Effect Of AOB And ClO₂ On The Quality Of Tilapia And Its Products

Tilapia is rich in polyunsaturated fatty acids and protein.Tilapia is the world's important cultured freshwater fish with the advantages of strong adaptability and high reproduction rate.China is a big tilapia export country in the world.Preservation processing is usually needed to extend the shelf life of product,keep good qualities and business value of the tilapia products.Natural biological preservatives are gradually applied in tilapia processing enterprises as a environmental friendly preservation technology.The traditional single antistaling agent has been unable to meet the market demand.New type of preservative and compound preservative will be of great significance in tilapia industry.In view of this,this topic makes tilapia and tilapia pill as the research objects.The main research contents and conclusions are as follows:1.To study the antibacterial property and stability of preservative bamboo antioxidant(AOB)and stable chlorine dioxide,the antibacterial activity,antibacterial spectrum and the minimum bacteriostasis concentration(MIC),pH stability,thermal stability and other performance indicators were investigated.The results showed that bamboo antioxidant and stable chlorine dioxide had a broad-spectrum antibacterial property.AOB had a normal bacteriostatic effect of beer yeast.The mould inhibition effect was not obvious.The stable chlorine dioxide had a strong bacteriostatic action.The sterilization effect is remarkable under low concentration.The using temperature of stable chlorine dioxide was within 50?.It would explode when heated.The pH effect was very weak.AOB had good heat resistance,acid and alkali adaptability.It made almost no influence within 100? heat treatment.AOB remained steady when heated at 120 ? for 10 min.In the pH range of 3.0-11.0,bacteriostatic action of AOB was very stable.2.The impacts of new antistaling agent in different concentration on the quality of tilapia and their products under the condition of refrigeration were studied.According to the nature of antistaling agent,0.05%,0.1% and 0.05% AOB solutions were used to treat tilapia fillets of respectively.10,30 and 50 mg/L ClO2 solutionswere used to treat tilapia pill.The results showed that:(1).Under the condition of cold storage(4±1)?,compared with the control group,AOB could obviously reduce the total number of tilapia fillets colonies.The TVB-N value,pH value and TBA value were lower than average level.The sensory score in late storage stage was higher than that of control group.In conclusion,AOB had good preservation capacity.The preservation effect of AOB in 0.1% and 0.2% concentration was obvious.Considering sensory evaluation,when the concentration was 0.1%,sensory score of AOB was the highest.0.1% was the best treatment concentration.(2).Under the condition of cold storage(4±1)?,shelf life of tilapia pills under stable chlorine dioxide treatment was extended 6-10 d than control group.The TVB-N value,pH value and TBA value were maintained in low level.At the same time,the hardness was improved.The flexibility and whiteness were maintained.The higher the concentration of chlorine dioxide was,the better the stable ClO2 preservation effect was.Bacteriostatic test showed that stable chlorine dioxide had a good bacteriostatic effect and significantly extended the shelf life of tilapia fillets.When chlorine dioxide content was 50 mg/L.It had an obvious preservation effect.3.The influence of new antistaling agent combined with different packaging methods on tilapia and its products quality was studied.By studying product quality changing rules in the storage process,the product shelf life was determined.The influence and mechanism of antistaling agent on tilapia and its product quality were analyzed.The results showed that shelf life of tilapia and its products under the condition of iced storage was longer than cold storage(4±1)?.(1).Under the condition of iced storage,tilapia fillets shelf life treated with 0.1% AOB combined with vacuum packaging or gas packaging was up to 18 d,about 10 d longer than the contrast group.AOB combined with vacuum packaging and gas packaging could significantly inhibit the growth of bacteria breeding,reduce the TVB-N and TBA values,slow the decline speed of sensory quality,prolong the shelf life.(2).Under the condition of iced storage,tilapia fish balls shelf life treated with 50 mg/L ClO2 combined with vacuum packaging or gas packaging was up to 35 d,20 d longer than the contrast group.The preservation effect was the best.4.The influence of compound antistaling agent in iced storage process on tilapia and its products quality was studied.The experimental results showed that tilapia fillets and balls shelf life treated with compound antistaling agent under the condition of iced storage was respectively extended 6 d and10 d than the controlgroup,3 d and 5 d than a single antistaling agent group respectively.The compound antistaling agent could reduce the total number of colonies of tilapia and their products,TVB-N value and TBA value.It could maintain good sensory score,extend the shelf life.The preservation effect was better than the single antistaling agent.5.To study the protein biochemistry change of the tilapia and its products treated with compound antistaling agent in the process of iced storage,myofibril protein soluble salt,Ca2+-ATPase activity,surface hydrophobicity,thiol and carbonyl content change were evaluated taking tilapia fillets as an example.The results showed that,myofibril protein soluble salt,Ca2+-ATPase activity and sulphur content declined slowly in the process of iced storage in the compound antistaling agent group.The actomyosin surface hydrophobicity and carbonyl content rose slowly.After 20 d of iced storage,tilapia myofibril protein soluble salt,Ca2 +-ATPase activity and content of thiol of the compound antistaling agent group reduced by 77.47%,84.52% and63.83% respectively,while the control group reduced by 58.53%,85.27% and 49.12%respectively.On the other hand,surface hydrophobicity of actomyosin and carbonyl content of treated group increased by 110.71% and 83.67% respectively,while those of control group rose by 65.60% and 52.04%.At the same storage time,the myofibrilla protein salt solubility,Ca2+-ATPase activity and total sulfhydryl content of treated group were lower than those of control group,and both surface hydrophobicity of actomyosin and carbonyl content were slower than those of control group.The compound antistaling agent e can inhibit lipid oxidation,delay protein denaturation and protect the protein.