Mycobiota and Co-Occrurence of Mycotoxins in Green and Roasted Coffee Beans

Abstract

A total of 20 samples of green and roasted coffee beans (the same varieties as green coffee beans were used) [Coffea arabica L. (19 samples) and Coffea robusta L. (1 sample)] were collected from the various coffee roasters in Slovakia (2017/2020) and their mycobiota were analyzed. Mycological analysis was carried using standard media with focus on genera Aspergillus and Penicillium. To determine endogenous and exogenous mycobiota the method of direct placing of surface-sterilized coffee beans (green and roasted) on agar plates and the plate dilution method were used. All obtained pure cultures were classified into the genera and identified to the species according to micro- and macromorphological properties. Next the potentially toxigenic isolates were tested on their ability to produce mycotoxins (cyclopiazonic acid, penitrem A, sterigmatocystin, aflatoxins (AFB1, AFG1), ochratoxin A, patulin, roquefortine C, citrinin, and griseofulvin). From green coffee samples with higher isolation frequency (FR%) and relative density (RD%) were the genus Aspergillus (FR 100% and RD 67.39%) and the genus Penicillium (FR 90% and RD 24.60%) recorded. Aspergillus section Nigri was the most widespread in green coffee samples (RD 47.7%). The genus Aspergillus was the most occurred genus in roasted coffee bean samples, too (RD 36.58%; FR 90%). In green and roasted coffee samples were detected mainly producers of aflatoxins (AFB1 and AFG1), cyclopiazonic acid, OA, sterigmatocystin and patulin. Due to the detected presence of mycotoxins in green as well as in roasted coffee bean samples, it is very important to prevent fungal contamination and control of coffee beans before and after roasting process.

Inocuidad del café durante la interrupción del secado mecánico

“…Los daños causados por los hongos en el grano de café reducen la calidad sensorial de la bebida y ponen en peligro la seguridad del producto final. Los estudios microbiológicos han demostrado que los principales géneros de hongos filamentosos que atacan los granos de café son Aspergillus spp, Penicillum spp y Fusarium spp (Hlebová et al, 2022), los cuales están presentes tanto en el campo como durante el almacenamiento (Puerta, 2003). Batista et al (2009), determinaron que los frutos recogidos del suelo y los retirados por medio de flotación, presentan mayor riesgo de contaminación por hongos que producen ocratoxina A, lo que muestra la importancia de clasificar el café durante todas las actividades relacionadas con el proceso de beneficio y evitar interrupciones durante el proceso de secado.…”

Mycotoxin contamination profiling in coffee bean by targeted LC-HRMS

“…Aflatoxins are highly toxic compounds produced by certain strains of fungi, primarily Aspergillus flavus and Aspergillus parasiticus, during the growth and storage of agricultural crops [3]. Ochratoxin are toxin compounds produced by certain species of fungi, such as Aspergillus and Penicillium, during the growth of agricultural commodities like coffee beans [4,5]. Patulin are produced by some species of Penicillium, Aspergillus, and Byssochlamys.…”