Germination of Coffee Seeds and its Significance for Coffee Quality

Abstract

Besides genotypic characteristics, the crucial factor that determines coffee quality is the mode of post-harvest treatment, i.e., the wet and dry processing. Up to now, the resulting characteristic flavour differences between these differentially processed coffees were attributed exclusively to differences in starting material. However, as these quality differences are still evident, even when identical coffee samples were processed by the two methods in parallel, the differences must be created by metabolic processes in the coffee beans themselves. Based on expression studies of the germination-specific isocitrate lyase and the resumption of cell cycle activity, monitored by the abundance of beta-tubulin, we evidence that germination is initiated in coffee seeds during the course of standard coffee post-harvest treatments. The extent and nature of the germination processes depend on the processing method. The coherence of metabolic events, substantial differences in the chemical composition of the coffee beans, and the generation of specific coffee qualities establishes the basis for a quite novel approach in coffee research.

Impact of Sun Drying Methods and Layer Thickness on the Quality of Highland Arabica Coffee Varieties at Limmu, Southwestern Ethiopia

“…The above finding also supports with the findings given by Subedi [18] who confirmed that coffee dried on bricks floor in contact with soil becomes dirty and blotchy resulting into dull aroma and earthy flavor in coffee beverage. Similar results were reported by ICO and Selmar et al [15,19] processing Arabica coffee on drying tables covered in mesh or mats are used and simplify protection of the crop from re-wetting. Furthermore, the finding of the present work supported by Negussie et al [20] who pointed out that properly processed coffee is free off-flavor and very few defective beans.…”

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

“…Changes in the fermenting mucilage were also reflected in the endosperms, where high concentrations of microbial end metabolites (e.g., acetic acid, ethanol, glycerol, lactic acid, and mannitol) occurred. In addition, the anoxia of underwater submersion triggered the germination of the endosperms, resulting in an anaerobic carbohydrate consumption response, which was even more intense during the extended fermentation of depulped and thus injured coffee beans (28,32,33,46,47). The coffee beans under anoxia consumed the carbohydrate resources continuously through glycolysis, as the sucrose concentration decreased in the endosperms.…”

“…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).…”

Correlação entre precursores e voláteis em café arábica brasileiro processado pelas vias seca, semiúmida e úmida e discriminação através da análise por componentes principais

“…9 A comparação sobre os teores de açúcares e aminoácidos entre grãos lavados e não lavados sugere a ocorrência de germinação e processos bioquímicos que, embora ainda não totalmente elucidados, resultam em diferenças importantes nos teores de precursores do flavor, que ao final conferem as características peculiares de cada produto. [10][11][12][13][14] O processo de torra do café aumenta a pressão dentro do grão, necessária para que as reações químicas ocorram. Pelo aumento de temperatura ocorrem, principalmente, a decomposição dos açúcares, a descarboxilação de ácidos carboxílicos, os rearranjos e as reações entre aminoácidos e açúcares via reações de Maillard e Strecker, formando inúmeros compostos de classes químicas bastante distintas.…”