'嘎拉'苹果对不同浓度1-MCP处理的反应

以'嘎拉'('Kid's Orange'×'Delicious')苹果为试材,研究了0℃贮藏期间及贮藏30、60、90和120 d后转入室温7d货架期间1-MCP(1-甲基环丙烯)对果实呼吸速率、乙烯释放速率、品质和蛋白质变化的影响.结果表明,1-MCP处理显著抑制嘎拉苹果贮藏期间和贮后货架期间呼吸和乙烯释放速率,延缓果实硬度、可滴定酸含量的下降,对可溶性固形物含量无影响.对照果实在贮藏过程中,出现5条明显的特异性蛋白条带,1-MCP处理能抑制特异蛋白表达.300 nL·L-1浓度1-MCP处理与600 nL·L-11-MCP处理作用效果无显著差异.     

1-MCP对室温贮藏下不同成熟度猕猴桃的生理效应

以适期采收(成熟度Ⅰ)和晚采收(成熟度Ⅱ)的'海沃德'猕猴桃果实为材料,研究0.5 μL·L~(-1) 1-甲基环丙烯(1-MCP)处理对室温贮藏(20℃)条件下两种果实的生理生化指标的影响.结果显示:1-甲基环丙烯(1-MCP)处理能有效延缓贮藏期间两种成熟度果实的硬度、可滴定酸含量、维生素C含量的下降,显著降低二者的乙烯释放速率和呼吸强度及其峰值,提高果实的POD、CAT和SOD活性.与成熟度Ⅰ相比,成熟度Ⅱ果实的硬度下降较快,且丙二醛含量和呼吸速率却明显较高,呼吸速率和乙烯释放量高峰时间相对提前.研究表明,在相同的贮藏条件下,晚采收的'海沃德'猕猴桃果实成熟衰老进程明显快于适期采收果实,贮藏效果较差;1-MCP能够明显延长猕猴桃果实的贮藏时间,表现出显著的保鲜效果.     

木瓜果实贮藏期间香气成分的变化研究

采用同步蒸馏萃取(SDE)法提取不同贮藏期木瓜果实的香气成分,通过GC-MS进行分析,结果表明:木瓜果实成熟后随着贮藏期延长,香气成分总体呈现出醇类、酮类、醛类相对含量下降,酯类、烯烃及萜烯类上升趋势。贮藏初期果实的主要香气成分包括4-甲基-5-(1,3-二戊烯基)-四氢呋喃-2-酮、二氢-β-紫罗兰醇、(Z)-3-己烯醇等。当8℃贮藏40 d时,香气物质主要以萜烯类、酯类和醇类为主,相对含量分别为21.07%、18.73%和16.34%。当贮藏90 d时脂肪酸乙酯类相对含量明显增加,达到34.86%,其中3-壬烯酸乙酯相对含量最高(21.67%),成为构成木瓜香气的关键物质。α-金合欢烯相对含量在整个贮藏期间不断上升,由贮藏初期的3.63%上升到贮藏40 d时的19.00%,当贮藏90 d时达到35.22%。     

神湾菠萝夏季果与秋季果香气成分差异性分析

以'神湾'菠萝夏季果和秋季果为材料,采用顶空固相微萃取法(HS-SPME),提取果实中的香气成分,并经气相色谱/质谱(GC-MS)联机分析.结果表明,夏季果中检测出5类共21种香气成分,分别为酯类、烯类、酸类、醇类和酮类,其中酯类11种,相对含量为92.03%,含量最高的为己酸甲酯(44.91%);烯类6种,相对含量为3.99%;酸类、醇类和酮类分别检测出2种、1种和1种,其相对含量分别为0.72%、0.37%和0.22%.在秋季果中仅检测出2类共8种香气成分,其中酯类7种,总相对含量为92.11%,含量最高的为己酸甲酯(68.36%);烯类物质1种,相对含量为7.89%.     

甜柿采后生理特性及对1-MCP处理的反应

以甜柿品种‘阳丰’为材料,在20℃和0℃贮藏条件下研究了1-MCP(1-甲基环丙烯)处理对不同成熟度甜柿果实采后乙烯释放速率、呼吸速率和品质特性的影响。结果表明:1-MCP处理可延缓贮藏和货架期间甜柿果实的软化、抑制呼吸速率和可溶性固形物含量(SSC)的变化,但对乙烯释放速率的作用不一致。1-MCP处理对成熟度I果实的效果优于成熟度Ⅱ。低温贮藏虽然能显著延缓果实硬度的下降,但在0℃贮藏30、60和90 d后7 d货架期结束时,对照果完全软化,而经1-MCP处理后果实果肉硬度仍保持“脆”性。因此,贮前0.50μL.L-11-MCP处理结合低温贮藏是延长‘阳丰’甜柿贮藏期的有效途径,具有广泛的应用前景。     

采前果面喷施钙制剂对苹果果实品质的影响北大核心CSCD

以‘富士’、‘金冠’和‘粉红女士’3个苹果品种为试验材料,并用氯化钙、硝酸钙和氨基酸钙3种钙制剂在采前30 d对果实进行喷施处理,采用常规方法测定基本果实品质指标,应用顶空固相微萃取及气相色谱质谱联用技术等测定果实香气等13项品质指标,并结合主成分分析和线性加权求和等方法对钙制剂处理的果实品质进行综合评价,以探究比较钙制剂对不同品种苹果果实品质的改进效果,为提高苹果果实品质和品种改良提供理论依据。结果表明:(1)采前钙处理对‘富士’和‘金冠’的单果重影响不显著,但‘粉红女士’采用氯化钙和氨基酸钙处理后单果重显著上升。(2)采前用氯化钙处理显著提高了苹果果实的糖酸比和硬度等;硝酸钙处理能够显著提高果皮亮度和色泽饱和度等;氨基酸钙处理则显著提升了果实的各类香气物质含量。(3)主成分分析和综合评价结果显示,经氯化钙、硝酸钙和氨基酸钙处理后,各品种苹果果实品质的综合得分均高于对照,且以氨基酸钙处理后果实的品质综合得分最高。研究发现,采前30 d钙处理可有效提升苹果果实的色泽、糖酸比、硬度以及香气等品质,且以氨基酸钙的处理效果最佳,而且对‘粉红女士’苹果果实品质的提升效果最为明显。     

不同后熟期‘菊水’梨果实对外源乙烯和1-MCP处理的生理响应

用80uL·L-1外源乙烯和1.0 uL·L-11-甲基环丙烯(1-MCP)处理不同后熟期'菊水'梨果实,分析处理后果实品质和生理指标在(25±1)℃贮藏温度下的变化特征.结果显示:在采收当天(采后0 d)和呼吸跃变初期(采后4 d),外源乙烯处理能明显促进果实硬度和可溶性同形物含量(SSC)的下降,降低活性氧清除酶(SOD、CAT和APX)的活性,提高呼吸速率和乙烯释放速率,促进果实后熟,1-MCP处理却表现出与乙烯相反的效应,且采收当天比呼吸跃变初期的作用效果更明显;在呼吸跃变中期(采后12 d),外源乙烯和1-MCP处理效果均不明显.研究发现,外源乙烯能促进果实后熟而1-MCP却抑制果实后熟,其效果因处理果实后熟期的不同而存在显著差异,果实后熟程度越高,其处理的效果越不明显.     

1-甲基环丙烯对猕猴桃乙烯产生和贮藏品质的影响

室温和0℃两种贮藏条件下,100 nL*L-1的1-MCP显著抑制“秦美“猕猴桃果实乙烯的释放,延缓乙烯高峰的出现,延缓果实硬度和可滴定酸含量的下降以及可溶性固形物含量的增加.     

‘南红梨’采后生理特性及其后熟过程中的品质变化分析

以‘南果梨’及其红色芽变品种‘南红梨’为试材,对两种果实的采后生理特性及后熟期间品质变化进行比较分析。结果表明:(1)与‘南果梨’相比,‘南红梨’果实外观红色鲜艳,可溶性固形物含量高、可滴定酸含量低、固酸比较高,口感更甜。(2)采后‘南红梨’呼吸高峰值及后熟前期乙烯生成量显著高于‘南果梨’,果实硬度下降更快,并在贮藏第6天至第18天均小于同期的‘南果梨’果实,使口感更绵软。(3)最佳食用期时,两种果实均检测到43种香气成分,其中40种相同,并各有3种香气成分对方为检出;‘南红梨’香气成分总生成量显著大于‘南果梨’,并且酯类香气成分相对含量(80.335%)显著高于‘南果梨’(75.713%),因此,‘南红梨’的香气更加浓郁。     

低温贮藏过程中溶质和硬质桃冷害发生的生理差异

该试验以溶质型桃品种(中油桃13号、春美和中油桃4号)和硬质型桃品种(中油桃18号、中桃9号和白如玉)为试材,分析桃果实在4℃低温贮藏过程中的品质变化以及乙烯释放规律,探索不同肉质桃果实冷害的发生机制。结果表明:(1)硬质型桃果实的冷害症状主要表现形式是果肉发生褐变,而溶质型桃的冷害症状以果肉木质化和絮败为主。(2)相对室温贮藏而言,短时间冷藏可以抑制溶质型桃果实内源乙烯的释放,但长时间低温冷藏会导致冷害发生,刺激乙烯释放量迅猛攀升;长时间的低温贮藏也会诱导硬质型桃内源乙烯的释放;在低温贮藏期间,毛桃品种果实乙烯释放高峰会比同种肉质类型的油桃品种推迟5～10 d,毛桃相较于油桃对低温的耐受性更强。(3)溶质型桃果实采后软化迅速,但其果实硬度下降速率在低温下受到明显抑制,在冷藏后期还维持在15N上下,而硬质型桃果实硬度在低温和常温贮藏期间受影响较小。(4)不同肉质类型桃果实的可溶性固形物含量在贮藏期间变化幅度均不大。研究发现,不同肉质型桃受到冷害的症状和乙烯释放的模式均不相同,该结果为不同质地的桃果实合理低温贮藏提了供理论依据。     

Differential Suppression of Ethylene Biosynthesis and Receptor Genes in ‘Golden Delicious’ Apple by Preharvest and Postharvest 1-MCP Treatments

Harvista?, a sprayable formulation of 1-methylcyclopropene (1-MCP), has recently been developed for preharvest use on horticultural products, whereas SmartFresh? is a widely used 1-MCP treatment for products after harvest. The effects of Harvista? on apple fruit ripening when sprayed at different maturities and on expression patterns of ethylene biosynthesis and receptor genes during storage have been investigated. Harvista? applied to on-tree maturing apple fruit at an average starch pattern index of 2.5 resulted in a higher at-harvest firmness value compared with those treated at a starch pattern index of 1.5 and 3.5. This indicates that the timing of the Harvista? application is critical. An application of Harvista? led to better postharvest fruit firmness retention as well as reduced ethylene production. In addition, both preharvest and postharvest 1-MCP treatments resulted in contrasting responses in the expression patterns of two ethylene biosynthesis genes and in differentially suppressing effects on four ethylene receptor genes. Furthermore, the combined application of Harvista? + SmartFresh? resulted in greater fruit firmness retention and longer ethylene suppression. The expression profiles of these genes during on-tree fruit maturation prior to Harvista? application were also characterized. Different regulation patterns of receptor genes could contribute to differential effects by 1-MCP treatments. The potential roles of Harvista? to manipulate the ripening process as well as the molecular mechanism influencing 1-MCP treatment efficacy are discussed.     

Delay ripening of ‘Qingnai’ plum (Prunus salicina Lindl.) with 1-methylcyclopropene

‘Qingnai’ plum fruit were treated with 0, 250, 500 or 1000 nL L⁻¹ of 1-methylcyclopropene (1-MCP) for 6 h and stored at 20 °C. The fruit firmness, peel color, chlorophyll content, titratable acidity (TA), respiration rate and ethylene production, chlorophyllase, pectin methylesterase (PME) and polygalacturonase (PG) activities were monitored during postharvest ripening of ‘Qingnai’ plums. ‘Qingnai’ plums without 1-MCP treatment soften very rapidly at room temperature after harvest, showing a continuing decrease in hue angle, chlorophyll content, TA and increase in chlorophyllase, PME and PG activities during postharvest storage. In contrast, the 1-MCP-treated fruits showed reduced ethylene production and respiration rate and delayed softening, which was associated with the reduction in the activity of PME and PG. The 1-MCP treatment also significantly inhibited the chlorophyllase activity and peel color development in ‘Qingnai’ plums during postharvest ripening at 20 °C. These results suggest that 1-MCP treatment may be useful for maintaining the fruit quality and extending the postharvest shelf-life of ‘Qingnai’ plums.     

挥发性香气物质和乙烯生产在"湖景蜜露"桃果实发育过程中的变化

以"湖景蜜露"水蜜桃(Prunus persica L.)为试材,检测了果实从未成熟到成熟发育过程中乙烯生成、呼吸速率及挥发性香气性物质的变化;同时对果实大小、果皮色泽、果肉硬度、可溶性固形物、可滴定酸进行了测定;对与果实乙烯产生密切相关的1-氨基环丙烷-1-羧酸(ACC)含量、ACC合成酶活性、ACC氧化酶活性也进行了测定.结果表明,随果实成熟度的增加,果实大小、果皮L*值、可溶性固形物含量增加,而果实硬度、果皮h°值、可滴定酸含量减少.在未成熟的果实中,C6的醛类(反式-2-己烯醛)和醇类(顺式-3-己烯醇)是主要的成分;乙烯生成量很低;呼吸速率较高.到跃变阶段C6～C12的内酯类物质明显增加,尤其是γ和δ-内酯类成为果实主要的香气挥发性物质.推测果实乙烯、呼吸作用等基本的生理变化可能调节着内酯类物质的生成.在乙烯跃变上升时果肉中ACC氧化酶的活性下降,ACC含量和ACC合成酶活力的变化与乙烯生成量变化的趋势一致.根据以上结果可以认为桃果实主要的香气挥发性物质的形成与乙烯、呼吸跃变的开始密切相关.香气物质形成速率动态变化可能是桃果实发育过程中成熟度的另一个生理学指标.     

1-MCP对梨采后某些生理生化指标的影响

1.0μL·L-1 1-MCP抑制梨品种"京白"、"五九香"、"锦香"果实采后呼吸速率.随着冷藏期的延长,货架期间经1-MCP处理的果实呼吸速率逐渐上升;冷藏后货架期间1-MCP延缓果实硬度下降,梨果实的酸度、淀粉、果皮叶绿素含量得以保持,但作用大小因品种而异;1-MCP还可以抑制"锦香"梨冷藏和货架期间黑皮病的发生,防止果实腐烂.     

Responses of strawberry fruit to 1-Methylcyclopropene (1-MCP) and ethylene

1-Methylcyclopropene (1-MCP), a competitive inhibitorof ethylene action, binds to the ethylene receptor toregulate tissue responses to ethylene. In this work,we investigated the effects of 1-MCP and exogenousethylene on ripening, respiration rate, ionicconductivity and peroxidase activity in strawberryfruit. Strawberry fruit can ripen without exogenousethylene treatment, but exogenous ethylene inducessecondary ripening processes. Results indicated thatstimulation of respiration by ethylene wasdose-dependent. Fruit colour development and softeningwere slightly accelerated by ethylene, but changes insoluble solid content were not. 1-MCP may/may notaffect the respiratory rise induced by exogenousethylene dependent on fruit maturity. Cycloheximide(CHI) reduced the ethylene-induced respiratoryincrease. Combinations of 1-MCP and CHI reducedrespiration more than CHI alone. 1-MCP and CHI did notinfluence the primary respiratory change in nonethylene-treated fruit. This indicates that ethyleneinduced respiratory increase may involve an ethylenereceptor in early harvested fruit, but not in laterharvested fruit. Exogenous ethylene stimulatedrespiration by regulating new respiratory enzyme(s)synthesis in strawberry fruit. Ethylene induced anionic leakage increase, and this was positivelycorrelated to fruit water loss and peroxidaseactivity. These results suggest that non-climactericfruit, such as strawberry, may have different ethylenereceptor(s) and/or ethylene receptor(s) may havedifferent regulatory functions. It may be thesecondary effect of ethylene to stimulate respirationin strawberry. Non-climacteric fruit ripening may berelated to the development of active oxygen species(AOS) induced by postharvest stress.     

Effects of 1-MCP and exogenous ethylene on fruit ripening and antioxidants in stored mango

Mango (Mangifera indica L. cv. Tainong) fruits were harvested at the green-mature stage in Hainan and air-freighted to the laboratory at Peking. The fruits were treated with either 1 μl l⁻¹ 1-MCP or 5 μl l⁻¹ ethylene for 24 h and stored at 20°C for up to 16 days. 1-MCP maintained fruit firmness, whereas exogenous ethylene decreased fruit firmness. Exogenous ethylene accelerated the increase in ethylene and 1-aminocyclopropane-1-carboxylate (ACC) oxidase, whereas 1-MCP reduced both. Exogenous ethylene stimulated and 1-MCP inhibited the production of H₂O₂ of mango fruit during storage. Ascorbic acid was maintained at a high concentration in 1-MCP-treated fruit but was low in ethylene-treated fruit. 1-MCP inhibited activities of antioxidant enzymes including catalase, superoxide dismutase and ascorbate peroxidase. These results suggest that 1-MCP could play a positive role in regulating the activated oxygen metabolism balance. Baogang Wang and Jianhui Wang contributed equally to this work.     

Effect of 1-methylcyclopropene on postharvest physiological changes of ‘Zaohong’ plum

Plum is a highly perishable fruit and postharvest fruit softening limits its shelf life. The aim of this work was to study the specific effects of 1-methylcyclopropene (1-MCP) treatment on physiological changes in ‘Zaohong’ plums. Plums were treated with 500 nL L⁻¹ 1-MCP at 20°C for 18 h followed by 20°C storage. The results showed that 1-MCP treatment significantly reduced endogenous ethylene production and the activities of ethylene biosynthetic enzymes’ (1-aminocyclopropane-1-carboxylic acid synthase, ACS and 1-aminocyclopropane-1-carboxylic acid oxidase, ACO) in plum fruit during storage when compared with untreated fruit. Although 1-MCP treatment inhibited ethylene production and 1-aminocyclopropane-1-carboxylic acid (ACC) accumulation, it did not inhibit the accumulation of N-malonyl-ACC (MACC). Higher firmness was also found in 1-MCP-treated plums than in controls. During storage, superoxide anion (O₂^−·) and hydrogen peroxide (H₂O₂) levels decreased in 1-MCP-treated fruit. 1-MCP treatment also regulated superoxide dismutase (SOD) and catalase (CAT) activities during storage. Xylanase activity was upregulated while activities of polygalacturonase (PG), pectin methyl esterase (PME) and cellulase enzymes in the fruit were downregulated by 1-MCP treatment. In conclusion, 1-MCP might be a potent compound for extending both storage period and shelf life of ‘Zaohong’ plums by suppressing ethylene biosynthesis, regulating cell wall degradation enzymes and reducing fruit softening.