on the analysis of volatile compounds by SPME-GC-MS for individual roasted coffee beans. The aim was to understand the relative abundance and variability of volatile compounds between individual roasted coffee beans at constant roasting conditions. Twenty-five batches of Arabica and robusta species were sampled from 13 countries, and 10 single coffee beans randomly selected from each batch were individually roasted in a fluidised-bed roaster at 210 °C for 3 min. High variability (CV = 14.0–53.3%) of 50 volatile compounds in roasted coffee was obtained within batches (10 beans per batch). Phenols and heterocyclic nitrogen compounds generally had higher intra-batch variation, while ketones were the most uniform compounds (CV < 20%). The variation between batches was much higher, with the CV ranging from 15.6 to 179.3%. The highest variation was observed for 2,3-butanediol, 3-ethylpyridine and hexanal. It was also possible to build classification models based on geographical origin, obtaining 99.5% and 90.8% accuracy using LDA or MLR classifiers respectively, and classification between Arabica and robusta beans. These results give further insight into natural variation of coffee aroma and could be used to obtain higher quality and more consistent final products. Our results suggest that coffee volatile concentration is also influenced by other factors than simply the roasting degree, especially green coffee composition, which is in turn influenced by the coffee species, geographical origin, ripening stage and pre- and post-harvest processing. Volatile compounds associated with individual roasted coffee beans were analysed by SPME-GC-MS. High inter- and intra-batch variability was observed, especially for 3-ethylpyridine. Multivariate statistics allowed prediction of coffee origin (species and location). Variability of volatiles is wide, with different chemical classes showing diverse behaviour.
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Abstract
The production of furfuryl alcohol from green coffee during roasting and the effect of multiple parameters on its formation were studied employing HPLC-DAD. Results show that coffee produces furfuryl alcohol in larger quantities (418µg/g) compared to other beans or seeds (up to 132µg/g) roasted under the same conditions. The kinetics of furfuryl alcohol production resemble those of other process contaminants (e.g., HMF, acrylamide) produced in coffee roasting, with temperature and time of roasting playing significant roles in quantities formed. Different coffee species yielded different amounts of furfuryl alcohol. The data point out that the amounts of furfuryl alcohol found in roasted coffee do not reflect the total amounts produced during roasting because great amounts of furfuryl alcohol (up to 57%) are evaporating and released to the atmosphere during roasting. Finally the effect of the moisture content on furfuryl alcohol formation was found to be of little impact.
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Affiliation(s)
- Abdullatif Albouchi
- Institute of Biochemistry, Graz University of Technology, Petersgasse 10-12/II, 8010 Graz, Austria.
| | - Michael Murkovic
- Institute of Biochemistry, Graz University of Technology, Petersgasse 10-12/II, 8010 Graz, Austria.
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14
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Kim SY, Ko JA, Kang BS, Park HJ. Prediction of key aroma development in coffees roasted to different degrees by colorimetric sensor array. Food Chem 2017; 240:808-816. [PMID: 28946345 DOI: 10.1016/j.foodchem.2017.07.139] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 07/06/2017] [Accepted: 07/25/2017] [Indexed: 11/29/2022]
Abstract
We developed a colorimetric sensor array (CSA) that is sensitive to highly contributory volatile compounds of coffee aroma for discrimination of coffee samples roasted to different roast degrees. Strecker aldehydes and α-diketones were significantly higher for the medium roast than the other roast degrees. The development of several sulfur compounds was pronounced in the medium-dark and dark roasts, except for dimethyl sulfide, which was only detected in the light roast. The CSA method coupled with principal component analysis or hierarchical cluster analysis successfully distinguished the roasted coffee samples according to roast degree. Partial least squares regression results showed that the CSA responses were well-correlated with the concentrations of volatile compounds in the coefficient of determination (rp2) range of 0.686-0.955. These results demonstrate that the CSA rapidly responded to coffee aroma compounds and was capable of predicting coffee aroma development.
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Affiliation(s)
- Su-Yeon Kim
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Anam-dong, Seongbuk-gu, Seoul 02841, Republic of Korea; World Institute of Kimchi, Gwangju 61755, Republic of Korea
| | - Jung-A Ko
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Anam-dong, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Bo-Sik Kang
- Department of Wine and Coffee, Daekyeung University, Jain-myeon, Gyeongsan-Si, Gyeongbuk 38547, Republic of Korea.
| | - Hyun-Jin Park
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Anam-dong, Seongbuk-gu, Seoul 02841, Republic of Korea.
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Abstract
Two CO2 formation pathways (chlorogenic acid (CGA) degradation and Maillard reaction) during coffee roasting were investigated. CGA is shown not a major contributor to CO2 formation, as heating of this compound under typical roasting conditions did not release a large quantity of CO2. However, heating of a CGA moiety, caffeic acid, resulted in high yield of CO2 (>98%), suggesting that CGA hydrolysis could be the rate limiting step for CO2 formation from CGA. A large amount of CO2 was detected from glycine-sucrose model system under coffee roasting conditions, implying the importance of Maillard reactions in CO2 formation. Further studies on the heating of various components isolated from green coffee beans showed that CO2 was generated from various green coffee components, including water insoluble proteins and polysaccharides. Around 50% of CO2 was formed from thermal reactions of lower molecular weight compounds that represent ∼25% by weight in green coffee.
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16
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McCoy MJ, Hoppe Parr KA, Anderson KE, Cornish J, Haapala M, Greivell J. Diacetyl and 2,3-pentanedione in breathing zone and area air during large-scale commercial coffee roasting, blending and grinding processes. Toxicol Rep 2017; 4:113-122. [PMID: 28959632 PMCID: PMC5615090 DOI: 10.1016/j.toxrep.2017.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 01/23/2017] [Accepted: 01/29/2017] [Indexed: 12/01/2022] Open
Abstract
Recently described scientific literature has identified the airborne presence of 2,3-butanedione (diacetyl) and 2,3-pentanedione at concentrations approaching or potentially exceeding the current American Conference of Industrial Hygienists’ (ACGIH) Threshold Limit Values (TLVs) at commercial coffee roasting and production facilities. Newly established National Institutes of Occupational Safety and Health (NIOSH) Recommended Exposure Limits for diacetyl and 2,3-pentanedione are even more conservative. Chronic exposure to these alpha-diketones at elevated airborne concentrations has been associated with lung damage, specifically bronchiolitis obliterans, most notably in industrial food processing facilities. Workers at a large commercial coffee roaster were monitored for both eight-hour and task-based, short-term, 15-min sample durations for airborne concentrations of these alpha-diketones during specific work processes, including the coffee bean roasting, blending and grinding processes, during two separate 8-h work periods. Additionally, the authors performed real-time Fourier transform infrared spectroscopy (FTIR) analysis of the workers’ breathing zone as well as the area workplace air for the presence of organic compounds to determine the sources, as well as quantitate and identify various organic compounds proximal to the roasting and grinding processes. Real-time FTIR measurements provided both the identification and quantitation of diacetyl and 2,3-pentanedione, as well as other organic compounds generated during coffee bean roasting and grinding operations. Airborne concentrations of diacetyl in the workers’ breathing zone, as eight-hour time-weighted averages were less than the ACGIH TLVs for diacetyl, while concentrations of 2,3-pentanedione were below the limit of detection in all samples. Short-term breathing zone samples revealed airborne concentrations for diacetyl that exceeded the ACGIH short-term exposure limit of 0.02 parts per million (ppm) in two samples collected on a grinder operator. FTIR analysis of air samples collected from both the workers’ breathing zone and area air samples revealed low concentrations of various organics with diacetyl and 2,3-pentanedione at concentrations less than the limit of detection for the FTIR methods. Neither the breathing zone nor area air samples measured using the FTIR reflected airborne concentrations of organic compounds that, when detected, approached the ACGIH TLVs or regulatory standards, when available. FTIR analysis of headspace of ground coffee beans revealed ppm concentrations of expected alpha diketones, carbon monoxide and other volatile organic compounds (VOCs). Coffee roasting and grinding, with adequate building ventilation and typical roasted bean handling and grinding, appears to generate very low, if any, concentrations of diacetyl and 2,3-pentanedione in the workers’ breathing zones. This study also confirmed via FTIR that roasted coffee beans naturally generate alpha-diketones and other organic compounds as naturally occurring compounds resultant of the roasting and then released during the grinding process.
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Affiliation(s)
- Michael J McCoy
- GZA GeoEnvironmental, Inc., 20900 Swenson Drive, Suite 150, Waukesha, WI 53186, United States
| | - Kimberly A Hoppe Parr
- GZA GeoEnvironmental, Inc., 20900 Swenson Drive, Suite 150, Waukesha, WI 53186, United States
| | - Kim E Anderson
- GZA GeoEnvironmental, Inc., 20900 Swenson Drive, Suite 150, Waukesha, WI 53186, United States
| | - Jim Cornish
- Gasmet Technologies, Inc., Vancouver, British Columbia, Canada
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17
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Rakvaag E, Dragsted LO. Acute effects of light and dark roasted coffee on glucose tolerance: a randomized, controlled crossover trial in healthy volunteers. Eur J Nutr 2015; 55:2221-30. [PMID: 26342706 DOI: 10.1007/s00394-015-1032-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 08/26/2015] [Indexed: 12/17/2022]
Abstract
PURPOSE Epidemiological evidence suggests that coffee consumption is associated with a lower risk of type 2 diabetes. Coffee contains caffeine and several other components that may modulate glucose regulation. The chlorogenic acids (CGA) in coffee have been indicated as constituents that may help to normalize the acute glucose response after a carbohydrate challenge. The aim of this study was to investigate whether two coffee beverages that differ in CGA content due to different roasting degrees will differentially affect glucose regulation. METHODS In a controlled crossover trial, 11 healthy fasted volunteers consumed 300 mL of either light (LIR) or dark (DAR) roasted coffee, or water, followed 30 min later by a 75-g oral glucose tolerance test (OGTT). Blood samples were drawn at baseline, 30, 60, and 120 min. Differences in glucose and insulin responses and insulin sensitivity index (ISI) were analyzed. The CGA and caffeine contents in the coffees were analyzed using UPLC-MS/MS. RESULTS No differences in glucose area under the curve (AUC) were found between treatments. Glucose concentrations were higher at 60 min after ingestion of DAR compared with water, while ingestion of LIR showed similar glucose concentrations as ingestion of water. Insulin AUC was higher after ingestion of DAR compared with water, and both coffees raised insulin concentrations and reduced ISI compared with water, with no difference between the two coffees. CONCLUSION Two coffees with different CGA contents did not differentially affect glucose or insulin responses during an OGTT, but both increased the insulin response compared with water.
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Affiliation(s)
- Elin Rakvaag
- Institute for Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Rolighedsvej 26, 1958, Frederiksberg C, Denmark
| | - Lars Ove Dragsted
- Institute for Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Rolighedsvej 26, 1958, Frederiksberg C, Denmark.
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