Abstract
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.
Highlights
A number of studies demonstrate the ability of cold atmospheric plasma (CAP) devices to generate reactive oxygen (ROS) and reactive nitrogen species (RNS) in a way that the viability and integrity of bacteria and viruses on food surfaces [1,2,3,4,5,6,7,8,9] and food packaging [10]exposed to such gas species can be substantially impaired
It has been demonstrated that a jet-type CAP device can reduce surrogate foodborne viruses in an oyster (Crassostrea gigas) slurry without compromising colour and pH [39], and it can be speculated that CAP treatment of the surrounding water [40] could effectuate disinfection of live oysters
A cold atmospheric plasma generating device based on dielectric barrier discharge was highly effective in inactivating an enveloped RNA virus
Summary
A number of studies demonstrate the ability of cold atmospheric plasma (CAP) devices to generate reactive oxygen (ROS) and reactive nitrogen species (RNS) in a way that the viability and integrity of bacteria and viruses on food surfaces [1,2,3,4,5,6,7,8,9] and food packaging [10]exposed to such gas species can be substantially impaired. In particular mussels and Ostreidae, has been implicated in foodborne bacterial and viral poisoning [23,24,25,26,27,28,29,30,31,32], and the control of biological hazards in these food items is a challenging task in food safety assurance [33,34,35,36,37] This is especially as most mussel species are traded alive and some are consumed raw, which makes heat treatment [38] as a control measure impossible. It has been demonstrated that a jet-type CAP device can reduce surrogate foodborne viruses in an oyster (Crassostrea gigas) slurry without compromising colour and pH [39], and it can be speculated that CAP treatment of the surrounding water [40] could effectuate disinfection of live oysters
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