冷藏过程中温州蜜柑角质层组分变化及其对指状青霉生长的影响

角质层在果实采后贮藏中具有多重重要的生理功能。本实验以温州蜜柑（Citrus unshiu）为材料,对其冷藏过程中角质层的变化特征及其对指状青霉（Penicillium digitatum）孢子萌发和菌丝生长的影响进行了分析。结果表明：温州蜜柑冷藏过程中蜡质、角质含量整体上呈先上升后下降的趋势,其中角质含量的变化幅度最大;脂肪酸是外蜡中含量最丰富的蜡质组分,在冷藏前10 d,脂肪酸含量从0.73 μg/cm2增加到3.09 μg/cm2,之后下降至0.64 μg/cm2（40 d）;萜类物质主要存在于内蜡中,内蜡中萜类物质含量在冷藏过程中呈下降-上升的反复波动状态;角质单体成分主要为肉桂酸和十六碳二酸,冷藏时,肉桂酸含量逐渐下降,在第40天时最低,为13.90 μg/cm2,十六碳二酸含量先增加到17.90 μg/cm2（10 d）,然后下降到6.60 μg/cm2（40 d）;体外实验表明,角质能显著抑制指状青霉孢子萌发,而内蜡能显著抑制菌丝生长（P＜0.05）。这些结果揭示了贮藏过程中角质层变化的生化基础及角质层各组分对指状青霉的影响,为提高温州蜜柑柑橘品种的耐贮性提供了参考。     

电子束辐照对不同品种猕猴桃品质的影响

以4 个品种（‘海沃德’‘徐香’‘华优’‘亚特’）猕猴桃为试材,采用剂量分别为0.4、0.8、1.2 kGy的高能电子束辐照处理,于0～1 ℃、相对湿度90%～95%条件下贮藏,每15 d取样一次,测定电子束辐照处理对果实冷藏期硬度、质量损失率、可溶性固形物质量分数、可滴定酸质量分数、VC含量等品质指标的影响,探究电子束辐照对猕猴桃贮藏品质的影响,为猕猴桃采后保鲜技术提供理论依据。结果表明,电子束辐照处理对维持猕猴桃的贮藏品质有一定积极作用。适宜剂量电子束辐照能抑制猕猴桃贮藏期间果实的质量损失,延缓可滴定酸质量分数的下降,提高类黄酮含量,在贮藏前期提升多酚含量,但硬度、VC含量经辐照后有所降低,且可溶性固形物质量分数升高。相比其他剂量,0.8 kGy电子束辐照能够较好地延缓猕猴桃可溶性固形物质量分数升高和可滴定酸含量降低,提高多酚和类黄酮的含量。整体来看,4 个品种中‘海沃德’‘亚特’更加耐受电子束辐照,且0.4、0.8 kGy剂量的电子束辐照对‘海沃德’‘亚特’的采后贮藏保鲜效果较好,推荐0.4、0.8 kGy为‘海沃德’‘亚特’的采后保鲜辐照剂量。结论：适宜剂量的电子束辐照可以作为提升猕猴桃保鲜效果的有效手段。     

热水处理对新余蜜橘采后贮藏品质的影响

为探明热水处理对新余蜜橘贮藏品质的影响,采用主成分分析法分析热水(53℃、3 min)处理对冷藏条件下[(5±0.5)℃,80%～95%RH]贮藏120 d的‘彭家39号’新余蜜橘采后贮藏品质的影响。结果表明,热水处理可减少新余蜜桔采后腐烂的发生,延缓可溶性固形物(total soluble solids content,TSS)、可滴定酸(titratable acidity, TA)、维生素C (Vitamin C, Vc)含量的降解,抑制果实呼吸速率及丙二醛(malondialdehyde, MDA)的积累,提高果实抗氧化酶如超氧化物歧化酶(superoxide dismutase, SOD)、过氧化氢酶(catalase, CAT)和过氧化物酶(peroxidase, POD)活性,延缓果实后熟衰老。主成分分析和综合得分显示,冷藏60 d后,对照组新余蜜橘的综合品质急剧下降,而热水处理可使果实贮藏时间延长20 d左右。因此,热水处理可作为一种延长新余蜜橘贮藏寿命和维持果实采后品质的理想措施。     

几种保鲜处理对贮藏期间‘红阳’猕猴桃抗氧化生理特性变化的影响

为了研究不同保鲜处理对‘红阳’猕猴桃果实采后抗氧化相关生理特性变化的影响,以‘红阳’猕猴桃为试材,分别用1-甲基环丙烯(1-MCP)、臭氧、气调和热激处理后于(4±1)℃,相对湿度90%~95%条件下贮藏,定期测定其维生素C(VC)、总酚、花色苷的含量以及DPPH·清除率、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)的活性,探讨不同保鲜处理对猕猴桃果实抗氧化活性的影响。结果表明:4种处理均能不同程度地抑制果实VC、花色苷含量的降低,延缓总酚、DPPH·清除率、SOD、POD和CAT峰值的出现,抑制其活性的下降;其中,臭氧(臭氧浓度200mg/m3,处理时间0.5h)处理‘红阳’猕猴桃果实效果最佳,能很好地保持果实的抗氧化活性,从而提高其贮藏期间的抗氧化能力。     

温州蜜柑和冰糖橙果实表面角质层组分及微观结构差异分析

柑橘果皮表面覆盖着一层蜡质,具有多重重要的生理功能。以温州蜜柑（Citrus unshiu Marc.）和冰糖橙 （Citrus sinensis Osbeck ）果实为原料,采用气相色谱-质谱联用（gas chromatography-mass spectrometry,GC-MS） 对2 种类型柑橘果皮角质层组分进行定性和定量分析,并采用扫描电子显微镜对其微观结构进行观察。GC-MS分析 表明,温州蜜柑和冰糖橙外蜡含量分别为3.7 μg/cm2和2.2 μg/cm2,内蜡含量分别为13.9 μg/cm2和18.4 μg/cm2。温州 蜜柑和冰糖橙的外、内蜡中脂肪族物质主要成分相同,分别为烷烃、脂肪酸、伯醇,但品种间各组分比例及碳原子 数分布存在差异。角鲨烯为冰糖橙果实外蜡结构特有组分。此外,三萜类物质仅在内蜡中检测出。温州蜜柑和冰糖 橙的角质膜层含量分别为44.00 μg/cm2和70.00 μg/cm2,二者含量差异显著（P＜0.05）。扫描电子显微镜结果显示 温州蜜柑的外蜡晶体呈不规则血小板状,冰糖橙的外蜡晶体呈倒伏的血小板状。除去外蜡导致温州蜜柑和冰糖橙的 水分损失速率显著增加（P＜0.05）。相对于脂肪酸,烷烃在保水方面具有更重要的作用。两种类型柑橘的角质层 组分及微观结构的差异可能促成了果实采后不同的贮藏特性,这为提高不同品种柑橘耐贮性提供了重要依据。     

壳聚糖涂膜对延缓菜心采后衰老效果的研究

研究了菜心在不同浓度壳聚糖涂膜处理后4℃下贮藏时的质量损失、叶绿素含量、主要营养和过氧化物酶活性的变化。结果表明,与对照相比,壳聚糖涂膜处理明显减少了菜心的质量损失,延缓了菜心的叶绿素、蛋白质、可溶性总糖及Vc含量的下降速度,降低了过氧化物酶活性。2%和3%的壳聚糖处理显著延缓了菜心采后衰老,延长了冷藏菜心的保鲜期。     

植物精油结合壳聚糖涂膜对板栗采后的保鲜效果

板栗是难以贮藏的坚果之一,本文旨在探索提高板栗采后保鲜效果的有效方法。以湘栗四号板栗为材料,采用1.5%壳聚糖涂膜（处理1）、复合植物精油[山苍子、肉桂、迷迭香和牛至精油按1:1:1:1（v/v/v/v）混合]（处理2）和复合植物精油+1.5%壳聚糖涂膜（处理3）3种处理,除防虫试验的板栗置于室温条件下贮藏75 d外,其他的在（0±1）℃、RH85%~90%下贮藏150 d,考察不同处理对采后板栗的保鲜效果。结果表明:与对照组相比,除了处理1的防虫效果不明显外,各处理组的保鲜效果明显好于前者;处理3可减少板栗的失重,防止霉变、虫害,抑制石灰化,减少V_C的消耗,提高过氧化氢酶（catalase, CAT）、超氧化物歧化酶（superoxide dismutase, SOD）的活性并减少丙二醛（malondialdehyde, MDA）积累,效果明显好于处理1和处理2,在150 d后好果率仍高达93%。植物精油处理结合1.5%壳聚糖涂膜在板栗采后保鲜实践中可能具有良好的应用前景。     

壳聚糖对新鲜银耳保鲜效果及贮藏品质的影响研究

以新鲜银耳(Tremella fuciformis)为材料研究壳聚糖对其保鲜效果及贮藏品质的影响。用浓度为0.3%壳聚糖和0.05%柠檬酸配制而成的保鲜液处理新鲜银耳,实验结果表明,壳聚糖处理能显著降低银耳的自然发病率和失重率,保持和提高尤其是贮藏后期鲜银耳的含水量和亨特白度,延缓还原糖含量的下降,促进可溶性蛋白和银耳多糖的转化和积累,对提高和保持银耳采后贮藏品质有较好的作用。     

1-MCP延缓采后‘油木奈’果实衰老及其与能量代谢的关系

研究1-甲基环丙烯(1-MCP)处理对采后‘油木奈’果实衰老的影响及其与能量代谢的关系。采后‘油木奈’果实分别用0(对照)和1.2μL/L的1-MCP处理12 h,之后在(25±1)℃下贮藏。贮藏期间定期测定果实细胞膜透性,ATP、ADP和AMP含量,NAD激酶(NADK)活性,NAD、NADH、NADP和NADPH含量。结果表明:与对照果实相比,1-MCP处理能延缓‘油木奈’果实细胞膜透性的上升,促进贮藏后期(12~18 d)ATP含量的积累,延缓整个贮藏期间能荷值的下降;1-MCP处理可保持‘油木奈’果实较高的NADK活性,降低NAD和NADH含量,提高NADP和NADPH含量。据此认为,1-MCP处理能较好维持采后‘油木奈’果实细胞膜结构的完整性、延缓果实衰老可能与保持较高的能荷值有关。     

杏采后的品质变化及保鲜技术的研究进展

我国鲜杏产量很大,但是采后易腐烂变质,造成了很大的经济损失。介绍了杏采后品质的变化,并探讨了杏果采后的贮藏保鲜技术如涂膜保鲜、冷藏保鲜、气调保鲜、钙处理等。微观多糖纳米结构研究表明,杏采后质地变化是由多糖链降解引起,冷藏和气调技术可有效维持杏的抗氧化等特性。通过延缓杏果实内生化反应和多糖链降解可有效延长采后杏的货架期。     

Changes in cuticle compositions and crystal structure of ‘Bingtang’ sweet orange fruits (Citrus sinensis) during storage

Changes in composition and structure of orange cuticle during storage at 4°C or 25°C for 40 days were investigated. The total epicuticular wax content of fruits increased during storage at 4°C for 30 days and then decreased as storage time prolonged to 40 days, while it increased continuously at 25°C for 40 days. The total intracuticular wax content of fruits increased to 9.70 μg cm^?2 stored at 4°C for 10 days and then decreased to 6.74 μg cm^?2 for 40 days. The total intracuticular wax content of fruits was decreased to 5.17 μg cm^?2 stored at 25°C for 10 days and then increased to 10.06 μg cm^?2 for 30 days. Fatty acids were the most abundant component of the epicuticular wax and terpenoids were restricted to the intracuticular wax. Terpenoids were restricted to the intracuticular wax, and their amounts in the fruit stored at 4°C increased continuously during the first 20 days of storage at 4°C and then decreased as storage time increased up to 40 days. Although significant changes were found in the contents of the cutin monomer, their proportions did not change significantly during storage at 4°C or 25°C. Size of wax platelets crystals wax increased during storage of fruits at 4°C up to 30 days; however, the crystals were degraded and decreased as storage prolonged to 40 days. Furthermore, the shape of the fruit cuticle surface wax crystals changed from flattened platelets to small granulelike after storage at 25°C for 20–40 days. The obtained results provide detailed information about the changes in orange cuticle occur during storage at varying temperatures, which may help in preserving the quality of citrus fruits during storage.     

果实表皮蜡质代谢和调控与品质之间的关系研究进展

果实表皮蜡质是与外界接触的第一道屏障，在其生长和贮藏过程中有十分重要的作用。蜡质是由醇类、酯类、脂肪酸、萜类、醛类和烃类等物质组成的复杂混合物，它们在蜡质的合成及运输途径当中发挥着重要的作用。同时，在这两个途径中，与蜡质代谢相关的基因也发生了显著变化。此外，表皮蜡质也会影响果实的采后品质，从而对其货架期产生影响，进而使其商业价值发生变化。因此，本文阐述了表皮蜡质的合成途径(超长链脂肪酸的合成、脱羰基途径和酰基还原途径)和运输途径等代谢过程对果实品质的影响，以及采后贮藏过程中通过调控蜡质以维持果实品质的技术手段，包括物理方法和化学方法，另外研究表皮蜡质代谢及调控机制来减少果实采后损失 ，并对果蔬表皮蜡质的研究前景进行了讨论与展望，为延长果实采后货架期及培育采后耐贮藏的优良品种提供了理论基础。     

采后果实组织结构抗病性研究进展

从角质层、表皮蜡质、皮孔等非细胞组织结构与果实细胞结构等方面综述采后病原菌侵染过程中果实组织结构抗病性的研究进展,探讨在抵御病原菌侵染过程中果实组织结构抗病性变化,以及采后处理对果实组织结构抗病性的影响。     

The cuticles of citrus species. Composition of the intracuticular lipids of leaves and fruits

The qualitative and quantitative compositions of the intracuticular lipids of the leaves and fruits of four species of Citrus have been examined. The leaf cuticular membranes (280–316 μg/cm²) were well developed and contained high proportions of cutin (77–87%) of which isomers of dihydroxyhexadecanoic acid (79–82%) were the most abundant monomers. The fruit membranes (221–271 μg/cm²) contained smaller proportions of cutin (59–67%) whose major monomeric constituents were dihydroxyhexadecanoic acid (30–62%) and 16-hydroxyoxo-hexadecanoic acid (21–57%). The substantial amounts of cuticular wax (34–68 μg/cm²) located within the membranes consisted largely of fatty acids (68–97%) with hexadecanoic acid (44–78%) and octadecanoic acid (11–39%) present as the main components.     

Effect of surface waxes on the persistence of chlorpyrifos-methyl in apples, strawberries and grapefruits

The effects of the cuticle and epicuticular waxes of grapefruit, strawberry and apple on the photodegradation and penetration of chlorpyrifos-methyl were studied. Photodegradation experiments were conducted by exposing the insecticide to the light of a xenon lamp in the presence of a film of wax extracted from the fruit surface. The half-life of chlorpyrifos-methyl irradiated in absence of waxes was 9.6 min. The half-lives of pesticide irradiated in the presence of wax extracts of apple, grapefruit and strawberry were 83, 34 and 26 min, respectively. In penetration studies, fruit with and without wax layers were treated with an aqueous suspension of pesticide. The penetration of the pesticide from the cuticle to the pulp was measured after 24 h. Samples without wax contained a higher total amount of insecticide than those with wax. No pesticide was detected in samples of apple and grapefruit pulp. Residues were detected in all fractions of strawberry. The waxes and cuticle appear to have some effect on the photodegradation and penetration of chlorpyrifos-methyl in fruit samples.     

Dynamic changes in wax and cutin compounds and the relationship with water loss in 'Red Fuji' and 'Golden Delicious' apples during shelf life

Knowledge of the dynamic composition changes of combined cuticular wax and cutin in apples during their shelf life is scarce. Therefore, this issue was addressed using GC-MS analyses of the respective epidermal components in 'Red Fuji' and 'Golden Delicious' apples at 5 days intervals during the shelf life of 25 days. Water loss from the apples was also assessed. The proportion of total n-alkanes decreased in cuticular wax, whereas total acids increased gradually, and cutin monomer content significantly changed during the first 5 days. The predominant wax compound, nonacosane (C₂₉), decreased by 40.13% and 26.22% in 'Red Fuji' and 'Golden Delicious' apples, respectively. The cutin monomers 10,16-dihydroxy hexadecanoic acid (10,16-diOH C_16:0) and 9,10,18-trihydroxyoctadecanoic acid (9,10,18-triOH C_18:0) were detected only at the beginning of shelf life in apples of both cultivars. Regression analysis indicated that the rate of water loss significantly correlated with eight components. Our results expand the understanding of the dynamics of both wax and cutin compounds in postharvest apples and help to target specific compounds to maintain the quality of apples throughout their shelf life.     

Taste and aroma of fresh and stored mandarins

During the last decade there has been a continuous rise in consumption of fresh easy‐to‐peel mandarins. However, mandarins are much more perishable than other citrus fruit, mainly due to rapid deterioration in sensory acceptability after harvest. In the current review we discuss the biochemical components involved in forming the unique flavor of mandarins, and how postharvest storage operations influence taste and aroma and consequently consumer sensory acceptability. What we perceive as mandarin flavor is actually the combination of basic taste, aroma and mouth‐feel. The taste of mandarins is principally governed by the levels of sugars and acids in the juice sacs and the relative ratios among them, whereas the aroma of mandarins is derived from a mixture of different aroma volatiles, including alcohols, aldehydes, ketones, terpenes/hydrocarbons and esters. During postharvest storage and marketing there is a gradual decrease in mandarin sensory acceptability, which has been attributed to decreases in acidity and typical mandarin flavor, paralleling an accumulation of off‐flavor. Biochemical analysis of volatile and non‐volatile constituents in mandarin juice demonstrated that these changes in sensory acceptability were concomitant with decreases in acidity and content of terpenes and aldehydes, which provide green, piney and citrus aroma on the one hand, and increases in ethanol fermentation metabolism products and esters on the other, which are likely to cause ‘overripe’ and off‐flavors. Overall, we demonstrate the vast importance of the genetic background, maturity stage at harvest, commercial postharvest operation treatments, including curing, degreening and waxing, and storage duration on mandarin sensory quality. Copyright © 2010 Society of Chemical Industry     

Effects of 1‐MCP applied postharvest on epicuticular wax of apples (Malus domestica Borkh.) during storage

BACKGROUND: Certain apple cultivars develop a greasy feel when overripe. Treating fruits with the ripening inhibitor 1‐methylcyclopropene (1‐MCP, SmartFresh^™) reduces fruit greasiness. This study examines the nature of this phenomenon. ‘Royal Gala’ apples were treated with 1‐MCP at 1.0 µl L⁻¹ following harvest. Periodically, during storage at − 1 °C for up to 6 months, fruits were evaluated for internal ethylene concentration, fruit epicuticular wax morphology (using scanning electron microscopy) and non‐polar organic solvent‐extractable (NPOSE) wax constituents of the cuticle (using gas chromatography/mass spectrometry). RESULTS: In 2004, 1‐MCP strongly inhibited internal ethylene production; however, total weight of NPOSE wax during storage was unaffected by treatment. In 2005, several wax constituents present in both ‘Autumn Gold’ and ‘Royal Gala’ showed differences during storage. In 2006, cuticular wax constituents comprising 80% of the total from ‘Royal Gala’ showed no treatment differences. Although several minor constituents did exhibit differences within treatment and sampling date, these did not appear sufficient to cause the subtle differences in surface wax morphology. CONCLUSION: 1‐MCP strongly inhibited ethylene production and delayed development of certain wax constituents thought responsible for fruit greasiness during cold storage. Subtle differences in surface wax morphology appeared unrelated to wax production. Published in 2008 by John Wiley & Sons, Ltd.