Effect Of The Slightly Acidic Electrolyzed Water On Preservation Of Grass Carp (Ctenopharyngodon Idella) During The Chilling Storage

Grass carp(Ctenopharyngodon idella)is one of the economic fish in China.Palatability and nutritional content also contribute to its popularity among consumers.Chilled storage is an effective preservation technique to maintain the freshness of ready-to-eat fish.However,it cannot entirely inhibit the deterioration of fish quality during storage,so additional pretreatments are sought to improve the quality of fish and extend its shelf life.Slightly acidic electrolyzed water(SAEW)is a safe and efficient sanitizer with a broad bactericidal spectrum,no pollution,and no residue.This paper systematically investigates the antibacterial effect of SAEW under different pretreatment parameters(available chlorine concentration [ACC],temperature,solid/liquid ratio,treatment time)on grass carp meat during cold storage.These results provide a theoretical reference for improving the quality of grass carp and promoting the application of SAEW in the food industry.The specific research results are as follows :(1)The antibacterial effect of SAEW on grass carp meat increased significantly(P < 0.05)as the ACC increased,but not when ACC exceeded 40 mg/L(P > 0.05).As the ACC in SAEW was increased,total volatile base nitrogen(TVB-N),thiobarbituric acid-reactive substances(TBARS),and the pH value of grass carp meat decreased during storage(P < 0.05),which delayed the deterioration of hardness,springiness,chewiness,and whiteness of grass carp meat compared with the blank control group(P < 0.05).In addition,pretreatment with SAEW inhibited the water loss of grass carp meat during storage(P < 0.05)but had no significant effect on water activity(P >0.05).Among the ACC tested,SAEW with an ACC of 40 mg/L had the best effect on improving the microbial safety and quality of grass carp meat during chilling storage(P < 0.05).(2)The antibacterial effect of SAEW on grass carp increased with the decrease in pretreatment temperature(P < 0.05),but the difference between SAEW at 0 and 4 °C was not significant(P > 0.05).Pretreatment with SAEW at 0 and 4 °C decreased TVB-N,TBARS,and the pH value of grass carp during chilling storage compared with SAEW at 20 °C and inhibited the increase in fish whiteness(P < 0.05).However,the water content and water activity of the fish were not significantly affected by SAEW(P > 0.05).There was a greater inhibitory effect on the increase in TBARS and deterioration of hardness,springiness,and chewiness of grass carp meat during storage when pretreatment with SAEW occurred at 0 °C than at 4 °C(P < 0.05).Therefore,pretreatment with SAEW at 4 °C has the best antibacterial and preservation effects on grass carp meat during storage(P < 0.05).(3)The antibacterial effect of SAEW on grass carp increased(P < 0.05)as the solid/liquid ratio increased(1:5,1:10,1:15,1:20),but this effect was not significant at the solid/liquid ratio of1:15 and above(P > 0.05).Increasing the solid/liquid ratio decreased TVB-N,TBARS,and the pH value of grass carp meat during chilling storage(P < 0.05),but also delayed the deterioration of whiteness,hardness,and springiness to maintain the fresh quality of the fish meat(P < 0.05).The solid/liquid ratio of 1:15 was the best among those tested at maintaining the quality of grass carp meat during storage(P < 0.05).(4)The antibacterial effect of SAEW on grass carp meat increased(P < 0.05)as soaking time was extended(0,2,4,6,8,and 10 min),but the effect was not significant when soaking time exceeded 6 min(P > 0.05).Soaking treatment inhibited the increase in TVB-N,TBARS,and pH value of grass carp during storage(P < 0.05)and delayed the deterioration of hardness,springiness,chewiness,and whiteness(P < 0.05).In addition,SAEW soaking treatment inhibited the water loss of grass carp meat during storage(P < 0.05)but had no significant effect on water activity(P >0.05).Compared to shorter or longer soaking times,soaking for 6 min led to the best preservation effect of SAEW on grass carp meat during storage(P < 0.05).In summary,the optimal preservation parameters of SAEW for grass carp during cold storage were ACC of 40 mg/L,temperature of 4 °C,solid/liquid ratio of 1:15,and soaking time of 6 min.Compared with the control group,the total number of colonies on grass carp meat treated with SAEW under this parameter condition was reduced(P < 0.05).The sterilization rate reached81.2%,showing the most significant antibacterial effect on Pseudomonas.Pretreatment with SAEW reduced TVB-N,TBARS,and the pH value of grass carp meat during storage(P < 0.05).For example,on day 9,TVB-N and TBARS were decreased by 16.72% and 67.32%,respectively,compared with the control group.In addition,besides increasing the water content,hardness,springiness,and chewiness of grass carp meat during storage compared with the control group(P <0.05),pretreatment with SAEW maintained the color of fish meat.In summary,pretreatment with SAEW can significantly inhibit the growth of microorganisms in grass carp meat,delay the deterioration of quality,and ultimately extend the shelf life of the fish by 3-4 days during chilling storage.