Effects Of Electron-beam Irradiation On Fresh Pork Quality In Vacuum-packaged

Food of animal origin, such as unprocessed meat, were usually contained by large numbers ofspoilage micro-organisms as well as possible pathogens. The United States Department of Agriculture,the World Health Organization, the Food and Drug Administration, industries, and retailers have astrong interest on the evaluation of alternatives to minimize this problem. Irradiation is one possiblemethod to help assure meat safety. The advantages of irradiation in controlling microorganisms andimproving the storability of different kinds of meat are well known. Treatment with low doses ofionizing radiation is considered as an effective procedure for meat decontamination and shelf-lifeextension at refrigeration temperature. Irradiation is being used in an increasing number of countries fordecontamination and sterilization of dehydrated vegetables, fruits, poultry, meats, fish and seafood inorder to improve product safety, and an increasing number of clearances for radiation-decontaminatedfoods have been issued or are expected to be granted in the near future.A major concern in irradiatingmeat, however, is its effect on meat quality, mainly because of free radical reactions resulting in thepossibility of odor generation during irradiation. The microbicidal effect of irradiation has been welldemonstrated at relatively low doses that may or may not affect the sensorial quality of foods. Thus,optimizing the irradiation dose is critical if mandatory microbial safety levels are to be achieved whilstminimizing changes in sensory properties.The objectives of this study were to determin the appropriate dosage to extend the shelf-life offresh pork without changing its physicochemical properties and investigate the reasons of uncommonflavour. The contents and results were as followed:(1)To investigate the effects of electron beam irradiation on the shelf-life of fresh pork, packs wereexposed to doses of0kGy,1.5kGy,2.0kGy,2.5kGy,3.0kGy,3.5kGy and4.0kGy. Irradiated andnon-irradiated samples were stored at refrigeration temperature4℃. Microbial population, chemicalchanges and sensory properties were evaluated every5days during storage time. The results indicatedthat electron beam reduced the counts of microorganisms and the contents of TVB-N and increased theshelf-life of fresh pork from3days to10-12days. The dosage of2kGy was appropriate to extend theshelf-life and protect its qualities.(2)To investigate the influence of electron-beam irradiation on the fat quality of pork, thephysicochemical properties (TBARS, acid values, POV values) and sensory characteristics invacuum-packaged were examined at4℃. The results indicated that increasing electron beam irradiationdosage did not change the production of MDA of fresh pork significantly. After irradiation, the acidvalues of fresh pork decreased and the sensory characteristics were better than the quality of0kGy, butthe water capacity decreased and the odor deteriorated. As days increased, the bad odor decreased; itwas concluded that: the effects of low dosage of electron-beam irradiation on fresh pork wereacceptable;1.9kGy of electron-beam irradiation in vacuum-packaged was better.（3）To investigate the influence of electron-beam irradiation on the protein quality of pork, thephysicochemical properties (protein solubility, cutting force, cooking loss, water capacity, NPN, protein contents) and sensory characteristics in vacuum-packaged were examined at4℃. The results indicatedthat electron beam had no significant difference on tenderness, but it could increase its cooking loss anddecrease its water capacity. It produced more small-molecular materials. After irradiation, it increasedthe total protein solubility and sarcoplasmic protein solubility.(4)To determin the reason of uncommon flavor, the effects of fat content with vacuum package onphysicochemical qualities of pork patties by electron-beam irradiation were investigated in a4℃storage trial. Pork patties were irradiated at1.8kGy with a linear electron beam accelerator.Non-irradiated ground pork patties served as a control.The purpose of this study was to determine whateffects of low dose (1.8kGy) having on different types of meat containing different fat contents (0,30%,70%,100%). Oxidative damage to lipids induced by EBI in ground pork pattie was determined at3days intervals throughout at13days storage period at4℃. The fat ration of70%was the hightest of fatoxidation. The addition of fat significantly increases MDA values. Increasing the fat ration,the fatoxidation increase fistly,then decrease.The pattern for increase in the TBARS value during storage wassignificantly reduced (P≤0.05) by EBI doses (1.8kGy) up to day10, and the level continued to increasegradually up to13days storage,which was consistent with odour sensory.