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In this work, the electrochemical determination of antioxidant compounds in green coffee beans using a low-pressure chromatographic system based on a single 1-cm length monolithic column is presented. Screening of the antioxidant compounds in green coffee beans using this approach was performed under different elution conditions, considering different supporting electrolyte media and applied potential values at detection. Mass spectra analyses for the structure elucidation of the separated compounds are presented. Under the selected experimental conditions, five chlorogenic acids (3-, 4-, 5-, cis-5-caffeoylquinic acids, and 5-feruloylquinic acid) and caffeine were identified. Resolution values higher than 1.5 were achieved for all identified compounds. The limits of detection for 5-caffeoylquinic acid and caffeine were 9.25 µmol L−1 and 6.73 µmol L−1, respectively. Acetonitrile consumption was of 0.325 mL per analysis. The figures of merit obtained plus the simplicity of the analytical system assembling and handling highlight the high competitiveness of the presented low-cost approach to be used in substitution of HPLC methodologies currently performed to this end, and for further analytical applications in complex matrices.
Alexandra Rangel Silva; João Rodrigo Santos; P. J. Almeida; J. A. Rodrigues. Screening of Antioxidant Compounds in Green Coffee by Low-Pressure Chromatography with Amperometric Detection. Food Analytical Methods 2021, 1 -11.
AMA StyleAlexandra Rangel Silva, João Rodrigo Santos, P. J. Almeida, J. A. Rodrigues. Screening of Antioxidant Compounds in Green Coffee by Low-Pressure Chromatography with Amperometric Detection. Food Analytical Methods. 2021; ():1-11.
Chicago/Turabian StyleAlexandra Rangel Silva; João Rodrigo Santos; P. J. Almeida; J. A. Rodrigues. 2021. "Screening of Antioxidant Compounds in Green Coffee by Low-Pressure Chromatography with Amperometric Detection." Food Analytical Methods , no. : 1-11.
Several scientific studies point fruits as rich sources of antioxidants but mainly focus on their edible part. However, fruits wastes are abundant sources of bioactive compounds and nutrients, which are considered to be health beneficial. The main purpose was to characterise juice, pulp, peel and seeds of Piel de Sapo melon, in terms of several physicochemical characteristics (soluble solids content, titratable acidity, pH, potassium, colour and water activity), some bioactive compounds (total phenolics, vitamin C, chlorophylls and total carotenoids) and total antioxidant activity. Juice, pulp, peel and seeds represent 47, 19, 27 and 5% of melon total weight, respectively. Peel and seeds stood out by their higher concentration of total phenolics compounds and antioxidant activity when compared to edible parts. The highest potassium concentration was found in seeds. Chlorophylls were only detected in peel, while carotenoids were not detected in any part of the melon analysed. Juice and pulp contributed to 69% of vitamin C amount of the whole fruit. However, its concentration in peel was equivalent to the ones observed in juice and pulp. These results pointed out the importance of fruit wastes valorisation and the development of strategies for their re-utilisation.
Fátima Alves Miller; Joana Freitas Fundo; Ester Garcia; João Rodrigo Santos; Cristina Luisa Miranda Silva; Teresa Ribeiro Silva Brandão. Physicochemical and Bioactive Caracterisation of Edible and Waste Parts of “Piel de Sapo” Melon. Horticulturae 2020, 6, 60 .
AMA StyleFátima Alves Miller, Joana Freitas Fundo, Ester Garcia, João Rodrigo Santos, Cristina Luisa Miranda Silva, Teresa Ribeiro Silva Brandão. Physicochemical and Bioactive Caracterisation of Edible and Waste Parts of “Piel de Sapo” Melon. Horticulturae. 2020; 6 (4):60.
Chicago/Turabian StyleFátima Alves Miller; Joana Freitas Fundo; Ester Garcia; João Rodrigo Santos; Cristina Luisa Miranda Silva; Teresa Ribeiro Silva Brandão. 2020. "Physicochemical and Bioactive Caracterisation of Edible and Waste Parts of “Piel de Sapo” Melon." Horticulturae 6, no. 4: 60.
In this work, an analytical methodology for the analysis of volatile carbonyl compounds in barley and malt samples is presented. A simple low-pressure extraction system for volatile compounds was developed. This analytical tool enabled the extraction of volatile compounds directly from barley or malt solid samples (15 min extraction, 10.0 g sample) to an acceptor derivatizing liquid solution, thereafter analyzed by HPLC-DAD-ESI-MS/MS. The low-pressure conditions, pressure of 20 ± 2 in. Hg vac. (33.7 ± 3.7 kPa), enabled to increase the efficiency of the extraction process of some volatile compounds up to 3-fold comparing to normal conditions. Also, no heating procedures were applied, avoiding possible sample degradation and adulteration. Barley and different malt samples, namely pilsner, caramel, chocolate and black, were evaluated. Relevant differences were observed in the volatile carbonyl compounds profile between the samples analyzed. Specialty malts showed richer volatile profiles comparing to barley and pilsner malt samples. Some marker compounds, such as hydroxyacetone and furfural responsible for caramellic, burnt and bready flavours, could be assigned for the most intensely roasted malt samples. In comparison, 2- methylbutanal and 3-methylbutanal were characteristic for caramel malt. The results herein obtained showed that this analytical methodology could be a valuable analytical tool in the characterization, as well as in the quality control of these important raw materials during the malting and roasting processes.
Sebastian Reichel; Daniel O. Carvalho; João Santos; Petr Bednar; José A. Rodrigues; Luís F. Guido. Profiling the volatile carbonyl compounds of barley and malt samples using a low-pressure assisted extraction system. Food Control 2020, 121, 107568 .
AMA StyleSebastian Reichel, Daniel O. Carvalho, João Santos, Petr Bednar, José A. Rodrigues, Luís F. Guido. Profiling the volatile carbonyl compounds of barley and malt samples using a low-pressure assisted extraction system. Food Control. 2020; 121 ():107568.
Chicago/Turabian StyleSebastian Reichel; Daniel O. Carvalho; João Santos; Petr Bednar; José A. Rodrigues; Luís F. Guido. 2020. "Profiling the volatile carbonyl compounds of barley and malt samples using a low-pressure assisted extraction system." Food Control 121, no. : 107568.
In this work, the characterization of volatile carbonyl compounds profiles in healthy and defective green coffee beans was performed. The objective of this characterization was to identify carbonyl marker compounds related to the main bean defects of both arabica and robusta species (black, sour, immature and bored) in non-aged and aged beans. A simple and innovative procedure for volatile compounds extraction was developed, so that usual heating procedures that may adulterate samples’ identity can be avoided. The coffee sample and an acceptor solution containing a carbonyl derivatizing reagent are placed inside a screw-cap flask featuring an inner electric fan. The efficiency of the volatile carbonyl compounds mass transfer could be increased due to the fan’s operation. The experimental parameters, fan rotation speed, extraction period and sample mass were studied to improve the volatile compounds extraction before HPLC analysis. Defective green beans showed higher contents of some volatile carbonyl compounds than healthy green beans. The volatile carbonyl compounds profile obtained during the forced ageing assay revealed that butanal, benzaldehyde, 3-methylbutanal and hexanal were, consistently, found in higher amounts in both arabica and robusta defective beans, in comparison with healthy beans of the same lot.
João Rodrigo Santos; José A. Rodrigues. Characterization of volatile carbonyl compounds in defective green coffee beans using a fan assisted extraction process. Food Control 2020, 108, 106879 .
AMA StyleJoão Rodrigo Santos, José A. Rodrigues. Characterization of volatile carbonyl compounds in defective green coffee beans using a fan assisted extraction process. Food Control. 2020; 108 ():106879.
Chicago/Turabian StyleJoão Rodrigo Santos; José A. Rodrigues. 2020. "Characterization of volatile carbonyl compounds in defective green coffee beans using a fan assisted extraction process." Food Control 108, no. : 106879.
In this work, the use of ion pair chromatography strategy in low pressure chromatographic flow systems is explored for the first time. The straightforward flow manifold encompassed a peristaltic pump, an injection valve and a 1 cm-length C18 monolithic column. The amperometric detection system relied on a boron-doped diamond electrode, used as working electrode. The determination of trigonelline in coffee samples was the case-study selected. This alkaloid is an important quality marker for this commodity and is usually determined using HPLC-UV methodologies. The proposed methodology, based on ion-pair chromatography with amperometric detection, enabled the quantitative resolution of the studied analyte from the matrix compounds by adding to the mobile phase the ion pair reagent, 1-tetradecanosulfonate sodium. The present work, following the recent developments of the low pressure chromatography approach, demonstrates the potentialities of coupling monolithic columns to traditional flow analysis systems for separation and quantification of ionic or ionisable compounds.
Manuela B.T. Sousa; João Rodrigo Santos; P.J. Almeida; J.A. Rodrigues. Low pressure ion pair chromatography with amperometric detection for the determination of trigonelline in coffee samples. Food Research International 2018, 114, 223 -229.
AMA StyleManuela B.T. Sousa, João Rodrigo Santos, P.J. Almeida, J.A. Rodrigues. Low pressure ion pair chromatography with amperometric detection for the determination of trigonelline in coffee samples. Food Research International. 2018; 114 ():223-229.
Chicago/Turabian StyleManuela B.T. Sousa; João Rodrigo Santos; P.J. Almeida; J.A. Rodrigues. 2018. "Low pressure ion pair chromatography with amperometric detection for the determination of trigonelline in coffee samples." Food Research International 114, no. : 223-229.
In this work, an analytical methodology for volatile carbonyl compounds characterization in green and roasted coffee beans was developed. The methodology relied on a recent and simple sample preparation technique, gas diffusion microextraction for extraction of the samples' volatiles, followed HPLC-DAD-MS/MS analysis. The experimental conditions in terms of extraction temperature and extraction time were studied. A profile for carbonyl compounds was obtained for both arabica and robusta coffee species (green and roasted samples). Twenty-seven carbonyl compounds were identified and further discussed, in light of reported literature, with different coffee characteristics: coffee ageing, organoleptic impact, presence of defective beans, authenticity, human's health implication, post-harvest coffee processing and roasting. The applied methodology showed to be a powerful analytical tool to be used for coffee characterization as it measures marker compounds of different coffee characteristics.
Liliana Cordeiro; Inês Valente; João Rodrigo Santos; José António Rodrigues. Qualitative carbonyl profile in coffee beans through GDME-HPLC-DAD-MS/MS for coffee preliminary characterization. Food Research International 2018, 107, 536 -543.
AMA StyleLiliana Cordeiro, Inês Valente, João Rodrigo Santos, José António Rodrigues. Qualitative carbonyl profile in coffee beans through GDME-HPLC-DAD-MS/MS for coffee preliminary characterization. Food Research International. 2018; 107 ():536-543.
Chicago/Turabian StyleLiliana Cordeiro; Inês Valente; João Rodrigo Santos; José António Rodrigues. 2018. "Qualitative carbonyl profile in coffee beans through GDME-HPLC-DAD-MS/MS for coffee preliminary characterization." Food Research International 107, no. : 536-543.
This work proposes the use of near infrared (NIR) spectroscopy in diffuse reflectance mode and multivariate statistical process control (MSPC) based on principal component analysis (PCA) for real-time monitoring of the coffee roasting process. The main objective was the development of a MSPC methodology able to early detect disturbances to the roasting process resourcing to real-time acquisition of NIR spectra. A total of fifteen roasting batches were defined according to an experimental design to develop the MSPC models. This methodology was tested on a set of five batches where disturbances of different nature were imposed to simulate real faulty situations. Some of these batches were used to optimize the model while the remaining was used to test the methodology. A modelling strategy based on a time sliding window provided the best results in terms of distinguishing batches with and without disturbances, resourcing to typical MSPC charts: Hotelling's T and squared predicted error statistics. A PCA model encompassing a time window of four minutes with three principal components was able to efficiently detect all disturbances assayed. NIR spectroscopy combined with the MSPC approach proved to be an adequate auxiliary tool for coffee roasters to detect faults in a conventional roasting process in real-time.
Tiago A. Catelani; João Santos; Ricardo N.M.J. Páscoa; Leonardo Pezza; Helena Pezza; Joao Lopes. Real-time monitoring of a coffee roasting process with near infrared spectroscopy using multivariate statistical analysis: A feasibility study. Talanta 2018, 179, 292 -299.
AMA StyleTiago A. Catelani, João Santos, Ricardo N.M.J. Páscoa, Leonardo Pezza, Helena Pezza, Joao Lopes. Real-time monitoring of a coffee roasting process with near infrared spectroscopy using multivariate statistical analysis: A feasibility study. Talanta. 2018; 179 ():292-299.
Chicago/Turabian StyleTiago A. Catelani; João Santos; Ricardo N.M.J. Páscoa; Leonardo Pezza; Helena Pezza; Joao Lopes. 2018. "Real-time monitoring of a coffee roasting process with near infrared spectroscopy using multivariate statistical analysis: A feasibility study." Talanta 179, no. : 292-299.
Joana F. Fundo; Fátima A. Miller; Ester Garcia; João Santos; Cristina L. M. Silva; Teresa R. S. Brandão. Physicochemical characteristics, bioactive compounds and antioxidant activity in juice, pulp, peel and seeds of Cantaloupe melon. Journal of Food Measurement and Characterization 2017, 12, 292 -300.
AMA StyleJoana F. Fundo, Fátima A. Miller, Ester Garcia, João Santos, Cristina L. M. Silva, Teresa R. S. Brandão. Physicochemical characteristics, bioactive compounds and antioxidant activity in juice, pulp, peel and seeds of Cantaloupe melon. Journal of Food Measurement and Characterization. 2017; 12 (1):292-300.
Chicago/Turabian StyleJoana F. Fundo; Fátima A. Miller; Ester Garcia; João Santos; Cristina L. M. Silva; Teresa R. S. Brandão. 2017. "Physicochemical characteristics, bioactive compounds and antioxidant activity in juice, pulp, peel and seeds of Cantaloupe melon." Journal of Food Measurement and Characterization 12, no. 1: 292-300.
This paper describes the development of a real-time method based on near-infrared spectroscopy (NIRS) for determination of total antioxidant capacity (TAC) and total phenolic content (TPC) in coffee during the roasting process. The real-time non-invasive monitoring procedure involved pointing a diffuse reflectance probe directly at the roasting chamber through a glass window in order to monitor the roasting process. The figures of merit of the chemometric models to estimate TAC and TPC showed selectivity values higher than 12% and determination coefficients (R2P) above 0.90. The TAC and TPC profiles during the roasting procedure are discussed in terms of the antioxidant compounds likely to be present in green and roasted coffee. NIRS was found to be a satisfactory real-time tool for monitoring the content of antioxidant compounds in coffee during the roasting process, complementing other established procedures.
Tiago A. Catelani; Ricardo Páscoa; João Rodrigo Santos; Leonardo Pezza; Helena Pezza; José Lima; Joao Lopes. A Non-invasive Real-Time Methodology for the Quantification of Antioxidant Properties in Coffee During the Roasting Process Based on Near-Infrared Spectroscopy. Food and Bioprocess Technology 2016, 10, 630 -638.
AMA StyleTiago A. Catelani, Ricardo Páscoa, João Rodrigo Santos, Leonardo Pezza, Helena Pezza, José Lima, Joao Lopes. A Non-invasive Real-Time Methodology for the Quantification of Antioxidant Properties in Coffee During the Roasting Process Based on Near-Infrared Spectroscopy. Food and Bioprocess Technology. 2016; 10 (4):630-638.
Chicago/Turabian StyleTiago A. Catelani; Ricardo Páscoa; João Rodrigo Santos; Leonardo Pezza; Helena Pezza; José Lima; Joao Lopes. 2016. "A Non-invasive Real-Time Methodology for the Quantification of Antioxidant Properties in Coffee During the Roasting Process Based on Near-Infrared Spectroscopy." Food and Bioprocess Technology 10, no. 4: 630-638.
In this work, a real-time and in-situ analytical tool based on near infrared spectroscopy is proposed to predict two of the most relevant coffee parameters during the roasting process, sucrose and colour. The methodology was developed taking in consideration different coffee varieties (Arabica and Robusta), coffee origins (Brazil, East-Timor, India and Uganda) and roasting process procedures (slow and fast). All near infrared spectroscopy-based calibrations were developed resorting to partial least squares regression. The results proved the suitability of this methodology as demonstrated by range-error-ratio and coefficient of determination higher than 10 and 0.85 respectively, for all modelled parameters. The relationship between sucrose and colour development during the roasting process is further discussed, in light of designing in real-time coffee products with similar visual appearance and distinct organoleptic profile.
João Rodrigo Santos; Olga Viegas; Ricardo N.M.J. Páscoa; Isabel M.P.L.V.O. Ferreira; António O.S.S. Rangel; João Almeida Lopes. In-line monitoring of the coffee roasting process with near infrared spectroscopy: Measurement of sucrose and colour. Food Chemistry 2016, 208, 103 -110.
AMA StyleJoão Rodrigo Santos, Olga Viegas, Ricardo N.M.J. Páscoa, Isabel M.P.L.V.O. Ferreira, António O.S.S. Rangel, João Almeida Lopes. In-line monitoring of the coffee roasting process with near infrared spectroscopy: Measurement of sucrose and colour. Food Chemistry. 2016; 208 ():103-110.
Chicago/Turabian StyleJoão Rodrigo Santos; Olga Viegas; Ricardo N.M.J. Páscoa; Isabel M.P.L.V.O. Ferreira; António O.S.S. Rangel; João Almeida Lopes. 2016. "In-line monitoring of the coffee roasting process with near infrared spectroscopy: Measurement of sucrose and colour." Food Chemistry 208, no. : 103-110.
In this work, a total flow analysis system based on a novel solid–liquid extraction chamber is presented. This strategy enables all the main experimental procedures for the analysis of a solid sample to be performed automatically: enrichment of the liquid extract, sample treatment, filtration of the liquid extract from the solid sample, directing the extract towards detection, and finally cleansing of the chamber for the following solid sample to be analyzed. The chamber designed to be incorporated in the flow manifold presents two main features: it accommodates stirring bars for enhancing the extraction process, and it presents replaceable solid sample containers (a spare part of the solid–liquid extraction chamber) to easily replace the solid sample and therefore enhance sample analysis throughput. The chamber performance was assessed using two different solid samples, an ion exchanger resin and vegetable samples, focussing on proton and nitrate ion extraction, respectively. The main figures of merit achieved were relative standard deviation (RSD) and relative error values below 7 % for all determinations. The determination rate for vegetable samples was ca. 12 samples h−1. The proposed strategy may be exploited to perform automatically the analysis of solid samples as it embodies a simple automatic strategy of a very important but time-consuming and laborious analytical operation.
Andrea C. Galvis-Sánchez; João Rodrigo Santos; António Rangel. A total analytical system featuring a novel solid–liquid extraction chamber for solid sample flow analysis. Analytical and Bioanalytical Chemistry 2016, 408, 7651 -7661.
AMA StyleAndrea C. Galvis-Sánchez, João Rodrigo Santos, António Rangel. A total analytical system featuring a novel solid–liquid extraction chamber for solid sample flow analysis. Analytical and Bioanalytical Chemistry. 2016; 408 (27):7651-7661.
Chicago/Turabian StyleAndrea C. Galvis-Sánchez; João Rodrigo Santos; António Rangel. 2016. "A total analytical system featuring a novel solid–liquid extraction chamber for solid sample flow analysis." Analytical and Bioanalytical Chemistry 408, no. 27: 7651-7661.
This work focused on the monitoring during the roasting process of one of the main characteristics of coffee's organoleptic profile: acidity. Batches of Arabica and Robusta coffee varieties from different origins were roasted following different process conditions. Simultaneously, real-time on-line monitoring of the coffee roasting process was performed with near infrared spectroscopy (NIRS) using a diffuse reflectance probe. Spectral data were analysed with chemometric tools and acidity profiles were estimated directly from NIR spectra, revealing an encouraging agreement with values obtained with the reference analytical methodology. NIRS proved to be a reliable non-invasive technique for real-time monitoring of coffee roasting processes and may be used as an end-roasting signalizing tool. Furthermore, the approach presented also revealed good perspectives for the exploration of NIRS in the monitoring of other relevant compounds during coffee roasting
João Santos; Miguel Lopo; António Rangel; João Almeida Lopes. Exploiting near infrared spectroscopy as an analytical tool for on-line monitoring of acidity during coffee roasting. Food Control 2016, 60, 408 -415.
AMA StyleJoão Santos, Miguel Lopo, António Rangel, João Almeida Lopes. Exploiting near infrared spectroscopy as an analytical tool for on-line monitoring of acidity during coffee roasting. Food Control. 2016; 60 ():408-415.
Chicago/Turabian StyleJoão Santos; Miguel Lopo; António Rangel; João Almeida Lopes. 2016. "Exploiting near infrared spectroscopy as an analytical tool for on-line monitoring of acidity during coffee roasting." Food Control 60, no. : 408-415.
In this work, an analytical flow system able to perform low pressure chromatography with amperometric detection is presented. As case study, the determination of niacin (vitamin B3) in coffee brewed samples was selected. The manifold comprised a 1.0 cm length monolithic column coated with didecyldimethylammonium bromide, a laboratory-made boron doped diamond electrode, and featured in-line ionic strength adjustment of the mobile phase. The figures of merit concerning the selected case study namely, detection limit, 7.90 10 7 M, determination rate, ca. 10 samples h 1, mobile phase and ISA solution consumption, ca. 2.6 mL per analysis, and CV, below 5% for retention time and peak height, showed the competitiveness of this analytical strategy comparing to the described HPLC methods for niacin determination. The strategy displays a simple configuration, low cost, fast and easy assembling, foreseeing its use to general purpose applications
João Rodrigo Santos; António Rangel. Development of a chromatographic low pressure flow injection system using amperometric detection: Application to the analysis of niacin in coffee. Food Chemistry 2015, 187, 152 -158.
AMA StyleJoão Rodrigo Santos, António Rangel. Development of a chromatographic low pressure flow injection system using amperometric detection: Application to the analysis of niacin in coffee. Food Chemistry. 2015; 187 ():152-158.
Chicago/Turabian StyleJoão Rodrigo Santos; António Rangel. 2015. "Development of a chromatographic low pressure flow injection system using amperometric detection: Application to the analysis of niacin in coffee." Food Chemistry 187, no. : 152-158.
A standard addition method was implemented by using a flow manifold able to perform automatically multiple standard additions and in-line sample treatment. This analytical strategy was based on the in-line mixing of sample and standard addition solutions, using a merging zone approach. The flow system aimed to exploit the standard addition method to quantify the target analyte particularly in cases where the analyte concentration in the matrix is below the lower limit of linear response of the detector. The feasibility of the proposed flow configuration was assessed through the potentiometric determination of fluoride in sea salts of different origins and different types of coffee infusions. The limit of quantification of the proposed manifold was 5×10(-6) mol L(-1), 10-fold lower than the lower limit of linear response of the potentiometric detector used. A determination rate of 8 samples h(-1) was achieved considering an experimental procedure based on three standard additions per sample. The main advantage of the proposed strategy is the simple approach to perform multiple standard additions, which can be implemented with other ion selective electrodes, especially in cases when the primary ion is below the lower limit of linear response of the detector.
Andrea C. Galvis-Sánchez; João Rodrigo Santos; António Rangel. Standard addition flow method for potentiometric measurements at low concentration levels: Application to the determination of fluoride in food samples. Talanta 2015, 133, 1 -6.
AMA StyleAndrea C. Galvis-Sánchez, João Rodrigo Santos, António Rangel. Standard addition flow method for potentiometric measurements at low concentration levels: Application to the determination of fluoride in food samples. Talanta. 2015; 133 ():1-6.
Chicago/Turabian StyleAndrea C. Galvis-Sánchez; João Rodrigo Santos; António Rangel. 2015. "Standard addition flow method for potentiometric measurements at low concentration levels: Application to the determination of fluoride in food samples." Talanta 133, no. : 1-6.
João R. Santos; António O.S.S. Rangel. Determination of Caffeine in Coffee Using Low-Pressure Chromatography. Coffee in Health and Disease Prevention 2015, 983 -991.
AMA StyleJoão R. Santos, António O.S.S. Rangel. Determination of Caffeine in Coffee Using Low-Pressure Chromatography. Coffee in Health and Disease Prevention. 2015; ():983-991.
Chicago/Turabian StyleJoão R. Santos; António O.S.S. Rangel. 2015. "Determination of Caffeine in Coffee Using Low-Pressure Chromatography." Coffee in Health and Disease Prevention , no. : 983-991.
Ricardo N.M.J. Páscoa; Mafalda C. Sarraguça; Luís M. Magalhães; João R. Santos; António O.S.S. Rangel; João A. Lopes. Use of Near-Infrared Spectroscopy for Coffee Beans Quality Assessment. Coffee in Health and Disease Prevention 2015, 933 -942.
AMA StyleRicardo N.M.J. Páscoa, Mafalda C. Sarraguça, Luís M. Magalhães, João R. Santos, António O.S.S. Rangel, João A. Lopes. Use of Near-Infrared Spectroscopy for Coffee Beans Quality Assessment. Coffee in Health and Disease Prevention. 2015; ():933-942.
Chicago/Turabian StyleRicardo N.M.J. Páscoa; Mafalda C. Sarraguça; Luís M. Magalhães; João R. Santos; António O.S.S. Rangel; João A. Lopes. 2015. "Use of Near-Infrared Spectroscopy for Coffee Beans Quality Assessment." Coffee in Health and Disease Prevention , no. : 933-942.
Characterisation of coffee quality based on bean quality assessment is associated with the relative amount of defective beans among non-defective beans. It is therefore important to develop a methodology capable of identifying the presence of defective beans that enables a fast assessment of coffee grade and that can become an analytical tool to standardise coffee quality. In this work, a methodology for quality assessment of green coffee based on near infrared spectroscopy (NIRS) is proposed. NIRS is a green chemistry, low cost, fast response technique without the need of sample processing. The applicability of NIRS was evaluated for Arabica and Robusta varieties from different geographical locations. Partial least squares regression was used to relate the NIR spectrum to the mass fraction of defective and non-defective beans. Relative errors around 5% show that NIRS can be a valuable analytical tool to be used by coffee roasters, enabling a simple and quantitative evaluation of green coffee quality in a fast way
João Rodrigo Santos; Mafalda Sarraguça; António Rangel; João A. Lopes. Evaluation of green coffee beans quality using near infrared spectroscopy: A quantitative approach. Food Chemistry 2012, 135, 1828 -1835.
AMA StyleJoão Rodrigo Santos, Mafalda Sarraguça, António Rangel, João A. Lopes. Evaluation of green coffee beans quality using near infrared spectroscopy: A quantitative approach. Food Chemistry. 2012; 135 (3):1828-1835.
Chicago/Turabian StyleJoão Rodrigo Santos; Mafalda Sarraguça; António Rangel; João A. Lopes. 2012. "Evaluation of green coffee beans quality using near infrared spectroscopy: A quantitative approach." Food Chemistry 135, no. 3: 1828-1835.
In this work, a methodology based on near-infrared spectroscopy (NIRS) was exploited in order to discriminate between commercial coffee brands. The main advantages of this approach compared to other strategies (e.g., wet chemistry methods) are its lower cost, less labor, and lower time per analysis. Two commercial brands were discriminated among several others present in the Portuguese market. The chemometric method used to estimate discriminant models was partial least squares discriminant analysis (PLSDA). Results show that it is possible to discriminate coffee brands using this strategy with a correct classification of 100 %. The spectral region, more favorable to discrimination of roasted coffee brands, can be related with differences in the concentrations of compounds, such as, chlorogenic acid and sucrose, and also due to differences on lipid fraction. This methodology is adequate for field implementation, namely, adopting handheld NIRS instruments.
Mafalda Cruz Sarraguça; João Rodrigo Santos; António O. S. S. Rangel; João Almeida Lopes. Authenticity Control of Roasted Coffee Brands Using Near-Infrared Spectroscopy. Food Analytical Methods 2012, 6, 892 -899.
AMA StyleMafalda Cruz Sarraguça, João Rodrigo Santos, António O. S. S. Rangel, João Almeida Lopes. Authenticity Control of Roasted Coffee Brands Using Near-Infrared Spectroscopy. Food Analytical Methods. 2012; 6 (3):892-899.
Chicago/Turabian StyleMafalda Cruz Sarraguça; João Rodrigo Santos; António O. S. S. Rangel; João Almeida Lopes. 2012. "Authenticity Control of Roasted Coffee Brands Using Near-Infrared Spectroscopy." Food Analytical Methods 6, no. 3: 892-899.
In this work, the coupling of a commercial monolithic column to a traditional low pressure FIA system is proposed for the analysis of theobromine, theophylline and caffeine in coffee brewed samples using UV detection. The parameters mobile phase composition, flow rate and loop volume were evaluated and discussed considering the various chromatographic parameters in order to enable resolution of the methylxanthines studied within the coffee brewed sample matrix. The analyses of methylxanthines in coffee brewed samples by the proposed methodology were in good agreement with those obtained by the reference procedure based on HPLC. Relative errors were below 6% for all samples analyzed. Detection limits in the selected experimental conditions were within 10−6M range for theobromine and theophylline, and 10−5M for caffeine. The determination rate of the three methylxanthines for coffee brewed samples was ca of 10 h−1. The main advantage of the proposed flow system was the possibility to perform chromatographic separations in low pressure flow systems. This substantial improvement was achieved due to the compatibility of monolithic columns within the flow injection system surpassing in this way one of the main handicaps of traditional flow analysis systems. Additional features of the strategy presented were low cost, efficiency, high versatility and low reagent consumption comparing to HPLC methodologies usually followed in the case study herein presented
João Rodrigo Santos; António O.S.S. Rangel. Development of a chromatographic low pressure flow injection system: Application to the analysis of methylxanthines in coffee. Analytica Chimica Acta 2012, 715, 57 -63.
AMA StyleJoão Rodrigo Santos, António O.S.S. Rangel. Development of a chromatographic low pressure flow injection system: Application to the analysis of methylxanthines in coffee. Analytica Chimica Acta. 2012; 715 ():57-63.
Chicago/Turabian StyleJoão Rodrigo Santos; António O.S.S. Rangel. 2012. "Development of a chromatographic low pressure flow injection system: Application to the analysis of methylxanthines in coffee." Analytica Chimica Acta 715, no. : 57-63.
In this work a single interface flow system (SIFA) with potentiometric detection was for the first time implemented and applied to the determination of nitrate in waters and plant extracts. The analytical potential of the SIFA system was exploited not only to transport the sample towards detection but also to carry out, in a reproducible and automated way, the tasks associated with sample pre-treatment, namely ionic strength, pH adjustment and interfering species suppression. The advantageous aspects of combining a SIFA system with potentiometry with enhanced simplicity, ease of implementation and automation were further discussed and emphasised. The obtained results showed relative deviations lower than 5%, for both types of samples, with sampling rates of about 40 h−1. In addition, an innovative and straightforward process for constructing plastic membrane ion selective electrodes with a tubular configuration able to be coupled to flow-based analytical systems is also proposed. The developed approach, consisting of assembling the electrode inside a flow tubing connector is very simple to implement, robust, particularly adequate to be combined with flow methodologies and maintains all dynamic and analytical characteristics exhibited by previous assembling processes.
João Rodrigo Santos; João L.M. Santos; José L.F.C. Lima. Single interface flow system with potentiometric detection for the determination of nitrate in water and vegetables. Talanta 2010, 80, 1326 -1332.
AMA StyleJoão Rodrigo Santos, João L.M. Santos, José L.F.C. Lima. Single interface flow system with potentiometric detection for the determination of nitrate in water and vegetables. Talanta. 2010; 80 (3):1326-1332.
Chicago/Turabian StyleJoão Rodrigo Santos; João L.M. Santos; José L.F.C. Lima. 2010. "Single interface flow system with potentiometric detection for the determination of nitrate in water and vegetables." Talanta 80, no. 3: 1326-1332.