采收成熟度对核桃青皮褐变及相关代谢酶的影响

Effects of Harvest Maturity on Browning and Related Metabolic Enzymes of Green Walnut Fruits

【目的】研究采收成熟度对核桃青皮褐变及其相关代谢酶的影响,分析核桃青皮褐变发生机制,为生产中核桃适宜采收期的确定及其褐变定向调控提供理论依据。【方法】以温185青皮核桃为试材,分别于8月22号(成熟度Ⅰ,花后125 d)、8月27号(成熟度Ⅱ,花后130 d)、9月1号(成熟度Ⅲ,花后135 d)采收,置于(-1±1)℃,相对湿度为75%~85%条件下贮藏,定期测定不同采收成熟度核桃青皮褐变指数、总酚含量及褐变代谢相关酶。【结果】青皮成熟度不同,褐变指数不同,成熟度Ⅱ(8月27日)采收的核桃青皮贮期褐变指数显著低于其它2个成熟度,总酚及PPO、POD、PAL、SOD、CAT及APX活性显著高于其它两个成熟度,温185核桃青皮褐变与总酚及PPO、POD、PAL、SOD、CAT及APX活性存在极显著负相关关系。【结论】成熟度Ⅱ(8月27日)是温185青皮核桃适宜采收期,其贮期青皮褐变与总酚含量及PPO、POD、PAL、SOD、CAT及APX活性密切相关。

【Objective】To discuss the effects of harvest maturity on browning and related metabolic enzymes of green walnut fruits in the hope of revealing the browning mechanism of it.The result provides suitable harvest period and a theoretical basis of the directional control of browning of green walnut fruits in production.【Methods】The’Wen 185’green walnut fruits were studied as the test material,which were harvested respectively on August 22(maturityⅠ,125 d after flowering),August 27(maturityⅡ,130 d after flowering),and September 1(Maturity III,135 d after flowering),and stored at(-1±1)℃and a relative humidity of 75%-85%,and afterwards the browning index,total phenolic content and the metabolism-related enzymes of green walnut fruits were determined regularly.【Results】If the fruit skin maturity was different,its browning index was different.The browning index of maturity II(August 27th)was significantly lower than the other two maturity levels,and the total phenols and PPO,POD,PAL,SOD,CAT and APX activities were significantly higher than those of the other twos.The correlation analysis results showed that there was a very significant negative correlation between the browning index of total phenols,PPO,POD,PAL,SOD,CAT and APX activities of the’Wen 185’green walnut fruits.【Conclusion】The MaturityⅡ(August 27)is a suitable harvest period for the’Wen 185’green walnut fruits.Its browning is closely related to the total phenol content,PPO,POD,PAL,SOD,CAT and APX activities of green walnut fruits during storage.