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.
Zurich University of Applied Sciences Winterthur, Department of Chemistry and Biological Chemistry, Technikumstrasse 9, Postfach 805, CH-8401 Winterthur, Switzerland.
Marc
M
Zollinger
Walter
W
Krebs
Helmut
H
Brandl
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