Bioaerosol formation during grape stemming and crushing.
Indoor formation of airborne particles during pre-fermentation grape processing was assessed by particle counting using laser particle sizers. Particle numbers of four different aerodynamic size classes (0.3 to 0.5 microm, 0.5 to 1 microm, 1 to 5 microm, and >5 microm) were determined during unloading of harvest containers and subsequent grape stemming and crushing. 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. Grape handling resulted in a sixfold increase in total (biological and non-biological) airborne particles. The generation of bacterial and fungal aerosols was associated mostly with particles of aerodynamic diameters>5 microm (mainly 7 to 11 microm) 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 colony forming units (cfu/m3), whereas 146,000 cfu of fungi and yeasts were detected per cubic meter of air. 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 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.
Zollinger
Marc
M
Zurich University of Applied Sciences Winterthur, Department of Chemistry and Biological Chemistry, Technikumstrasse 9, Postfach 805, CH-8401 Winterthur, Switzerland.
Krebs
Walter
W
Brandl
Helmut
H
D000336:Aerosols / Q000737:chemistry*; D000391:Air Microbiology; D000393:Air Pollutants / Q000032:analysis*; D005285:Fermentation / Q000502:physiology; D005434:Flow Cytometry; D006090:Gram-Negative Bacteria / Q000502:physiology; D010316:Particle Size; D013997:Time Factors; D027843:Vitis / Q000737:chemistry / Q000382:microbiology*
D000336:Aerosols; D000393:Air Pollutants