Overview on the mechanisms of coffee germination and fermentation and their significance for coffee and coffee beverage quality

Waters, Deborah M.; Arendt, Elke K.; Moroni, Alice

doi:10.1080/10408398.2014.902804

Cited by 39 publications

(47 citation statements)

References 117 publications

(164 reference statements)

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“…The on-farm postharvest coffee processing is essential for ensuring high coffee cup quality (2) and constitutes a chain of interlinked phases mainly aimed to remove the mucilage of the cherries and dry the beans to a low moisture content of 10 to 12% (mass/mass). The final quality of the green coffee beans is thus dependent on the agricultural and farm practices applied, which in turn depend on the coffee plant cultivar, geography, weather conditions, and infrastructure available (3).…”

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confidence: 99%

“…Microorganisms are ubiquitous during the different stages of postharvest coffee processing (2,(19)(20)(21)(22). Enterobacteriaceae and other Gram-negative bacteria, including acetic acid bacteria (AAB), bacilli, lactic acid bacteria (LAB), yeasts, and filamentous fungi have been found through culture-dependent and -independent methods during coffee fermentation processes (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)22).…”

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confidence: 99%

“…Their metabolite production capacities can have beneficial and/or detrimental effects on the sensory characteristics of the green coffee beans and final coffee cup quality (3,(24)(25)(26). However, it is not yet clear to what extent microorganisms are essential for the production of high-quality coffee (2). Recently, the ability of naturally occurring yeasts to act as selected starter cultures and to influence the in-cup attributes of coffee has been shown during semidry processing (14,15,27).…”

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confidence: 99%

“…Recently, the ability of naturally occurring yeasts to act as selected starter cultures and to influence the in-cup attributes of coffee has been shown during semidry processing (14,15,27). Also, the beans (endosperms) remain metabolically active during coffee processing and are impacted by the processing method implemented, thereby affecting the final coffee cup quality (2,(28)(29)(30)(31)(32)(33).…”

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confidence: 99%

“…Despite the complexity of coffee processing and the numerous factors contributing to the quality traits of the green coffee beans, all studies conducted so far only targeted specific steps of the processing (2,19,21). Their primary goal has been the identification of the microbiota associated with the fermentation part of the processing and the chemical profiling of the green coffee beans and/or bean germination process.…”

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confidence: 99%

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Exploring the Impacts of Postharvest Processing on the Microbiota and Metabolite Profiles during Green Coffee Bean Production

Bruyn

Zhang

Pothakos

et al. 2017

Appl Environ Microbiol

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193

164

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The postharvest treatment and processing of fresh coffee cherries can impact the quality of the unroasted green coffee beans. In the present case study, freshly harvested Arabica coffee cherries were processed through two different wet and dry methods to monitor differences in the microbial community structure and in substrate and metabolite profiles. The changes were followed throughout the postharvest processing chain, from harvest to drying, by implementing up-to-date techniques, encompassing multiple-step metagenomic DNA extraction, highthroughput sequencing, and multiphasic metabolite target analysis. During wet processing, a cohort of lactic acid bacteria (i.e., Leuconostoc, Lactococcus, and Lactobacillus) was the most commonly identified microbial group, along with enterobacteria and yeasts (Pichia and Starmerella). Several of the metabolites associated with lactic acid bacterial metabolism (e.g., lactic acid, acetic acid, and mannitol) produced in the mucilage were also found in the endosperm. During dry processing, acetic acid bacteria (i.e., Acetobacter and Gluconobacter) were most abundant, along with Pichia and non-Pichia (Candida, Starmerella, and Saccharomycopsis) yeasts. Accumulation of associated metabolites (e.g., gluconic acid and sugar alcohols) took place in the drying outer layers of the coffee cherries. Consequently, both wet and dry processing methods significantly influenced the microbial community structures and hence the composition of the final green coffee beans. This systematic approach to dissecting the coffee ecosystem contributes to a deeper understanding of coffee processing and might constitute a state-of-the-art framework for the further analysis and subsequent control of this complex biotechnological process.IMPORTANCE Coffee production is a long process, starting with the harvest of coffee cherries and the on-farm drying of their beans. In a later stage, the dried green coffee beans are roasted and ground in order to brew a cup of coffee. The on-farm, postharvest processing method applied can impact the quality of the green coffee beans. In the present case study, freshly harvested Arabica coffee cherries were processed through wet and dry processing in four distinct variations. The microorganisms present and the chemical profiles of the coffee beans were analyzed throughout the postharvest processing chain. The up-to-date techniques implemented facilitated the investigation of differences related to the method applied. For instance, different microbial groups were associated with wet and dry processing methods. Additionally, metabolites associated with the respective microorganisms accumulated on the final green coffee beans.

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Exploring the Impacts of Postharvest Processing on the Microbiota and Metabolite Profiles during Green Coffee Bean Production

Bruyn

Zhang

Pothakos

et al. 2017

Appl Environ Microbiol

Self Cite

193

164

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Impact of roasting on the phenolic and volatile compounds in coffee beans

Liu

et al. 2022

Food Science & Nutrition

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Phenolic compounds present in coffee beans could generate flavor and bring benefits to health. This study aimed to evaluate the impacts of commercial roasting levels (light, medium, and dark) on phenolic content and antioxidant potential of Arabica coffee beans (Coffea arabica) comprehensively via antioxidant assays. The phenolic compounds in roasted samples were characterized via liquid chromatography–electrospray ionization quadrupole time‐of‐flight mass spectrometry (LC‐ESI‐QTOF‐MS/MS). Furthermore, the coffee volatile compounds were identified and semi‐quantified by headspace/gas chromatography–mass spectrometry (HS‐SPME‐GC‐MS). Generally, for phenolic and antioxidant potential estimation, light roasted samples exhibited the highest TPC (free: 23.97 ± 0.60 mg GAE/g; bound: 19.32 ± 1.29 mg GAE/g), DPPH, and FRAP. The medium roasted beans performed the second high in all assays but the highest ABTS+ radicals scavenging capacity (free: 102.37 ± 8.10 mg TE/g; bound: 69.51 ± 4.20 mg TE/g). Totally, 23 phenolic compounds were tentatively characterized through LC‐ESI‐QTOF‐MS/MS, which is mainly adopted by 15 phenolic acid and 5 other polyphenols. The majority of phenolic compounds were detected in the medium roasted samples, followed by the light. Regarding GC‐MS, a total of 20 volatile compounds were identified and semi‐quantified which exhibited the highest in the dark followed by the medium. Overall, this study confirmed that phenolic compounds in coffee beans would be reduced with intensive roasting, whereas their antioxidant capacity could be maintained or improved. Commercial medium roasted coffee beans exhibit relatively better nutritional value and organoleptic properties. Our results could narrow down previous conflicts and be practical evidence for coffee manufacturing in food industries.

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Chemical and sensory characterization of coffee from Coffea arabica cv. Mundo Novo and cv. Catuai Vermelho obtained by four different post‐harvest processing methods

et al. 2022

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BACKGROUND: After the harvest, green coffee beans are dried on the farm using several methods: the wet process, natural process, pulped natural process, or mechanical demucilaging. This study evaluated how the choice of a specific processing method influenced the volatile organic compounds of the coffee beans, before and after roasting, and the sensory characteristics of the beverage. Coffea arabica beans of two varieties (cv. Mundo Novo and cv. Catuai Vermelho) were subjected to these four processing methods on a single farm in the Cerrado area of Brazil.RESULTS: Analysis by gas chromatography-mass spectrometry headspace solid-phase microextraction identified 40 volatile organic compounds in green coffee beans and 37 in roasted beans. The main difference between post-harvest treatments was that naturally processed green beans of both varieties contained a different profile of alcohols, acids, and lactones. In medium-roasted beans, those differences were not observed. The coffee beverages had similar taste attributes but distinct flavor profiles. Some of the treatments resulted in specialty-grade coffee, whereas others did not.CONCLUSION: The choice of a specific post-harvest processing method influences the volatile compounds found in green beans, the final beverage's flavor profile, and the cupping score, which can have a significant impact on the profitability of coffee farms' operations.

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Overview on the mechanisms of coffee germination and fermentation and their significance for coffee and coffee beverage quality

Cited by 39 publications

References 117 publications

Exploring the Impacts of Postharvest Processing on the Microbiota and Metabolite Profiles during Green Coffee Bean Production

Exploring the Impacts of Postharvest Processing on the Microbiota and Metabolite Profiles during Green Coffee Bean Production

Impact of roasting on the phenolic and volatile compounds in coffee beans

Chemical and sensory characterization of coffee from Coffea arabica cv. Mundo Novo and cv. Catuai Vermelho obtained by four different post‐harvest processing methods

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