Effects Of Eugenol And Its Compound Preservative On The Storage Quality Of Seasoned Lateolabrax Japonicus Fillets And Their Antibacterial Mechanism

Lateolabrax japonicas(L.japonicus)are tender and nutritious.Its surface microorganisms,endogenous protease and protein oxidation are the important reasons for the quality change of L.japonicas fillets during storage.Moreover,sales model of L.japonicus is relatively single.In order to improve the product diversity and quality of L.japonicas,L.Japonicas fillet as the raw material in this paper to prepared seasoned L.Japonicas fillet.The effects of salt and antibacterial seasonings on the freshness indexes,texture characteristics and muscle structure of L.japonicas fillets at 4?and vacuum packaging were studied.The effects of eugenol,eugenol/thymol and eugenol/lysozyme(food grade and biological grade)as preservative on fresh keeping performance of L.japonicas fillets were studied.Shewanella putrefaciens of aquatic products superior spoilage bacteria,as the antibacterial target,which were treated with eugenol and its compound preservative to study their antibacterial properties,and antibacterial action mechanism.Meanwhile,the relationship between the antioxidant properties of eugenol with its compound preservative and the oxidation degree of MP of L.japonicas fillets was investigated.(1)After L.japonicas fillets were treated with salt,cloves and cinnamon,the smell,color and elasticity of L.japonicas fillets were changed slowly,the change of sensory score was slow down,the changes of TVC,TVB-N,and WHC were significantly delayed,the p H rose slowly,and the tissue structure of L.japonicas fillets could be better maintained,the rate of decline of sensory score was decreased.Among them,compound seasoning is better on fresh-keeping properties of L.japonicas and can prolong the shelf life fillets for about 7 d,because of its synergistic inhibition on the growth and reproduction of microorganisms and the protein oxidation denaturation.(2)After L.japonicas fillets were treated with 0.3%(m/v)eugenol,the change of sensory score was slow down,freshness indexes such as,TVC,TVB-N and WHC were significantly delayed,the rising degree of p H was slowed down,texture indexes such as hardness,elasticity,chewing degree,recovery and the tissue structure of L.japonicas fillets were slightly changed.In addition,thymol and lysozyme(food grade and biological grade)were respectively combined with eugenol,which had synergistic fresh-keeping performance and could significantly extend the shelf life of seasoned L.japonicas fillets for more than 7 days.(3)The microstructure of Shewanella putrefaciens treated with eugenol were damage to some extent,the MIC of eugenol on Shewanella putrefaciens was0.3%(m/v).Eugenol combined with other preservative enhanced the ability to damage the structure of bacteria,the integrity of bacteria membrane was worse,their permeability was increased,the activity of ATP enzyme and AKP enzyme was significantly decreased,and the effect on bacterial protein synthesis expression was further increased.(4)Using 1,1-diphenyl-2-trinitrobenzene hydrazine(DPPH)scavenging method,ABTS⁺scavenging method,Fe³⁺reduction method and hydroxyl free radical(OH·)scavenging method came to a conclusion that eugenol and its compounded preservative had good antioxidant activity.Among them,eugenol/thymol had the highest scavenging rate of ABTS free radicals and hydroxyl free radicals,indicating that they had synergistic antioxidant properties.The results of oxidative denaturation degree of MP of L.japonicas fillet shown,the MP solubility and total sulfhydryl content of L.japonicas fillets treated with compound seasoning decreased more slowly,and the surface hydrophobicity was lower,which could inhibit the MP oxidation denaturation of L.japonicas fillets.Compared with compound seasoning,eugenol treated L.japonicas fillets had higher MP solubility and total sulfhydryl content,lower surface hydrophobicity of MP,that is,the anti-oxidation effect of MP on L.japonicas fillets was better.Among them,eugenol/lysozyme(food grade)has the best inhibitory effect on carbonyl formation of protein on L.japonicas fillets.Eugenol/thymol had the best hydrophobic effect on the surface of L.japonicas fillets,above those indicats that eugenol combined with thymol,lysozyme(food grade)and lysozyme(biological grade)had further increased anti-oxidation effect on MP of L.japonicas fillets because of synergistic antioxidant effect.