【作者】 董晓庆；

【导师】 饶景萍；

【作者基本信息】 西北农林科技大学 ， 果树学， 2013， 博士

【摘要】 本研究以苹果和番茄果实为试材，探讨了1-甲基环丙烯（1-methylcyclopropene，1-MCP）在采后果实内的吸附和扩散特点；系统地研究了‘红富士’生长过程中（采收前30d和10d）、采收时以及采后1-MCP处理（0±1）℃贮藏过程中蜡质主要成分和品质生理的变化；同时研究了短时间的1-MCP与低压低氧结合处理对延缓转色期番茄果实成熟衰老的作用及其机理。主要研究结果如下：1．通过对8个苹果品种‘Honeycrisp’、‘Cameo’、‘Gala’、‘Delicious’、‘Empire’、‘Rome’、‘McIntosh’和‘Redcort’进行整果和鲜切1-MCP处理研究发现，苹果整果果实处理12h内部1-MCP含量较高，鲜切果实处理1h内部1-MCP含量较高。不同品种果实内部1-MCP的含量差别很大，其中‘Honeycrisp’的内部1-MCP含量最高，其次为‘Cameo’和‘Gala’‘，Delicious’和‘Empire’内部1-MCP含量中等，而‘Rome’、‘McIntosh’和‘Redcort’内部1-MCP积累较少，基本上检测不到内部1-MCP气体。内部1-MCP含量最高的‘Honeycrisp’是含量最低‘Redcort’的69倍。商业蜡处理能够降低所有品种对1-MCP的吸附。苹果鲜切块经过1-MCP处理后，瓶内的1-MCP气体基本上被消耗掉，而内部没有积累1-MCP；但是鲜切苹果块经过抗氧化剂处理后，内部1-MCP含量显著升高，1-MCP的积累与在整果内的积累趋势基本相同，且各品种苹果块内部1-MCP积累量呈显著不同。品种不同反应了1-MCP气体在胞间的扩散、物理吸附和代谢不同。分切的果实组织不是一个很好的评价1-MCP在果实中吸附和扩散的模型，这可能是由于伤诱导的氧自由基破坏了1-MCP的原因。然而鲜切组织经过陈化、低氧和抗氧化剂抗坏血酸和连二亚硫酸等处理减弱伤诱导的氧化代谢后，可以作为一个很好的评价1-MCP吸附扩散的模型。2．用番茄表皮和梗洼组织为试材，通过双瓶系统测定1-MCP通过它们的消耗扩散变化。1-MCP通过番茄表皮与通过番茄梗洼组织的扩散表现不同，通过番茄表皮的上部三角瓶内1-MCP的浓度没有降低，下部三角瓶内也没有积累1-MCP，通过番茄表皮的乙烯和1-MCP表现了相同的变化规律；通过番茄梗洼的1-MCP，24h后上部三角瓶内1-MCP的浓度降低了70%，下部三角瓶内没有积累1-MCP，但乙烯表现了与1-MCP明显不同的变化趋势，在上下三角瓶内的乙烯达到了扩散平衡。进一步利用整个番茄果实为试材，用20μL L-11-MCP处理整个番茄果实，然后抽取内部气体。1-MCP在整个番茄果实内积累非常快，3~6h后，在番茄梗洼1cm深处抽取的内部1-MCP含量达到7~9μL L-1。经过1-MCP处理后的番茄果实在空气中放置1h和3h后，内部1-MCP降低了74%和94%。不同成熟阶段番茄果实内部积累的1-MCP量相同，涂蜡后番茄果实内部1-MCP含量降低45%。将番茄果实梗洼和果顶用水覆没后，内部1-MCP的积累降低60%。将经过20μL L-11-MCP处理3h后的番茄果实分别放入水中和空气中，在水中的番茄果实内部1-MCP含量仍然为原始值的45%，表明整个果实不能很快的吸附和代谢1-MCP。液体1-MCP处理后也能很快的被番茄吸附。不同果实内1-MCP的吸附和散失不同，可能和果实的吸附量、表面特征（皮孔、蜡质）、成分、原生和商业蜡的结构以及组织的水化等有关。3．通过气相色谱-质谱法研究了‘红富士’表面的蜡质成分。总蜡成分被分成非极性成分和极性成分两部分。其中非极性蜡质成分检测出11种，极性蜡质成分检测出22种。二十九烷是非极性成分中含量最高的成分，占整个非极性成分的95.0%，其次是二十七烷，占整个非极性成分的1.6%。极性成分由一系列脂肪酸及其衍生物、二十九-10-醇和二十九-10-酮组成，其中二十九-10-醇和二十九-10-酮分别占极性成分的29.0%和16.0%。脂肪酸中含量最高的饱和脂肪酸是十六烷酸（16.8%），含量最高的不饱和脂肪酸是9,12-十八碳二烯酸（0.4%）。在苹果果实生长过程中，表皮的总蜡含量逐渐升高，在贮藏的过程中逐渐降低。果实总蜡降低，主要是由占主要成分的二十九烷含量的降低所致，且1-MCP能够抑制贮藏过程中总蜡含量的降低。二十九烷、二十七烷和二十九烯在果实生长过程中含量升高、在（0±1）℃贮藏过程中降低，1-MCP能够抑制其在贮藏过程中的降低。十六烷酸、9,12-十八碳二烯酸、二十九-10-醇和二十九-10-酮在生长过程中显示了不同的变化规律，但在贮藏后期含量都极显著地升高，且这个升高能被1-MCP抑制。1-MCP能延缓果实硬度的下降、可溶性固形物和可滴定酸的降解速度，降低固酸比率和失重率，抑制呼吸速率和乙烯释放速率，且可以抑制苹果贮藏后期油腻的发生。无论从对蜡质成分的影响，还是对果实贮藏品质的影响来看，1-MCP都具有很好的效果。4．研究了500nL L-11-MCP气体在低压低氧（hypobaric hypoxia, HH）条件下（10kPa,2.1kPaO2）同时处理1h对转色期‘Tasti Lee’番茄果实生理品质的影响。常压常氧（normobaric conditions, NbC）下1-MCP处理1h对番茄果实的成熟和乙烯峰出现的时间及跃变峰值影响较小，对呼吸速率、番茄红素含量和PG活性影响较大。与之相反，HH下1-MCP处理1h极显著地抑制了番茄的成熟。HH下1-MCP处理番茄果实硬度和色泽度的降低推迟了10d，乙烯高峰的出现推迟了11d，且其峰值小于NbC处理乙烯峰值的一半，并且没有明显的呼吸峰值出现。无论在HH还是NbC下，对照果实的软化相似，这表明HH对番茄果实软化的抑制作用很小，番茄果实软化显著地被抑制是1-MCP和HH共同作用的结果。为了进一步证明1-MCP在HH条件下的作用，测定了20μL L-11-MCP在HH下处理番茄后内部1-MCP含量。HH下1-MCP处理1h和10min内部1-MCP含量是NbC下的1倍，而处理2min，HH下的内部1-MCP含量是NbC下的9倍，这表明1-MCP在HH条件下能够快速扩散到果实内部。在HH下，处理容器内的氧含量（低于空气中的氧分压）对果实内部1-MCP含量没有影响。HH下1-MCP能够快速扩散到果实内部并显著地推迟果实的成熟。HH下1-MCP对番茄果实的显著效应是由于果实内部短暂积累了大量的1-MCP。更多还原

【Abstract】 Absorption and diffusion of1-MCP in apple (Malus domestica Borkh.) and tomato(Solanum lycopersicum L.) fruit were studied, and changes in surface wax composition of‘Red Fuji’ apple (Malus domestica Borkh.‘Red Fuji’) during development (30d and10dbefore harvest) and during storage at (0±1)℃after1-MCP treatments were investigated, andphysiological quality of ‘Red Fuji’ apple during storage at (0±1)℃after1-MCP treatmentswas evaluated, and effects of combination of1-MCP and HH on tomato (Solanumlycopersicum L.‘Tasti-Lee’) were identified. The main results of this study were exhibited asfollows:1. Eight varieties of apple ‘Honeycrisp’,‘Cameo’,‘Gala’,‘Delicious’,‘Empire’,‘Rome’,‘McIntosh’ and ‘Redcort’ were studied. It accumulated the relative maximum amount ofinternal1-MCP with treatment12h for whole apple, and1h for fresh-cut apple slices. Ingressof gaseous1-MCP varied significantly among the apple varieties tested.‘Honeycrisp’accumulated the highest internal1-MCP, followed by ‘Cameo’ and ‘Gala’.‘Delicious’ and‘Empire’ had the moderate internal1-MCP. However,‘Rome’,‘McIntosh’ and ‘Redcort’accumulated the lowest internal1-MCP. The content of internal1-MCP in ‘Honeycrisp’ was69-fold high compared with ‘Redcort’. Wax treatment caused significant declines in1-MCPingress among all cultivars. Ingress/accumulation of gaseous1-MCP did not occur infresh-cut tissue. However,1-MCP in the jar was nearly delepted. Accumulation trends of1-MCP in fresh-cut tissue of the different varieties treated with antioxidants closely paralleledthose of intact fruit, and it was significant different among eight apple varieties. Varietydifferences in ingress of gaseous1-MCP could reflect differences in intercellular diffusivity,and capacities for physical sorption or metabolism. Excised fruit tissues are likely not suitablesystems for estimating1-MCP diffusivity in fresh-cut fruits, possibly due to1-MCP wasdestroyed by reactive oxygen species (ROS) induced by wounded. However, it is anappropriate model after apple slices were treated with tissue aging, anoxia, and theantioxidants ascorbate and hypotaurine to alleviate wound-related oxidative metabolism.2. Disks from tomato epidermis and stem-scar were used to examine ingress of gaseous1-MCP using a dual-flask system. Changes in1-MCP concentrations in the dual-flask system showed different patterns between tomato epidemis and tomato stem-scar. For tomatoepidermis tissues,1-MCP and ethylene in the top (source) flask did not deplete, and in thebottom flask it did not accumulate. However, for tomato stem-scar,1-MCP declined as muchas70%in source flasks with negligible accumulation in sink flasks, the pattern of ethylenedistribution was markedly different from that of1-MCP, which approached equal distributionwith tomato stem-scar.1-MCP ingress was further addressed by exposing whole tomato fruitto20μL L-11-MCP followed by sampling of internal fruit atmosphere (1-MCP). Tomato fruitaccumulated internal gaseous1-MCP rapidly, reaching approximately7to9μL L-1within3to6h at20℃. Internal1-MCP declined around74%and94%at1h and3h after exposure,respectively. Ingress was similar at all ripening stages and reduced by45%in fruit coatedwith commercial wax. Blocking1-MCP ingress through stem-scar and blossom-scar tissuesreduced accumulation by around60%, indicating that ingress also occurs through epidermaltissue. Fruit preloaded with1-MCP and immersed in water for2h retained about45%ofpost-exposure gaseous1-MCP, indicating that1-MCP is not rapidly sorbed or metabolized bywhole tomato fruit. Rapid ingress of gaseous1-MCP was also observed in tomato fruitexposed to aqueous1-MCP. Both accumulation and post-exposure decline in internal gaseous1-MCP are likely to vary among different fruits and vegetables in accordance with inherentsorption-capacity, surface properties (e.g., waxes, stoma), volume and continuity of gas-filledintercellular spaces and tissue hydration.3. Wax composition of ‘Red Fuji’ apple (Malus domestica Borkh.‘Red Fuji’) duringdevelopment and during storage at (0±1)℃after1-MCP treatment was studied by means ofgas chromatography-mass spectrometry. Total waxes were chromatographically separatedinto nonpolar and polar components. There were11nonpolar components and22polarcomponents. Nonacosane was the most abundant nonpolar wax, comprising95.0%of totalhydrocarbons, followed by heptacosane, which was1.6%of total hydrocarbons. Polar waxcomponents were comprised of a series of fatty acids and derivatives and nonacosan-10-oland nonacosan-10-one, the latter two comprised29.0%and16.0%of polar component,respectively. Hexadecanoic acid (16.8%) was the most abundant saturated fatty acid and9,12-octadecadienoic acid (0.4%) was the richest polyunsaturated fatty acid.Total wax, nonacosane, heptacosane and nonacosene increased during development anddecreased over seven months of fruit storage at (0±1)℃. Declines were delayed or slightlysuppressed in1-MCP–treated fruit. By contrast, hexadecanoic acid,9,12-octadecadienoicacid, nonacosan-10-ol and nonacosan-10-one showed variable accumulation trends duringdevelopment, but significant increases during late storage that were strongly suppressed in1-MCP–treated fruit.1-MCP delayed the decline in flesh firmness, titratable acid and sosluble solid content and reduced ethylene and respiration rates and weight loss.1-MCP was moreeffective than control for suppressing changes wax composition and maintaining storagequality.4. The effect of gaseous1-MCP of500nL L-1applied to turning tomato fruit under HH(10kPa,2.1kPa O2) for1h. Application of500nL L-11-MCP under NbC had little effect onsoftening and timing and magnitude of peak ethylene production, and moderate effects onrespiration and lycopene and PG accumulation. By contrast, turning fruit exposed to500nLL-1gaseous1-MCP under HH for1h showed acute disturbance of ripening. Firmness and hueangle declines were delayed for ten days and peak ethylene production for eleven dayscompared with trends for the other treatments. Maximum ethylene production did not exceed50%of maxima for the other treatments and a definitive respiratory climacteric was notobserved. Without1-MCP treatment under HH or NbC had the same effect on tomato qualityand physiology, indicating that HH had minimal effect on tomato ripening and the significantdelay of the fruit softening was the result of the combination of1-MCP and HH, not just byHH alone.In order to further demonstrate the effect of1-MCP under HH, the internal atmosphere1-MCP of the tomato fruit after treatment with20μL L-11-MCP under HH was measured.Internal1-MCP under HH doubled compared with under NbC for treatments1h and10min,internal1-MCP under HH showed a9-fold increase compared with under NbC for treatment2min, indicating that1-MCP can immediately diffuse to fruit under HH. However, oxygencontent in the container under HH had no difference for internal1-MCP.1-MCP under HHtreatment can significantly diffuse to fruit and delay their ripening. The high efficacy of1-MCP applied under HH is due to rapid ingress and accumulation of internal gaseous1-MCP.更多还原