Title: Bioaerosol formation during grape stemming and crushing
Authors : Zollinger, Marc
Brandl, Helmut
Krebs, Walter
Conference details: 65. Jahresversammlung der Schweizerischen Gesellschaft für Mikrobiologie SGM/SSM, Lausanne, 2006
Issue Date: 2006
License (according to publishing contract) : Licence according to publishing contract
Type of review: Peer review (Abstract)
Language : English
Subjects : Mikrobiologie; Aerobiologie
Subject (DDC) : 570: Biology
Abstract: The surface of grapes harbors a rich microflora. It has been estimated that 1000 to 100’000 cfu per gram are present on the grape surface. Massive colonization of the grape surface can occur due to damage of the grape skin resulting from hail events leading to increased microbial fouling. Under these circumstances, population densities of 10E06 to 10E08 cfu might be found per gram. Regarding pre-fermentation grape handling, the first processing step includes stemming and crushing. Nevertheless, during this process the grape-specific microflora can be aerosolized and distributed within the occupational environment. We assessed indoor formation of airborne particles during grape processing by particle counting using laser particle sizers. Particle numbers of four different aerodynamic size classes (0.3 to 0.5 µm, 0.5 to 1 µm, 1 to 5 µm, and >5 µm) were determined during unloading of harvest containers and grape processing. Regarding these size classes, composition before grape handling was determined as 87.9, 10.4, 1.7, and 0.1%, respectively, whereas the composition changed during grape handling to 50.4, 15.2, 33.0, and 1.5%, respectively. Airborne bacteria and fungi originating from grape processing were collected by impactor and liquid impinger samplers. The generation of bioaerosols was associated mostly with particles of aerodynamic diameters >5 µm (mainly 7 to 11 µm) as determined by flow cytometry. This fraction was increased 150fold in relation to background levels before grape crushing. Maximum concentrations of culturable bacteria reached 485’000 cfu/m3, whereas 146’000 cfu of fungi and yeasts were detected. Culturable Gram-negative bacteria occurred only in small numbers (180 cfu/m3). In relation to the total number of airborne particles emitted, culturable microorganisms comprised only 0.1 to 0.2%. As soon as grape crushing was stopped, particle concentrations decreased rapidly either due to passive settling or due to air currents in the occupational indoor environment reaching background levels.
Departement: Life Sciences and Facility Management
Organisational Unit: Institute of Chemistry and Biotechnology (ICBT)
Publication type: Conference Poster
URI: https://digitalcollection.zhaw.ch/handle/11475/14145
Appears in Collections:Publikationen Life Sciences und Facility Management

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