【摘要】 采用对白凤桃生长期树冠喷施Ca(NO3)2的方法,研究了采前补钙影响溶质桃采后贮藏品质及后熟软化进程的生理机制。结果表明,喷施10 g/L Ca(NO3)2处理的桃果实果皮、果肉及细胞壁物质中钙含量分别提高了18.8%、17.7%和11.3%,果实硬度提高了7.8%;处理果实呼吸高峰推迟1 d出现,并且果实软化前期的呼吸速率低于对照果实。贮藏过程中,喷钙果实出汁率显著下降,可溶性固形物、可滴定酸含量与对照相比无显著差异(α=0.05)。喷钙处理对细胞膜透性和酚类物质的含量没有影响,但显著抑制了采后贮藏过程中脂氧合酶(LOX)和多酚氧化酶的活性。此外,采前喷钙处理显著降低了果实细胞壁共价结合果胶和离子结合果胶的含量,抑制了常温贮藏半纤维素的降解(α=0.05),然而果实细胞壁水溶性果胶和纤维素的变化不受喷钙处理的影响。常温贮藏和冷藏2周后货架期间,喷钙果实的PG活性显著低于对照,PME酶活性则相反(α=0.05)。研究认为,采前喷钙对桃采后品质的影响主要体现在提高果实硬度上,喷钙抑制了果实的呼吸作用,细胞壁半纤维素的降解以及LOX、PG酶的活性,影响了细胞壁果胶组分的变化,从而延缓了果实的后熟软化进程。更多还原

【Abstract】 Melting flesh peach ’Hakuho’ was selected to study the effect of pre-harvest calcium sprays on fruit quality and softening during storage after harvest.Calcium nitrate was used as Ca2+ source.Results showed that the calcium content increased significantly in the peel,flesh and cell wall by 18.8%,17.7% and 11.3% in Ca-sprayed fruits,respectively.The respiration rate was reduced during post-harvest storage and Ca-sprayed fruits showed higher firmness and lower juice extraction rate.However,the soluble solid content(SSC) and titrate acid(TA) were not influenced by the pre-harvest calcium sprays(α=0.05).Although LOX and PPO activity decreased in Ca-sprayed fruits,slight differences in cell membrane permeability and phenolics content were noticed.In addition,the pectin components and hemicellulose as well as PG and PME activity were influenced by the pre-harvest calcium sprays.The content of covalently bound pectin fraction(CBP) and ionically-associated pectin(IAP) decreased during shelf life in Ca-sprayed fruits,and the PG activity was decreased significantly by calcium sprays during shelf life after 0—2 weeks cold storage,while PME activity showed reverse pattern(α=0.05).Collectively,these results suggest that fruit softening process was delayed by pre-harvest calcium sprays mainly due to its effect on respiration,hemicellulose degradation,cell wall pectin components and LOX,PG activity.更多还原