Study On Sterilization And Preservation Of Tilapia Fillet Using Slightly Acidic Electrolyzed Water

Tilapia?Oreochromis mossambicus?is a large number of cultured economic fish in China,its high protein,low fat,by the majority of consumers like.Tilapias most are processed into fillets for sales,in this process the bacterial reduction treatment is a necessary link.Slightly acidic electrolyzed water has been widely used in food processing industry because of its green safety,low cost,broad-spectrum sterilization and so on.However,the research on the bactericidal effect and quality of slightly acidic electrolyzed water on tilapia fillet has not been reported in the literature.In this experiment,the changes of physical and chemical indexes of slightly acidic electrolyzed water under different storage conditions are explored,and the bactericidal effect of slightly acidic electrolyzed water on tilapia fillets is optimized by response surface analysis?RSM?,and the optimum sterilization process parameters are obtained.The effects of slightly acidic electrolyzed water treatment on the quality of tilapia fillets during storage were studied,and the changes of actomyosin salt soluble,total sulfhydryl content,carbonyl content and Ca²⁺-ATPase activity in tilapia meat with different concentrations of slightly acidic electrolyzed water are discussed.It provides the basic theory basis for the application of slightly acidic electrolyzed water in tilapia processing and preservation,and expands the application of slightly acidic electrolyzed water in aquatic product processing industry.?1?Changes of Physicochemical Properties of slightly acidic Electrolyzed Water during StorageIn order to study the changes of physical and chemical indexes of slightly acidic electrolyzed water under different storage conditions,the changes of physical and chemical indexes of slightly acidic electrolyzed water in 30 days storage process were determined under the conditions of light avoidance sealing,light avoidance exposure and light exposure.The results show that the available chlorine concentration of the electrolyzed water decreased gradually with the prolongation of storage time,and the available chlorine concentration of slightly acidic electrolyzed water was more stable under the conditions of sealing and avoiding light.Under the condition of avoiding light,the Oxidation reduction potential?ORP?value of slightly acidic electrolyzed water changed slowly,and during the 30-day storage period it was basically stable,but under the condition of sunlight,the ORP value of slightly acidic electrolyzed water increased with the increase of storage time,and the ORP value was higher than that under the open condition under the sealing condition.Relatively speaking,the effect of light on the ORP value was more obvious.The pH value of slightly acidic electrolyzed water decreased with the prolongation of storage time,the pH value changed more rapidly under the condition of sunlight,but the pH value changed slowly or even remained stable under the condition of avoiding light and darkness,and the sealing also had a certain effect on the pH value,but compared with light,the effect of sealing was slightly weaker.?2?Effect of slightly acidic Electrolyzed Water on Sterilization and quality of Tilapia filletsIn order to study the sterilization effect of slightly acidic electrolyzed water on fresh tilapia fillets,single factor and response surface experiments were carried out with bactericidal logarithmic value as index,the mathematical model between each factor and response value was established,and the optimum sterilization conditions were determined.The results show that the corresponding 0 level value of each single factor was the available chlorine concentration of 30 mg/L,and the soaking time of 20 min,and the ratio of material to liquid was 1:6.The bactericidal process of tilapia fillets with slightly acidic electrolyzed water was optimized by using response surface.The results show that the optimum sterilization conditions were as follows:the available chlorine concentration was 35 mg/L,the soaking time was 22 min,the ratio of material to liquid was 1:6?w/v?,and under these conditions,The bactericidal logarithm was 0.735±0.001lg?CFU/g?,and the bactericidal rate was?81.59±0.04?%.The effect of slightly acidic electrolyzed water on the quality of fish fillet was studied.The results show that the color,sensory and texture of fish fillets changed no significantly?p>0.05?when the immersion time was no longer than 30 min or the available chlorine concentration of slightly acidic electrolyzed water was lower than 30 mg/L,but the color difference,sensory and texture of fish fillets changed obviously when the immersion time was longer than 30 min or the available chlorine concentration of slightly acidic electrolyzed water was higher than 30 mg/L?p<0.05?.?3?Effect of slightly acidic Electrolyzed Water on Preservation of refrigerated Tilapia filletsThe effect of slightly acidic electrolyzed water on the preservation of tilapia fillets under cold storage was studied.The tilapias were sliced,washed,soaked in slightly acidic electrolyzed water with available chlorine concentration of 31.39±1.48 mg/L,soaked for 10 min,then put into PE fresh-keeping bag and stored at 4?.Sensory evaluation,Total Volatile Base Nitrogen?TVB-N?,k value,total bacterial count and pH value were used as evaluation indexes to determine the quality changes of tilapia fillets during cold storage.The results show that the TVB-N value,k value,total bacterial count and pH value of tilapia fillets treated with slightly acidic electrolyzed water were lower than those of the blank group during the same storage period,while the sensory score was higher than that of the blank group.The shelf life of tilapia fillets treated with the slightly acidic electrolyzed water was 5-6 days,while that of the blank control group was 3-4 days.After the fish fillets were treated with slightly electrolyzed water,the shelf life of the tilapia fillets was prolonged by 2-3 days compared with the control group.?4?Effect of bacteriostatic treatment with slightly acidic electrolyzed water onbiochemical characteristics of tilapia fillets muscle protein.The effects of slightly acidic electrolyzed water treatment with different available chlorine concentrations on the biochemical characteristics of tilapia fillets and their muscle protein were studied.Tilapia was sliced and washed,soaked in slightly acidic electrolyzed water with different available chlorine concentrations for 0-40 min.After leaching,the tilapia fillets were put into PE fresh-keeping bag.The effects of different concentrations of slightly acidic electrolyzed water on the biochemical characteristics of tilapia fillets muscle protein were determined by using actomyosin salt soluble,total sulfhydryl content,carbonyl content,Ca²⁺-ATPase activity as evaluation indexes.The results show that the actomyosin salt soluble,total sulfhydryl content,carbonyl content,Ca²⁺-ATPase activity in tilapia fillets muscle were significantly affected by slightly acidic electrolyzed water.The actomyosin salt soluble,total sulfhydryl content,Ca²⁺-ATPase activity in tilapia meat decreased gradually with the increase of available chlorine concentration and soaking time in slightly acidic electrolyzed water,in particular,0-10 min,changed rapidly,while 10-40 min changed relatively slowly.However,the change of carbonyl content was the opposite.