【作者】 乔勇进；

【导师】 冯双庆；

【作者基本信息】 中国农业大学 ， 农产品加工和贮藏工程， 2003， 博士

【摘要】 热处理是一种无毒无害、无环境污染、无化学药物残留而又简单的物理处理方法，前人研究表明热处理可以抑制果蔬低温贮藏中的冷害发生，目前这一处理技术受到了人们的普遍重视。多胺是一种生物体代谢过程中产生的具有生物活性的脂肪族含氮碱，在植物体内具有十分重要的生理调节作用，如多胺处理可以延缓贮藏果蔬的衰老、减轻贮藏果蔬的冷害，但有关热处理后果蔬体内的多胺含量变化、多胺代谢途径变化及这种变化减轻贮藏果蔬冷害的作用机理目前还未见相关研究报道。本研究旨在以典型冷敏型植物材料—黄瓜(津春2号和新丹4号)为试材，研究热处理和多胺处理对低温贮藏过程中的黄瓜冷害发生、贮藏品质、生理生化变化、多胺组成成分和含量、膜脂肪酸组成成分及含量以及组织细胞超微结构的变化等，探讨热处理后内源多胺变化抑制黄瓜冷害发生的作用机理，为热处理和多胺的研究和应用提供理论依据。 热处理和多胺处理可以减轻黄瓜(“津春2号”和“新丹4号”)低温贮藏过程中的冷害发生率和冷害指数，减缓叶绿素降解；延缓可滴定酸、可溶性固形物、维生素C及硬度等指标的下降；应用多胺合成抑制剂DCHA和D-arg均能抵消和弱化热处理对冷害的抑制效果。 热处理可以显著抑制黄瓜果皮膜渗透率的升高，减少低温贮藏期间丙二醛的积累；延缓可溶性蛋白含量的降低，提高自由基清除酶(SOD、POD、CAT)的活性。多胺处理使果皮的膜渗透率和组织细胞内的丙二醛积累显著降低；抑制了黄瓜果皮中可溶性蛋白含量的降低，提高了三种自由基清除酶(SOD、POD、CAT)的活性。应用多胺合成抑制剂(DCHA和D-arg)处理则明显降低三种自由基清除酶(POD、SOD、CAT)的活性。 热处理显著提高并维持黄瓜果皮内的Put、Spd和Spm含量，其中Put高峰出现时间与黄瓜冷害发生时间基本一致。贮藏过程中多胺总量和氨基总量也表现相似变化趋势。Put／(Spd+Spm)在贮藏后期显著高于对照，说明热处理后贮藏后期黄瓜体内Put的积累大于Spd和Spm的积累，也表明腐胺与冷害的关系比后两者更为密切。多胺合成抑制剂(DCHA和D-arg)可以延缓和降低黄瓜果皮内源Put、Spd和Spm含量的升高。 热处理和多胺处理能减缓不饱和脂肪酸的下降，保持较高的膜脂不饱和脂肪酸组成。热处理和多胺处理使脂肪酸不饱和指数下降减缓；热处理使脂肪酸不饱和度下降减缓，多胺处理促进了高价位不饱和度脂肪酸的合成，可见多胺可调节脂肪酸的代谢途径。 研究表明热处理和多胺处理可以提高细胞内膜系统的稳定性，抑制膜脂过氧化，提高黄瓜对低温的适应和抵抗能力。电镜研究结果表明，在低温胁迫下，细胞内不同细胞器对低温的敏感性表现不同，其中叶绿体对冷害的敏感性最高，线粒体次之，其它细胞器较弱。热处理和多胺处理是可延缓叶绿体和线粒体的膨大和膜结构的破裂，提高细胞膜和液泡膜的稳定性，抑制细胞核的变形，核仁、核孔和核膜的一系列衰老变化，减少胞间层增厚、高电子密度物资的大量积累以及胞间腔的不断增大。 研究证明多胺含量的增加是热处理减轻冷害的主要作用机制之一。适宜的外源多胺处理也可以代替热处理达到减轻黄瓜贮藏冷害的效果。更多还原

【Abstract】 Heat treatment(HT) was a harmless, nonpoisonous and non-pollution physical treating method without deposit of any chemistry on fruits and vegetables. It has been proved to inhibit chilling injury(CI) of fruits and vegetables during storage, and was taken more attention for its simplicity and free-pollution in the field of postharvest in recent years. Polyamines (PAs), which was a nitrogenous base with high biological activity coming from biological metabolism, was an important physiological regulating substance used for delaying senescence or inhibiting CI in fruits and vegetables during storage. However the metabolic mechanism of PAs after HT and the action of PAs in inhibiting CI weren’t understood clearly. The incidence of CI in cucumber, storage Quality, the changing of physiological and chemistry, the constitution and content of endogenous PAs and membrane fatty, ultrastructure of cell were also not studied after the treatment of HT and exogenous PAs. This paper selected two varieties of cucumber "No.4 XINDAN" and "No.2 JINCHUN" as testing material which were all sensitive to chilling, and in order to investigate the action and mechanism of PAs in inhibiting CI in cucumber after HT.The incidence and index of CI, the content of Chlorophyll in cucumber were all declined slowly in cold storage(2*C) after HT and PAs treatment compared to CK. The TA, TSS, Vc, and firmness in cucumber were also delayed by HT and PAs treatment. The synthetic inhibitor of PAs (DCHA, D-arg) could eliminate the effect of HT and PAs in inhibiting CI.The HT Could retard the increase of membrane permeability significantly, decrease accumulation of MDA, delay dropping of soluble protein content. The HT could improve the activities of POD, SOD and CAT enzyme during storage. The PAs treatment had the similar role as HT. The synthetic inhibitor of PAs (DCHA, D-arg) could decrease the activities of POD, SOD,CAT enzyme in the peel of cucumber.The HT could maintain the high level of Put, Spd and Spm content in cucumber. The onset of the peak of Put content was at the same time as the emergence of CI in cucumber. The ration of Put/ (Spd+Spm) was higher significantly than the CKs during the late storage period, the result showed that the accumulating speed of Put had a close correlation to the chilling resistance of cucumber. The treatment of synthetic inhibitor of PAs (DCHA, D-arg) could decrease the content of Put, Spd and Spm in the peel of cucumber during storage.The HT and PAs treatment could retard the decrease of crude fat content, decrease the loss of unsaturated fatty acid content, maitain the constitution of unsaturated fatty acid. The decrease of IUFA after HT and PAs treatment were lower than that of CK . HT could retard the drop of UFA/FA slowly, although the UFA/FA after exogenous PAs treatment dropped more quickly than that of HT, The content of unsaturated fatty acid was maintained; it was proved that exogenous PAs treatment could regulate the metabolism ways of fatty acid, maitain the high content of higher unsaturated fatty acid, the result showed that metabolism of linolenic acid had a close correlation to the chilling resistance of cucumber.The result showed that HT and exogenous PAs treatment could maintain stabilities of membrane system in cell, retard the peroxidation of membrane lipid, improve the ability of resistance and adaptation of cucumber to CI. Organelles in cells which was sensitive to the low temperature were very different, hloroplast was more sensitive than Mitochondrion and organelles. HT and exogenous PAs treatment could retard the enlargement and structural changing of Chloroplast and Mitochondrion; maintain stability of membrane and vacuolus; restrain transformation of nucleus, and series changes of nucleus, nucleopore and nuclear membrane; retard the widening of Interstitial layer, the accumulation of electron dense material, and the enlargement of Interstitial cavity. The above experimental results proved that increase of PAs content was an important regulating way for HT to inhibit chi更多还原