Article

Water content determination in green coffee – Method comparison to study specificity and accuracy

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Abstract

Green coffee behaves very differently at high and low water content with a number of unwanted consequences like microbial growth, mycotoxin formation, altered sensorial quality of end product, instable production conditions and unclear trade issues. Generally, a water content ranging between 8.0% and 12.5% is considered to be adequate to avoid the mentioned issues. ISO has therefore issued a number of standards for reference, routine and rapid methods. Nevertheless, on-going discussions on how effective the methods are capable to principally determine the water content lead to modifications of the official approach. This work was therefore focused on clarifying the specificity and accuracy of several available methods. We could demonstrate that only ISO 1446 exclusively measures water but leaves some residual water content difficult to extract from the dried coffee matrix. For all drying oven based methods we observe degradation of the product contributing to the overall weight loss. We used near-infrared spectroscopy and color measurement to establish the degree of degradation and the completeness of the drying process. Repeatability was found excellent for all methods despite degradation and incomplete drying which should negatively affect accuracy.

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... There is also a layer of wax on their surface, accounting for 0.2e0.3% of the coffee weight ( Farah, 2012). Several methods are available for the measurement of moisture in coffee, including the oven drying method, Karl-Fischer titration, conductivity meters and water activity measurement ( Reh et al., 2006). Conductivity meters are relatively rapid and easy to use but cannot measure a single coffee bean, and so alternative methods should be applied when focusing on individual coffee beans. ...
... grinding, extraction or purification ( Pizarro et al., 2004). Although NIRS is an indirect technique with high accuracy for moisture prediction in coffee beans, the need for good calibration has been highlighted ( Reh et al., 2006). Despite being a powerful technique, NIRS does not readily permit detailed analysis in the spatial domain, which is key to understanding beanto-bean variation and the spatial distribution of moisture and lipids across seeds. ...
... Moisture content was analysed by oven drying using an adaption of the method ISO 11294: 1994 (1994), which involved using a slightly lower temperature and longer time to avoid excessive sample degradation. This is because the analysis of moisture content through the official ISO method could result in a partial degradation of the product when analysing the coffee beans, which will influence the overall weight loss ( Reh et al., 2006). The individual samples of green coffee beans were placed on an aluminium tray and dried in a Sanyo 112-F (San Diego, CA, USA) oven at 95 C for about 24h. ...
Article
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Hyperspectral imaging (1000–2500 nm) was used for rapid prediction of moisture and total lipid content in intact green coffee beans on a single bean basis. Arabica and Robusta samples from several growing locations were scanned using a “push-broom” system. Hypercubes were segmented to select single beans, and average spectra were measured for each bean. Partial Least Squares regression was used to build quantitative prediction models on single beans (n = 320–350). The models exhibited good performance and acceptable prediction errors of ∼0.28% for moisture and ∼0.89% for lipids. This study represents the first time that HSI-based quantitative prediction models have been developed for coffee, and specifically green coffee beans. In addition, this is the first attempt to build such models using single intact coffee beans. The composition variability between beans was studied, and fat and moisture distribution were visualized within individual coffee beans. This rapid, non-destructive approach could have important applications for research laboratories, breeding programmes, and for rapid screening for industry.
... As water is quite cheap compared to coffee, its amount is also interesting from a commercial point of view. Thus, a precise knowledge of water content in green coffee is fundamental to ensure quality, as it should be in the range of 8–13% to allow for safe transportation and storage (Clarke, 1985; Reh, Gerber, Prodolliet, & Vuataz, 2006). Reference methods for water content determination in green coffee are based on oven drying. ...
... The major drawback associated to oven drying methods is that they usually require long measuring times, which can be overcome by using infrared dryers. However, depending on heating conditions, some level of decomposition and ARTICLE IN PRESS water formation due to Maillard reactions should occur (De Caro, Aichert, & Walter, 2001; Reh et al., 2006). There are three standards issued by ISO International Standard (1978 Standard ( , 1983 Standard ( , 2001 ) for water content determination in green coffee: 1446 (slow drying at 48 1C under phosphorous pentoxide up to constant weight); 1447 (two step drying at 130 1C) and 6673 (16 h drying at 105 1C). ...
... There are three standards issued by ISO International Standard (1978 Standard ( , 1983 Standard ( , 2001 ) for water content determination in green coffee: 1446 (slow drying at 48 1C under phosphorous pentoxide up to constant weight); 1447 (two step drying at 130 1C) and 6673 (16 h drying at 105 1C). A recent study by Reh et al. (2006) presented a comparison of those methods and showed they were highly correlated to each other (R 2 values above 0.99). They also showed that none of the procedures allowed complete drying of green coffee and concluded that ISO 6673 was appropriate for routine analysis since it was the one that required the least input of labor (one step of drying, no grinding required) and was found to be independent of climate conditions and the presence of forced ventilation. ...
Article
The main objective of this study was to compare methods for mass loss evaluation in green coffee to water content determination by Karl Fischer titration (KFT). The following methodologies were tested: (i) ISO 6673 (oven drying at 105 °C for 16 h); (ii) the reference method employed by the Brazilian Agriculture Ministry (oven drying at 105 °C for 24 h)—BRAMw, employing whole beans and BRAMg, employing ground beans; and (iii) infrared drying (IRD). Reference oven drying methodologies ISO 6673 and BRAMw presented results statistically equivalent (p>0.05) to those from KFT in the moisture content range that is of interest for green coffee commercialization (8–13 g/100 g), whereas IRD results were lower than those for KFT. ISO 6673 and BRAMw also presented the highest values of correlation coefficients to KFT. Differences in moisture content determination became more significant for lower moisture content values (4–7 g/100 g), probably due to loss of organic volatile substances during drying and occurrence of moisture loss during sample grinding.
... The safety range for MC is 8.0-12.5%, based on fresh matter [1][2][3]. MC outside the safety range impairs the bean quality and safety. Beans with a MC above 12.5% are not allowed to be shipped and traded [4]. ...
... Up to date, the standard method for determining MC is the gravimetric method, where a drying chamber with a certain temperature and time is used to dry the beans and afterwards the mass loss is calculated. International standards for MC measurement of green coffee beans are The International Organization for Standardization (ISO) 1446, 1447, and 6673 [3,14]. Thereof, ISO 6673 which requires less preparation and the shortest drying time (105 °C for 16 h) is widely accepted as a reference method among importing and exporting countries. ...
... Specific wavelengths (1450 and 1940 nm) were identified to be highly correlated with water content [3,18,19]. Predicting MC using NIRS in any agricultural product is more complex and should not be based on wavelengths limited to 1450 and 1940 nm. MC does not only reflect water, but also loss of volatile compounds during drying [3]. ...
Article
Full-text available
Moisture content (MC) is one of the most important quality parameters of green coffee beans. Therefore, its fast and reliable measurement is necessary. This study evaluated the feasibility of near infrared (NIR) spectroscopy and chemometrics for rapid and non‐destructive prediction of MC in intact green coffee beans of both Coffea arabica (Arabica) and Coffea canephora (Robusta) species. Diffuse reflectance (log 1/R) spectra of intact beans were acquired using a bench top Fourier transform NIR instrument. MC was determined gravimetrically according to The International Organization for Standardization (ISO) 6673. Samples were split into subsets for calibration (n = 64) and independent validation (n = 44). A three‐component partial least squares regression (PLSR) model using raw NIR spectra yielded a root mean square error of prediction (RMSEP) of 0.80% MC; a four component PLSR model using scatter corrected spectra yielded a RMSEP of 0.57% MC. A simplified PLS model using seven selected wavelengths (1155, 1212, 1340, 1409, 1724, 1908, and 2249 nm) yielded a similar accuracy (RMSEP: 0.77% MC) which opens the possibility of creating cheaper NIR instruments. In conclusion, NIR diffuse reflectance spectroscopy appears to be suitable for rapid and reliable MC prediction in intact green coffee; no separate model for Arabica and Robusta species is needed.
... Due to the importance to the coffee quality, several methods for measuring the moisture content have been developed such as oven or hot air heating method [9,11,12], P2O5 reference method [12], microwave [13], infrared spectroscopy [12], colour [11,12], hardness and brittleness [11], and electronic meters [11,14]. Among all those methods, moisture content measurement using the electronic meter with the capacitive principle is the most widely used method due to the practical and fast measurement of the capacitive properties that related to physical and chemical properties of the material [11,14,15]. ...
... Due to the importance to the coffee quality, several methods for measuring the moisture content have been developed such as oven or hot air heating method [9,11,12], P2O5 reference method [12], microwave [13], infrared spectroscopy [12], colour [11,12], hardness and brittleness [11], and electronic meters [11,14]. Among all those methods, moisture content measurement using the electronic meter with the capacitive principle is the most widely used method due to the practical and fast measurement of the capacitive properties that related to physical and chemical properties of the material [11,14,15]. ...
... Due to the importance to the coffee quality, several methods for measuring the moisture content have been developed such as oven or hot air heating method [9,11,12], P2O5 reference method [12], microwave [13], infrared spectroscopy [12], colour [11,12], hardness and brittleness [11], and electronic meters [11,14]. Among all those methods, moisture content measurement using the electronic meter with the capacitive principle is the most widely used method due to the practical and fast measurement of the capacitive properties that related to physical and chemical properties of the material [11,14,15]. ...
Article
Full-text available
Moisture content is one of the most important parameters for coffee commodity especially related to quality and taste. However, research on measurement instruments which capable to measure moisture content directly from a coffee sample is still very rare. Therefore, in the current study, this prototype is realized by utilized a capacitive sensor made from couple of copper plates to measure capacitive signal from the sample, which subsequently converted to a voltage signal by an oscillator and comparator, and then finally converted to the moisture content by a microcontroller which can be shown on an LCD screen. An accuracy testing is carried out by comparing the moisture content measured from the oven heating reference method and the prototype. The results show the average of measurement errors is 0.08 % and 0.22 % for coffee evaporated sample and coffee-water mixed sample respectively. Based on the maximum permissible error stated in OIML International Recommendation of R-059, this prototype meets the requirement of moisture meter of Class I.
... MC in green coffee, indeed, governs fermentation and mold growth during storage and transport, which could lead either to the development of off-flavors at the cup level and/or to the formation of mycotoxins (MC 8-13% enables safe transportation and storage). Besides, from an economical point of view, the coffee is paid by weight and buyers are thus more interested in buying solid coffee materials than water which, additionally, affects the bean shelf life (Mendonça et al., 2007;Reh et al., 2006). As for green coffee, an inadequate MC after the roasting phase reduces the shelf life of the final product. ...
... The reference analysis (ISO 11294, in the present study) is the key element for the construction and the final performance of the calibration models. Therefore, a lack of accuracy of the reference method produces an increased error in the prediction from secondary techniques, like NIR spectroscopy (Reh et al., 2006). Considering the numerous phases of the ISO analysis, even though performed by skilled personnel, an evaluation of the inner variability between the three replicates (sub-aliquots of 5.0 ± 0.2 g) was performed, with the aim of removing any possible gross error from the dataset. ...
Article
Moisture content (MC) is one of the main issues that the coffee industry has to monitor. The international standards (ISO 11817 and ISO 11294) for MC evaluation are incompatible with the rhythm of a modern productive chain. As an alternative, thermogravimetric moisture analyzers (TMA) are widely applied, but they cannot provide a real-time monitoring and management of MC. The present research aims at evaluating the performance of a near-infrared (NIR) spectrophotometer in measuring the MC of roasted beans and ground coffee, in comparison with a TMA. PLS regression models provided high predictive performances (R²Pred = 0.95 and RMSEP = 0.15%, and R²Pred = 0.97 and RMSEC = 0.13% for roasted and ground coffee, respectively). Passing-Bablok regression was performed to compare NIR and TMA measurements, but no significant differences were highlighted. The residual dispersion index (RDI%) was proposed, showing the higher predictive accuracy of the NIR spectrophotometer, envisaging this technology as a routine standard method for coffee MC evaluation.
... However, the degradation into polypeptides and the formation of volatile (pyrroles, pyridines, pyrazines, etc) and non-volatile (pigments, such as melanoidins, and others) nitrogenous components during roasting (Homma, 2001) also contributes to protein nitrogen determination by Kjeldahl and therefore the protein results for roasted coffee remain practically unaltered on an as is basis. Sivetz and Desrosier, 1979;Clarke and Macrae, 1985;Clarke and Macrae, 1987;Speer and Kölling-Speer, 2001;Reh et al., 2006;Mendonça et al., 2007. b Determined by difference. ...
... As water is quite cheap compared to coffee, its amount within the beans is also of interest from a commercial point of view . Its ammount is usually controlled by processing conditions, and, for green coffee, it is kept at about 12% to allow for safe transportation and storage (Clarke, 1985;Reh et al., 2006). Immediately after roasting, coffee moisture content can be as low as zero moisture, especially for dark roasts (Clarke, 1985) when water quenching is not employed. ...
Article
Full-text available
The term "coffee" is usually employed in reference to the consumable beverage obtained by extracting roasted coffee with hot water, but it actually comprises a wide range of intermediate products, starting from the freshly harvested fruit (coffee cherries), then to green beans and to the final product of consumption (roasted coffee). Green coffee beans are the main item of international trade, and their quality is evaluated according to a wide variety of criteria, including bean size, color, and shape, processing method, crop year and flavor (cup quality). Among these, flavor is the most important criterion, and it is directly affected by the presence of the so-called defective coffee beans. The presence of defective beans is usually a consequence of problems that occur during harvesting and pre-processing operations. The most important defects are black, sour or brown, immature, bored or insect-damaged, and broken beans. Both black and sour defects are associated with bean fermentation and play a major role in downgrading coffee flavor. Immature beans (from immature fruits) contribute to beverage astringency. Such defective beans are usually present in the coffee produced in Brazil, due to the strippicking harvesting and processing practices adopted by the coffee producers. They are separated (color sorting) from the non-defective beans prior to commercialization in external markets, and the majority of these beans are dumped on the Brazilian internal market. Thus, the roasting industry in Brazil has been using these defective beans in blends with healthy ones, and, overall, a low-grade roasted coffee is consumed in the country. Currently there are no analytical methodologies that allow for detection and quantification of defective beans in roasted coffee, and thus an assessment of chemical attributes that could provide differentiation between defective and healthy coffee beans is of relevance. Thus, a review on physical and chemical attributes of defective coffee beans in comparison to healthy ones is herein provided, for both green and roasted coffees. Physical attributes include bean size, volume, density, color and water activity. Chemical attributes include proximate composition, acidity, pH, sucrose levels, caffeine, trigonelline, chlorogenic acids, amines and volatile substances. The evaluation of such attributes indicates that, in the case of green coffee, it is possible to differentiate defective and non-defective (healthy) beans by color, size, acidity levels, sucrose levels, and the presence of histamine. In the case of roasted coffee, only an evaluation of the volatile profile will effectively provide the means for differentiation.
... Likewise for roasted and unroasted coffee seeds readings are taken. Percentage of moisture content is calculated using Equation (1) [9]. % of moisture content in sample ...
... Generally it varies from 0 to 1 (in fraction) and 0 to 100 (in percent). Porosity was calculated by the standard relationship of true and bulk density using equation (9). ...
Article
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The knowledge about engineering properties of coffee beans is important in case of design of machine/equipment, developing processes and handling procedures, packaging practices and transporting the processed powders. This work primarily focused on evaluating engineering properties of Roasted, Unroasted coffee beans and Coffee powder. These engineering properties were listed by researchers as size, dynamic angle of repose, coefficient of static friction, bulk and true densities, and porosity. The geometrical statistical data collected for these coffee seeds and beans in terms of their average length, width and thickness are 8.57 mm, 6.91 mm and 4.39 mm for unroasted and 11.43 mm, 8.61 mm, 5.66 mm for roasted coffee beans. Bulk density, True density, Angle of repose, Specific gravity, Porosity, Moisture content are calculated for Unroasted, Roasted coffee seeds and Coffee powder. Porous density, Compact density, Compressibility index, Hauser ratio, Sieve analysis, Static coefficient of friction is calculated for coffee powder on Glass, Paper board, Thermocol. There is no doubt that the work done here definitely will aid optimal design of machines required for harvesting, processing and handling of coffee seeds and beans for good quality products at high efficiency.
... It is also economically important as payment is made based on the mass of coffee. 4,6 Green coffee beans with moisture above 12.5% are more prone to microbial growth, fermentation, mycotoxin formation, and alteration of sensory characteristics. 6,7 On the other hand, beans with moisture content below 9% may shrink, making them look like poor quality coffee. ...
... 4,6 Green coffee beans with moisture above 12.5% are more prone to microbial growth, fermentation, mycotoxin formation, and alteration of sensory characteristics. 6,7 On the other hand, beans with moisture content below 9% may shrink, making them look like poor quality coffee. 8 The determination of moisture is usually carried out using a gravimetric method, requiring time. ...
Article
Background The chemical compounds of coffee are important indicators of quality. This composition varies according to several factors related to planting and processing of coffee. Thus, this study proposed to use the near infrared spectroscopy (NIR) associated with partial least squares regression (PLS) for quickly estimate of some chemical properties (moisture content, soluble solids, and total and reducing sugars) in intact green coffee samples. For this, a total of 250 samples produced in Brazil were analyzed in the laboratory by the standard method and also had their spectra recorded. Results The calibration models were developed using PLS regression with cross‐validation and tested in a validation set. The models were elaborated using original spectra and preprocessed by five different mathematical methods. These models were compared in relation to the coefficient of determination, RMSECV, RMSEP and RPD and demonstrated different predictive capabilities for the chemical properties of coffee. The best model was obtained to predict grain moisture and the worst performance was observed for the soluble solids model. The highest determination coefficients obtained for the samples in the validation set were equal to 0.810, 0.516, 0.694 and 0.781 for moisture, soluble solids, total sugar and reducing sugars, respectively. Conclusion The statistics associated with these models indicate that NIR technology has potential to be routinely applied for predicting green coffee chemical properties, in particular, for moisture analysis. However, the content of soluble solids and total sugars did not show high correlations with the spectroscopic data and need to be improved. This article is protected by copyright. All rights reserved.
... All of the wet SCG samples were stored in a refrigerator so as to avoid formation of mould, as water governs fermentation and mould growth during storage (Reh et al., 2006). The fresh (pre-brewing) coffee ground sample was provided from the same coffee shop as RCG2 and will be referred to as FRCG (fresh retail coffee grounds). ...
... This can likely be attributed to larger interstitial gaps forming between particles of larger diameter that retain more unbound moisture during brewing. The particle size of SCG can also impact on drying rate as it modifies the distance the bound water has to diffuse (Reh et al., 2006). ...
Thesis
Spent coffee grounds (SCG) are the main residues of the coffee industry, and a potentially valuable source of lipids for sustainable biodiesel production. However, feedstock properties, such as the high SCG moisture content and the relatively high free fatty acid (FFA) content of recovered oil, can impact on the efficiency of the extraction and the quality of extracted oil and derived biodiesel, thus reducing the possible environmental benefits of producing biodiesel from this waste stream. Therefore, a better understanding of feedstock properties and processing steps is required to improve the efficiency of SCG valorization as a biodiesel feedstock and contribute to its future industrialization. This work presents experimental studies including feedstock characterization of SCG, laboratory and pilot plant scale solvent extraction experiments and utilization of mechanical pressing for processing of coffee residues. The solvent extraction experiments investigated effects of solvent type, SCG moisture content and particle size, SCG-to-solvent ratio, and the duration, temperature and pressure of the extraction process on oil extraction efficiency and composition. Transesterification was performed with SCG oil containing high FFA content, and the combustion of derived biodiesel was investigated in a compression-ignition engine. Instant SCG were found to possess higher lipid and FFA content than retail SCG. Solvent extraction experiments showed that longer durations, higher temperatures, low moisture presence and mixed size SCG particles generally improved extraction efficiency, while the impact of pressure depended on temperature. A correlation was observed between longer extraction durations and lower FFA content, while extraction temperature and solvent selection affected the oil composition. Pilot plant extraction showed reduced sensitivity to moisture, while mechanical pressing was efficient in removing a fraction of residual moisture. A two-step transesterification process achieved a biodiesel conversion yield of 86.7 % relative to initial oil weight. SCG biodiesel showed similar combustion and emissions characteristics to commercial soybean and rapeseed biodiesel.
... Near infrared spectroscopy (NIRS) has been successfully used in the coffee industry, focusing on water content determination (Reh, Gerber, Prodolliet, & Vuataz, 2006), discrimination between Arabica and Robusta varieties (Downey, Boussion, & Beauchêne, 1994), roasting control (Alessandrini, Romani, Pinnavaia, & Rosa, 2008), and organoleptic characterisation (Pizarro, Esteban-Diez, & Gonzalez-Saiz, 2004) of roasted coffee. ...
Article
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.
... Coffee beans enter to dryer from washing process and the moisture content is decreased from 53%w.b. to 12%w.b.. If this process is badly performed, microorganism can grow on coffee bean surface, exposing it to biochemical reactions that could affect sugar content [1], and modifying organoleptic properties such as taste, aroma, color, body [2]. Also, coffee trading requires a proper dried product. ...
Conference Paper
Modeling of processes is becoming a powerful tool for understanding their dynamic behavior. In coffee drying process, the current models are based on empiric approximations and fluid dynamic studies. These last models are very computationally demanding for control and dynamic analysis purposes. The proposed model is an approximation that permits prediction, optimization and control systems design without losing rigorousness. Model is based on conservative principles and causal equations. Model validation is qualitative and this model can be used for analysis and design.
... The moisture content was determined by use of the methods of Reh et al. (2006) and described by Ismail et al. (2013). ...
Article
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The study aimed at comparing the effects of three coffee pulping methods on the physico-chemical properties and sensory qualities of coffee. The coffee cherries were processed by disc pulper, drum pulper and eco-pulper methods which varied on mode of operations and mucilage removal methods. The coffee parchment were dried to moisture content of 10 ± 1% and green coffee beans were evaluated for parameters including moisture content, mass, volume, density, pH, titratable acidity, protein, sucrose and lipids content of green coffee beans. The parameters such as moisture, mass, volume and density were determined by actual measurements. Protein was determined by Kjeldhal method, lipids were extracted by Soxhlet method and sucrose extracted and determined by HPLC. The pH showed some significant difference (p<0.05) between the treatments. There was no significant difference on other parameters such as mass, volume, density and titratable acidity, protein, lipids and sucrose. The processing methods showed similar levels on the scores of sensory attributes analyzed by qualified panelist and the scores varied between 7.0-10. The final quality was not significantly different between the processing methods and no defects and faults noted in the samples. It was concluded that the three processing methods do not vary on the levels of physico-chemical components of coffee and gives similar characteristics on sensory attributes and final quality of coffee beverage.
... Drying is considered an important step in quality coffee production, since moisture levels higher than 12% can promote microbial growth and mycotoxin formation (Reh et al., 2006;Getachew et al., 2015). Generally, degree of dryness was tested with two methods: dental and digital. ...
... Metode Near infrared spectroscopy (NIRS) dapat menganalisis dengan kecepatan tinggi, tidak menimbulkan polusi, penggunaan preparat contoh yang sederhana, tidak menggunakan bahan kimia dan dapat menganalisis bahan dengan tidak merusak (nondestruktif). Metoda NIRS telah berhasil untuk penentuan mutu kopi, antara lain penentuan karakterisasi organoleptik kopi roasting (Pizarro et al. 2004), perbedaan antara varietas Arabika dan Robusta (Downey et al. 2005), kadar air (Reh et al. 2006) dan roasting control (Alessandrini et al. 2008). Huck et al. (2005), menganalisis kandungan kafein bubuk kopi. ...
Article
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Caffein is one of the important quality indicator of coffee. Caffein content usually determined by chemical method. Alternative method such Near Infrared Spectroscopy (NIRS) is needed to determine caffein content of coffee rapidly and nondestructively. Applications of NIRS to predict caffein content of coffee were carried out in coffee powders and liquid not in coffee beans. The objective of this study was to assess NIRS method to predict caffein content of arabica coffee bean. Coffee bean samples were placed in petri dish with 2 and 3 layers. The reflectances are measured BY FT-NIR Spectrometer in wavelengths of 1000 – 2500 nm, followed by determination of caffein content by chemical method. Some pre-processing NIRS data such as normalization between 0 and 1 (n01), first derivative of Savitzky-Golay 5 points (dg1), second derivative of Savitzky-Golay 5 points (dg2), combination n01 and dg1, combination n01 and dg2, and PLS calibration to increase accuracy of NIRS prediction. The best prediction is obtained by second derivative and 5 factors PLS with 3 layers of coffee beans with the high R = 0.97 and RPD (5.93), low of SEP and CV (0.007%, 1.76%). This study demonstrated that NIR spectroscopy had excellent potential analysis to determine caffein content of coffee beans. Abstrak Kafein merupakan salah satu indikator mutu terpenting dari kopi. Biasanya kandungan kafein kopi ditentukan dengan metoda kimia. Metoda alternatif seperti Near Infrared Spectroscopy (NIRS) diperlukan untuk penentuan kandungan kafein biji kopi secara cepat dan nondestruktif. Hingga saat ini, aplikasi NIRS untuk penentuan kandungan kafein dilakukan pada kopi bubuk atau kopi cair dan bukan pada biji kopi. Tujuan penelitian ini adalah mengkaji metoda NIRS untuk memprediksi kandungan kafein biji kopi arabika gayo. Biji kopi diletakkan dalam cawan petri dengan 2 dan 3 tumpukan. Reflektan biji kopi diukur menggunakan FT-NIR Spectrometer pada panjang gelombang 1000 – 2500 nm. Dilanjutkan dengan penentuan kandungan kafein kopi dengan metode kimia. Beberapa pra-pengolahan data NIRS seperti normalisasi antara 0 – 1 (n01), derivatif pertama Savitzky-Golay 5 point (dg1), derivatif kedua Savitzky-Golay 5 point (dg2), kombinasi n01 dan dg1, dan kombinasi n02 dan dg2 serta kalibrasi dengan PLS dilakukan untuk meningkatkan akurasi metoda NIRS. Prediksi NIRS terbaik diperoleh dengan pra-PLS dengan 3 tumpukan dengan koefisien korelasi (R = 0.97) dan RPD (5.93) yang tinggi, SEP dan CV yang rendah (0.007%, 1.76%). Penelitian ini membuktikan metode NIRS berpotensi untuk analisis kandungan kafein biji kopi.
... Water content and distribution is a crucial factor for green coffee quality, shelf-life and determines finally also the quality of roasted coffee. Information on the amount and state of water can be obtained by dry weight and water activity measurements (Clarke, 1985;Reh et al., 2006). However, more detailed information on the behaviour of water molecules is needed to better correlate water properties with coffee quality. ...
Conference Paper
The goal of this study was to determine the ability of high-resolution magic angle spinning (HR-MAS) NMR spectroscopy to assess the quality of green coffee before roasting. To this purpose, ten Arabica green coffee samples, half of which had produced good quality coffees (G samples) while the others resulted in worse tasting beverages (B samples), were analysed by HR-MAS 1H NMR spectroscopy at high field (600 MHz) to determine their chemical composition and water hydration. From the proton NMR spectrum of each coffee powder a metabolic profile was obtained and a comparison between the average profile of G and B samples was made using different statistical methods. Principal component analysis (PCA) gave a good separation of G and B samples and this separation was mainly due to the amount of bound water. Two water signals, attributed to internal and external water, were in fact observable in the 1H NMR spectrum at different chemical shift, after the addition of a small amount of water. Thus, more detailed information on the water structure was obtained by studying the position, intensity and shape of the NMR resonances as a function of the hydration. Finally, pulsed field gradient (PFG) HR-MAS 1H NMR spectroscopy was applied to measure self-diffusion coefficients of water and oil molecules in the coffee powder. We showed that the externally added water diffuse in large pores within the powder particles whereas the fatty acids diffuse in a restricted environment within the coffee matrix.
... This can likely be attributed to larger interstitial gaps forming between particles of larger diameter that possibly retain more unbound moisture. The particle size of SCGs can also impact on drying rate as it modifies the distance the bound water has to diffuse [41]. The average particle diameter of FRCG increases after brewing and the larger size of RCG2 particles can be explained by the compression and compaction of coffee grounds during the brewing process, leading some particles to compact together. ...
Article
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Spent coffee grounds (SCG) are a potentially valuable source of lipids for sustainable production of biofuels. However, there are several feedstock properties and solvent extraction parameters that can impact on the oil yield and quality, potentially reducing the possible environmental benefits of deriving oils from this waste stream. This study presents results of laboratory and pilot plant scale experimental investigations into lipid recovery from spent coffee, determining the effects of solvent extraction variables including duration, SCG-to-solvent ratio and SCG residual moisture. SCG samples from both the industrial production of instant coffee and retail coffee shops were characterized in terms of moisture content, particle size distribution and oil content to identify the impact of these variables on the efficiency of lipid recovery by solvent extraction. The dry weight oil content of the instant SCG samples ranged from 24.2 to 30.4% w/w, while the retail SCG samples contained considerably lower amounts of lipids with their oil content ranging between 13.4 and 14.8% w/w. The highest oil yields were found at an extraction duration of 8 h, while a moisture content of ~2% w/w led to increased yields relative to completely dry samples. A pattern of increasing acidity with decreasing extraction duration was observed, suggesting preferential extraction of free fatty acids (FFA), with the fatty acid (FA) profile of the oil found to be similar to lipids commonly utilized for biofuel production.
... 23 nIrS and color measurements have been used to study different drying methods, establishing the degree of degradation in the drying process, and to establish the specificity and accuracy of the standard determination methods for water content. 123 The drying process was monitored on the basis of the absorption at 1940 nm, owing to the specificity of this band for water molecules. The effectiveness of water evaporation during coffee drying was evaluated by comparing the weight loss results with the residual nIrS absorption left over after drying. ...
... The initial MC content of green coffee beans was 7.49 ± 0.19% (w.b.), and lower than the safety range of 8 to 12.5% (w.b.) as the world coffee quality standard [38]. Low MC content in GCB causes an undesirable appearance and the beans shrink, leading to poor-quality coffee [37,39,40]. Lower MC with high unsaturated fatty acids in GCB forms oxidation reactions, producing rancid odors, loss of quality and secondary product oxidation [25]. ...
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The storage conditions of green coffee beans (GCBs) are indispensable in preserving their commercial value. In Thailand, coffee farmers and roasters typically store GCBs for six months to a year before roasting. However, the beans undergo oxidation during storage, influencing both quality and taste. This study investigated changes in GCB lipid oxidation under different accelerated storage conditions (30 ◦C, 40 ◦C and 50 ◦C with 50% RH) and packaging, i.e., plastic woven (PW), low-density polyethylene (LDPE) and hermetic/GrainPro® (GP) bags. Samples were collected every five days (0, 5, 10, 15 and 20 days) and analyzed for lipid oxidation parameters including acid value (AV), free fatty acids (FFA), peroxide value (PV), ρ-anisidine value (PAV), total oxidation value (TOTOX), thiobarbituric acid reactive substances (TBARS), moisture content (MC), water activity (aw) and color. Primary oxidation was observed, with AV, FFA and PAV gradually changing during storage from 1.49 ± 0.32 to 3.7 ± 0.83 mg KOH/g oil, 3.82 ± 0.83 to 9.51 ± 1.09 mg KOH/g oil and 0.99 ± 0.03 to 1.79 ± 0.14, respectively. Secondary oxidation changes as PV and TBARS were reported at 0.86 ± 0.12 to 3.63 ± 0.10 meq/kg oil and 6.76 ± 2.27 to 35.26 ± 0.37 MDA/kg oil, respectively, affecting the flavor and odor of GCBs. Higher storage temperature significantly influenced a lower GCB quality. GP bags maintained higher GCB quality than LDPE and PW bags. Results provided scientific evidence of the packaging impact on oxidation for GCB under accelerated storage.
... Many studies have been published about the utilization of NIRS in the classification of coffee properties. It has also been used to determine the compositions of coffee such as caffeine [23,24,26] , the obromine and theophylline [27], water content [28] and moisture content [29]. According to these studies, coffee properties and features produce specific spectra that can be used to differentiate one group from another. ...
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Civet coffee is regarded as the most expensive coffee in the world. Owing to its high price the conventional method of harvesting civet coffee in the wild has been replaced by a farming method, wherein the wild civet cats are being captured, caged, and then force-fed with ripe, hand-picked, coffee cherries. This is contrary to the production of wild civet coffee from the ripest and sweetest coffee cherries, carefully picked by the civet cat. As the wild civet coffee is quite hard to obtain, most of the civet coffee commercially sold as authentic civet coffee is actually from a caged civet cat. Traders and consumers have no way of differentiating the civet coffee from other types of coffee. This study aimed to differentiate caged civet coffee beans from ordinary green coffee beans. The technique used was the near infrared spectroscopy (NIRS) as it is non- destructive and can generate quick results. A total of 218 samples were scanned, which generated absorbance in the entire 780 wavelength capacity of the Cavite State University Indium, Gallium and Arsenic (CvSU InGaAs)-based NIR instrument, ranging from 904 to 1684 nanometres (nm). A total of 170,040 spectra were generated. The average spectral absorbance's having major differences between the two groups, were chosen, which are 907nm, 1088 nm, 1540 nm and 1650 nm, respectively. Out of 218 samples, 130 samples were used as training data, 40 samples as testing data, and the remaining 48 samples for validation purposes. The training data were subjected to the 4 layers, 15 neurons feed forward back propagation artificial neural network (FFBPANN) for training. Classification scores of 95% to 100% were achieved. Using the combined NIRS and FFBPANN, the civet coffee can be successfully discriminated from coffee beans not eaten by a civet.
... Traditionally, spectroscopic methods in the near infrared (NIR) range have been used as a fast, practical and nondestructive alternative method for moisture analysis and other compounds in pharmaceutical and food processing industries (Pasquini, 2003, Nagarajan, Singh, & Mehrotra, 2006. This technique is growing as a processing analytical technology (PAT), because it brings some advantages, such as the possibility of spectral data acquisition for solid and liquid samples (with minimum or no sample pre-treatment); it provides physicochemical information of the sample (such as viscosity, water content, polymorphism); it predicts and determines multiple parameters through a single spectrum (Buckton, Yonemochi, Hammond, & Moffat, 1998, Blanco & Alacalá, 2006, Reh, Gerber, Prodolliet, & Vuataz, 2006, Nagarajan et al., 2006. This spectroscopic technique was associated with chemometrics, which is based on mathematical and statistical techniques to extract fundamental analytical data from analyzed samples (Pasquini, 2003). ...
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High productivity and meantime perishability of in natura eggs, make powdered egg attractive for patisseries and pasta industries. Water reduction in 65%, extends shelf life from 1 to 12 months, preventing also Salmonella. Maximum powdered egg moisture allowed by Brazilian law is 6.0% (w w-1). However, its determination by reference technique (oven at 105 º C for 8 hour) is lengthy for processing industry. Therefore, the purpose of this study was to investigate the influence of several spectral pre-processing techniques in the application of near-infrared spectroscopy associated with chemometrics models for determination of moisture content in powdered egg, without the need of sample preparation and destruction, held at 0.5 min. Several pre-treatment techniques were evaluated to ensure spectral data reliability such as: standard normal variation; multiplicative scatter correction; smoothing and detrend. The principal component regression (PCR) and partial least squares (PLS) were evaluated with and without pre-treatment. The best results were observed in NIR/PLS model (49 samples), providing an adequate correlation (r) of 0.96, for cross-validation. Using 21 samples as prediction set, NIR/PLS showed relative error (RE) < 2.0%, compared to primary methods oven and thermobalance, indicating to be suitable for industrial quality control. Investigação de métodos de pré-processamento em espectros NIR combinados com regressão multivariada para determinação de umidade em ovo em pó industrial RESUMO. A alta produtividade e perecibilidade dos ovos in natura torna o ovo em pó atrativo para o uso em confeitarias e indústrias de massas. A redução em 65% de água estende a vida de prateleira do produto de 1 para 12 meses, prevenindo a Salmonella. Pela legislação brasileira, a umidade máxima permitida para o ovo desidratado é de 6% (m m-1). Entretanto, sua determinação por técnica de referência (estufa a 105ºC por 8h) demanda um tempo muito longo para seu uso em processo. Portanto, este estudo teve como propósito avaliar a viabilidade da aplicação da espectroscopia do infravermelho próximo, associada a modelos quimiométricos na determinação da umidade do ovo em pó, feita em 0,5 min., sem a necessidade do preparo e nem destruição de amostra. Pré-tratamentos foram avaliados com intuito de aumentar a confiabilidade dos dados espectrais do modelo de calibração: variação de padrão normal; correção multiplicativa de sinal; e alisamentos. Regressões por componentes principais (PCR) e por mínimos quadrados parciais (PLS) foram avaliadas, juntamente com os pré-tratamentos. Os melhores resultados foram observados na modelagem PLS (49 espectros), apresentando um coeficiente de correlação (r) de 0,96 para a validação cruzada. O conjunto preditor (21 amostras) mostrou um erro relativo (ER) < 2,0% para o modelo NIR/PLS, comparado à estufa e à termobalança, mostrando-se adequado para o controle de qualidade industrial. Palavras-chaves: quimiometria, espectroscopia no infravermelho-próximo (NIR), termobalança, estufa-método de referência, modelo de calibração, PLS.
... Nevertheless, there are discussions on how effective the methods are to determine the water content. The work of Reh et al. (2006) focused on clarifying the specificity and accuracy of several available reference methods for determination of water content in green coffee, demonstrating that only ISO 1446 exclusively measures water. For all drying oven based methods it was observed degradation of the product contributing to the overall weight loss. ...
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During the last two decades, near and mid-infrared spectral analyses have emerged as a reliable and promising analytical tool for objective assessment of coffee quality attributes. The literature presented in this review clearly reveals that near and mid-infrared approaches have a huge potential for gaining rapid information about the chemical composition and related properties of coffee. In addition to its ability for effectively quantifying and characterizing quality attributes of some important features of coffee such as moisture, lipids and caffeine content, classification into quality grades and determination of sensory attributes, it is able to measure multiple chemical constituents simultaneously avoiding extensive sample preparation. Developing a quality evaluation system based on infrared spectral information to assess the coffee quality parameters and to ensure its authentication would bring economical benefits to the coffee industry by increasing consumer confidence in the quality of products. This paper provides an overview of the recently developed approaches and latest research carried out in near and mid-infrared spectral technology for evaluating the quality and composition of coffee and the possibility of its widespread deployment.
... Stress metabolism takes place due to drying that influences the chemical compounds content available in coffee [21]. Moisture less than 12% is adequate for hindering the microbial growth besides the formation of mycotoxin [89]. Intensive research reveals that nearly 800 chemical elements have been noticed in roasted coffee which strongly influences the flavor and other characteristics of coffee [40,42]. ...
... Moisture content of green beans influences the stability during storage and alters sensorial quality of end product, thus, a moisture content ranging between 8.0% and 12.5% is considered to be adequate (Reh et al., 2006). Moisture content of coffee beans analysed was about 11.42±0.94%, ...
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Chlorogenic acids are a group of cinnamic acid derivatives with biological effects mostly related to their antioxidant and antiinflammatory activities. This paper aims to determine the chlorogenic acid (CGA) and total phenolic (TP) concentration in various solvent extracts of green coffee beans (Coffea canephora syn. Coffea robusta). Also, the influence of brewing time (water at 90 °C) on the extraction of CGA was analyzed. 70% methanol and 70% 2-propanol were the most effective solvents in extraction of CGA from dried grinded green coffee beans of C. canephora (34.80±0.21 mg CQAE/g d.w. and 31.20±0.32 mg CQAE/g d.w., respectively). The most important CGA concentration was registered after 10 to 15 minute of coffee brewing (38.20±0.24 mg CQAE/g d.w.), when CGA represents approximately 45% of total phenolic compounds. Data obtained are useful both for experts from the food (functional food) and pharmaceutical industry, and also for traders and consumers.
... The result in Table 10 shows that 89.36% respondents determine moisture content by their sense organs which mean by crashing with their teeth, 10.64% test by other methods. Drying is considered an important step in quality coffee production, since moisture levels higher than 12% can promote microbial growth and mycotoxin formation (Reh et al., 2006;Getachew et al., 2015). ...
... To estimate the water content in green coffee samples, a few ISO reference methods are available. 1 Among them, those known as oven-based methods are commonly used for commercial reasons, even though they generally suffer from some common drawbacks, and the water content measured is influenced by the particular procedure adopted. The reasons for the protocol dependence of the water/ moisture estimates is, on the one hand, that additional water can be produced as a result of the drying process, due to the decomposition of the material or due to chemical reactions, such as the Maillard reaction; 1,2 on the other hand, the large variety of bonding states of water in a given raw bean may result in a nonexhaustive dehydration. ...
Article
Water distribution in green coffee was studied by means of pulsed nuclear magnetic resonance (NMR). Hydration experiments for relaxometry measurements were performed by adding either H2O or D2O to dried green coffee beans up to 35% (dry basis) or, alternatively, by moisture absorption in a controlled humidity environment. The CPMG experimental relaxation decay curves were acquired using a benchtop time-domain NMR analyzer at each hydration level and as a function of time. All NMR data were fitted according to the Laplace inversion approach to obtain the proton mobility distributions of water in the hydrated beans. By comparing the T 2 relaxograms of the hydrated beans with the ones observed in the untreated raw beans, it was found that up to ∼10% water exhibits a rather restricted proton mobility. Hydration experiments carried out with D2O highlighted the contribution of the chemical exchange between the water protons and those of the solid matrix to the overall NMR signal. A possible interpretation of the data in terms of the antiplasticizer and plasticizer effect of water is offered. KeywordsGreen coffee beans–Spin–spin relaxation–Proton mobility–D2O
... Al respecto, Reh et al. (2006) sustentan que un porcentaje de contenido de humedad entre el 8 y 12.5% se considera adecuado, porque evita problemas de crecimiento microbiano y formación de micotoxinas, las cuales alteran la calidad sensorial en taza debido a la generación de sabores desagradables. Asimismo, Puerta (2006) enfatiza que un grano de café que no ha sido secado de forma adecuada desarrolla mal olor y sabor, se aplasta en la trilladora y pierde mucho peso durante el proceso de tostación, en consecuencia, su calidad es menor. ...
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La evaluación de la calidad en taza en agrosistemas de Coffea arabica L. es necesaria para generar alternativas que aseguren la calidad y diferenciación del café en Coatepec, Veracruz, México. El presente estudio se realizó con el objetivo de evaluar la calidad física y sensorial de las variedades Typica y Mundo Novo a través del análisis de componentes principales, durante el período 2017-2018, para identificar las variables que se asocian a la calidad en taza de las variedades. Once muestras de café cereza se procesaron con beneficio húmedo para evaluar sus características físicas y sensoriales. Las particularidades físicas fueron evaluadas conforme a las normas internacionales de la Specialty Coffee Association of America (SCAA). De acuerdo con la prueba t de student, los resultados indican, que no existen diferencias significativas entre variedades respecto a la calidad física definidas por tamaño, forma y defectos del grano. Las propiedades sensoriales se analizaron mediante la técnica de componentes principales. Los resultados muestran que dos de los siete componentes explican 73.67% de variabilidad total. El primero refiere 47.24% y se correlaciona negativamente con las variables sabor, sabor residual, acidez y apreciación global. Mientras que, el segundo explica 26.43% y se correlaciona positivamente con las variables cuerpo y balance. Finalmente, los resultados indican que no hubo diferencias significativas en relación con la calidad física del grano y en taza entre variedades, ya que ambas obtuvieron 80 puntos y se consideran cafés de muy buena calidad.
... If the drying process is poor, microorganism could grow on coffee bean surface, lead to biochemical reactions that could be toxic and unconsumable. It could also affect sugar content [1], and changes in organoleptic properties such as taste, color, and aroma [2]. Besides the biodegradation, coffee trading requires a standard dried coffee bean. ...
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This paper proposes a new type of vertical mixed flow dryer and evaluates the characteristic of the dryer for coffee bean drying. The specific design of vertical mixed flow dryer was in the drying chamber that equipped with a perforated-sloped tray to retard grain flow while drying. The dryer characteristic was presented in a form of humidity and temperature behaviour during the drying process. This characteristic could be a database to get coffee with standard moisture content (MC). Parameter stated were air temperature (°C), humidity (kg/kg dry air), coffee bean mass flow rate (kg/s), and air velocity (m/s). For air velocity of 2 m/s, this dryer was able to dry coffee bean from 52% initial MC to final 14% MC for 11,5 hours.
... P. Selecta,S. A. No. Serial #:0473987 Barcelona,Spain) at 105 o C for 24 hours (Reh et al., 2006). The weight loss of samples was recorded and the moisture content was determined in percentages. ...
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Coffee Arabica is an essential commodity to the livelihood of millions of Ethiopians and its quality had critical importance to the coffee industry. A study was conducted to determine engineering physical properties of nine newly released coffee cultivars dried by open sun drying (direct sun light) .Coffee cultivars were (Gawe , Dessu , 744, 7440, 74148, Gesha , Merdacheriko , Wushwush and CJ 19) prepared using wet (washed) processing method during harvesting of 2017/18 cropping season, which were collected from different altitude of south west, Ethiopia. Physical properties of the green bean such as dimensions (length, width and thickness), geometric mean diameter, arithmetic mean diameter, equivalent mean diameter, frontal surface area, cross sectional area, sphericity, aspect ratio, shape index, hundred bean weight, bulk and true density, bean volume, porosity and angle of repose for each cultivar were studied. Most large values of physical properties such as major dimensions, arithmetic mean, geometric mean and equivalent mean diameters; frontal surface area, hundred bean weight and volume of beans were recorded for cultivar 744 at moisture content of 11.67% (wb) and highest values of bulk density, true density, porosity and angle of repose and the lowest values of 100 bean weight, moisture content and volume were recorded for cultivar74148 at moisture content of 9.60%. In the future study other engineering properties should be studied to provide fairly comprehensive information on design parameters involved in recent coffee post-harvest machineries.
... Finally, studies show that drying causes stress metabolism that can also play a role in the composition and concentration of chemical compounds present (Bytof, Selmar, & Schieberle, 2000). Drying is also considered an important step in quality coffee production as moisture levels higher than 12% can promote microbial growth and mycotoxin formation, which can rapidly reduce product quality (Reh, Gerber, Prodolliet & Vuataz, 2006). ...
... The moisture content of ground green and roasted coffee was determined by dehydration in an oven with forced air ventilation (Tecnal, Piracicaba, SP, Brazil) at 105 ± 2°C until constant weight (Reh, Gerber, Prodolliet, & Vuataz, 2006). This information was used to express the amounts of the analytes on a dry weight basis. ...
Article
The levels of free and total tryptophan and of 5-hydroxytryptophan (5-HTP) were investigated in green and roasted grains and beverages of Coffea arabica L. (Arabica) and Coffea canephora Pierre var. robusta (Robusta). Grains were light, medium and dark roasted. Free and protein tryptophan were extracted before and after hydrolysis. The levels of tryptophan and 5-HTP were quantified simultaneously by ion-pair HPLC and fluorimetric detection after derivatisation with o-phthalaldehyde. Robusta green coffee had higher total and protein tryptophan, whereas Arabica had higher free tryptophan levels. 5-HTP was not detected in the samples before and after roasting. Free tryptophan was completely degraded during roasting. Roasting significantly affected protein tryptophan. The rate of loss was smaller in Arabica compared to Robusta at every roasting degree. A beverage prepared the Brazilian way with a medium-roasted coffee provided 1.4–2.5 mg tryptophan/50 ml cup.
... Coffee bean drying: Drying is considered an important step in quality coffee production, since moisture levels higher than 12% can promote microbial growth and mycotoxin formation [18,32,40]. The main propose of drying is to maintain the moisture content of the parchment optimum for storage. ...
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Coffee Arabica is an essential commodity to the livelihood of millions of Ethiopians and its quality had critical importance to the coffee industry. A study was conducted to evaluate coffee quality attributes of nine newly released coffee cultivars subjected to open sun (direct sun light) and lath house-drying methods. The experiment was designed in complete randomized design factorial with two factors (cultivars and drying methods). Coffee cultivars were (Gawe, Dessu, 744, 7440, 74148, Gesha, Merdacheriko, Wushwush and Catimor J-19) prepared using wet (washed) processing method during harvesting of 2017/18 cropping season, which were collected from different altitude of south west, Ethiopia. Cup quality was evaluated by a team of certified panelists at Jimma agricultural research center coffee processing and quality analysis laboratory. The highest value in most cup quality attributes were record in cultivars of Gesha and 74148. Similarly, cultivars of 744 and 7440 were highest in all cup quality parameters. Net lath house drying method was better in all cup quality attributes. Effect of drying method was significant difference (P<0.05) on cup quality parameters such as aromatic quality, astringency, bitterness, body and flavor. The interaction effect of cultivar and drying method shown significant difference (P<0.05) on cup quality parameter except aromatic intensity. In the future to improve and maintain coffee quality different drying method should be practiced. Keywords: Coffee Arabica, Coffee Quality, Coffee Cultivar, Drying Method
... Moisture content of green beans influences the stability during storage and alters sensorial quality of end product, thus, a moisture content ranging between 8.0% and 12.5% is considered to be adequate (Reh et al., 2006). Moisture content of coffee beans analysed was about 11.42±0.94%, ...
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This paper presents some aspects concerning the influence of the environment factors between 2011-2013, registered in the Iasi area, on the productivity and fruits quality for cherry species. In 2011 (432,4 mm) and 2012 (446,6 mm) there were registered quantities below the multiannual limit (524,6 mm), getting a deficit of 92,2 mm in 2011 and 78,0 mm in 2012 (this climatic variability influences negatively the fruit’s growth) and in 2013 the multiannual was exceeded, being achieved 705,4 mm (a surplus of 180,8 mm). Analyzing the average productions on three years (the years XII-XIV from plantation), from the statistic point of view, we can see that the cultivars Margo (30,9 kg/tree) and Ludovic (19,9 kg/tree) registered positive production differences compared to the cultivars average. Under the aspect of the fruits weight (g) and of the equatorial diameter (mm), there were remarked the cultivars Alex (9,6 g and 24,8 mm), Ludovic (8,8 g and 24,1 mm) with positive significant differences compared to the witness and Paul (8,0 g with 22,9 mm), being significantly positive compared to the witness.
... La proliferación del hongo del género Aspergillus no se da en las cerezas de café frescas , debido a que otras especies microbianas presentes (entre ellos, hongos antagónicos de los productores de micotoxinas), protegen de manera natural la cereza de la invasión (25). Un parámetro que favorece la contaminación por micotoxinas es la actividad de agua (aw), que se define como la relación que existe entre la presión de vapor de un alimento dado en relación con la presión de vapor del agua pura a la misma tem- TABLA 1 Resultados del análisis microbiológico realizado a las muestras de café procesado en los beneficios de20,28 ) mencionan en sus estudios , que la determinación del contenido de humedad es una herramienta simple pero muy útil, como parámetro por considerar, para el almacenaje de los granos de café verde. Se considera un rango de contenido de agua óptimo para el almacenamiento, entre 8,0% y 12,5% (28), aunque otros autores mencionan que un contenido de humedad de hasta el 14,5% puede prevenir el crecimiento de hongos durante el almacenaje (20). ...
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SUMMARY. Levels of Ochratoxin A and total Aflatoxins in Panamanian exportation coffee by an ELISA Method. A study about processing conditions of exportation coffee in 15 benefits located in Chiriquí, western region of Panama, was conducted. In addition, 21 samples of processed coffee (green beans), from the benefits, were analyzed. The samples were microbiologically tested in order to quantify total aflatoxins (B1, B2, G1 and G2) and Ochratoxin A (OTA), using the immunoaffinity ELISA method. A detection limit of 0.017 ng/mL, was determined for Ochratoxin A, which is equivalent to a concentration of 0.829 μg/kg, and a detection limit of 0.027 ng/mL, for total aflatoxins, which is equivalent to a concentration of 1.350 μg/kg. It was found that four (19%) out of the 21 samples were positive to the presence of Ochratoxin A and three (14%) to the presence of total aflatoxins. Samples showed levels of Ochratoxin A in the range 4.90 - 37.73 μg/kg; only three of them exceeded the maximum limit allowed by the European Union, for the concentration of Ochratoxin, which is of 5.0 μg/kg. Total aflatoxins were found in the range 1.51 - 1.93 μg/kg, below 10μg/kg which is the maximum limit allowed for coffee by the European Union. The results indicate that the processing of coffee produced in Panama successfully meets international standards for postharvest handling, which leads to a low incidence of mycotoxins and very low levels of mycotoxin- producing fungi. Key words: Mycotoxin, Ochratoxin, aflatoxin, processed coffee, immunoaffinity ELISA method, post-harvest handling, Panama.
Article
Volumetric Karl Fischer titration (V-KFT) is the reference method to determine the water content in a whole range of organic and inorganic matrices. The method has several important drawbacks e.g. a high solvent consumption and a rather large measurement uncertainty when determining the water content in reference and candidate reference materials containing starch (e.g. maize, toasted bread, etc.). It is also labour intensive for routine measurements. In order to overcome these disadvantages, a relatively new method of coulometric Karl Fischer titration, equipped with a fully automated oven system, has been established and optimised.The objective of this study was to establish the robustness of the vaporisation coulometric Karl Fischer titration method (vap-C-KFT) and to compare measurement uncertainties with those obtained by V-KFT. The overall results obtained with the proposed vap-C-KFT methods correlate well with the results obtained by V-KFT (R2=0.998). Due to the good repeatability and intermediate precision of the vap-C-KFT methods compared to V-KFT, significant lower measurement uncertainties were obtained from vap-C-KFT measurements.
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The thin layer coffee beans dehumidification and hot water storage were investigated in solar greenhouse dryer simultaneously. The thermal energy was stored for use in the absence of sunlight. The conditions were studied the flow rate of water circulating, model of installation for solar collector assistance, the area ratio of product dehumidification to solar hot water producing (Ad:Ac), flow pattern of water circulation and capacity tank of water circulating in the system. The experiments were found the flow pattern of water circulation within the force flow 0.20 kg/s-mˆ2, tray products temperature (45 deg. C) at (Ad:Ac) 1:1, capacity tank of water circulating (60 L). The thermal energy can be used and stored in the form of hot water and reused at a time without sunlight as well. The initial coffee beans moisture content was dropped from 55 to below 12 (%w.b.) in 12 h drying time. The optimum of mathematical equations for thin layer coffee beans drying based on Midilli mathematical model i.e. (MR = a exp(-ktˆn) – bt); k = 0.03838, n = 1.56771, a = 1.03046, b = −0.00477, R² = 0.9896, RMSE = 0.0420. Moreover, the effective moisture diffusivity coefficient of 9.754 × 10ˆ-11 mˆ2/s.
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A study about processing conditions of exportation coffee in 15 benefits located in Chiriqui, western region of Panama, was conducted. In addition, 21 samples of processed coffee (green beans), from the benefits, were analyzed. The samples were microbiologically tested in order to quantify total aflatoxins (B1, B2, G1 and G2) and Ochratoxin A (OTA), using the immunoaffinity ELISA method. A detection limit of 0.017 ng/mL, was determined for Ochratoxin A, which is equivalent to a concentration of 0.829 µg/kg, and a detection limit of 0.027 ng/mL, for total aflatoxins, which is equivalent to a concentration of 1.350 µg/kg. It was found that four (19%) out of the 21 samples were positive to the presence of Ochratoxin A and three (14%) to the presence of total aflatoxins. Samples showed levels of Ochratoxin A in the range 4.90 - 37.73 µg/kg; only three of them exceeded the maximum limit allowed by the European Union, for the concentration of Ochratoxin, which is of 5.0 µg/kg. Total aflatoxins were found in the range 1.51 - 1.93 µg/kg, below 10 µg/kg which is the maximum limit allowed for coffee by the European Union. The results indicate that the processing of coffee produced in Panama successfully meets international standards for postharvest handling, which leads to a low incidence ofmycotoxins and very low levels ofmycotoxin-producing fungi.
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The objective of this study was to evaluate the effect of the mass of the sample and the type of method used in determining the moisture content of different food matrices. For moisture determination by the muffle method the Colombian norms were followed for each particular product by triplicate: the AOAC norms for squash and mango; the NTC 2558 norm for coffee and the NTC 1663 norm for sausage. These were compared with the halogen moisture analyzer method. It was found that the mass of the sample is an important factor in the determination of moisture by the two methods used, since there were statistically significant differences in some products studied. However, between the two methods no significant differences in determining the percentage of moisture were found. This allowed demonstrating that the standardized moisture analyzer method is reliable for the determination of this parameter.
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Green coffee beans are stored for a certain period and under certain conditions until they are finally utilized. The storage period may depend on customer demand while the storage conditions depend on where the coffee beans are stored. Thus, this research emphasizes the physico-chemical changes that occur in Liberica coffee beans during storage under the Malaysian climate (average temperature and relative humidity of 29.33°C and 71.75% respectively). The changes in the physico-chemical (coffee size, mass, densities, colour, proximate analysis, sucrose, chlorogenic acid content) and microbiological (yeast and mould count) properties were evaluated during eight months of storage. After the storage, the physical properties of the coffee changed as the coffee beans expanded in size, reduced in mass and density and became brighter in colour. Changes in the chemical properties were also detected where the moisture decreased and the ash content increased. In addition,the sucrose level was found to decrease with a corresponding increase in chlorogenic acid. During storage, the counts of yeast and mould were reduced. Model equations describing the changes in the properties were developed. The overall conclusion was that the coffee beans reduced in quality during storage.
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Liberica coffee is the most important coffee species grown in Malaysia. However, there is little or no research at all conducted on coffee berries and green coffee beans since the plant itself is a low income crop in Malaysia. Therefore, research on Malaysian Liberica coffee can help to increase the knowledge of coffee farmers and coffee manufacturers in the processing and handling of the coffee. Physical properties of Liberica coffee berries and beans were investigated the current study. The properties investigated include the size, mass, density, coefficient of friction, angle of repose, fracture force and colour. In comparison to Arabica and Robusta coffee, Liberica coffee has the biggest size, mass, true density and fracture force values but were lower in bulk density in both berries and beans. The Liberica berries and beans were found to be orange-ish and yellowish colour respectively. Angle of repose was low and approximately similar in berries and beans while jute fibre gave the highest friction to both Liberica berries and beans.
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INTRODUCTION - 1 1 LE CAFÉ - 4 1.1 PRÉSENTATION DU CAFÉ - 4 1.1.1 Un produit très consommé - 4 1.1.2 Le commerce du café - 5 1.1.3 Les variétés de café - 5 1.1.4 La production des grains de café - 6 1.1.5 La production du café moulu et de sa boisson - 13 1.2 COMPOSITION DU CAFÉ - 16 1.2.1 La composition des grains de café vert - 17 1.2.2 La composition des grains de café torréfiés - 27 1.2.3 La composition du café boisson - 37 1.2.4 Conclusion sur la composition du café - 41 1.3 LES EFFETS PHYSIOLOGIQUES DU CAFÉ BOISSON - 41 1.3.1 Les effets bénéfiques pour la santé - 41 1.3.2 Les effets préjudiciables pour la santé - 44 1.4 LES HYDROCARBURES AROMATIQUES POLYCYCLIQUES DANS LE CAFÉ - 46 1.4.1 Les teneurs en HAP de divers cafés - 46 1.4.2 Les procédures analytiques mises en oeuvre - 50 1.4.3 Les sources de contamination du café par les HAP - 51 1.4.4 Conclusion sur les HAP dans le café - 57 2 MATERIELS ET METHODES - 60 2.1 PRODUITS ET RÉACTIFS - 60 2.1.1 Solvants - 60 2.1.2 Standards et réactifs - 60 2.1.3 Matériel utilisé pour l’extraction en phase solide - 61 2.1.4 Cafés étudiés - 62 2.2 MÉTHODES DE TRAITEMENT DES ÉCHANTILLONS DE CAFÉ BOISSON - 62 2.2.1 Procédure de préparation du café boisson - 62 2.2.2 Extraction en phase solide directe du café boisson - 63 2.2.3 Saponification préalable du café boisson - 64 2.3 MÉTHODES DE TRAITEMENT DES ÉCHANTILLONS DE CAFÉ MOULU - 65 2.3.1 Mise en oeuvre de l’extraction accélérée par solvant - 66 2.3.2 Mise en oeuvre de l’extraction par Soxhlet - 73 2.3.3 Mise en oeuvre d’une saponification alcaline directe - 74 2.4 TORRÉFACTION DES ÉCHANTILLONS DE CAFÉ VERT - 75 2.5 MÉTHODES ANALYTIQUES - 76 2.5.1 Analyse quantitative des HAP par HPLC-FD - 77 2.5.2 Analyse qualitative des HAP par HPLC-UV-DAD - 77 2.5.3 Identification des HAP par GC-MS/MS et analyse semi-quantitative - 78 xvii 3 MISE AU POINT DE PROCÉDURES ANALYTIQUES POUR LA DÉTERMINATION DES HAP DANS LE CAFÉ - 84 3.1 DÉTERMINATION DES HAP DANS LE CAFÉ MOULU - 84 3.1.1 Choix d’une méthode de purification de l’extrait PSE - 84 3.1.2 Choix des conditions de mise en oeuvre de l’extraction PSE - 95 3.1.3 Intérêt de la mise en oeuvre d’une extraction PSE - 100 3.1.4 Evaluation des performances de la méthode - 104 3.1.5 Application à la détermination des HAP dans divers cafés moulus - 105 3.2 DÉTERMINATION DES HAP DANS LE CAFÉ BOISSON - 114 3.2.1 Optimisation des conditions d’extraction en phase solide - 114 3.2.2 Mise en oeuvre de la méthode SPE retenue - 126 3.2.3 Etude de la mise en oeuvre d’une étape de saponification - 132 3.2.4 Conclusion - 134 3.3 ESTIMATION DES COEFFICIENTS DE TRANSFERT DES HAP DU CAFÉ MOULU VERS LE CAFÉ BOISSON - 134 3.4 CONCLUSION - 136 4 INFLUENCE DE LA TORREFACTION SUR LA PRESENCE DES HAP DANS LE CAFE - 138 4.1 INTRODUCTION - 138 4.2 ETUDE DES CONDITIONS DE TORREFACTION SUR LA TENEUR EN HAP DU CAFE MOULU - 138 4.2.1 Infuence de la durée de torréfaction à 260°C - 139 4.2.2 Infuence de la température de torréfaction à durée constante - 151 4.2.3 Modélisation avancée de la formation des HAP - 161 4.2.4 Confirmation de la présence des HAP dans les cafés torréfiés - 169 4.2.5 Conclusion - 172 4.3 ETUDE DES CONCENTRATIONS EN HAP DES CAFES BOISSONS - 172 4.3.1 Analyse des cafés boissons préparés à partir de cafés torréfiés pendant 5 min172 4.3.2 Analyse des cafés boissons préparés à partir de cafés torréfiés pendant 20 min174 4.3.3 Estimation des coefficients de transfert des HAP - 175 4.3.4 Conclusion sur le café boisson - 177 4.4 CONCLUSION - 178 CONCLUSIONS ET PERSPECTIVES - 180 RÉFÉRENCES BIBLIOGRAPHIQUES - Référence 183 ANNEXES ANNEXE 1 : Les composés volatils extraits du café torréfié par HS-SPME ANNEXE 2 : Structures chimiques et propriétés des 16 HAP classés polluants prioritaires par l’US EPA ANNEXE 3 : Les HAP et leur toxicité xviii ANNEXE 4: LA CHROMATOGRAPHIE LIQUIDE HAUTE PERFORMANCE COUPLEE A UN DETECTEUR DE FLUORESCENCE ANNEXE 5 : LA CHROMATOGRAPHIE LIQUIDE HAUTE PERFORMANCE COUPLEE A UN DETECTEUR UV ANNEXE 6 : LA CHROMATOGRAPHIE EN PHASE GAZEUSE COUPLEE A LA SPECTROMETRIE DE MASSE ANNEXE 7 : EVALUATION DU POTENTIEL TOXIQUE DU MELANGE DES HAP ANNEXE 8 : IDENTIFICATION DES HAP DANS LES CAFES MOULUS DU COMMERCE PAR GC-MS/MS ANNEXE 9 : ETUDE DE LA CINETIQUE DE FORMATION DES HAP ANNEXE 10 : MODELISATION DE LA FORMATION DES HAP A L’AIDE D’UN RESEAU DE NEURONES ANNEXE 11 : IDENTIFICATION DES HAP DANS LES CAFES MOULUS TORREFIES PAR GC-MS/MS
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