Effect of CaCl₂ and 6-BA Solution on Softening, Browning and Activity of Related Enzyme in Postharvest Jujube Fruits

The relation between softening browning and activity of PG and PPO as well as the effect of CaCl₂ and 6-BA solution preharvest treatments on softening browning, PG activity and PPO activity in postharvest Zanhuang Chinese date were studied. The results showed that the flesh hardness gradually decreased and negatively correlated with storage time significantly; the PG activity fluctuated during the storage periods and had little relation with softening. During storage periods, the browning index and PPO activity increased, the PPO activity related to the flesh browning. 1% CaCl₂, 15 mg/kg 6-BA and 1% CaCl₂+15 mg/kg 6-BA were sprayed on jujube fruits before harvest. The PG and PPO activity were all reduced, the decline of flesh hardness and course of browning were restrained by the treatments. With 1% CaCl₂ treatment the flesh hardness of Zanhuang Chinese date was improved 1.2 kg/cm², with 1% CaCl₂+15 mg/kg 6-BA treatment the flesh hardness was increased 1.5 kg/cm² at the last stage of storage. The effect of 15 mg/kg 6-BA on the flesh hardness, PG activity and PPO activity was lower than that of CaCl₂ treatment.