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1 Green coffee beans are viable and metabolically active. A coffee bean was sliced in thin disks and incubated in triphenyltetrazoliumchloride (TTC) solution as described by Selmar et al. (2008). After the viable and metabolic active cells have imported the TTC, it is reduced and a red dye is formed.  

1 Green coffee beans are viable and metabolically active. A coffee bean was sliced in thin disks and incubated in triphenyltetrazoliumchloride (TTC) solution as described by Selmar et al. (2008). After the viable and metabolic active cells have imported the TTC, it is reduced and a red dye is formed.  

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The mode of coffee processing strongly influences the quality of green coffee and thereby establishes the characteristic differences in the flavor of wet and dry processed coffees. These variations are due to differences in the metabolic processes occurring within the vital coffee seeds during the course of processing. Biochemical and molecular bio...

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... The phenolic compounds carried by smoke were adsorbed by the fruit and further glycosylated [42]. However, it happened in growing fruit, displaying many metabolic activities, whereas green CB containing 10-12% of humidity are known to be not metabolically active [43]. ...
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Coffee volatile compounds formation has been studied for years and the main flavour precursors have been identified. Coffee glycosidically bound volatiles (GBVs) are still underexplored and, yet, can act as aroma precursors during the post-harvesting processing and roasting. Free volatile compounds and GBVs of green coffee beans (CB), roasted CB and spent coffee ground (SCG) were analysed. Roasting led to the formation of a new GBVs pool from green to roasted CB and SCG. Most of the GBVs of green CB were hydrolysed during roasting. On the other hand, pyrroles, cycloketones, pyridines and pyrans were identified for the first time as bound volatiles and occurred only after the roasting process. This study supports the importance of GBVs on coffee aroma formation during the post-harvest processing. The release of the GBVs of roasted CB during brewing could enhance the varietal aromas of industrial ready-to-drink coffees. Furthermore, the SCG GBVs could be used as a new source of natural flavours for perfume industries.
... Additionally, in the course of deriving the green coffee beans from the coffee cherries, various postharvest processing steps influence the volatile composition of the coffee product by altering temperature, water activity, enzymatic or microbial reactions amongst other parameters. The numerous postharvest processing treatments of coffee have been reviewed in depth (notably Kleinwächter et al. (2015), Sanz-Uribe et al. (2017), and de Melo Pereira et al. (2019)), of which dry processing (natural) and wet processing (washed) are the two major treatments, while the less common semi-dry processing (pulped natural or honey) offers a middle ground. Otherwise, several "boutique" styles of postharvest processing exist: 'digestive bio-processing' (as with Indonesian kopi luwak by civet cats and Thai Black Ivory Coffee by elephants), monsooning (as with Indian monsoon Malabar), wet hulling, carbonic maceration, and more (Sanz-Uribe et al., 2017). ...
Article
Coffee has attracted significant research interest owing to its complex volatile composition and aroma, which imparts a pleasant sensorial experience that remains challenging to analyse and interpret. This review summarises analytical challenges associated with coffee’s volatile and matrix complexity, and recent developments in instrumental techniques to resolve them. The benefits of state-of-the-art analytical techniques applied to coffee volatile analysis from experimental design to sample preparation, separation, detection, and data analysis are evaluated. Complementary method selection coupled with progressive experimental design and data analysis are vital to unravel the increasing comprehensiveness of coffee volatile datasets. Considering this, analytical workflows for conventional, targeted, and untargeted coffee volatile analyses are thus proposed considering the trends towards sorptive extraction, multidimensional gas chromatography, and high-resolution mass spectrometry. In conclusion, no single analytical method addresses coffee’s complexity in its entirely, and volatile analysis must be tailored to the key objectives and concerns of the analyst.
... These compounds contribute to coffee's flavor. However, its concentration is reduced during the roast (Buffo and Cardelli-Freire, 2004;Kleinwächter et al., 2015). ...
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Wet coffee fermentation is widely used in coffee-producing regions such as Colombia and Hawaii, but it is not widespread in Brazil. This study aimed to evaluate inoculating the lactic acid bacteria Leuconostoc mesenteroides CCMA1105 and Lactiplantibacillus plantarum CCMA 1065 and the yeasts Saccharomyces cerevisiae CCMA0543 and Torulaspora delbrueckii CCMA0684 as starter cultures on wet coffee fermentation using the SIAF method (self-induced anaerobiosis fermentation). The microbial activity resulted in high consumption of the carbohydrates glucose (98.6%), fructose (97.6%), and sucrose (100%), in addition to the production of lactic and acetic acids, impacting the final quality of the beverage. A total of 108 volatile compounds belonging to 17 classes were identified in the green and roasted coffee samples, including 2,3-butanediol produced by lactic acid bacteria, contributing to coffee's aromatic profile. The final scores for the coffees from the different treatments ranged from 79.0 to 83.25. The inoculated fermentations were classified as specialty according to the Specialty Coffee Association. Therefore, whole coffee fruit processed via wet using SIAF method and yeast and lactic acid bacteria starter is an alternative for improving wet fermented coffee quality and obtaining coffee beverages with a different sensory profile.
... The coffee cherries are instantly set to dry with sunshine in dry processing. Depending on the weather, with a cherry water-content of approximately 65%-70% [53,54], the drying process might take up to 2-4 weeks. Coffee beans are dried until reaching a water-content level of approximately 15%. ...
... This method was originally widely used in arabica coffee, but currently, many are using robusta coffee. The wet process produces coffee with more flavor and pleasant acidity, but with less body than the dry method [54,55,68] It was formerly assumed that this was because wet-processed coffee used ripe fruit, whereas dry-processed coffee paid less regard to fruit ripeness consistency [54]. However, the results of Valio's research [57] show that although coffee cherries may have the same maturity level, the characteristics of coffee produced by dry processing and wet processing remain different. ...
... This method was originally widely used in arabica coffee, but currently, many are using robusta coffee. The wet process produces coffee with more flavor and pleasant acidity, but with less body than the dry method [54,55,68] It was formerly assumed that this was because wet-processed coffee used ripe fruit, whereas dry-processed coffee paid less regard to fruit ripeness consistency [54]. However, the results of Valio's research [57] show that although coffee cherries may have the same maturity level, the characteristics of coffee produced by dry processing and wet processing remain different. ...
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Coffee is consumed not just for its flavor, but also for its health advantages. The quality of coffee beverages is affected by a number of elements and a series of processes, including: the environment, cultivation, post-harvest, fermentation, storage, roasting, and brewing to produce a cup of coffee. The chemical components of coffee beans alter throughout this procedure. The purpose of this article is to present information about changes in chemical components and bioactive compounds in coffee during preharvest and postharvest. The selection of the appropriate cherry maturity level is the first step in the coffee manufacturing process. The coffee cherry has specific flavor-precursor components and other chemical components that become raw materials in the fermentation process. During the fermentation process, there are not many changes in the phenolic or other bioactive components of coffee. Metabolites fermented by microbes diffuse into the seeds, which improves their quality. A germination process occurs during wet processing, which increases the quantity of amino acids, while the dry process induces an increase in non-protein amino acid γ-aminobutyric acid (GABA). In the roasting process, there is a change in the aroma precursors from the phenolic compounds, especially chlorogenic acid, amino acids, and sugars found in coffee beans, to produce a distinctive coffee taste.
... Çizelge 1. Kahve çekirdeklerinin fermantasyon uygulamaları (Huch, 2015) Kuru Kuru proseste ise kuruma meyvenin içinde gerçekleşmekte ve nemli meyvelerin kuruma süresi daha uzun olmaktadır. Bununla beraber mekanik kurutma işlemleri enerji gerektiren ve maliyetli bir işlemdir (Kleinwächter, 2015). ...
... Tersi durumda da de çekirdeklerin su içeriği yeterli seviyede olduğu müddetçe, çeşitli metabolik faaliyetler devam etmektedir. Doğal fermantasyonun meydana geldiği bu süre, klasik yaş proses işlemi için 2-4 gün arasındadır (Kleinwächter, 2015). Kahve işlemede tüm metabolik faaliyetler, kullanılan üretim tekniğine göre değişkenlik göstermekte ve proses şartlarından etkilenmektedir. ...
... Due to the intense use of water, the industry encourages the use of the dry method; however, this method does not produce the same quality of coffee [40][41][42]. In Costa Rica, most of the coffee is processed following the wet method, and it is still one of the most important processes used worldwide. ...
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Tropical crops are an important source of wealth in many countries. The current agribusiness model is based on the production of a final commodity, leading to the production of organic by-products (biowastes) that in many cases contain bioactive compounds with a potential added value. The exploitation of these by-products is the foundation of the circular economy that leads to the generation of greener bioprocesses for the industry with foreseeable economic improvements in production systems. This review aims to point out the idle opportunities of agricultural production systems and their associated biowastes to contribute to the establishment of a bioeconomy. Hence, the focus lies on five tropical extensive crops: coffee, oil palm, sugar cane, banana, and pineapple. This first part of the review explores agricultural wastes originated from the coffee and oil palm industrial process and is oriented on the potential use of these by-products as a starting material for the alternative obtention of chemicals, otherwise obtained from petrochemistry. The second part of the review focuses on prospective use of lignocellulosic rich biowaste that is derived from the industrialization of sugar cane, banana, and pineapple. A fundamental difference for the use of coffee biomass compared to other crops is the presence of numerous bioactive compounds that are not yet properly utilized, such as antioxidants (i.e., caffeic acid, chlorogenic acid, ferulic acid), as well as their possible use in the manufacture of products of interest in the cosmetic (i.e., quinic acid) or pharmaceutical industry (i.e., caffeic acid phenethyl ester). In the case of oil palm, its potential lies in obtaining chemicals such as glycerol and carotenoids, or in the bioenergy production.
... It has often discussed that processing factors were responsible for the specific flavor expressions of differently processed coffees [9]. In other words, the type of processing influences the differences in the constituents of green coffee which, during roasting, give rise to aroma compounds and express the characteristics of roasted coffee beans [14]. In addition, large amounts of co-products such as coffee pulp, mucilage and parchment, and wastewater are generated during the wet processing [15]. ...
Article
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Many technical challenges still need to be overcome to improve the quality of the green coffee beans. In this work, the wet Arabica coffee processing in batch and continuous modus were investigated. Coffee beans samples as well as by-products and wastewaters collected at different production steps were analyzed in terms of their content in total phenols, antioxidant capacity, caffeine content, organic acids, reducing sugars, free amino group and protein content. The results showed that 40% of caffeine was removed with pulp. Green coffee beans showed highest concentration of organic acids and sucrose (4.96 ± 0.25 and 5.07 ± 0.39 g/100 g DW for the batch and continuous processing). Batch green coffee beans contained higher amount of phenols. 5-caffeoylquinic Acid (5-CQA) was the main constituent (67.1 and 66.0% for the batch and continuous processing, respectively). Protein content was 15 and 13% in the green coffee bean in batch and continuous processing, respectively. A decrease of 50 to 64% for free amino groups during processing was observed resulting in final amounts of 0.8 to 1.4% in the processed beans. Finally, the batch processing still revealed by-products and wastewater with high nutrient content encouraging a better concept for valorization.
... It has often discussed that processing factors were responsible for the specific flavor expressions of differently processed coffees [9]. In other words, the type of processing influences the differences in the constituents of green coffee which, during roasting, give rise to aroma compounds and express the characteristics of roasted coffee beans [14]. In addition, large amounts of co-products such as coffee pulp, mucilage and parchment, and wastewater are generated during the wet processing [15]. ...
Article
Full-text available
Many technical challenges still need to be overcome to improve the quality of the green coffee beans. In this work, the wet Arabica coffee processing in batch and continuous modus were investigated. Coffee beans samples as well as by-products and wastewaters collected at different production steps were analyzed in terms of their content in total phenols, antioxidant capacity, caffeine content, organic acids, reducing sugars, free amino group and protein content. The results showed that 40% of caffeine was removed with pulp. Green coffee beans showed highest concentration of organic acids and sucrose (4.96 ± 0.25 and 5.07 ± 0.39 g/100 g DW for the batch and continuous processing). Batch green coffee beans contained higher amount of phenols. 5-caffeoylquinic Acid (5-CQA) was the main constituent (67.1 and 66.0% for the batch and continuous processing, respectively). Protein content was 15 and 13% in the green coffee bean in batch and continuous processing, respectively. A decrease of 50 to 64% for free amino groups during processing was observed resulting in final amounts of 0.8 to 1.4% in the processed beans. Finally, the batch processing still revealed by-products and wastewater with high nutrient content encouraging a better concept for valorization.
... This is ensured only when all the fruits are collected at perfect maturation stage. However, since this is rarely achieved in reality, perfectly mature fruits are usually mixed with some fruits that are excessively mature or, instead, immature fruits necessitating for the coffee processing techniques to be selected carefully in order to protect coffee from the acquisition of undesirable characteristics during all this process (Alves, Rodrigues, Antónia Nunes, Vinha, & Oliveira, 2017;Kleinwächter, Bytof, & Selmar, 2015). ...
Article
Research interests in coffee byproducts showed increased attraction. This is partly driven by the increasing annual coffee production, which leads to increased generation of solid residues creating environmental concern. Additionally, compositional profile of coffee byproducts stimulate more investigations into their role of affecting human physiological function. Driven by increased demand of valorizing agro-industrial residues into value added products, many research findings present justifiable importance and possible application of coffee byproducts in food. This extensive review therefore presents up-to-date information with reference to compositional data, potential of incorporating coffee byproducts as ingredients in food formulations and new product development with respect to their biological functionality and technological importance. Reviewed byproducts are coffee husk, pulp, parchment, silverskin and spent coffee ground. Processing steps are elaborated and description of each process with respect to characteristics of starting material and generated main products and resulting residues is made to clearly distinguish the corresponding byproducts. Respective nutritional and phytochemical composition, food formulation and their distinctive characteristics are described. Production of value added products and food product development as well as applications made so far to incorporate the byproducts into food formulation are reviewed. Finally, safety related references and prospective insights of coffee processing byproducts in the current changing economy with possible indication into future trend of the subject matter in universal context are presented.
... Alanine was found to be the free amino acid with the highest amount in green coffee (Murkovic & Derler, 2006). The molar ratio of 1:1 was selected since similar molar ratios between simple carbohydrates and free amino acids were reported in Robusta green coffee (Kleinwächter, Bytof, & Selmar, 2015), therefore the mitigation results can be rationally compared between the dry model systems and the Robusta model system. ...
Article
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The mitigation of furfuryl alcohol, 5-hydroxymethylfurfural, 2-furoic acid, and 5-hydroxymethyl 2-furoic acid was conducted in two dry model systems mimicking coffee and an actual coffee system by incorporating 14 chemicals, that are categorized to phenolic acids, flavonoids, non-phenolic antioxidants, and non-antioxidant agents. Mitigation effects were determined as the decrease in the levels of the studied furan derivatives after the systems went through a controlled roasting process. Strong mitigation effects in the dry model systems were observed after the application of phenolic acids, quinic acid or EDTA. The mitigation effects of phenolic acids and flavonoids depended on the number and availability of phenolic hydroxyl groups. Certain agents exhibited a furan derivative-specific reducing effect while most of them showed a generalized effect. The mitigation efficacy decreased with the increasing complexity of the tested systems. In the coffee system, mitigation effects were almost completely lost in comparison with dry model systems. Still, taurine and sodium sulfite exerted the strongest mitigation effect in the coffee system.