| The global outbreak of SARS-Co V-2 poses a serious threat to human health,and the frequent detection of SARS-Co V-2 in cold-chain food poses a risk to food processing and transportation that is difficult to control effectively.In addition,cold-chain foods,including seafood,are highly susceptible to rapid spoilage and food poisoning due to the presence of spoilage bacteria and pathogens,severely limiting the consumption of seafood.A variety of physical and chemical disinfection techniques in cold chain food applications there are certain limitations.In recent years,electron beam irradiation has been widely used as a good non-thermal sterilization technique for food preservation and sterilization.Therefore,this study was conducted to investigate the killing effect and killing mechanism of electron beam irradiation on pathogenic microorganisms and contaminating viruses of rhubarb fish by treating cold chain preserved rhubarb fish with different doses of electron beam irradiation,and to evaluate the effect of electron irradiation treatment on the quality of rhubarb fish meat.The main findings of this paper are as follows:(1)In this study,the inactivation effect of E-beam irradiation on spoilage and pathogenic bacteria in rhubarb fish was investigated by in vitro culture and fish inoculation treated with E-beam irradiation,and the inactivation mechanism of E-beam irradiation was investigated in terms of bacterial intracellular ATP,cell membrane integrity,genomic DNA and RNA,and protein structure.The results of the microbiological analysis showed that electron beam irradiation below 2 k Gy had a significant inactivation effect on spoilage and pathogenic bacteria exposed to electron beam irradiation,as well as monoculture and co-culture biofilms,and the pathogenic bacteria(Vibrio parahaemolyticus)were more sensitive.The results of the intracellular ATP assay showed that electron beam irradiation above 1 k Gy could disrupt the integrity of the cytoplasmic membrane.The results of the nucleic acid analysis showed that E-beam irradiation treatment above 2 k Gy significantly disrupted the integrity of DNA and RNA,and the results of SDS-PAGE protein analysis showed that E-beam irradiation treatment less than 10 k Gy had no significant effect on the primary structure of bacterial proteins.In conclusion,electron beam irradiation can effectively inactivate spoilage and pathogenic bacteria in large yellow croakersa.(2)Exogenous viruses were added to the inner and outer surfaces of large yellow croaker packages and large yellow croaker fillets,and then treated with E-beam irradiation to investigate the inactivation effect of E-beam irradiation on the contamination of rhubarb with exogenous viruses.The results showed that the virus titers of Porcine epidemic diarrhea virus(PEDV)and Transmissible gastroenteritis virus(TGEV)on the outer surface of the foam treated with 2.12 k Gy E-beam irradiation were reduced in the cell culture medium.Transmission electron microscopy negative staining and cell section results showed that treatment with electron beam irradiation above 4 k Gy resulted in significant damage to the spines of coronavirus.Viral nucleic acid assay results showed no significant degradation of the genome of viruses treated with electron beam irradiation below 10 k Gy,and significant damage to a viral nucleic acid with electron beam irradiation above 10 k Gy.Therefore,electron beam irradiation treatment can effectively inactivate the coronavirus contaminated with rhubarb fish and destroy the spine structure of coronavirus.(3)To evaluate the effect of electron beam irradiation on the quality of large yellow croaker fish,the quality of large yellow croaker fillets treated with different doses of electron beam irradiation was measured.The results of the microbiological analysis showed that the total number of microorganisms in unirradiated frozen and frozen rhubarb was 4.77log10 CFU/g and 4.54 log10 CFU/g,respectively,and the treatment with electron beam irradiation above 1 k Gy could significantly inactivate the microorganisms in large yellow croaker fillets.The results of the biochemical analysis showed that the quality indexes such as p H,color difference,volatile salt nitrogen,and texture of rhubarb fillets did not change significantly after electron beam irradiation treatment.The results of thiobarbituric acid determination showed that thiobarbituric acid increased in large yellow croaker fillets treated with electron beam irradiation above 6 k Gy.The results of electron nose odor analysis and sensory evaluation showed that the quality of large yellow croaker fillets treated with electron beam irradiation above 6 k Gy decreased.In conclusion,there was no significant effect on the quality of large yellow croaker fillets treated with electron beam irradiation below 6 k Gy.In summary,this thesis investigated the effect of electron beam irradiation on the inactivation of spoilage and pathogenic bacteria and contaminating viruses in large yellow croaker and evaluated the effect of electron beam irradiation on the quality of large yellow croaker fillets.The results of the study provide theoretical guidance for the inactivation of spoilage and pathogenic bacteria and coronaviruses by E-beam irradiation and then provide theoretical support for the application of E-beam irradiation in cold-chain food preservation. |
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