Study On De-astringent And Cold-storage Of Diospyros Kaki Var.'Niuxin'

Niuxin persimmon(Diospyros kaki) is one of the best astringency persimmon breeds in ShanDong province. In order to find an effective deastringency and fresh-keeping method for persimmon storage, and study the machnism of the effection of the1-MCP and deastringency combination treatment on persimmon, also give a theoretical support for the astringent persimmon storage, the indexes of fruit quality by CO2or ethanol astringency removing treatment were tested and the physical changes of the combined use of astringent removing and1-MCP treatment during storage at O±1℃were studied in this experiment. Main results were as follows:1. Treatment with80%CO2for2days in room tempreture removed astringency of Niuxin persimmon, and its effect is better than the35%ethanol treatment for4days. The fruit firmness, color, SSC, TA content were well maintained during the storage time.2. Treating with1-MCP after deastringency persimmon is better than treating with1-MCP first. The method of using80%CO2deastringency persimmon then treating them with1μL/L1-MCP for20h and stored at0±1℃at last was determined as the best treatment for deastringency and crispness-keeping of Niuxin persimmon.3. The CX which degradate cellulose only influenced the early days of softening. PME was the key enzyme for persimmon softening, and its activity negatively related to the fruit firmness in the whole storage time(R=-0.81). PG activity had no significant relationship with firmness. LOX strengthened the decline of the fruit when the persimmon became senesecence.4. The fruit firmness, color, SSC were well maintained with CO2â†'1-MCP treatment. The activity of CX, LOX was decreased by1-MCP treatment, also the occurrence time of PME activity peak was delayed. But the inhibition to PG activity is not clear by1-MCP.5. Peel browning was seriously with CO2â†'1-MCP treatment in the late period of storage. The possible reason was CO2injury leading to the peel browning while1-MCP increasing the persimmon's sensitivity to the CO2. The fruit physical change was researched, results indicated that1-MCP increased the MDA content of deastringent persimmon, also increased the membrane permeability and PPO activity in the late period of storage.6. Niuxin persimmon is a climacteric fruit.1-MCP had no significant inhibitory action on the respiratory rate and ethyl ene production of astringent persimmon. The respiratory rate and ethylene production of astringent persimmon were increased by1-MCP during early storage time but inhibited slightly in the late period of storage. This may relate to the grade of maturity or breed of persimmon.