NO处理延缓采后枇杷果实木质化劣变及其与能量代谢的关系

【目的】枇杷果实采后生命活动旺盛,衰老速度快,常温下极易变质腐烂。低温贮藏虽然可以有效延长贮藏期,减少腐烂,但会出现果皮难以剥离、果肉木质化并褐变、质地糙硬少汁等品质劣变现象,这是造成冷藏枇杷商品性丧失和损失的主要原因,已成为其市场拓展的限制因素,是当前枇杷果实在冷链集散和流通中急需解决的关键问题。探讨外源NO处理对冷藏枇杷果肉木质化劣变进程的作用机制,并分析木质化劣变与能量代谢的关系,以期为进一步研究采后枇杷果实低温品质劣变进程调控的分子生物学机理和贮运保鲜技术奠定基础。【方法】将‘解放钟’枇杷（Eriobotrya japonica Lindl.）果实在密闭容器中用0（对照组）、15和25 μL•L-1 NO熏蒸2 h后,取出通风20 min,然后将各处理果实置于5℃、相对湿度85%条件下贮藏,测定冷藏期间各处理组果实细胞膜透性、硬度、出汁率、木质素含量、ATP含量、ADP含量、AMP含量、能荷值及琥珀酸脱氢酶（SDH）、细胞色素氧化酶（CCO）、H+-ATPase和Ca2+-ATPase活性的变化,并分析NO处理后木质素含量与能荷值间的相关性。【结果】随着贮藏时间的延长,枇杷果实细胞膜透性和硬度逐渐上升,出汁率逐渐下降,贮藏10 d后木质素含量迅速上升,果实冷害症状明显。与对照组相比, NO处理能延缓细胞膜透性和硬度的上升及出汁率的降低,显著抑制木质素的合成,较好地保持细胞膜的完整性,从而减轻果实冷害的发生。冷藏期间,枇杷果实ATP含量逐渐下降,贮藏前10 d ADP含量迅速下降并最终维持在较低水平,贮藏中后期（15-30 d）SDH、CCO、H+-ATPase和Ca2+-ATPase活性急剧下降,表明线粒体功能受损导致枇杷果实能荷水平迅速下降。与对照组相比,NO处理可以延缓ATP、ADP含量的下降,且显著抑制贮藏中后期SDH、CCO、H+-ATPase和Ca2+-ATPase活性的降低,保持枇杷果实较好的线粒体功能;贮藏30 d后,15 和25 μL•L-1 NO处理的枇杷果实能荷值分别比对照组高11.8%和12.9%。相关性分析表明,15和25 μL•L-1 NO处理的枇杷果实能荷值和木质素含量呈极显著负相关,相关系数（r）分别为 -0.715**、-0.598**。【结论】低温条件下,能量代谢失调与枇杷果实木质化劣变密切相关,NO处理可以通过调节SDH、CCO、H+-ATPase、Ca2+-ATPase线粒体代谢相关酶活性,维持较高的能量水平,从而有效地提高冷藏枇杷果实抗低温的能力,进而延缓果实木质化进程,其中以25 μL•L-1 NO处理效果较好。     

1-MCP延长翠冠梨果实的货架期

以翠冠梨为试材,研究室温条件下1-甲基环丙烯(1-MCP)处理对延长果实货架期的效果。结果表明,1-MCP处理可以延缓果实硬度的下降,降低果实的呼吸速率,推迟乙烯峰的出现并降低峰值,维持果实较高的可溶性固形物(TSS)和可滴定酸(TA)含量,1-MCP处理还可以明显抑制梨黑皮病的发生,从而保持较高的好果率。因此,1-MCP处理能较好地保持果实在贮藏期间的品质和风味,使翠冠梨的货架期延长10 d左右。     

1-MCP处理对不同预熟南果梨贮后生理及货架品质的影响

［目的］ 研究1-MCP处理对贮前不同预熟度南果梨贮后生理及货架品质变化规律的影响。 ［方法］以南果梨为试材,采收后用10 μl/L 1-MCP在室温（20～25 ℃）下处理18 h,将经1-MCP处理过的果实贮前分别进行0、5、10 d的预熟处理,研究1-MCP处理对冷藏后货架期间的不同预熟度南果梨生理和贮藏品质变化规律的影响。［结果］ 1-MCP处理显著地降低了南果梨果实呼吸强度与内源乙烯生成量,抑制果实硬度的下降,延缓了果皮转色,有利于果柄保鲜,抵制果实腐烂率、果心褐变的发生, 还明显地延长果实贮后货架期。1-MCP处理对贮前预熟5 d处理的果实各项指标均好于预熟10 d处理的果实。［结论］ 采用1-MCP处理南果梨果实,贮前预熟5 d的果实适于长期贮藏;贮前预熟10 d的果实适宜中短期贮藏。     

1-MCP对库尔勒香梨采后活性氧相关代谢的影响

[目的]研究1-甲基环丙烯(1-Methylcyclopropene,1-MCP)处理延缓库尔勒香梨采后衰老的机理,为香梨保鲜提供理论依据.[方法]以库尔勒香梨(Pyrus sinkiangensis Yu)为试材,研究1-甲基环丙烯处理对香梨果实贮藏期间活性氧代谢相关酶活性、超氧阴离子(O2·-)、丙二醛(MDA)、果皮色调角(h°)的影响.[结果]贮藏前期,1-MCP处理抑制了香梨果实超氧化物歧化酶(SOD)、过氧化物酶(POD)的活性,后期提高了POD的活性.整个贮藏期过氧化氢酶(CAT)活性低于对照;1-MCP处理果实丙二醛(MDA)含量低于对照果实;1-MCP处理在贮藏前期抑制超氧阴离子的产生,保持了较高的果实色调角.[结论]1-甲基环丙烯处理能够有效降低香梨活性氧产生速率,延缓果实衰老.     

采前喷施茉莉酸甲酯对火龙果采后品质和生理特性的影响

【目的】分析采前喷施茉莉酸甲酯（MeJA）对火龙果采收品质、耐贮性及生理特性的影响,为生产上应用MeJA提升火龙果采收品质和耐贮性提供技术支持。【方法】以紫红龙火龙果为试验材料,采用5种质量浓度（0、50、100、200和400μmol/L）的MeJA采前8 d喷施火龙果,调查采收时产量、单果重、一级果率、商品果率和病果率,观察比较采后腐烂时间和腐烂率变化,测定对照（0μmol/L）和最佳处理贮藏过程中品质和生理特性的变化。【结果】采前喷施MeJA对火龙果公顷产量和单果重无显著影响（P>0.05）,但采前喷施100μmol/L MeJA处理能明显提升火龙果采收时的商品性,其一级果率和商品果率分别较对照显著提高52.37%和104.38%（P<0.05,下同）,病果率较对照降低49.47%。常温贮藏期间采前喷施100μmol/L MeJA处理较对照延迟1 d出现腐烂现象,且腐烂率始终低于对照;维持贮藏期间较高的可溶性固形物、可溶性糖和可滴定酸等内在品质;显著提升贮藏期间果皮多酚含量和总抗氧化能力,以及多酚氧化酶（PPO）、过氧化物酶（POD）、β-1,3-葡聚糖酶（GLU）、几丁质酶（CHT）和苯丙氨酸解氨酶（PAL）活性,酶活性最大差值发生在果实开始腐烂前后,PPO、POD和CHT活性于贮藏第6 d差值最大,其酶活性分别较对照提高33.13%、140.38%和207.16%,PAL和GLU活性于贮藏第9 d差值最大,其酶活性分别较对照提高83.38%和25.29%。【结论】采前喷施适宜浓度的MeJA可减少生育期火龙果的感病率,提升商品果率,维持贮藏品质,提高贮藏期间的抗氧化能力和抗病能力,从而延缓果实衰老和控制贮藏期间腐烂的发生,延长贮藏期,以100μmol/L的处理效果最佳。     

茉莉酸甲酯对红地球葡萄采后贮藏品质和病害的影响

[目的]研究茉莉酸甲酯(MeJA)浸泡处理对葡萄采后病害的控制及贮藏品质的影响.[方法]以新疆红地球葡萄为试材,采用50、100和200μmol/L茉莉酸甲酯(methyl jasmonate,MeJA)室温(25℃)浸泡处理葡萄,(0±1)℃贮藏,每隔10 d测定果实硬度、可溶性固形物含量、可滴定酸含量及腐烂率的变化...     

Effects of 1-methylcyclopropene and modified atmosphere packaging on fruit quality and superficial scald in Yali pears during storage

The Yali pear(Pyrus bretschneideri Rehd.) is susceptible to superficial scald during prolonged cold storage and at shelf life. This study investigated the effects of 1-methylcyclopropene(1-MCP) and modified atmosphere packaging(MAP) on changes of fruit quality and superficial scald during cold storage and at shelf life in Yali pear. Compared with MAP, the combination of MAP and 1-MCP(MAP+1-MCP) treatment reduced the carbon dioxide and ethylene content inside the packaging bag. The 1-MCP, MAP, and MAP+1-MCP treatments reduced the superficial scald index, malondialdehyde content, O_2~-· production rate and relative conductivity and inhibited the accumulation of α-farnesene and conjugated trienes in the peel. 1-MCP and MAP+1-MCP treatments maintained a higher phenolic content and enhanced the catalase and superoxide dismutase activities in the fruit, while reduced activities of lipoxygenase and polyphenol oxidase in the peel preceding the onset of superficial scald. Comprehensive analysis indicated that the MAP+1-MCP treatment is the most effective method tested for improving the quality of Yali pears during cold storage and at shelf life.     

Optimal storage temperature and 1-MCP treatment combinations for different marketing times of Korla Xiang pears

Maintenance of green color is the primary indicator of quality in the market evaluation of Korla Xiang pears at present and can generally be achieved through early harvesting and decreasing the storage temperature, but the fruit quality was reduced by early harvesting, and the decreasing storage temperature increased the risk of chilling injury. The objectives of this study were to determine the optimal storage parameters for different storage times and to find ways to preserve the green skin color of pears. Specifically, we analyzed the effects of the ethylene inhibitor, 1-methylcyclopropene(1-MCP), combined with low temperature on quality and maintenance of the green color of Korla Xiang pears during storage. We found that 1-MCP and/or low temperature reduced the loss of green color at 20°C after being removed from cold storage. In addition, 1-MCP significantly inhibited the decline of titratable acid and ascorbic acid but had no significant effect on fruit firmness and total soluble solids. Low temperature with or without 1-MCP inhibited the release of ethylene, inhibited the decline in the stalk preservation index, inhibited the increase in decay rate and weight loss rate during storage, and inhibited the increase in the core browning index after 225 days of storage. Different storage temperatures had different effects on the quality of Korla Xiang pears. Despite inhibiting ethylene release, a storage temperature of –1.5°C increased the respiration rate. Storage at –1.5°C caused core browning early during storage due to chilling injury, whereas at 2°C core browning occurred late during storage due to senescence. In late storage, 1-MCP had no significant effect on the maintenance of Korla Xiang pear quality at 2°C. Based on these results, we determined the optimal combinations of low temperature and 1-MCP treatment to maintain pear quality while avoiding chilling injury. For different marketing times, the optimal conditions for storage until New Year's Day(a storage duration of 90 days) are 2°C or 1-MCP combined with 2°C. For storage until the Spring Festival(a storage duration of 150 days), the optimal conditions are 0°C or 1-MCP combined with 0°C, and for storage until May(a storage duration of 225 days), the best conditions are 1-MCP combined with –1.5°C.     

Methyl Jasmonate Reduces Chilling Injury and Maintains Postharvest Quality in Peaches

Zhaohui peaches (Prunus persica Batsch) were treated with 0 (CK), 1, 10 or 100 μmol L-1methyl jasmonate (MeJA) vapor at 20℃ for 24 h before stored at 0℃ for 35 d. The untreated fruits showed chilling injury (CI) symptoms after 4 wk of storage, as indicated by increased fruit firmness and reduced extractable juice, which is referred as leatheriness. Treatment with 1 and 10 μmol L-1 MeJA promoted normal ripening and softening, maintained higher levels of extractable juice, titratable acidity, pectinesterase (PE)and polygalacturonase (PG) activities, inhibited increases in fruit fresh weight loss, decay incidence, electrolyte leakage and MDA content, and improved color development, thereby preventing chilling injury symptoms development and maintaining edible quality. MeJA treatment also delayed the climacteric rise in respiratory rate, but promoted ethylene production during the later period of cold storage, suggesting that ethylene may involve in CI development of peaches. These results indicate that 1 and 10 μmol L-1 MeJA treatments could be used to reduce CI development and decay incidence in peaches.     

温度对余甘子采后贮藏期间感官及营养品质的影响

[目的]探讨贮藏温度对余甘子果实采后贮藏期间感官及营养品质的影响,为其贮藏保鲜提供理论依据.[方法]将余甘子果实分别置于5、10、15℃及室温条件下贮藏,测定果实的失重率、好果率及可溶性固形物、维生素C（Vc）、蛋白质和有机酸含量.[结果]贮藏温度对余甘子果实贮藏期间感官及营养品质影响的优劣表现顺序为：5℃＞10℃＞15℃＞室温;余甘子果实贮藏至12d,其水分、可溶性固形物、Vc、蛋白质和有机酸损失均以5℃贮藏的最小;5℃贮藏能使余甘子果实贮藏期延长6～9 d.[结论]低温贮藏能有效延缓采后余甘子果实感官及营养品质的下降,延长贮藏期,且以5℃贮藏保鲜效果最佳.     

精确定量施肥技术对丰水梨品质和贮藏特性的影响

以丰水梨(Hosui)为试材,采用常规施肥+叶面喷水、常规施肥+叶面施肥和精确定量施肥3种施肥方法,在室温贮藏和1-MCP(1-甲基环丙烯)处理条件下,对其生理和品质的变化进行了研究。结果表明,室温贮藏条件下,3种不同施肥方式的丰水梨果实在贮藏过程中都出现呼吸高峰,呈现跃变型果实的特征,常规施肥的果实最先到达呼吸高峰,且峰值最高;果实可溶性固形物(TSS)含量表现出先升高后下降的趋势。精确施肥的果实在贮藏期间乙烯高峰出现时间晚,失水率低,能保持相对较高的硬度和TSS含量。室温条件下1-MCP处理12 h后,可以明显延缓果实硬度和果实失水率的下降,推迟乙烯高峰的出现,并阻碍TSS的增加速率,从而较好地保持果实在贮藏期间的品质和风味。     

褪黑素处理对梨果实采后黑斑病及贮藏品质的影响

【目的】 探究褪黑素（Melatonine,MT）处理对梨果实采后黑斑病及贮藏品质的影响,为外源物质调控果实抗采后病害及贮藏品质提供理论依据和参考。【方法】 以‘翠冠’梨果实为试验材料,喷施0.1 mmol·L^-1 MT溶液置室温,48 h后沿梨果实赤道两侧刺直径1 mm、深度3 mm大小两个小孔,待伤口晾干后注入20 µL浓度为1.0×10⁶ spores/mL黑斑病菌（Alternaria alternata）孢子悬浮液,以无菌水处理作为对照。接种后果实置于25℃,分析梨果实病斑直径、诱导效果及过氧化氢酶（PpCAT）、过氧化物酶（PpPOD）、多酚氧化酶（PpPPO）、铜-锌超氧化物歧化酶（Cu-ZnSOD）等防御酶相关基因和几丁质酶（PpCHI）、β-1, 3葡聚糖酶（PpGLU）等病程相关基因的表达量,研究MT诱导梨果实抗黑斑病的效应和机理。此外,梨果实喷施0.1 mmol·L^-1 MT溶液晾干后于（5±1）℃、相对湿度85%—90%贮藏42 d,以无菌水处理为对照,定期测定果实腐烂率、失重率、呼吸强度、硬度、可溶性固形物、可滴定酸、维生素C、总酚和丙二醛含量,从而探讨MT处理对梨果实贮藏效果和品质的影响。【结果】 梨果实接种A. alternata后,病斑直径随接种时间延长而逐渐增大,MT处理组果实病斑直径显著小于对照组（P<0.05）,接种后第3、5和7天,MT对梨果实抗黑斑病的诱导效应分别为29.16%、45.03%和23.26%;梨果实PpCAT、PpPOD、PpPPO、Cu-ZnSOD、PpCHI和PpGLU相对表达量在接种后第4—7天均显著高于对照,最大值分别为对照的1.35、2.08、2.28、2.02、2.89和3.45倍,其中PpPOD、PpPPO和PpCHI在接种后第1—6天表达量持续上升,且MT处理可显著提高表达量,表明MT处理诱导梨果实抗黑斑病可能与其提高防御酶基因和病程相关蛋白基因表达密切相关。在低温贮藏期间,MT处理组果实腐烂率与对照组差异不显著,或因病原菌在低温下生长受到抑制,果实腐烂降低;梨果实硬度在贮藏期内逐渐下降,但MT处理组果实硬度均高于对照组,在28 d时差异显著,MT处理组为对照组的1.06倍;梨果实呼吸强度在贮藏前期（7—14 d）上升后下降,但与对照组相比,MT处理抑制果实呼吸强度,延缓果实衰老的效果在贮藏前期较后期更明显;此外,MT处理也可显著降低果实失重率,维持较高水平的可溶性固形物,延缓可滴定酸和维生素C降解,同时促进果实总酚含量积累,增强果实抗氧化能力,抑制MDA含量积累,减轻细胞膜脂过氧化伤害。以上结果揭示MT可能通过调节梨果实糖、酸和细胞壁代谢,从而增强果实品质与耐贮性。【结论】 0.1 mmol·L^-1 MT处理诱导了梨果实对采后黑斑病的抗性,激发了果实防御酶和病程相关蛋白基因的表达,且能显著提高梨果实贮藏品质。     

Pre-harvest spraying of oxalic acid improves postharvest quality associated with increase in ascorbic acid and regulation of ethanol fermentation in kiwifruit cv. Bruno during storage

The kiwifruit trees (Actinidia deliciosa cv. Bruno) were sprayed with 5 mmol L^–1 oxalic acid (OA) or water (as control) at 130, 137 or 144 d after full-blossom, and then the fruit were harvested at commercial maturity and stored at room temperature (20±1)°C for 13 d. The effect of pre-harvest spraying of OA on postharvest quality of kiwifruit was evaluated during storage. The OA spraying slowed the increase in soluble solids content (SSC) and decrease in titratable acid (TA), as well as increased contents of ascorbic acid (AsA) and total-AsA accompanied with higher AsA/DHA ratio in kiwifruit during storage. Moreover, the OA spraying significantly reduced the contents of acetaldehyde and ethanol in kiwifruit, along with significant decrease in activities of enzymes involved in ethanol fermentation metabolism during the later period of storage, which was beneficial to control off-flavor associated with over accumulation of ethanol during postharvest. It was suggested that pre-harvest spraying of OA might maintain the postharvest quality of kiwifruit in relation to delay in fruit ripening, AsA maintenance and regulation of ethanol fermentation.     

茉莉酸甲酯对‘克瑞森无核’葡萄果实着色及品质的影响

研究不同浓度茉莉酸甲酯(MeJA)对吐鲁番地区‘克瑞森无核’葡萄果实着色及品质的影响,为合理利用茉莉酸甲酯改善‘克瑞森无核’葡萄果实着色及品质提供参考。以吐鲁番地区‘克瑞森无核’葡萄为试材,于果实着色前和着色初期分别使用不同浓度(20、60、100 mg/L)茉莉酸甲酯喷施果穗2次。采收期测定果实色泽和品质指标,分析不同处理下指标间差异,并通过隶属函数法对果实色泽指标和品质指标进行综合评价,以确定最适宜的施用浓度。结果表明,着色前和着色初期用茉莉酸甲酯处理‘克瑞森无核’葡萄,能够显著提高果皮中花色苷含量、降低叶绿素含量,进而显著提高果实着色指数;处理后的果实红绿色差指标a值、彩度指标C值显著增大,而果面亮度指标L值和黄绿色差指标b值显著降低,果面色泽显著改善;茉莉酸甲酯处理能够显著增大果粒纵径、横径,减小果形指数,增大果粒质量和果穗质量,同时显著增大果梗粗度、可溶性固形物含量、可滴定酸含量。浓度过高会造成果梗耐拉力减小,耐贮运性能下降,可滴定酸含量过高,花色苷含量增幅不大、着色指数不高;而低浓度处理容易出现果粒萎蔫现象。选取与‘克瑞森无核’葡萄果实品质密切相关的15个指标,运用隶属函数法对4个处理的果实品质进行综合评价,果实品质优劣顺序为60 mg/L> 20 mg/L> 100 mg/L> CK。综上,吐鲁番地区于果实着色前和着色初期使用浓度为60 mg/L的茉莉酸甲酯喷施‘克瑞森无核’葡萄果穗2次,可显著改善果实着色,提高果实品质。     

干制骏枣在不同温度贮藏中品质和生理变化的研究

以阿克苏验枣（干枣）为试验材料经0.08mm PE袋密封包装后贮藏于常温和低温（5℃）条件下研究分析干制验枣呼吸强度、乙烯释放量、总酸含量、总糖含量、维生素C含量、水分含量及可溶性固形物含量的变化情况,结果表明与常温处理相比低温（5℃）贮藏能抑制干制验枣的乙烯释放影响枣果的呼吸强度;减缓维生素C含量的下降;较好的保留了枣果中的水分含量;延缓了干制验枣的生理代谢活动延长了贮藏期限保证了干制验枣的品质.     

Inhibitory Effects of 1-MCP and DPA on Superficial Scald of Dangshansuli Pear

Dangshansuli pear is one of crisp pears and has a non-climacteric respiratory pattern.Dangshansuli pear fruits were treated with 1 000 or 2 000 μL L-1 diphenylamine (DPA) for 1 min,or with 0.5 μL L-1 1-methylcyclopropene (1-MCP) for 12 h before cold storage at (2±0.5)℃ for up to 210 d.Incidences of superficial scald and related physiological indexes were investigated during storage.The results showed that superficial scald occurred in control fruit with a rate of over 90％ after 210 d at cold storage plus 10 d at room temperature.Treatments with 1 000 and 2000 μL L-1 DPA and 0.5 μL L-1 1-MCP inhibited the accumulation of αt-farnesene,conjugated trienes,total phenolic contents,and malondialdehyde (MDA) during storage.The treatments also decreased leakage of cell membrane and the activity of polyphenol oxidase (PPO) in the peel.These results indicate that I-MCP and DPA treatments inhibit and postpone the occurrence of superficial scald of Dangshansuli pears remarkably in cold storage and post-storage shelf life,respectively,while the mechanisms were different.The results above may provide a theoretical evidence for the agriculture production.     

Changes of Reactive Oxygen Species and Related Enzymes in Mitochondria Respiratory Metabolism During the Ripening of Peach Fruit

The fruits of peach cultivar Yuhua 3 were used as materials to investigate the changes of active oxygen and related enzymes in mitochondria respiratory metabolism during ripening of peach fruit, involving their influence on the proceeding of peach fruit senescence. The results showed that the large decrease in firmness occurred between maturity II and IV. The decrease in firmness coincided with an increase in respiratory intensity. Obvious peaks of respiratory intensity lagging to the rapid change of fruit firmness could be shown during peach ripening. Reactive oxygen species （ROS） had a cumulative process and positively correlated with respiratory intensity. During peach ripening, the content of Ca^2＋ increased, the activities of succinic dehydrogenase （SDH）, cytochrome C oxidase （CCO）, H＋-ATPase, and Ca^2＋-ATPase decreased varying in different degree at the later step of ripening. These suggested a close relationship existed between ROS metabolism and mitochondrial respiration, namely, both ROS metabolism and mitochondrial respiration probably played important roles in ripening and senescing of peach fruit.     

室温和低温贮藏沙田柚果实的有机酸含量变化

【目的】研究沙田柚果实贮藏过程中的有机酸代谢及变化规律,为采后沙田柚品质保持及贮藏方式选择提供参考依据。【方法】采用高效液相色谱仪测定室温和4℃低温贮藏1~75 d沙田柚果实的柠檬酸、苹果酸、草酸、酒石酸、琥珀酸、乌头酸和延胡索酸含量。【结果】沙田柚果实的有机酸中,以柠檬酸含量最高,苹果酸含量次之,草酸、酒石酸及琥珀酸含量较低,乌头酸和延胡索酸含量为微量。室温贮藏条件下,沙田柚果实的柠檬酸含量在贮藏前期略有下降,贮藏15 d开始上升,贮藏60 d后下降;琥珀酸、乌头酸和延胡索酸含量变化趋势与柠檬酸基本相同,但出现峰值时间不同;苹果酸含量变化趋势与柠檬酸相反;草酸含量在贮藏前期上升,后期下降;酒石酸含量在贮藏前期略有下降,然后上升,60 d后下降。低温贮藏条件下,沙田柚果实的有机酸含量变化趋势与室温贮藏基本一致,但柠檬酸、草酸和延胡索酸含量低于室温贮藏,苹果酸和琥珀酸含量高于室温贮藏。【结论】沙田柚果实贮藏过程中有机酸含量变化受贮藏温度影响较小,室温贮藏沙田柚果实的总有机酸含量能维持在较高水平波动,对果实品质无明显影响。     

壳聚糖复合涂膜保鲜剂对南果梨的保鲜作用

以南果梨为试材,研究壳聚糖复合涂膜处理对不同预熟度的果实在冷藏条件下贮藏效果及其生理变化,以及冷藏后常温货架期间果实表观品质的影响。结果表明:在冷藏条件下壳聚糖复合涂膜处理可以明显抑制南果梨果实的脂氧合酶活性、丙二醛含量,延缓可溶性固形物含量、叶绿素含量和果实硬度的变化进程。用稀释一倍的壳聚糖复合涂膜保鲜剂处理可以有效的抑制冷藏后南果梨在常温货架期间果皮的褐变。     

Effects of harvesting time on fruit quality and internal browning of ��Wonhuwang�� pear during cold storage

Average fruit weight, seed browning, flesh firmness, total soluble solids, internal browning, and skin blackening were used to determine the optimum harvesting time of ‘Wonhuwang’ pear. Pears for storage were picked three times at 5-day intervals before, during, and after estimated optimum harvesting date. Average fruit weight and seed browning degree were calculated at each picking time. Quality changes, internal browning, and skin blackening were employed to estimate the optimum harvest date. It was found that fruit quality parameters both at harvest and after storage depended on the stage of ripeness at which the pears were picked. Pears harvested earliest (H1) had the highest firmness both before and after storage and lost less percentage of their firmness during storage. The latest picked pears (H3) showed higher total soluble solids value and serious internal browning and skin blackening due to their over ripeness. Pears picked on the 15th of August (H2) had higher firmness and total soluble solids, lower extent of internal browning, and no skin blackening. Based on the changes in fruit firmness and physiologic disorder during ripening and storage, the optimal harvesting time for ‘Wonhuwang’ pear in Shijiazhuang area is around the 15th of August.