外源过氧化氢处理对采后荔枝褐变及活性氧代谢的影响

Effects of exogenous hydrogen peroxide treatment on browning and reactive oxygen metabolism of postharvest litchi

    摘要
  • 摘要: 【目的】研究外源过氧化氢（H2O2）处理对采后荔枝褐变及活性氧代谢的影响，为荔枝采后保鲜提供途径，以期提高果实的贮藏品质。【方法】以清水处理为对照（CK），采用不同浓度（1、5和10 mmol/L）的外源H2O2浸泡荔枝3 min，在4℃下冷藏放置，每隔3 d取样一次，进行失重率、褐变指数、丙二醛（MDA）含量、细胞膜透性、内源H2O2含量、超氧阴离子（O2-）产生速率、多酚氧化酶（PPO）活性和超氧化物歧化酶（SOD）活性等生理指标的测定。【结果】不同浓度的外源H2O2处理对采后荔枝会产生不同的贮藏效果。以5 mmol/L外源H2O2处理保鲜效果最佳，明显降低果皮中MDA含量、内源H2O2含量和PPO活性，并提高SOD活性，减缓O2-产生速率。至贮藏末期（12 d），经5 mmol/L外源H2O2处理的采后荔枝SOD活性较CK显著提高31.41%（P<0.05，下同），MDA含量、PPO活性、O2-产生速率和内源H2O2含量较CK分别降低44.72%、38.72%、22.63%和13.75%，其失重率、褐变指数和相对电导率最低。1 mmol/L外源H2O2处理效果稍逊于5 mmol/L外源H2O2处理，而经10 mmol/L外源H2O2处理显著提高采后荔枝的MDA和内源H2O2含量，加速采后果实衰老。【结论】采用5 mmol/L外源H2O2处理可调节采后荔枝的活性氧代谢而延缓其衰老进程，为H2O2应用于采后荔枝保鲜提供理论支撑。

     

    Abstract: 【Objective】To explore the effects of exogenous hydrogen peroxide（H2O2）treatment on browning and reactive oxygen metabolism of postharvest litchi, so as to provide a method to keep litchi fresh after harvest and improve the storage quality of litchi.【Method】Litchi was used as material，in contrast to clean water（CK），and soaked with different concentrations（1，5，10 mmol/L）of exogenous H2O2 for 3 min，and then placed under 4 ℃，measured once every 3 d， weight loss rate，browning index，malondialdehyde（MDA）content，cell membrane permeability，endogenous H2O2 content，superoxide anion（O2-）production rate，polyphenol oxidase（PPO）activity，superoxide dismutase（SOD）activity and other physiological indicators were determined.【Result】Different concentrations of exogenous H2O2 treatment could produce different storage effects on postharvest litchi. 5 mmol/L exogenous H2O2 treatment had the best preservation effect， and it could decrease MDA content，endogenous H2O2 content and PPO activity in fruit peel，increase SOD activity，and slow down the production rate of O2-. At the end of storage（12 d），SOD activity of postharvest litchi treated with 5 mmol/L exogenous H2O2 treatment significantly increased by 31.41%（P<0.05，the same below）compared with CK. Compared with CK，MDA content，PPO activity，O2- production rate and endogenous H2O2 content were decreased by 44.72%， 38.72%，22.63% and 13.75%，respectively，and weight loss rate，browning index and relative conductivity of postharvest litchi were the lowest. The effect of 1 mmol/L exogenous H2O2 treatment was slightly inferior to that of 5 mmol/L exogenous H2O2 treatment，while 10 mmol/L exogenous H2O2 treatment significantly increased MDA content and endogenous H2O2 content in postharvest litchi，and accelerated the senescence of post-harvest fruits.【Conclusion】5 mmol/L exogenous H2O2 treatment can delay the senescence process of litchi by regulating the metabolism of reactive oxygen species，which will provide theoretical support for the application of hydrogen peroxide in the preservation of postharvest litchi.

     

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