| Actinidia arguta has the small size and a rind-free surface.Besides,it has the internal structure which is similar to the kiwifruit.It also is rich in nutrients and becomes a new and healthy economic crop recently.So it has great market demand.However,the hardy kiwi is very easy to soften after deastringency.It is difficult to store and transport,which greatly affects commercial value of hardy kiwi.Therefore,it is so necessary that suitable methods to preserve the quality attributes of Actinidia arguta are applyed.In this experiment,three kinds of preservation methods containing a chitosan active coating with a concentration of 1.5%(CH group)and a chitosan lemon essential oil composite coating(CHO group)and a concentration of 1 μL/L1-MCP(1-MCP group)respectively were used.And a control group(CK group)was set up.The changes in nutrient content and antioxidant enzyme activity of Actinidia arguta during the storage for 35 days at 4℃ were studied.The results are as follows:Compared with the CH group,the chitosan solution added with lemon essential oil had lower viscosity and rheological properties.Besides,elongation at break and tensile strength of CHO group were reduced.In general,chitosan edible film incorporating lemon essential oil(CHO)had poorer mechanical properties.During the storage,Actinidia arguta reached maturity first,and then continued to soften into the state of post-maturity and aging.Compared with the CK group,the three treatment which included 1-MCP,CH and CHO groups effectively delayed the aging of Actinidia arguta.From the sensory point of view,the Actinidia arguta,which has been preserved fresh,delayed the shrinkage of the peel and deepened the color,and inhibited the occurrence of soften corruption.Overall,the appearance of the CH group remained the best,which had the most obvious effect.From the point of view of nutritional indicators,the reduction of titratable acid,fruit firmness and water loss were delayed.The contens of Vc and soluble solids were maintained betterly,and the respiratory intensity was delayed and reduced.It can be seen from all the indicators that in the early storage period,the 1-MCP group had the best fresh-keeping effect,and in the later storage period,the CH group had the best effect.In order to further explore the changes of antioxidant enzyme activity of Actinidia arguta treated with three preservation ways including chitosan coating film,chitosan essential oil composite coating film and 1-MCP,three synergistic enzymes were selected.They are superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT).The results showed that the Actinidia arguta of the CH and CHO and the1-MCP groups showed higher antioxidant enzyme activity than the CK group.The activities of SOD and POD firstly increased and then decreased and increased finally,and CAT activity first increased,then decreased,then increased and finally decreased.Overall,it increased first and then decreased gradually.The activity of antioxidant enzyme reached a peak at 20 d.The activities of the three enzymes SOD,POD and CAT were significantly positively correlated. |
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