The Effect Of Vacuum Packaging And Antioxidants On Frozen Tilapia Fillets Quality

To research the effect of vacuum packaging and antioxidants on quality changes in frozen tilapia fillets,Tilapia was used as test subjects in this paper and thiobarbituric acid(TBA)value, Ca2+-ATPase activity, salt extractable protein content, total volatile basic nitrogen(TVB-N), whiteness and texture of tilapia fillets were measured during frozen storage.Orthogonal test was designed to complex with the best mixed antioxidants. As the same time, the frozen stability of the best mixed antioxidants and the mixture of the best mixed antioxidants and trehalose were researched. The goal was to improve the quality of frozen tilapia fillets at the most. The main results were as follows:With the extension of frozen time, TBA value and TVB-N content of tilapia fillets were on the rise, but TBA value and TVB-N content of vacuum packed group were significantly lower than the control group. As time went on, the Ca2+-ATPase activity, salt extractable protein content, whiteness and texture of tilapia fillets decreased gradually and it was the most significant declined in the first 30 days, but the effect was not obvious between the vacuum packed group and control group. After frozen 150 days, compared with the control group, the vacuum packed group not only improved the Ca2+-ATPase activity, but reduced TVB-N content. However, no significant difference in other indicators between them.By single factor experiments of vitamin E, sodium isoascorbate and tea polyphenols and index analysis, determine the the best solution concentrations of vitamin E, sodium isoascorbate and tea polyphenols were 6g/L, 6g/L and 4g/L, Sodium isoascorbate solution was the best among the three. In order to reduce costs of sodium isoascorbate that the most expensive of the three antioxidant and further keep the original quality of tilapia fillets during frozen storage, L9(34) orthogonal experiment was designed. The best mixed antioxidants formula which the best quality and lowest cost was: sodium isoascorbate solution 4g/L, vitamin E 2g/L, tea polyphenols solution 2g/L. The best mixed antioxidants was not only keeped the quality of frozen tilapia fillets, but also achieved a lowest cost.In order to study frozen stability of the best mixed antioxidants and the best mixed antioxidants+ trehalose, tilapia fillets were soaked in two kinds of mixture and soaked in distilled water as a control group. The results showed that: after frozen 150 days, the TBAvalue of the best mixed antioxidants group and the best mixed antioxidants+ trehalose group wrer far lower than control group, but there is no difference between the two experimental groups. The Ca2+-ATPase activity of them were 2.30 and 2.42 μmol Pi/mgprot/h and increased by 18.6% and 21.7% compared to the control group. The salt extractable protein content of them were 67.80 and 70.15 mg/g and increased by 14.6% and 16.9% compared to the control group. After frozen 150 days, TVB-N content of the control group was close to the critical value of the secondary freshness 25 mg/100 g, but the two experimental groups were much lower than the critical value. The whiteness value of the control group was also slightly lower than the two experimental groups. For texture, the best mixed antioxidants group and the best mixed antioxidants+ trehalose group have greatly improved compared with the control group, chewiness of them were increased by 25.8% and 28.6%. By contrast, the best mixed antioxidants+trehalose group was better than the best mixed antioxidants group which was better than single antioxidants. It could be seen, the best mixed antioxidants could keep quality of tilapia fillets during frozen storage. If add trehalose in the best mixed antioxidants, the quality of tilapia fillets would be better.