The Effects Of DBD Plasma Treatment On The Main Postharvest Pathogenic Fungi Of Goji Berries And Its Preservation Properties

Goji berries(Lycium barbarum L.)are rich in nutrients,including vitamins,polysaccharides,dietary fiber,and minerals,and have various biological activities and pharmacological functions that provide significant health benefits to the human body.However,due to their high metabolic rate,fresh goji berries quickly deteriorate after harvesting,which seriously affects their nutritional and economic value.Additionally,their thin and juicy skin makes them susceptible to damage and infection by pathogenic fungi during transportation and storage,leading to decay and spoilage.Traditional control methods are costly and highly polluting.Therefore,the use of physical technology to control post-harvest diseases is an important measure for exploring green development in the industry.Low-temperature plasma technology is a novel non-thermal processing technology that has been found to effectively inhibit microbial growth.In this study,we used post-harvest goji berries as the experimental material,isolated and identified the main pathogenic fungi,investigated the effects of dielectric barrier discharge(DBD)plasma treatment on the quality and surface microbial diversity of fresh goji berries,and studied the changes in the growth,reproduction,and transcriptional level of Alternaria alternata induced by DBD plasma treatment.The aim of this study was to reveal the mechanism of A.alternata inhibition by DBD plasma and provide theoretical references for the application of DBD plasma in the preservation of fruits and vegetables.The main research results are as follows:1.This study analyzed the main pathogenic fungi of goji berries after harvest and the effect of DBD plasma on the surface microbial diversity of goji berries.For the isolation and identification of fungi causing decay in harvested goji berries,results showed that five strains of pathogenic fungi infected the fruit,including Alternaria alternata,Alternaria brassica,Rhizopus oryzae,Cladosporium,and Fusarium.Among them,A.alternata and A.brassica were the main pathogenic fungi during the storage period of goji berries.In addition,DBD plasma treatment was able to continuously reduce the total number of fungal and bacterial colonies on the surface of goji berries during storage.High-throughput sequencing analysis of surface microbial diversity showed that DBD plasma treatment significantly changed the composition of surface microorganisms on goji berries,reducing their diversity,evenness,and richness.2.Using transcriptomic analysis,this study investigated the antibacterial mechanism of DBD plasma on A.alternata.Different voltage DBD plasma treatments were used on A.alternata,and the results showed that DBD plasma effectively inhibited spore growth(including hyphal diameter and spore germination rate)of A.alternata.DBD plasma also disrupted the spore cell membrane integrity,causing changes in the morphology of the cell membrane and leading to the leakage of intracellular biomolecules(such as proteins and nucleic acids)into the extracellular environment.Transcriptomic data showed that DBD plasma treatment inhibited the DNA repair pathway of A.alternata,preventing the normal repair of damaged spore DNA and affecting its normal physiological activity,thereby achieving a bactericidal effect.3.The effect of dielectric barrier discharge(DBD)plasma treatment on the quality of postharvest wolfberry was investigated.The study results showed that DBD plasma treatment can reduce the incidence of post-harvest disease in wolfberry,delay the decline in fruit hardness and ethylene release,maintain fruit quality during storage,promote the accumulation of phenolic compounds,and induce an increase in the activity of peroxidase(POD),leading to a decrease in the degree of membrane lipid peroxidation and inhibition of the increase in malondialdehyde(MDA)content.These results indicate that DBD plasma treatment can maintain the antioxidant capacity of wolfberry fruits during storage,delay fruit aging,and thus maintain fruit quality.In summary,this study investigated a technique called DBD plasma,which effectively controls post-harvest diseases in goji berries.The main mechanisms by which DBD plasma prevents post-harvest diseases in goji berries include altering the total number and community structure of microorganisms on the surface of goji berries,inhibiting the growth and metabolic pathways of the main pathogenic fungus A.alternata,reducing the pathogenicity of A.alternata,and improving the antioxidant capacity of goji berries to maintain their post-harvest quality.This research expands the application of plasma technology in the preservation of goji berries after harvest and provides a new solution for the prevention and control of post-harvest diseases in goji berries.