Effect of methyl jasmonate on quality and antioxidant activity of postharvest loquat fruit

BACKGOUND: Loquat fruit is rich in natural antioxidants and has shown a remarkably high antioxidant activity. To search for an effective method for maintaining or even improving antioxidant activity during postharvest storage, we investigated the effect of 10 µmol L^?1 methyl jasmonate (MeJA) treatment on levels of major individual sugars and organic acids, total phenolics, total carotenoids, total flavonoids and antioxidant activity in loquat fruit during storage at 1 °C for 35 days. RESULTS: The MeJA‐treated fruit exhibited significantly lower levels of respiration rate, ethylene production, phenylalanine ammonia‐lyase and polyphenol oxidase activities, and higher levels of sugars, organic acids, total phenolics and total flavonoids than control fruit. Meanwhile, the treatment also maintained significantly higher antioxidant activity as measured by the scavenging capacity against 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), superoxide and hydroxyl radicals, and by the reducing power test compared to the control. There was a significant positive linear relationship between total phenolic content and DPPH radical scavenging activity. CONCLUSION: MeJA treatment can improve the quality and functional properties of harvested loquat fruit by maintaining a higher level of antioxidants and enhancing antioxidant activity. Copyright © 2009 Society of Chemical Industry     

Preharvest application of methyl jasmonate increases fruit quality and antioxidant capacity in raspberries

The effects of preharvest methyl jasmonate (MJ) application on fruit quality, flavonoid content and antioxidant capacity in black raspberry cv. Jewel (Rubus occidentalis L) and red raspberry cv. Autumn Bliss (Rubus idaeus subsp.) were studied under field condition. Raspberries treated with MJ had higher soluble solids content, total sugars, fructose, glucose, sucrose and lower titratable acids (TAs), malic acid and citric acid than untreated fruit. MJ also significantly enhanced the content of flavonoids and the antioxidant capacities in the fruit. The cv. Jewel had higher soluble solids and lower TAs compared with the cv. Autumn Bliss. On the basis of fresh weight of fruit, ‘Jewel’ also had significantly higher anthocyanin, total phenolic content and antioxidant activity than ‘Autumn Bliss’.     

1-甲基环丙烯结合茉莉酸甲酯雾化熏蒸对石榴采后品质的影响

目的 探究1-甲基环丙烯(1-methylcycloproene,1-MCP)和茉莉酸甲酯(methyl jasmonate,MeJA)联合处理对石榴贮藏过程生理代谢和病害的协同调控作用。方法 以和田石榴为对象,采用1-MCP结合MeJA雾化熏蒸处理,研究其对冷藏条件下果实品质的影响。结果 1-MCP结合MeJA雾化熏蒸处理有效延缓了石榴果实在冷藏过程中的果皮褐变,较好保持了果实色泽,降低了果实腐烂率,保持了果实可溶性固形物、可滴定酸和总酚含量,抑制多酚氧化酶活性,减缓过氧化物酶、过氧化氢酶和超氧化物歧化酶活性的下降,同时保持较低的丙二醛含量和细胞膜透性。此外,结合处理还能维持较高的果实可溶性蛋白含量并保持良好的果皮微观结构。结论 1-MCP结合100μmol/L MeJA雾化熏蒸处理的石榴贮藏品质最佳,为石榴采后商品化处理提供了依据。     

不同运输和选果方式对蓝莓采后品质的影响

目的 探讨蓝莓的采后贮藏品质与运输和选果方式的关系。方法 以“莱克西”蓝莓为材料,采用不同运输方式联合选果方法,通过测定软果率、果霜覆盖指数、花色苷、Vc、可溶性固形物、呼吸强度、可滴定酸、硬度、△E等指标,以及主成分分析评价采后贮藏和货架品质。结果 公路运输-精细挑选可显著延缓果实硬度、Vc、花色苷、可滴定酸含量下降,抑制果实呼吸速率,保持较好的品质。对贮藏期和货架期的理化指标进行主成分打分,结合评价模型,4个处理组的得分高低排序为：公路运输-精细挑选>航空运输-精细挑选>公路运输-过筛挑选>航空运输-过筛挑选。结论 蓝莓采后适宜的运输和选果方式为公路运输联合精细挑选,为蓝莓采后保鲜减损技术提供了理论指导。     

茉莉酸甲酯对草莓果实采后腐烂、苯丙烷类代谢及抗氧化活性的影响

为研究茉莉酸甲酯处理(Methyl jasmonate,MeJA)对草莓果实采后腐烂、苯丙烷类代谢及抗氧化活性的影响,将果实先于20℃下以10μmol/L MeJA熏蒸处理6h,然后转入(1±1)℃下贮藏12d,每隔3d测定果实腐烂率、苯丙烷类代谢相关酶苯丙氨酸解氨酶(PAL)、对香豆酰-CoA连接酶(4-CL)、肉桂酸羟化酶(C4H)和二氢黄酮醇还原酶(DFR)活性以及总酚、总花色苷和酚类和花色苷类单体物质含量,并且同时测定果实DPPH(1,1-diphenyl-2-picrylhydrazyl)自由基清除率和总还原力。结果显示,MeJA处理可显著抑制草莓果实贮藏期间腐烂率的上升;同时MeJA可诱导PAL、4-CL、C4H和DFR活性的上升,从而有效延缓了酚类和花色苷类物质含量的下降,提高了果实DPPH自由基清除率和总还原力,维持了果实的抗氧化活性。这些结果表明,MeJA处理在草莓果实保鲜中具有较好的应用前景。     

茉莉酸甲酯预处理对鲜切火龙果品质和 抗氧化活性的影响

目的研究茉莉酸甲酯(Me JA)预处理对鲜切火龙果在10℃,4 d贮藏期间品质和抗氧化活性的影响。方法完整火龙果先用浓度分别为0、1、10和100μmol/L的Me JA熏蒸,再进行鲜切处理,测定其贮藏期间的品质和理化指标。结果 100μmol/L的Me JA熏蒸处理能最显著地诱导鲜切火龙果贮藏期间总酚、总黄酮等次级代谢产物的积累,提高鲜切火龙果贮藏期间DPPH自由基清除能力。Me JA预处理能有效地促进鲜切火龙果贮藏期间超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽还原酶(GR)等抗氧化酶活性的提高。同时,Me JA预处理抑制了可滴定酸(TA)含量的下降,对可溶性固形物(TSS)、维生素C含量无不良影响。结论 100μmol/L的Me JA预处理能较好地保持鲜切火龙果的品质,并有效地提高其抗氧化能力,最终提高鲜切火龙果的营养品质。     

Bioactive compounds and antioxidant activity from harvest to edible ripeness of avocado cv. Hass (Persea americana) throughout the harvest seasons

The influence of regular air cold storage (7 °C and 85 ± 5% RH) followed by ripening at shelf-life conditions (19–21 °C and 65 ± 5% RH), on bioactive compounds of Hass avocados was investigated. Results showed that the content of mannoheptulose and perseitol decreased significantly already during cold storage and ripening period. The fatty acid profile and contents of tocopherols (α- and β-tocopherol) and phytosterols (β-sitosterol, stigmasterol, campesterol) remained unchanged from day 0 to edible ripeness. Total phenolics, hydrophilic and lipophilic antioxidant capacity remained unchanged during cold storage and increased during the ripening period. At edible ripeness, significant amounts of phenolic acids, p-coumaric and caffeic and their derivatives were synthesised. Our results demonstrated that regular air cold storage for up to 37 days followed by ripening at shelf-life conditions enhances the phenolic compounds and mainly the hydrophilic antioxidant capacity without affecting the remaining bioactive compounds in Hass avocado.     

Delayed harvest and cold storage period influence ethylene production,fruit firmness and quality of ‘Cripps Pink’ apple

The effects of harvest date and cold storage period on ethylene production, fruit firmness and quality of ‘Cripps Pink’ apple were investigated. Fruit were harvested from Perth Hills and Donnybrook (Western Australia) at commercial maturity (CM), 2, 4 and 6 weeks after CM prior to 0, 45, 90 and 135 days cold storage in 2003 and 2004. Delayed harvest significantly increased ethylene production, CIE values a* and C* at both locations in 2 years. Delayed harvest and extended cold storage period increased the internal ethylene production and reduced fruit firmness, soluble solids concentration: titratable acidity (SSC:TA) ratio and reduced CIE values L*, b*, h° during both years and locations. Fruit harvested 2 weeks after CM can be cold‐stored for 90 days with acceptable fruit quality. If the fruit is intended to be sold fresh immediately in local markets, the harvest can be delayed up to 6 weeks after CM to harness substantially improved fruit colour with acceptable fruit quality.     

Effects of ozone and chlorine postharvest treatments on quality of fresh‐cut red bell peppers

The effects of chlorine (200 μL L^?1), ozonated water (1 μL L^?1) and gaseous ozone (0.7 μL L^?1) on physicochemical attributes and microbial quality of minimally processed red bell peppers were studied. In all the experiments, O₂ continuously decreased and CO₂ concentration increased, the pH augmented and a significant softening was observed in all the fruits. By day 14, L* values decreased in all the fruits, with the greatest changes found in the chlorinated samples (approximately 12 units). Peppers treated with the aqueous solutions showed greater changes in the quality attributes with increasing washing times and especially when chlorine was used. The exposure for three min to gaseous O₃ reduced the mesophiles, psychrotrophes and fungal populations of the fresh‐cut peppers in 2.5, 3.3 and 1.8 log units, respectively. Combined with modified atmosphere, this could be an appropriate method to maintain the quality and extend the storage period of minimally processed red bell peppers.     

柠檬醛对草莓贮藏期间品质和抗氧化能力的影响

目的 探讨不同植物精油对草莓贮藏期间品质和抗氧化能力的影响，为草莓保鲜提供新的方法。方法 以“红颜”草莓为试材，分别用不同质量浓度（40、80、160和320 μg/mL）的百里香精油、丁香花精油、肉桂精油、枯茗醛和柠檬醛进行处理，测定其在20℃贮藏期间的失重率、腐烂指数、理化性质、抗氧化物质含量和抗氧化酶活性等指标。结果 柠檬醛在40 μg/mL质量浓度时具有最佳保鲜效果，能够有效地降低草莓果实的失重率和腐烂指数，延缓可溶性固形物、可滴定酸和抗坏血酸含量的下降，维持较高的总酚和总黄酮含量，并提高果实对1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl, DPPH）自由基和羟基自由基的清除能力。此外，该处理还能显著提高过氧化氢酶、超氧化物歧化酶、抗坏血酸过氧化物酶等抗氧化酶的活性，且有效抑制丙二醛含量的升高。结论 柠檬醛在草莓贮藏中具有良好的保鲜效果，能够保持其品质和营养价值，这为柠檬醛在水果贮藏保鲜中的应用提供了依据。     

短波紫外线处理对采后山楂果营养品质及其抗氧化活性的影响

以大果山楂为试材,研究了不同剂量短波紫外线（UV-C）辐照处理对采后山楂果实常温贮藏条件下总酚、总黄酮、总三萜酸、还原糖、可滴定酸含量和抗氧化活性的影响。结果表明,UV-C辐照能引起山楂处理后24 h内总酚、总黄酮、三萜酸等生物活性物质含量和抗氧化活性的提高,并且提高了其在室温贮藏期间的抗氧化能力,而不对果实品质造成损害。UV-C处理对山楂果实中多酚、三萜酸等生物活性物质合成的激发效应具有较强的时效性,且与处理剂量密切相关,高剂量处理有助于多酚、三萜酸等生物活性成分的合成与积累和抗氧化活性的提高。      

Effects of hydrogen sulphide on quality and antioxidant capacity of mulberry fruit

Here we investigated the effect of hydrogen sulphide (H₂S) on postharvest quality of mulberry fruit and possible underlying mechanisms. Endogenous H₂S content first increased after harvest and then decreased sharply with the process of ripening and senescence. A fumigation with H₂S released from 0.8 mm NaHS solution could significantly enhance the endogenous H₂S content by increasing the activities of D‐cysteine desulfhydrase and L‐cysteine desulfhydrase. NaHS could significantly slow down the ripening rate of mulberry fruit and reduce the respiratory intensity and anthocyanin content. Moreover, H₂S fumigation was able to obviously delay or slow down the decreases in soluble protein, titratable acidity and ascorbate contents. Further results showed that activities of representative antioxidant enzymes in H₂S‐treated sample were higher than those of control samples during storage, resulting in a decrease in superoxide anion production. Together, these results clearly indicate that H₂S fumigation has a potential role in the preservation of mulberries.     

Influence of delayed cooling on storability and postharvest quality of European plums

BACKGROUND: Delayed cooling has been tested to delay the development of internal breakdown (IB) in other stone fruits, but the influence of delayed cooling on IB has not been studied to date in European plums. A controlled delayed treatment of 48 h at 20 °C was applied in order to study the storability and postharvest quality of European plum (Prunus domestica L.) cv. ‘Green Gage’. RESULTS: Market life of ‘Green Gage’ plums after shelf life was 10 days shorter in delayed fruits than in control fruits at earlier harvest dates. Sensory attributes affected by delayed cooling treatment at harvest were astringency and aroma. Prompt cooling was essential to lower the rate of physiological deterioration of plums, helping to maintain fruit quality and prolong market life. CONCLUSION: Delayed cooling increased IB symptoms in ‘Green Gage’ plums, so, when storability is needed, rapid cooling of fruits is necessary in order to extend their market life. Delayed cooling modified the total soluble solids/titratable acidity (TSS/TA) ratio and the sensory properties aroma and astringency at harvest, so it is desirable to deliver fruits directly to market in order to improve TSS/TA, the instrumental property best correlated with sensory characteristics. Copyright © 2009 Society of Chemical Industry