Impact of storage conditions on fungal community composition of green coffee beans Coffea arabica L. stored in jute sacks during 1 year.

AIMS: The purpose of this study was to evaluate the effect of warehouse storage conditions on the composition of the fungal community of green coffee beans (GCB) that were stored in jute sacks for 1 year. METHODS AND RESULTS: Molecular characterization of the fungal community composition and population dynamics obtained by Q-PCR, CE-SSCP (Simpson's diversity index D) and Illumina MiSeq sequencing indicated that Saccharomycetales dominated during the first 6 months of storage period with species as Meyerozyma guilliermondii and Pichia kluyveri. However, after 6 months of storage, the filamentous genus Wallemia became dominant. Principal components analysis correlated this fungal dynamic with storage conditions and other variables as chromaticity (colour), water activity, moisture content, reducing sugars concentration, fungal infection and ochratoxin A production. CONCLUSIONS: This study demonstrated that GCB stored in jute sacks after 6 months of storage lead to fungal population dynamics, decreased chromaticity in GCB by bleaching and, then, affected overall quality. SIGNIFICANCE AND IMPACT OF THE STUDY: Storage plays an important role in the quality evolution during the handling of the GCB. In this context, the composition of the microbial community could be considered a marker to assess the trade value of the coffee beans.

Anti-Aspergillus activity of green coffee 5-O-caffeoyl quinic acid and its alkyl esters.

The antifungal activities of 5-O-caffeoyl quinic acid (5-CQA) and of methyl, butyl, octyl, and dodecyl esters or 5-CQA, were tested on five toxigenic moulds from the Aspergillus genus (Aspergillus flavus, Aspergillus nomius, Aspergillus ochraceus, Aspergillus parasiticus, Aspergillus westerdijkiae). These mycotoxin producers' moulds may contaminate many types of food crops throughout the food chain posing serious health hazard to animals and humans. The use of chemical methods to decrease mycotoxin producer moulds contamination on food crops in the field, during storage, and/or during processing, has been proved to be efficient. In this work, the antifungal effect of 5-CQA and a homologous series of 5-CQA esters (methyl, butyl, octyl, dodecyl), was investigated using the microdilution method and the minimum inhibitory concentrations (MIC50 and MIC80). All molecules presented antifungal activity, and two esters showed a MIC for all fungi: octyl (MIC50 ≤ 0.5-0.75 mg/mL, MIC80 = 1.0-1.5 mg/mL) and dodecyl (MIC50 = 0.75-1.25 mg/mL) chlorogenates. Dodecyl chlorogenate showed a MIC80 (1.5 mg/mL) only for A. parasiticus. The maximum percent of growth inhibition on aspergillii was observed with octyl (78.4-92.7%) and dodecyl (54.5-83.7%) chlorogenates, being octyl chlorogenate the most potent antifungal agent. It was thus concluded that lipophilization improved the antifungal properties of 5-CQA, which increased with the ester alkyl chain length, exhibiting a cut-off effect at 8 carbons. As far as we know, it is the first report demonstrating that lipophilization may improve the antifungal activity of 5-CQA on five toxigenic moulds from the Aspergillus genus. Lipophilization would be a novel way to synthesize a new kind of antifungal agents with a good therapeutic value or a potential use as preservative in food or cosmetics.