| Avocado is a kind of tropical fruit tree which has developed rapidly in recent years. It has been regarded as grain, fruit and oil plant as same time. Avocado fruits has abundant nutritional value and great value in health protection . It has been treated as a kind of precious fruit for all ages. The development of avocado in the south of China is so rapidly recently, and showed good economy benefit. But avocado is jumping fruit, and it can’t be normal ripening in the tree,mature and soften rapidly at room temperature after postharvest. And it is easily suffered to the pre-harvest fungal infection and degeneration which resulting in rot and great loss of avocado after postharvest. At present, the domestic antiseptic technology of avocado is not mature, and became a great extent limit for the development of avocado industry, also set a great obstacle for China’s avocado to improve the competitiveness in international market. Therefore, it is urgent and important to study the factors that affect the storability of avocado, and to explore the safe, efficient and low cost avocado preservation technology.In this paper, the postharvest physiological differences of storage characteristics of different avocado cultivars with Hass and Pollock were studied. At the same time, the effects of MaxCitro and 1-MCP on the freshness of Hass avocado were studied .Moreover,the storage effects of the two kinds of pharmaceutical co-treatment also was studied by using the quadratic regression general rotation combination design, and then the relevant model was established, and the optimal mixing treatment was filtrated to improve the storability of avocado, and the test proved it was practicable and effective. The main findings are as follows:(1) The storability Hass avocado better than Pollock may associate mature and softening enzyme. Compared with the Pollock avocado, the mature process mature of Hass avocado were relatively slow, and the activity of PG、EC、PPO were lower than Pollock at the same period of storage, the peak of ethylene and respiration appeared more relatively late, and the peak value of them were lower, therefore the softening the reducing of hardness can be delayed at the storage period of avocado. Furthermore, the water retention capacity of Hass was also significantly better than Pollock, so it can reduce the loss of moisture and maintain the weight of the fruit in the storage period. The soluble solids,protein and oil content of Hass were higher than Pollock, but the VC content was lower when they ripened.(2) MaxCitro can effectively inhibit the storage disease of avocado, enhance storability of Hass, delay the decline in the hardness, maintain fruit weight and inhibit theactivity of PG and EC, reduce the hydrolysis of pectin, delay the climacteric time and slow the mature process of avocados. At same time, MaxCitro can make avocados keep green and fresh effectively,and reduce the activity of PPO observably. What’s more,the powerful antibacterial resulted in that the diseases was controlled effectively, but the higher concentration of MaxCitro treatment will increase the occurrence of phytotoxicity. In this test, the best concentration of MaxCitro was 5 mL/L, and it can make the shelf life of avocado extend for 10 d, and did not have any impact on the nutritional quality.(3) 1-MCP can delay the ripening of avocado fruits effectively, and extend the shelf time. 1-MCP pretreatment can inhibit PG and EC activity effectively and keep avocado harder. And the appeared time of the peak of ethylene and respiration delayed and the peak value of them reduced, the mature process postponed. As well as, 1-MCP can prevent the skin color of avocado to turn brown by inhibit the activity of PPO. But excessive concentration of 1-MCP will advance the occurrence of disease, than make degree of rot of avocado increased. And that the accumulation of nutrients in avocado can also be delayed effectively but did no effect on the total content when ripe, and the nutritional value of and taste flavor avocado fruit has no changes. In this trial, the best concentration of 1-MCP was 1200 nL/L, and it can make the date of ripe delay for 15 d and shelf life extend for 18 d.(4) The best mixing treatment within 1-MCP and MaxCitro is 4.25 mL/L MaxCitro+968.31 nL/L 1-MCP. This mixing treatment can make freshness and shelf life lengthen significantly. We designed a two-way Orthogonal Combination Test of 1-MCP and MaxCitro by Secondary Regression Universal Rotation Combination Design. This test showed that 1-MCP has a significant effect on the shelf life of avocado. The regression equation was used to obtain the quadratic equation model of the shelf life and the variables of each factor , and the equation is Y=39.00-1.69A-3.77B-1.50AB-7.19A2-9.94B2 ( Y stands for shelf time, A stands for the concentration of MaxCitro, B stands for the concentration of 1-MCP ) and correction coefficient is R2=0.9514.The effect of the optimal mixing treatment filtrated on avocado was significantly better than the same concentration of single factor processing, the shelf time extend to 38 d which is consistent with the model forecast of 39 d, so we considered the model stable relatively. |
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