外源乙烯对CA贮藏桃果实品质变化的影响

以"八月脆"桃果实为材料,研究了不同浓度外源乙烯(10～20、50～80μl/L)处理对桃果实气调贮藏(9%～11%CO2 9%～11%O2)期间及其回温3d后品质变化的影响.结果表明,外源乙烯处理可使贮藏后期桃果实及其回温果实正常软化,而未加乙烯处理的气调和冷藏对照处理果实在贮藏45d以后出现硬度升高,失去了后熟软化能力;外源乙烯处理使贮藏后期桃果实及其回温果实膜透性增加;外源乙烯处理使贮藏中后期桃果实总糖含量增加,但回温后桃果实总糖含量没有明显升高;外源乙烯处理加快了贮藏中期桃果实可滴定酸含量的下降,但可缓解回温桃果实可滴定酸的迅速下降.外源乙烯对气调贮藏桃果实各品质指标的影响主要表现在贮藏中后期.综合考虑不同浓度外源乙烯处理对桃果实各品质指标的影响,认为50～80μl/L外源乙烯处理对贮藏中后期桃果实的后熟及维持其品质有较好的作用.     

不同解冻方式对软儿梨果实品质与抗氧化物质含量的影响

冷冻和解冻是产区消费者传统上消费软儿梨的两个必要步骤,外源乙烯可以加速呼吸跃变型果实的后熟进 程。本实验以自然后熟和乙烯利催熟的软儿梨为材料,研究了传统的空气解冻和水浴解冻对解冻后果实品质和酚类 物质含量的影响。结果表明：对于自然后熟的软儿梨,空气解冻组果实的可滴定酸含量、可溶性固形物含量、固酸 比均显著高于水浴解冻组;同时使自然后熟组果实保留了更多的VC,降低了石细胞含量。空气解冻较水浴解冻降 低了乙烯利处理组果实的可滴定酸和可溶性固形物含量,但对其固酸比、VC和石细胞含量无显著影响。空气解冻 和水浴解冻均对自然后熟组果实的总酚含量无显著影响,但乙烯利处理组果实的总酚含量上升;两种解冻方式对几 种主要酚类物质的影响表现各异,但相似的是解冻后果实均不能测出绿原酸和阿魏酸。不同解冻方式对果实不同的 抗氧化指标影响各异,但从抗氧化能力综合指数来评价,不同工艺点的果实抗氧化能力依次为：水浴解冻＞空气解 冻＞后熟,在后熟和解冻中均为：乙烯利处理组果实＞自然后熟组果实。     

不同发育阶段欧李果实糖酸变化规律研究及相关性分析

目的:研究欧李果实中糖酸特点及在不同发育阶段的含量动态变化,探讨欧李果实糖酸积累规律以及不同种类糖酸间的相关性。方法:以京欧1号、京欧2号和京欧3号欧李品种为材料,用高效液相色谱法测定欧李果实在不同发育期蔗糖、葡萄糖、果糖、山梨糖醇、苹果酸、柠檬酸、琥珀酸、酒石酸和草酸含量。结果:欧李果实总糖和总酸含量高低顺序均为京欧3号京欧1号京欧2号。欧李果实总糖含量在坐果后着色期内增长趋势缓慢,果实发育后期总糖含量迅速增长,总酸含量随着果实成熟逐渐升高,京欧1号和京欧2号果实中总酸含量在完熟前一周略有下降,总糖含量的变化速率大于总酸含量变化速率。蔗糖、葡萄糖和果糖在绿熟期和着色期增长趋势缓慢,商熟期各种糖含量迅速增长,果实完熟时达到最高点,苹果酸含量整体呈上升趋势,在果实完熟前一周下降,而柠檬酸、草酸和琥珀酸随着果实的成熟含量降低。欧李果实中糖酸比与蔗糖含量正相关性最强,与草酸含量负相关性最强,糖酸比随坐果后天数呈显著指数函数y=0.05e(0.04x)变化趋势。结论:蔗糖与苹果酸的含量是影响欧李果实风味的主要因素,果实商熟期到果实完熟期是欧李果实生长、糖酸积累的关键时期。     

采后乙烯利处理对软儿梨果实后熟期生理及品质的影响

以软儿梨为试材,研究了1 mL/L乙烯利处理对(20±3)℃、相对湿度85%~90%条件下贮藏的采后软儿梨果实后熟期生理和品质指标的影响。结果表明:采后乙烯利处理软儿梨果实能够提高果实乙烯释放量并使其呼吸高峰提前2 d出现,加速了果实的后熟;在后熟第16天时,乙烯利处理组果实的质量损失率(5.4%)显著低于对照组果实(6.1%)(P0.05),提升了果实的色泽,但就整个后熟过程而言,对果实的硬度、还原糖、可滴定酸和石细胞含量无显著性影响(P0.05)。     

气调贮藏对芒果保鲜效果的研究

本实验研究了不同CO2浓度条件下贮藏的芒果成熟度、可溶性蛋白质含量、可溶性总糖的含量、乙烯及相对失重的变化,结果表明可溶性蛋白和可溶性糖含量的变化不同,且高浓度CO2能延缓果实成熟,降低果实乙烯生成量,推迟乙烯峰的出现,但对相对失重的影响无显著性差异。     

气调保鲜袋和乙烯脱除剂对冰温贮藏桃品质的影响

在冰温贮藏的基础上,研究气调保鲜袋及乙烯添加剂在冰温贮藏条件下对桃果实品质的影响。实验结果表明,冰温条件下采用气调保鲜袋可降低桃的腐烂指数,增加VC和可滴定酸的含量。添加乙烯脱除剂可推迟桃果实的后熟衰败,减少桃果实在贮藏期内的腐烂,但是它抑制了总糖的合成和胞壁物质的降解,使果实口感变淡,果实在后期不能正常软化。     

1-甲基环丙烯对香蕉食用品质变化的影响

1－甲基环丙烯（MCP）能与果蔬组织中的乙烯受体发生不可逆性的结合，因而阻断乙烯与受体的结合而抑制乙烯的催熟作用。已有研究证实MCP可以显著延迟香蕉果实软化，但缺乏了解MCP对综合食用品质变化影响。本结果表明：MCP处理显著地降低了香蕉肉中可溶性糖和可滴定酸含量的上升速率，延缓了原果胶及淀粉含量的下降，MCP能延缓香蕉果实的后熟进程，但并不会降低香蕉的综合食用品质。     

低温预贮对猕猴桃果实糖代谢的影响

目的：研究低温预贮结合外源乙烯催熟对采后猕猴桃果实糖代谢的影响。方法：将猕猴桃在0,4,8,12℃4个温度下分别放置3,5,7 d后,在室温(25℃)采用乙烯催熟,以其为对照,分别测定12个不同处理组以及对照组猕猴桃果实中可溶性糖含量、单糖含量(葡萄糖、果糖、蔗糖)、淀粉含量、关键糖代谢酶活性和淀粉酶活性。结果：低温预贮能够提高后熟猕猴桃中可溶性糖的含量,保持较高的淀粉酶活性;同时,低温预贮能加快淀粉降解速率,有效维持中性转化酶与蔗糖磷酸合成酶活性,而对果实的酸性转化酶与蔗糖合成酶活性无显著影响。通过主成分分析及聚类分析分析发现低温预贮对后熟猕猴桃糖代谢影响的最佳预贮条件是4℃下预贮7 d。结论：低温预贮可调控采后猕猴桃糖代谢相关酶活性,从而使其在后熟过程中保持较高的可溶性糖含量和营养价值。     

温度和乙烯对京白梨后熟进程及其品质的影响

研究温度、乙烯对京白梨果实后熟进程及品质的影响。测定果实乙烯释放量、呼吸强度、果实硬度、可溶性固形物含量、pH值、果皮颜色ΔE 值和h 值、失重率、病果率等指标,并进行感官评价。结果表明：温度和乙烯直接影响果实的后熟进程和后熟品质;后熟过程中果实硬度与后熟时间呈极显著线性负相关(P＜ 0.01),温度过高或过低均导致果皮转色和果实硬度后熟不一致,适度的低温(14℃)延迟了果实乙烯峰值的启动时间,高温(28℃)抑制乙烯的生成和果实的软化,温度越高,失重率和烂果率越高;外源乙烯有助于果实乙烯的生成和呼吸强度的增加,乙烯加快了果实的后熟进程,并且后熟更均匀一致,且品质最佳。研究表明：京白梨后熟的适宜温度范围17～23℃,最佳温度20℃,最佳乙烯催熟用量为100μL/L。     

1-MCP处理对蓝莓常温货架品质变化的影响

研究不同剂量1-甲基环丙烯(1-MCP)处理对采后蓝莓果实常温货架期品质变化的影响。结果表明：蓝莓果实在采后常温货架期间,还原糖含量不断上升,可滴定酸含量及可溶性固形物含量均不断下降。随着果实生理代谢进程,果实硬度逐渐降低,直至果肉软化,品质劣变。1-MCP处理明显抑制果实呼吸强度和乙烯的生成,延缓果实还原糖含量及细胞膜透性的升高和硬度、可溶性固形物、可滴定酸、总酚含量的下降,有效减少膜脂过氧化物的产生,极显著抑制果实的腐烂,保持了果实的采后品质。综合分析各项指标,1.0μL/L 1-MCP处理的保鲜效果好于0.5μL/L 1-MCP处理。相关分析结果表明,蓝莓果实腐烂率与呼吸强度、乙烯生成量、色调角呈极显著正相关,与果实硬度、总酚含量、可溶性固形物含量呈极显著负相关,与其他指标相关性不显著。果实硬度与可溶性固形物含量呈显著正相关,与果实呼吸强度、乙烯生成量、色调角呈显著负相关。     

Effect of ethylene and 1‐MCP treatments on strawberry fruit ripening

BACKGROUND: Strawberry is a soft fruit, considered as non‐climacteric, being auxins the main hormones that regulate the ripening process. The role of ethylene in strawberry ripening is currently unclear and several studies have considered a revision of the possible role of this hormone. RESULTS: Strawberry fruit were harvested at the white stage and treated with ethephon, an ethylene‐releasing reagent, or 1‐methylcyclopropene (1‐MCP), a competitive inhibitor of ethylene action. The effects of the treatments on fruit quality parameters and on the activity of enzymes related to anthocyanin synthesis and cell wall degradation were evaluated. Some aspects of ripening were accelerated (anthocyanin accumulation, total sugar content and increment of phenylalanine ammonia‐lyase (PAL; EC 4.3.1.24) and β‐galactosidase (EC 3.2.1.23) activities), while others were repressed (chlorophyll levels and increment of endo‐1,4‐β‐glucanase (EC 3.2.1.4) and β‐xylosidase (EC 3.2.1.37) activities) or unchanged (reducing sugar content, pH, titratable acidity and α‐L ‐arabinofuranosidase (EC 3.2.1.55) activity) by ethylene. 1‐MCP treatment caused the opposite effect. However, its effects were more pronounced, particularly in anthocyanin accumulation, phenolics, PAL and polygalacturonase (EC 3.2.1.15 and EC 3.2.1.67) activities. CONCLUSION: These observations probably indicate that strawberry produces low levels of ethylene that are sufficient to regulate some ripening aspects. Copyright © 2010 Society of Chemical Industry     

The Effects of Harvest Maturity on Storage Quality and Sucrose-Metabolizing Enzymes During Banana Ripening

Mature green “Baxi” banana (Musa spp. AAA Group, Cavendish) fruits were harvested at 60% and 80% maturity stages. In order to evaluate the effects of harvesting at different maturity stages on storage quality and changes in sucrose-metabolizing enzymes, fruit firmness, disease index, contents of starch, and total soluble sugars were determined, and enzyme activities associated with sucrose metabolism was investigated under natural and accelerated (treated with ethylene) ripening conditions. In fruit treated with ethylene, changes in flesh firmness, total sugar content, starch content, disease index, and activity of sucrose phosphate synthase (SPS), sucrose synthase (SS), acid invertase (AI), and neutral invertase (NI) were accelerated dramatically compared with untreated fruit with both 60% and 80% maturity. When fruit ripened under natural conditions, the changes in firmness, disease index, starch content, total sugar content, SPS activity, SS, AI, and NI activity in fruit with 80% maturity were significantly faster than those in fruit with 60% maturity. On the contrary, when fruit ripened under accelerated conditions, no significant differences in firmness, sugar, starch, disease index, SPS, SS, AI, and NI were observed between fruit harvested at 60% or 80% maturity. It is suggested that storage quality and sucrose-metabolizing enzymes of banana fruit stored under natural conditions are related to harvest maturity stage; storage quality of fruit with lower harvest maturity is better than fruit with higher maturity. However, when fruit ripening is accelerated by ethylene, the harvest maturity stage has no influence on storage quality and changes in sucrose-metabolizing enzymes.     

脱落酸处理对苹果成熟、乙烯合成及其信号转导基因表达的影响

为研究脱落酸（abscisic acid,ABA）对苹果果实采后成熟、乙烯合成及其信号转导基因表达的影响,本实验以‘Granny Smith’苹果果实为实验材料,将其进行外源ABA处理后置于20 ℃贮藏（以无菌水处理为对照）,测定贮藏过程中的硬度、可滴定酸质量分数、纤维素酶活力、果胶甲酯酶活力、叶绿素含量、内源ABA含量、乙烯产生速率及乙烯生物合成基因（ACO1、ACO2、ACS1、ACS3）、苹果乙烯信号转导基因（ERS1、ERS2、ETR2、ERF3、ERF4、ERF5）的表达量。结果表明,与对照组相比,ABA处理能降低苹果果实贮藏过程中的硬度和可滴定酸质量分数,提高果实中的纤维素酶和果胶甲酯酶活性,促进叶绿素a、叶绿素b和总叶绿素含量降低。定量聚合酶链式反应分析结果表明,与对照组相比,ABA处理能够显著提高苹果乙烯生物合成基因的表达量（P＜0.05）。同时,参与苹果乙烯信号转导的ERS2、ETR2和ERF3、ERF4、ERF5表达量随着果实采后成熟明显增加,并且ABA处理组果实中的表达量总体显著高于对照组（P＜0.05）。综上,外源ABA处理能够促进苹果内源ABA的合成,提高苹果乙烯生物合基因和信号转导基因的表达,促进苹果内源乙烯合成和乙烯信号的转导,加快苹果果实的采后成熟进程。     

Auxin treatment of pre‐veraison grape (Vitis vinifera L.) berries both delays ripening and increases the synchronicity of sugar accumulation

Background and Aims: Pre‐veraison auxin treatments can delay grape berry ripening, but there is little information about their effects on berry development and wine composition. The aim of this study was to further investigate these effects and explore the practical implications of delaying ripening. Methods and Results: Treatment of pre‐veraison Vitis vinifera L. cv. Shiraz berries with 1‐naphthaleneacetic acid (NAA) significantly delayed ripening as measured by the accumulation of total soluble solids (TSS) and anthocyanins. The onset of the post‐veraison phase of berry size increase was delayed in NAA‐treated fruit, but these fruit were significantly larger than Control fruit at harvest. NAA‐treatments significantly increased the synchronicity of berry sugar accumulation. GC‐MS analysis of wine headspace volatiles showed significant, but largely small, differences in the concentration of 19 compounds. No significant difference in sensory properties was found between replicate small‐scale wine lots made from Control and NAA‐treated fruit. Conclusions: Auxin treatment delayed berry ripening, increased the synchronicity of sugar accumulation between berries, increased berry size and changed the levels of some volatile compounds, but did not affect wine sensory properties. Significance of the Study: We propose that NAA sprays might be used to delay grape berry ripening and increase the synchronicity of sugar accumulation, and therefore ripening, without deleterious effects on wine quality. This may be useful in controlling winery intake and fruit composition.     

Fatty acid and sugar composition of avocado,cv. Hass,in response to treatment with an ethylene scavenger or 1-methylcyclopropene to extend storage life

This study reports on the effect of 1-methylcyclopropene (1-MCP) and a newly developed palladium (Pd)-promoted ethylene scavenger (e + ® Ethylene Remover) on changes in firmness, colour, fatty acids and sugar content of early and late season avocado (Persea americana Mill.), cv. Hass, during storage at 5 °C and subsequent ripening at 20 °C. The e + ® Ethylene Remover effectively delayed ripening of avocado stored at 5 °C. 1-MCP was more effective at inhibiting ripening, but, in contrast to e + ® Ethylene Remover, it impaired subsequent ripening. Fatty acid profile of late season fruit remained unchanged in response to treatments or storage time, whilst that of early season fruit was slightly, yet significantly, different according to treatments and storage time. Substantial amounts of perseitol were found in all fruit. In contrast, mannoheptulose was only present at high concentration in early season fruit whilst it was quasi-absent in late season fruit. Where ripening was inhibited in response to 1-MCP treatment, significantly more mannoheptulose and better maintenance of perseitol was found vs. controls. Similarly, but to a lesser extent and concomitant with trends in firmness retention and colour changes, e + ® Ethylene Remover led to greater maintenance of mannoheptulose and perseitol than that of controls. This is the first piece of research comparing effects of ethylene removal vs. ethylene action blocking on physical and biochemical changes in avocado cv. Hass and supports the view that C7 sugar metabolism could be an important feature of the avocado fruit-ripening process.     

Expression of genes associated with ethylene-signalling pathway in harvested banana fruit in response to temperature and 1-MCP treatment

BACKGROUND: Little attention has been paid to characterising the ethylene‐signalling pathway genes in relation to abnormal ripening of harvested banana fruit during storage at high temperature. The aim of the present study was to investigate banana fruit abnormal ripening and the expression of ten genes associated with the ethylene‐signalling pathway, namely MaACS1, MaACO1, MaERS1–4 and MaEIL1–4, at high temperature. Changes in these parameters of banana fruit at high temperature in response to 1‐MCP pretreatment were also investigated. RESULTS: High temperature accelerated the decline in fruit firmness, increased ethylene production and inhibited degreening in banana fruit, resulting in fruit abnormal ripening. In addition, the expression of MaACS1, MaACO1, MaERS2, MaERS3, MaERS4, MaEIL1, MaEIL3 and MaEIL4 was enhanced in banana fruit stored at high temperature. However, application of 1‐MCP prior to high temperature storage delayed fruit abnormal ripening and simultaneously suppressed the expression of MaACS1, MaERS2, MaERS3, MaEIL1, MaEIL3 and MaEIL4. CONCLUSION: The findings of this study suggested that the expression of genes associated with the ethylene‐signalling pathway might be involved in banana fruit abnormal ripening at high temperature. Application of 1‐MCP suppressed the expression of genes associated with the ethylene‐signalling pathway, which may be attributed at least partially to 1‐MCP delaying fruit abnormal ripening at high temperature. Copyright © 2010 Society of Chemical Industry     

Effect of pre‐ripening chilling temperatures on ripening,shelf life and quality of bananas treated with 1‐methylcyclopropene

Ethylene production, shelf life and fruit quality of Cavendish bananas (cv. Williams), held at different pre‐ripening storage temperatures (5 °C, 10 °C or 15 °C) prior to ethylene and/or 1‐methylcyclopropene (1‐MCP) application, were determined and compared. Levels of ethylene production during ripening were highest for control fruit that had been stored at 5 °C followed by 10 °C and then 15 °C. 1‐MCP treatment (at 300 nL L^?1) had no effect on ethylene production of fruit that had been stored at 10 °C by day 10 of storage, but ethylene production was significantly higher for fruit that had been stored at 15 °C and lower for those stored at 5 °C before 1‐MCP treatment. 1‐MCP also increased shelf life to a greater extent when applied to fruit that had been stored at 10 °C or 15 °C. Even though 1‐MCP had no significant effect on under peel chilling injury, it increased discolouration significantly, regardless of storage temperature. Firmness of 1‐MCP‐treated fruit decreased significantly compared to the control when fruit were held at 5 °C or 15 °C prior to ripening (and 1‐MCP application) but had no effect on fruit stored at 10 °C before ripening. These results indicate that pre‐ripening storage temperature affects ripening, shelf life and quality in both ethylene and 1‐MCP‐treated bananas.     

Enhancement of Fruit Sensory Quality by Post-Harvest Applications of Acetaldehyde and Ethanol

Post-harvest application of acetaldehyde vapors to blueberries, tomatoes, and pears led to the enhancement of the fruit sensory quality including an increase in the sugar content, sugar-acid ratio, and flavor changes judged to be acceptable by test panels. Applied ethanol vapors led to similar but limited enhancement of fruit sensory quality. Comparative applications of ethylene were more effective in stimulating changes in the background color, including an increase in the total carotenoid content in tomato and anthocyanines in blueberry. Ethylene, however, had little or no effect, and occasionally led to deleterious changes in the fruit sensory quality. Acetaldehyde and related volatiles may be important in the development of fruit sensory quality, as occurring normally during ripening, or as a post-harvest application for the improvement of fruit sensory quality.     

Effect of temperature on chlorophyllase activity, chlorophyll degradation and carotenoids of Cavendish bananas during ripening

Changes in chlorophyllase activity, chlorophyll and carotenoid content of Giant Cavendish banana fruit peel during ripening were measured at tropical temperatures (30–34°C) and at 20°C to relate them to the greenish and yellow colours of the fruit ripened at these temperatures. At 30–34°C bananas remained green on ripening due to incomplete chlorophyll degradation while at 20°C complete degreening occurred and fruits turned yellow. Peel total carotenoid content remained constant during ripening and did not change with temperature. Free xanthophylls decreased while xanthophyll esters increased on ripening. Chlorophyllase activity increased during ripening and paralleled the respiratory climacteric, although activity was not consistently related to the differential degradation of chlorophyll at these temperatures. Exogenous application of ethylene and ethrel accelerated ripening, but had no effect on chlorophyllase levels, chlorophyll degradation and carotenoid content of bananas ripened at either 30–34°C or at 20°C.     

The effects of 1-methylcyclopropene on peach fruit (Prunus persica L. cv. Jiubao) ripening and disease resistance

In order to learn how 1‐methylcyclopropene (1‐MCP) affects ripening and disease‐resistance of peach fruit (Prunus persica L. cv. Jiubao) after harvest, they were treated with 1‐MCP and some were inoculated with Penicillium expansum. Treating peach fruit with 0.2 μL L^?1 of 1‐MCP at 22 °C for 24 h effectively slowed the decline in fruit firmness. The minimal concentration of 1‐MCP able to inhibit fruit softening was 0.6 μL L^?1. Changes in other parameters related to peach ripening, such as content of soluble solids, total soluble sugar, titratable acidity, soluble pectin and ethylene production were also significantly reduced or delayed by 1‐MCP. Repeated treatment of peach with 1‐MCP resulted in more effective inhibition of ripening. Post‐harvest decay of peach fruit was reduced by treatment with 1‐MCP and disease progress in fruit inoculated with P. expansum was reduced. The activities of phenylalanine ammonialyase, polyphenoloxidase and peroxidase in the inoculated fruit were also enhanced by 1‐MCP.