Nitrogen Accumulation in Oyster (<i>Crassostrea gigas</i>) Slurry Exposed to Virucidal Cold Atmospheric Plasma Treatment
Isabella Csadek,
Peter Paulsen,
Pia Weidinger,
Kathrine H. Bak,
Susanne Bauer,
Brigitte Pilz,
Norbert Nowotny,
Frans J. M. Smulders
Affiliations
Isabella Csadek
Unit of Food Hygiene and Technology, Food Technology and Veterinary Public Health, Institute of Food Safety, University of Veterinary Medicine Vienna, Veterinärpl. 1, 1210 Vienna, Austria
Peter Paulsen
Unit of Food Hygiene and Technology, Food Technology and Veterinary Public Health, Institute of Food Safety, University of Veterinary Medicine Vienna, Veterinärpl. 1, 1210 Vienna, Austria
Pia Weidinger
Viral Zoonoses, Emerging and Vector-Borne Infections Group, Institute of Virology, University of Veterinary Medicine Vienna, Veterinärpl. 1, 1210 Vienna, Austria
Kathrine H. Bak
Unit of Food Hygiene and Technology, Food Technology and Veterinary Public Health, Institute of Food Safety, University of Veterinary Medicine Vienna, Veterinärpl. 1, 1210 Vienna, Austria
Susanne Bauer
Unit of Food Hygiene and Technology, Food Technology and Veterinary Public Health, Institute of Food Safety, University of Veterinary Medicine Vienna, Veterinärpl. 1, 1210 Vienna, Austria
Brigitte Pilz
Unit of Food Hygiene and Technology, Food Technology and Veterinary Public Health, Institute of Food Safety, University of Veterinary Medicine Vienna, Veterinärpl. 1, 1210 Vienna, Austria
Norbert Nowotny
Viral Zoonoses, Emerging and Vector-Borne Infections Group, Institute of Virology, University of Veterinary Medicine Vienna, Veterinärpl. 1, 1210 Vienna, Austria
Frans J. M. Smulders
Unit of Food Hygiene and Technology, Food Technology and Veterinary Public Health, Institute of Food Safety, University of Veterinary Medicine Vienna, Veterinärpl. 1, 1210 Vienna, Austria
Viral contamination of edible bivalves is a major food safety issue. We studied the virucidal effect of a cold atmospheric plasma (CAP) source on two virologically different surrogate viruses [a double-stranded DNA virus (Equid alphaherpesvirus 1, EHV-1), and a single-stranded RNA virus (Bovine coronavirus, BCoV)] suspended in Dulbecco’s Modified Eagle’s Medium (DMEM). A 15 min exposure effectuated a statistically significant immediate reduction in intact BCoV viruses by 2.8 (ozone-dominated plasma, “low power”) or 2.3 log cycles (nitrate-dominated, “high power”) of the initial viral load. The immediate effect of CAP on EHV-1 was less pronounced, with “low power” CAP yielding a 1.4 and “high power” a 1.0 log reduction. We observed a decline in glucose contents in DMEM, which was most probably caused by a Maillard reaction with the amino acids in DMEM. With respect to the application of the virucidal CAP treatment in oyster production, we investigated whether salt water could be sanitized. CAP treatment entailed a significant decline in pH, below the limits acceptable for holding oysters. In oyster slurry (a surrogate for live oysters), CAP exposure resulted in an increase in total nitrogen, and, to a lower extent, in nitrate and nitrite; this was most probably caused by absorption of nitrate from the plasma gas cloud. We could not observe a change in colour, indicative for binding of NOx to haemocyanin, although this would be a reasonable assumption. Further studies are necessary to explore in which form this additional nitrogen is deposited in oyster flesh.
