Επισκόπηση της μικροβιακής οικολογίας και των διαδικασιών ζύμωσης κόκκων καφέ – Επίδραση στην ποιότητα του αφεψήματος.

Coffee is the most important crop in the national economy of Ethiopia and continues to be still the leading export commodity.Despite the economic importance, productivity and quality of the crop is very low.Improper post harvest processing techniques such as harvesting immature cherries, lack of sorting during grading and processing, improper drying without considering drying time, drying place, thickness layer and drying material, transportation, storage, over fermentation etc largely contribute to the decline in coffee quality of Ethiopia.It is widely agreed that traditional hand-picking and husbandry labor, as opposed to mechanical harvest, produce the best quality green coffee by decreasing the percentage of defects in coffee batches.Then, depending on the postharvest process, strong consequences on coffee quality can be observed.However, lack of information on the effects of post harvest processing and drying on quality necessitates a comprehensive study.Therefore, work was carried out to review such constraints that affect coffee quality and to give more emphasis especially in small scale coffee production of Ethiopia for exporting premium quality coffee in higher percentage.

Quantification of Coffea arabica and Coffea canephora var. robusta concentration in blends by means of synchronous fluorescence and UV-Vis spectroscopies

VOLATILE PROFILE OF Coffea arabica AND Coffea canephora var. conilon BY SHS-GC-MS AND CHEMOMETRICS. The volatile composition of coffee exerts a substantial influence on its quality, as it defines the characteristics of the beverage. However, these compounds are influenced by factors within the coffee production chain, such as botanical origin, geography, processing methods, and roasting. Consequently, the identification of such compounds becomes a vital tool for characterizing coffees to these factors. In this context, gas chromatography with headspace extraction is widely used for aroma analysis, providing a composition closer to consumer perception. Headspace extraction offers speed, simplicity, minimal sample preparation, and no need for solvents. In this study, static headspace extraction (SHS) coupled with gas chromatography-mass spectrometry (SHS-GC-MS) was employed to establish the chemical profile of volatile compounds in Coffea arabica and Coffea canephora var. conilon and determine discriminants between the species. A total of 97 compounds, belonging to 17 chemical classes, were identified. The chemometric analysis highlighted furans, phenols, and carboxylic acids as key differentiating classes. Notably, furfuryl alcohol, acetic acid, 4-vinylguaiacol, N-acetyl-4(H)-pyridine, and N-furfurylpyrrole emerged as crucial volatile compounds. The variable selection using Fisher weight applied directly in the chromatograms, produced models consistent with relative area data, with furfuryl alcohol and 4-vinylguaiacol regions being particularly influential in differentiation.

Arabica and Robusta coffee are the two main coffee tree species that are cultivated around the world. Premium Arabica coffee is rich in flavour and aroma. Meanwhile, the cheaper Robusta coffee has a bitter taste, a muddy odour, and a weaker aroma and flavour. This study aimed to improve the quality of Robusta coffee through cellulase and protease assisted germination. Germination results in producing flavour precursors and can be accelerated by degrading the endosperm of coffee beans through the activity of cellulase and protease. Quality parameters were based on morphological study (scanning electron microscope [SEM]), flavour profile analysis (gas chromatography-mass spectrometry [GC-MS]) and sensory evaluation. Results indicated that sugar-and enzyme-added germinated Robusta (R5) has similar morphological characteristics and pH values to Arabica. Flavour profile analysis indicated that 2-Furanmethanol of treated Robusta, which contributes to bitter taste, was decreased compared to untreated Robusta (control). In sensory evaluation, the final score of sensory properties of germinated Robusta (R2), enzyme-added Robusta (R3), and sugar-and enzyme-added germinated (R5) was improved, which indicated that there was no significant difference (p>0.05) compared to Arabica. These results showed that the proposed additional processing method of green coffee beans in this study was able to improve the quality of cheaper Robusta coffee which has some similar properties to premium Arabica.

In Gedeo zone, coffee quality is declining from time to time due to several improper pre and post-harvest management practices. Therefore, this study was designed with the objective of assessing impact of pre and post-harvest management practices on Coffea arabica L. quality determining factors in Gedeo zone, Southern Ethiopia. Totally, 90 household respondents were used from three Woredas and selected purposively. Finally, quantitative data was analyzed by employing SPSS (version 20). In pre harvesting practices, the result indicated that most of the respondents owned old coffee trees (>20 years), prune their tree frequently within one year interval and observed various diseases on their coffee tree. According to the survey result, majority of farmers use shade trees, which is the most common cropping practiced by coffee producing farmers in the study area, and majority of the farmers use dry method of coffee processing. Descriptive statistics of the field survey revealed that majority responded the provision of support and training from the respective Agricultural research and Development offices. On the contrary, the coffee farming family suffered from shortage of money as well as time at harvesting stage of coffee. On the side of traders, they received extension services in maintaining coffee quality in particular. Most of the traders in the study area in order to buy and sell coffee, did not get advises from market advisers. In general, most management practices in addition to trading methods in the study area have problems in maintaining coffee quality in the zone. Key words: Coffea arabica L, coffee quality, pre-harvest, post-harvest, Gedeo zone. &nbsp

Research in the field of coffee has been very much. Post-harvest processing techniques for coffee are very important and affect the quality and taste of coffee. This study aims to look at research trends related to post-harvest coffee. This study obtained the database from ScienceDirect and performed a bibliometric analysis. Research data was taken starting from 2021 to 2023. Based on the results of a biblometric analysis, from 2021-2023 there have been 161 studies related to post-harvest coffee arabica from science direct. From this study, it was found that research trends related to post-harvest coffee were still minimal from 2021 to 2023 so it needed to be developed further. In this study, it was also found that the most coffee-related journal publication titles were food chemistry. Meanwhile, the authors who have published the most coffee-related studies are Schawan, Rosane Freitas with a total of 7 journals.

Electronic nose (e-nose) is a device that plays an important role for odor assessment due to its low cost and widerange applications. Currently, e-nose is widely used in the food industry such as coffee, wines, beers etc. Coffee is one of the most popular beverages in the human history. There are various types of products, for examples, roast/round, instant/soluble and ready-to-drink coffees etc. At present, coffee shop businesses are growing in Thailand and each of which has promoted its identity of coffee aroma. Nevertheless, the taste and aroma of the coffee are often not well controlled due to the lack of method to identify the odor standard. Hence, this problem should be solved to maintain consumers' satisfaction. In this paper, we have studied about the factors that affect on coffee taste and coffee aroma by using electronic nose. This instrument was designed to be portable and capable of measuring the coffee samples in both liquid and solid forms. Metal oxide semiconductors (MOS) were used as the sensing materials to detect changing of coffee odor at different conditions. The e-nose is composed of a flow system, a sensor array and data acquisition/analysis. It was found that the e-nose is capable to distinguish different brands of instant coffee products and is able to classify coffee odors at different mixtures. The results reveal that the concentrations and temperatures can affect the smell of quality of coffee. Based on this study, we are very optimistic that this e-nose will be very useful for coffee industry in Thailand.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Multivariate calibration applied to study of volatile predictors of arabica coffee quality

Influence of roasting levels on chemical composition and sensory quality of Arabica and Robusta coffee: A comparative study

Impacts of regulated deficit irrigation on yield, quality and water use efficiency of Arabica coffee under different shading levels in dry and hot regions of southwest China

Although causing extensive damage, bagging coffee cherries before drying occurs even in the field due to adverse factors soon after boltering, such as rain during the harvest, problems during transport to the drying area or even the poor plantation design, besides the lack of mechanical dryers for most small producers, thus requiring a more scientific foundation. Given this fact, the aim of this study was to evaluate the real effect of this practice on the quality of coffee in different stages of maturation, bagging from up to four days before drying, and to verify the behavior of different stages with regard to this procedure. Physical, chemical, and physicochemical analysis as well as classification according to type and drink were performed using Acaia coffee fruits (Coffea arabica L.) collected at Perdoes - MG and separated by hand after picking, in four maturation stages (green / greenish yellow, cherry, dried pruns and fruit mixture). After separation, they were packed in polyethylene bags and subjected to five bagging times ranging from 0, 1, 2, 3 and 4 days. After each period, samples were dried in a concrete yard for analysis. The analysis results showed that the electrical conductivity parameters, leaching of potassium and PPO activity were shown to be as important quality markers. Taste tests classified most treatments as “hard coffee”. Based on these results it was found that bagging promoted loss of bean quality from the first day

Steam pressure treatment of defective Coffea canephora beans improves the volatile profile and sensory acceptance of roasted coffee blends

Coffee is one of the most consumed beverages in the world and is crucial in the economy of many developing countries. The search to improve coffee quality comes from many fronts, as do the many ways to measure quality and the factors that affect it. Several techniques are used to measure the different metrics to assess coffee quality, across different types of coffee samples and species, and throughout the entire process from farm to cup. In this work, we conducted a systematic mapping study of 1,470 articles to identify the aspects of quality that are the most important in the scientific literature to evaluate coffee throughout the processing chain. The study revealed that cup quality and biochemical composition are the most researched quality attributes. The main objective of the reviewed studies is the correlation between different quality measurements. The most used techniques are the analytical chemistry methods. The most studied species is Coffea arabica. The most used sample presentation is green coffee. The postharvest stage is the most researched, in which quality control receives more attention. In the preharvest stage, management practices stand out. Finally, the most used type of research was the evaluation research.

Thailand has a growing demand in coffee consumption every year. Currently, the nation’s capacity for producing coffee is limited, necessitating a significant amount of imports from overseas. The Arabica coffee in the north of Thailand, where the scent and taste of coffee have a distinct identity based on varied cultivation locations, has reasonably good quality. Because of the impact of the environment, it is still challenging to maintain the quality of coffee beans from season to season. Moreover, fierce competition with nearby nations like Laos and Vietnam leads to lower prices of coffee beans. This forces Thai farmers and entrepreneurs to embrace more advanced technologies in order to comprehend the environment of each plantation region and boost their level of competition. This project aims to develop a trustworthy and cost-effective IoT field monitoring solution to assist farmers in understanding the climate conditions in various plantation areas. In order to examine the relationship between the environments, the data collected by the devices can be transferred back to the public cloud server. Then, it can be used as knowledge to raise Thai coffee beans’ quality to a premium level so they can continue to compete with coffee beans from other countries.