High Quality Coffee Research Articles

KEBIJAKAN BISNIS DALAM PENINGKATAN HASIL PANEN PETANI KOPI DI KABUPATEN BENER MERIAH

The issue is a lack of care for the coffee plant, which makes it easier for diseases and pests to spread and results in low harvests. In order for the community to experience progress, independence, and welfare in a setting of lasting social justice, the community must be prepared, and institutions within the community must be strengthened. Knowing in advance what coffee farmers require will allow the extension agency to create a collaborative program with farmer organizations as part of the Agriculture Service's empowerment approach to boost coffee yields. Developing the skills of communities that grow coffee and are part of farmer organizations through training. It is essential to take proper care of the plant, use high-quality seeds, get enough organic and inorganic fertilizer, and apply pesticides to keep out pests in order to improve the output of high-quality coffee.

The Quality of Arabica Coffee Beans Evaluation at Various Processing in Luwu Regency South Sulawesi, Indonesia

Arabica coffee plantations in Luwu Regency are planted at elevations above 1,000 mdpl, so that the Arabica coffee clones planted can produce high-quality coffee flavors. The aims of this study were to determine the physical, chemical, and taste profile of Arabica coffee Luwu in order to increase the added value and competitiveness of the product. The research was conducted using a survey method on Arabica coffee plantations in Latimojong District, Luwu Regency, South Sulawesi Province. Sampling using purposive random sampling method and analyzed in duplicate. Samples of coffee variants were obtained from several farmers and from several levels of the coffee trade system around Luwu Regency. Analysis of physical quality characters includes levels of live insects, foul-smelling seeds/mold, moisture content, dirt content, and special quality requirements on seed size, number of seed chips, and defect values. The chemical analysis includes water, ash, caffeine, protein, and fat. The taste of brewed coffee in an organoleptic manner refers to the Specialty Coffee Association of America/SCA standard covering aroma/fragrance, flavor, body, acidity, aftertaste, sweetness, balance, clean cup, uniformity, and overall. Based on the results of the study, the coffee beans met the general quality requirements, there were no live insects, no foul-smelling and/or moldy beans, moisture content of 12.5%, and a maximum dirt content of 0.5%. The value of ash content is 4.344%-5.514%, fat content is 11.194%-14.067%, the highest protein content is 11.687%-13.719%, the highest caffeine content is 0.041%-0.064%. The results of the taste test showed that ten samples had the potential for specialty coffee with a score above 8 and two samples below a score of 8.

Interactions between Geomorphology and Production Chain of High-Quality Coffee in Costa Rica

High-altitude coffee has an international reputation due to its high quality, especially in countries with a long production history, such as Costa Rica. Specific geographical characteristics determine the regions where high-altitude coffee can be cultivated. Over the last two decades, new production conditions have promoted the growth of smallholder coffee farms in the Upper Buenavista Catchment (UBC) in the South of Costa Rica. To understand this phenomenon’s process, we initially performed a detailed geomorphological mapping of the high-elevation production sites in the UBC. Then, we used remote sensing to determine the coffee land cover (2005, 2012, and 2018) to compare their landforms. Furthermore, we analyzed the production–processing–market chain that has promoted coffee plantations since 2005. Our results show that coffee farmers chose more unstable and erosive areas with short-term production prospects to cultivate premium-priced coffee. Moreover, farmers have changed their role in the coffee sector, evolving from small producers to entrepreneurs with specialized knowledge. These actions may reduce economic risks and improve the household incomes of smallholder coffee producers. However, limited research has been conducted along the tropics about the relationships between landforms, socioeconomic drivers, and high-altitude coffee yield. Therefore, our results are essential to present geomorphology and applied geography as baselines in land-use planning for agricultural landscapes.

How close do you like your coffee? - Examining proximity and its effects in relationship coffee models

Relationship coffee models are generally characterized by a shortened value chain and efforts to achieve social, economic, and environmental sustainability. In three case studies with farmers organized in cooperatives in Peru and buyers in Austria or Germany, we analyzed the proximity among the geographically distant value chain actors. This paper aims to provide a more nuanced perspective on relational (organizational, institutional, cognitive, and social) proximity in relationship coffee models. The comparative analysis of the proximities in our case studies revealed that initial face-to-face contacts are required to build further proximity dimensions. Proximate relationship coffee models have led to more recognition, pride, a good reputation of the actors, higher coffee quality and thus farm-gate prices, and stable long-term relationships. However, relationship coffees require more coordination and communication among chain actors and advanced farmer skills and efforts to produce high-quality coffee. In relationship coffee models, farmers still depend on buyers and roasters to benefit from higher quality of their green coffee.

Geospatial Distribution of the Quality of the Coffee of Minas Gerais by Methods of Data Mining Techniques

The state of Minas Gerais is located in one of the most privileged Brazilian regions for the production of high-quality coffees. Due to its large territorial extension and environmental variation, it favors the production of specialty coffees with a great diversity of flavor and aroma. These differences are related to the peculiar characteristics of each microregion, particulary climate variations, altitude, latitude and production systems. Although the relationship between environmental characteristics and coffee productivity in different biomes is already well explored, its relationship with beverage quality still requires research. Given the need for more information on areas with potential for special coffee production, this paper proposes to associate data concerning to sensorial quality of coffees in the Cafés of Minas Quality Contest, with climatic and geographical variations of each state region, applying association rules for data mining, used to understand the aptitude of the state through the generation of rules that describe the most relevant patterns in the data. The climatic, geographical and classificatory information of the coffee samples is the result of the database of the contest participants in 2007 and 2008. The results demonstrate that with data mining techniques it was possible to associate the regions with the greatest potential with the climatic and geographical characteristics of the environment.

Modeling of Forced and Natural Convection Drying Process of a Coffee Seed

HighlightsThe forced and natural convection drying processes of a single coffee grain can be predicted.The moisture distribution profiles depict the drying phenomena and water concentration zones.With accurate predictive drying curves, coffee growers can ensure high-quality coffee beans.Abstract. Different coffee drying technologies face complex tasks in ensuring an acceptable final seed moisture content. This research performed a Finite Element Analysis (FEA) study, simulating a single coffee bean's drying process as a transient mass diffusion model under mechanical and natural convection conditions, so the drying behavior and data of both case scenarios can be foreseen and controlled by a predictive Finite Element Model (FEM). A wet bean was 3D-scanned and digitized as the FEA simulation geometry; the water diffusion between the grain and the atmosphere was defined by a diffusion coefficient subject to the drying air temperature and the grain's moisture content. Three cases were studied: mechanical grain drying at three different temperatures (50, 45, and 40°C) in a forced convection environment; variable natural convection drying under environmental conditions (wet and dry season); and constant natural convection (wet and dry season), including the variation in day/night temperature and relative humidity. The results agree well with the data found in the literature, obtaining the graphical moisture distribution of the phenomena, predictive drying curves, diffusion coefficients, and isotherms. Both simulated drying scenarios provide essential information for coffee growers to improve and control their drying processes, thus obtaining high-quality grains, reducing contamination by microorganisms, and ensuring the integrity of their products. Keywords: Coffea arabica, Coffee Drying, Coffee Seed, Finite Element Model, Moisture Diffusion.

Bases for the Establishment of Robusta Coffee (Coffea canephora) as a New Crop for Colombia

Robusta coffee (C. canephora) covers 36% of world coffee production and has strategic relevance as a beverage that it is produced by thousands of small-scale producers around the world. Although mainly grown in Africa and Asia as opposed to Latin America, this situation is changing. Colombia is recognized as a producer of high-quality Arabica (C. arabica L.) coffee, however we argue that Robusta represents a great economic opportunity for small scale producers, for the industrialization of new products and for emerging coffee chains. Therefore, the objective of this review is to outline the agronomic value of Robusta coffee as a “new crop” in Colombia. As background we compare the better-known Arabica to the Robusta coffees from a Latin American perspective. Robusta shows differences in geographical distribution, genetics, originating species, physiology and phenology. Robusta and Arabica also differ in their chemistry, sensory attributes, industrial use, segments of market and price. Despite the marked differences between the two coffees, the popularity and consumption of Robusta has been on the increase due to the expansion of markets in emerging economies and in developed markers for home espresso preparation where it is used in high quality coffee blends. Robusta is currently replacing areas of other coffees due to hotter temperatures to which it is adapted. Although Robusta is still new to Colombia, this species has potential adaptation in lowland areas considered “non-traditional” for Colombian coffee cultivation and as a valuable component of agro-ecological production systems. Robusta is a novel crop option for certain regions that is needed for the future of coffee in Latin America and for growth of coffee production and consumption in Colombia.

The performance of the C12880MA MEMS sensor for classification of the roasting level of coffee bean

The cupping test has been widely used to assess the roasting level of coffee to produce high-quality coffee beans. However, the method requires a longer process and sophisticated sensory analysis. The procedure could only be assessed by the certified panellist. Lately, commercial microelectromechanical system (MEMS) technology has been developed, which could be used for building a small spectrometer sensor. This gives the opportunity to adopt bench-top spectrometer sensing into the low-cost portable sensor. This research aims to study the performance test on the C12880MA MEMS sensor to determine the level of roasted coffee. A total of 90 samples from each 30 medium roasting level (Light to Medium, Medium, and Medium to Dark) was prepared. Spectrum data of samples were measured using a C12880MA sensor ranging from 312.162nm to 868.503nm. Linear Discriminant Analysis (LDA) was performed to classify the roasting level. The result showed that both LDA using full-spectrum and interval spectrum gave 100% accuracy with no falsely classified.

Microbiological and Chemical Characteristics of Wet Coffee Fermentation Inoculated With Hansinaspora uvarum and Pichia kudriavzevii and Their Impact on Coffee Sensory Quality

Hansinaspora uvarum and Pichia kudriavzevii were used as starter cultures to conduct inoculated wet fermentations of coffee beans, and their growth, metabolic activities and impact on the flavor, aroma and overall sensory quality of coffee were compared with spontaneous fermentation (control). H. uvarum and P. kudriavzevii dominated the fermentations, growing to maximum populations of about 10.0 log CFU/ml compared with 8.0 log CFU/ml in the spontaneous fermentation. The dominance of the inoculated yeasts led to faster and more complete utilization of sugars in the mucilage, with resultant production of 2–3 fold higher concentrations of metabolites such as glycerol, alcohols, aldehydes, esters, and organic acids in the fermented green beans. Cup tests showed coffee produced from the inoculated fermentations, especially with P. kudriavzevii, received higher scores for flavor, aroma and acidity than the control. The findings of this study confirmed the crucial role of yeasts in the wet fermentation of coffee beans and their contribution to high quality coffee, and demonstrated the potential H. uvarum and P. kudriavzevii as starter cultures in the process.

Caffeine content and antioxidant activity of various brews of specialty grade coffee [pdf

BACKGROUND The aim of the study was to evaluate the caffeine level and antioxidant activity of brews of specialty grade coffee compared to popular coffee brands. METHODS Ten types of coffee were used, including 7 specialty Arabica, 1 Robusta and 2 popular cheap coffee brands. For caffeine determination, HPLC analysis and the spectrophotometric method were used as reference. The total polyphenol content and antioxidant capacity (DPPH and FRAP methods) were evaluated. For two selected high-quality coffees, the influence of the brewing method on the antioxidant activity and caffeine content in the brews was assayed. RESULTS Regarding the caffeine content, differences between specialty coffee brews and popular products were not found, and an average level amounted to 56 and 40 mg/ml, respectively. In contrast, the antioxidant capacity of specialty coffee brews was significantly higher than for popular ones, independently of the test used. The highest scavenging ability and total phenolic content was found for S3 specialty coffee (46.15% of DPPH inhibition and 58.7 mg GAE/ml, respectively), whereas the lowest was found for popular coffee (about 35% of DPPH inhibition and about 41 mg/GAE/ml). For two selected high-quality coffees, the influence of the brewing method on the antioxidant activity and caffeine content in the brews was tested. It was found that the use of a dripper (overflow brewing method) provides the brew with the best antioxidant properties but with moderate caffeine levels. CONCLUSIONS It was found that 'specialty' quality coffees do not differ from popular brands in terms of caffeine content, but significantly outweigh them in terms of antioxidant activity. This property can be beneficial in the case of a high consumption of coffee, due to antiradical protective effects without the risk of caffeine overdose.

Caffeine content and antioxidant activity of various brews of specialty grade coffee

The aim of the study was to evaluate the caffeine level and antioxidant activity of brews of specialty grade coffee compared to popular coffee brands. Ten types of coffee were used, including 7 specialty Arabica, 1 Robusta and 2 popular cheap coffee brands. For caffeine determination, HPLC analysis and the spectrophotometric method were used as reference. The total polyphenol content and antioxidant capacity (DPPH and FRAP methods) were evaluated. For two selected high-quality coffees, the influence of the brewing method on the antioxidant activity and caffeine content in the brews was assayed. Regarding the caffeine content, differences between specialty coffee brews and popular products were not found, and an average level amounted to 56 and 40 mg/ml, respectively. In contrast, the antioxidant capacity of specialty coffee brews was significantly higher than for popular ones, independently of the test used. The highest scavenging ability and total phenolic content was found for S3 specialty coffee (46.15% of DPPH inhibition and 58.7 mg GAE/ml, respectively), whereas the lowest was found for popular coffee (about 35% of DPPH inhibition and about 41 mg/GAE/ml). For two selected high-quality coffees, the influence of the brewing method on the antioxidant activity and caffeine content in the brews was tested. It was found that the use of a dripper (overflow brewing method) provides the brew with the best antioxidant properties but with moderate caffeine levels. It was found that 'specialty' quality coffees do not differ from popular brands in terms of caffeine content, but significantly outweigh them in terms of antioxidant activity. This property can be beneficial in the case of a high consumption of coffee, due to antiradical protective effects without the risk of caffeine overdose.

The Altitude of Coffee Cultivation Causes Shifts in the Microbial Community Assembly and Biochemical Compounds in Natural Induced Anaerobic Fermentations.

Coffee harvested in the Caparaó region (Minas Gerais, Brazil) is associated with high-quality coffee beans resulting in high-quality beverages. We characterize, microbiologically and chemically, fermented coffees from different altitudes through target NGS, chromatography, and conventional chemical assays. The genera Gluconobacter and Weissella were dominant in coffee’s fruits from altitudes 800 and 1,000 m. Among the Eukaryotic community, yeasts were the most dominant in all altitudes. The most dominant fungal genus was Cystofilobasidium, which inhabits cold environments and resists low temperatures. The content of acetic acid was higher at altitudes 1,200 and 1,400 m. Lactic acid and the genus Leuconostoc (Pearson: 0.93) were positively correlated. The relative concentration of volatile alcohols, especially of 2-heptanol, was high at all altitudes. Bacteria population was higher in coffees from 800 m, while at 1,000 m, fungi richness was favored. The altitude is an important variable that caused shifts in the microbial community and biochemical compounds content, even in coffees belonging to the same variety and cultivated in the same region under SIAF (self-induced anaerobic fermentation) conditions. Coffee from lower altitudes has higher volatile alcohols content, while high altitudes have esters, aldehydes, and total phenolics contents.

COFFEE CERTIFICATION PARTICIPATION AND ITS IMPACT ON SMALLHOLDER FARMERS’ INCOME IN JIMMA ZONE, SOUTHWESTERN ETHIOPIA

Certification is an instrument to add value to a product, and it addresses a growing worldwide demand for healthier and more socially and environmentally friendly products. Globally, coffee certification has received strong recognition as it is proved to increase smallholder farmers’ access to input and output markets, production, productivity and income. This study investigates the major determinants of coffee certification participation. It also analyzes the welfare gains of participation in the certification schemes by smallholder coffee growers. Both primary and secondary data were used. Primary data were collected from randomly selected 247 coffee producers. Structured questionnaires, focus group discussions and key informant interviews were employed to collect the primary data. Descriptive statistics and econometric models were used for data analysis. Probit model was used to identify factors affecting participation in coffee certification schemes. Propensity score matching technique was used to estimate the impact of coffee certification participation on smallholders’ annual revenue from coffee production. The probit model result revealed that access to training, family size, land size owned, experience in coffee production, education status were significantly determined the smallholders farmers’ participation decision in coffee certification. The propensity score matching model result also shows that participation in coffee certification significantly (p=0.001) improved farmers’ annual revenue by 2,902 Ethiopian birr compared to selling coffee without the certification schemes. This income impact is mainly attributed to the premium price the certification offer to farmers for high quality coffee. Therefore, policies or projects related to coffee value chains should target improving farmers’ access to training, boosting the access to education, working on farmers’ productivity and increasing their technical knowhow on coffee certification to increase farmers’ participation in coffee certification and to improve their annual revenue earning level in the study area.

Arabica-like flavour in a heat-tolerant wild coffee species.

There are numerous factors to consider when developing climate-resilient coffee crops, including the ability to tolerate altered climatic conditions, meet agronomic and value chain criteria, and satisfy consumer preferences for flavour (aroma and taste). We evaluated the sensory characteristics and key environmental requirements for the enigmatic narrow-leaved coffee (Coffea stenophylla), a wild species from Upper West Africa1. We confirm historical reports of a superior flavour1-3 and uniquely, and remarkably, reveal a sensory profile analogous to high-quality Arabica coffee. We demonstrate that this species grows and crops under the same range of key climatic conditions as (sensorially inferior) robusta and Liberica coffee4-9 and at a mean annual temperature 6.2-6.8 °C higher than Arabica coffee, even under equivalent rainfall conditions. This species substantially broadens the climate envelope for high-quality coffee and could provide an important resource for the development of climate-resilient coffee crop plants.

PENGARUH SUHU DAN LAMA WAKTU PENYANGRAIAN TERHADAP MASSA JENIS BIJI KOPI ROBUSTA MENGGUNAKAN MESIN ROASTING TIPE HOT AIR

Abstract: An important stage that will determine the quality of ready-to-consume coffee is roasting. This method has been developed and used to obtain the best and specific quality of coffee brewing. In addition to the method used, the type of coffee greatly influences the quality characteristics of the brewed coffee produced. Coffee beans will not have a high commercial value before being subjected to a roasting process for the formation of the best aroma and taste. Roasting is a combination of time and temperature that changes the structure and chemical properties in coffee beans through the pyrolysis process. Even high-quality coffee beans cannot have maximum aroma and flavor if the roasting process is not done properly. This research uses a roasting machine type Hot Air Roasting or with other names Air Roasting is a different roasted coffee method. Coffee roasting process is not on the surface of the roaster but in the air, this coffee roasting method was introduced by Michael Sivetz, a chemical engineer and consultant of the world coffee industry. Based on the results of this study that the decrease in density discussed in the previous paragraph shows that the longer the roasting, the weight of coffee will decrease because the water content in coffee beans has begun to decrease. This shows that the longer the coffee beans are roasted, the better the results of heating. This research process uses a hot air type roasting machine. Hot water is one type of roasting machine that is good and efficient, because the heating carried out by the machine uses electrical energy. The final results obtained in this study the temperature continues to rise but the density decreases. This shows the inverse relationship between temperature and density of coffee and the best roasting results and can be used for brewing robusta coffee at 200 ° C in 15-20 minutes.
 
 Keywords: Hot Air Roasting, Robusta Coffee

Specialty Coffee Shops in Mexico: Factors Influencing the Likelihood of Purchasing High-Quality Coffee

This study models the purchasing behavior of specialty coffee by 114 coffee shops across 15 cities in nine states in Mexico. Simple and multilevel mixed-effects logistic models are tested. Our models extend the framework used in prior research. We model the purchase of specialty coffee as a function of: (a) material attributes, (b) symbolic attributes, (c) coffee shop characteristics, (d) profile of the coffee shop’s owner, and (e) socio-economic variables of the cities where the coffee shops were located. Overall, our results are consistent with expectations developed from the coffee literature. That is, the likelihood of purchasing specialty coffee increases when: coffee’s aroma drives the purchase, coffee purchased is from the state of Oaxaca, the coffee shop has a value-added business model, the coffee shop is diversified selling both ground coffee and coffee drinks, the coffee shop owner’s knowledge on coffee supply chain activities is high, and the coffee shop is located in a city with a higher education index. In contrast, the likelihood of purchasing specialty coffee decreases when a coffee professional tastes the coffee before the purchase, when coffee shops are not given the opportunity to roast their own coffee, and in coffee shops located in larger cities. Overall, our research suggests that the specialty coffee niche in Mexico has some elements required for this segment to transition from a supply chain approach to a value-based supply chain approach. This might be particularly beneficial for smallholder coffee growers, who despite several constraints contribute to the sustainability of coffee supply chains.

Using contingent valuation to estimate consumers’ willingness to pay for differentiated coffees in Puerto Rico

Product differentiation is a strategy used to develop products with particular attributes valued by consumers who are willing to buy them at higher prices. We use a single-bounded dichotomous choice contingent valuation method through in-person interviews (N=575) to estimate consumers’ willingness to pay (WTP) for high-quality and regular coffees produced locally. The results show that consumers are willing to pay $13.60 for a 227-g (8-ounce) bag of highquality coffee produced locally and $10.90 for regular coffee produced locally. It may be inferred that consumers are willing to pay $2.70 more for high-quality coffee, holding all else constant, which suggest that consumers value more the attribute of being locally produced than that of quality. The results also suggest that household size, income and education level of consumers can affect WTP values. We provide evidence that additional revenue can be generated by producing differentiated coffees. However, a cost analysis is required to complement this study and to better understand the economic viability of producing coffee with the characteristics evaluated in this investigation.

Unsupervised classification of specialty coffees in Homogeneous sensory attributes through machine learning

Brazil is the largest exporter of coffee beans, 29% world exports, 15% this volume in specialty coffees. Thereby researches are done, so that identify different segments in the market, in order to direct the end consumer to a better quality product. New technologies are explored to meet an increasing demand for high quality coffees. Therefore, in this article has an objective to propose the use of machine learning techniques combined with projection pursuit in the construction of unsupervised classification models, in a sensory acceptance experiment, applied to four groups of trained and untrained consumers, in four classes of specialty coffees in which they were evaluated sensory characteristics: aroma, body coffee, sweetness and general note. For evaluating classifier performance, in the data with reduced dimension, all instances were used, and considering four groupings, the models were adjusted. The results obtained from the groupings formed were compared with pre-established classes to confirm the model. Success and error rates were obtained, considering the rate of false positives and false negatives, sensitivity and classification methods accuracy. It was concluded that, machine learning use in data with reduced dimensions is feasible, as it allows unsupervised classification of specialty coffees, produced at different altitudes and processes, considering the heterogeneity among consumers involved in sensory analysis, and the high homogeneity of sensory attributes among the analyzed classes, obtaining good hit rates in some classifiers. Key words: Classification models; Data dimension reduction; Groupings identification; Projection pursuit.

Determining the impact of roasting degree, coffee to water ratio and brewing method on the sensory characteristics of cold brew Ugandan coffee

In today’s market, there is a growing demand for high-quality coffee with distinctive sensory characteristics, such a cold brew (CB) coffee. The objectives of this study were to determine the impact of a) degree of roasting, b) coffee to water ratio (C2WR), and c) brewing method on the sensory characteristics of CB coffee from d) various Ugandan coffee beans, both Robusta and Arabica. Four distinct coffee samples, sourced from lowland and mountainous regions in Uganda, were roasted and tested using a factorial design. A highly trained sensory panel evaluated the samples using 42 attributes. Results showed that all factors studied had an impact on most of the attributes. Not surprisingly, Robusta coffees generally had more bitter taste than Arabica coffees and the dark roast samples generally were more bitter than the medium roast coffees. Also, coffee samples that were brewed using a higher C2WR generally were more bitter than the coffees using a lower C2WR. However, although most of the main effects had a significant impact, their effects were mitigated by their interaction with other factors. For example, Medium roast Robusta that was slow-dripped with a high C2WR had a more bitter taste than the corresponding Arabica samples. However, when the Medium roast Robusta was steeped with a high C2WR it had a similar bitter intensity with the corresponding Arabica samples. Thus, although major impacts are critical, individual sample combinations must be considered when evaluating coffee samples for their impact on the sensory characteristics.

The crucial role of yeasts in the wet fermentation of coffee beans and quality

The objective of this study was to investigate the role of yeasts in the wet fermentation of coffee beans and their contribution to coffee quality using a novel approach. Natamycin (300 ppm) was added to the fermentation mass to suppress yeast growth and their metabolic activities, and the resultant microbial ecology, bean chemistry and sensory quality were analyzed and compared to non-treated spontaneous fermentation we reported previously. The yeast community was dominated by Hanseniaspora uvarum and Pichia kudriavzevii and grew to a maximum population of about 5.5 log CFU/g in the absence of Natamycin, while when Natamycin was added yeasts were suppressed. The major bacterial species in both the spontaneous and yeast-suppressed fermentations included the lactic acid bacteria Leuconostoc mesenteroides and Lactococcus lactis, the acetic acid bacteria Gluconobacter cerinus and Acetobacter persici and the Enterobacteriaceae Enterobacter, Citrobacter and Erwinia. For both fermentations, the mucilage layers were completely degraded by the end of the process and the absence of yeast activities had no significant impact on mucilage degradation. During fermentation, reducing sugars were consumed while lactic acid was accumulated inside the beans, and its concentration was significantly higher in the spontaneous fermentation (3 times) than that where yeasts were suppressed by Natamycin. Glycerol was detected with a concentration of 0.08% in the absence of Natamycin and was not identified when Natamycin was added. Green beans fermented with yeast growth contained a higher amount of isoamyl alcohol (21 times), ethanol (3.7 times), acetaldehyde (8 times), and ethyl acetate (25 times) compared to beans fermented in the absence of yeast activities, which remained higher in the former after roasting. Beans fermented without yeast activities had a mild fruity aroma, and lower sensory scores of fragrances (7.0), flavor (6.5), acidity (6.3), body (7.0) and overall score (6.5) compared to the former. These findings demonstrated the crucial roles of yeasts in wet fermentation of coffee beans and for producing high quality coffee.