Catalase in the heat-induced chilling tolerance of cold-stored hybrid Fortune mandarin fruits

Hybrid Fortune mandarins developed chilling injury (CI) upon cold storage, unless the fruits were conditioned at 37 degrees C for 3 days before they were held at low temperature. This heat treatment induced 2.5-, 1.2-, and 1.4-fold increases in the activities of catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD), respectively, and reduced the activity of glutathione reductase (GR). The differences in the activities afforded by the heat treatment were, in general, maintained during cold storage. However, SOD levels in nonconditioned Fortune fruits exhibiting CI were similar to those of conditioned fruits stored for 0 or 6 weeks at 2 degrees C. No difference between APX activity in the conditioned and nonconditioned fruits stored for 6 weeks at 2 degrees C was found. The data indicate that CAT may be a major antioxidant enzyme operating in the heat-induced chilling tolerance of cold-stored Fortune mandarin fruits.     

Cd胁迫下绿豆和箭舌豌豆叶片抗氧化系统的变化

研究了Cd胁迫下绿豆（Phaseolus aureus）和箭舌豌豆（Vicia sativa）幼苗的生长,叶片内过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）、超氧化岐化酶（SOD）、愈创木酚过氧化物酶（GPOD）和谷胱甘肽还原酶（GR）的同工酶活性,还原性谷胱甘肽（GSH）和抗坏血酸（ASC）以及Cd含量的变化。结果显示,100μmol.L-1Cd胁迫9d期间,随着Cd胁迫时间的延长,绿豆和箭舌豌豆幼苗主根的伸长量和其根系干重显著降低（P〈0.05）,根表面出现越来越明显的褐色,绿豆叶表面出现可见的褐色斑点;两种植物叶片的CAT、APX和SOD同工酶活性以及绿豆叶片的GR活性呈先升后降的趋势,而两种植物叶的GPOD活性明显增加;在箭舌豌豆叶片中,GR活性随Cd暴露时间的延长而增加,而GSH先降后升;在绿豆叶片中,GSH和ASC随Cd暴露时间的延长而降低;与此同时,两种植物叶片中Cd的含量也随Cd胁迫时间的延长而增加,和箭舌豌豆相比,绿豆叶片中Cd含量增加更多。结果表明,箭舌豌豆有较强的抗氧化能力。     

盐胁迫下两种草坪草膜脂过氧化和抗氧化酶比较

Salinity stress is a major factor limiting the growth of turfgrass irrigated with recycled wastewater. The change in lipid peroxidation in terms of malondialdehyde (MDA) content and the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxide (APX) and glutathione reductase (GR) in the shoots and roots of Kentucky bluegrass and tall fescue were investigated under salinity stress. Plants were subjected to 0, 50, 100, 150 and 200 mmol L 1 NaCl for 40 d. The MDA content under salinity stress was lower in tall fescue than in Kentucky bluegrass in both shoots and roots. Activities of SOD in the shoots of both species increased with salinity stress. The activities of CAT and APX decreased in Kentucky bluegrass, but no significant difference in the activities of CAT and APX was observed in tall fescue. The activities of SOD, CAT and APX in the shoots of tall fescue were higher than those in Kentucky bluegrass. In the roots of Kentucky bluegrass, SOD and GR activities increased and CAT and APX activities decreased in comparison with the control. In the roots of tall fescue, salinity increased the activities of SOD, CAT, and APX. These results suggested that tall fescue exhibited a more effective protection mechanism and mitigated oxidative stress and lipid peroxidation by maintaining higher SOD, CAT and APX activities than Kentucky bluegrass.     

1-MCP负压渗透处理对鲜枣贮藏期间生理及抗氧化能力的影响

以山东大瓜枣为试材,研究1-甲基环丙烯（1-MCP）负压渗透处理对鲜枣贮藏期间生理指标及抗氧化能力的影响。结果表明：1-MCP处理可以维持鲜枣果实体内较低的活性氧水平（H2O2）,提高果实自身抗氧化能力（T-AOC、OH·、O2·-、DPPH）,维持果实自身的抗氧化物质抗坏血酸（AsA）及总酚含量;1-MCP处理对果实过氧化氢酶（CAT）呈现抑制表达作用,而对于抗坏血酸过氧化物酶（APX）、超氧化物歧化酶（SOD）、多酚氧化酶（PPO）和过氧化物酶（POD）则有一定的激活作用。     

不同机械伤处理对香蕉果皮活性氧代谢的影响

为探究不同机械伤处理对香蕉果皮活性氧代谢的影响，该研究以"桂蕉6号"为材料，采用划伤、穿刺、坠落3种不同机械伤处理，以未处理组为对照，测定贮藏过程中香蕉果皮活性氧代谢的变化，并进行相关性分析和主成分分析。结果表明，3种不同机械损伤处理均加速了香蕉果实硬度和叶绿素含量的下降；引起O2-产生速率和H2O2含量的积累，其中划伤处理组的O2-产生速率在贮藏第8 天为对照组的2.0倍，H2O2含量为对照组的2.5倍，这可能与机械伤处理抑制了果皮组织中过氧化物酶、超氧化物歧化酶、过氧化氢酶及抗坏血酸过氧化物酶活性有关；同时，3种不同机械损伤处理加速细胞膜脂过氧化的进程，造成香蕉细胞膜透性及丙二醛含量的升高，其中对照、划伤、穿刺和坠落处理组的丙二醛含量在贮藏第8 天分别是贮藏初期的3.3、3.4、5.4和7.5倍。；此外，划伤和穿刺处理均可显著提高香蕉果皮中PPO活性（P <0.01)。相关性聚类热图分析表明，H2O2含量与香蕉果实硬度、叶绿素含量和抗坏血酸过氧化物酶活性呈极显著负相关（P <0.01)，与超氧化物歧化酶活性呈显著负相关（P <0.05)；同时，多酚氧化酶活性与H2O2含量、丙二醛含量和细胞膜透性呈现极显著正相关（P <0.05)。结合主成分分析可知，不同机械伤处理均可加速香蕉果皮活性氧的积累进而导致香蕉果实的衰老腐败，其中划伤处理对香蕉果皮活性氧代谢影响最大，其次是穿刺处理，坠落处理对香蕉果皮活性氧代谢影响最小。该研究阐明了香蕉果实机械伤、活性氧和贮藏品质三者的关系，并为香蕉采后不同机械伤控制提供理论依据。     

Active oxygen detoxifying enzymes and phenylalanine ammonia-lyase in the ethylene-induced chilling tolerance in citrus fruit

The effects of applying ethylene (2 microL x L(-)(1)) during cold storage of Fortune mandarins on the development of chilling-induced peel damage and on changes in the activities of the enzymes of the antioxidant system, superoxide dismutase, catalase (CAT), ascorbate peroxidase, guaiacol peroxidase, and glutathione reductase, and on phenylalanine ammonia-lyase (PAL) have been investigated. Chilling damage was reduced by applying ethylene during fruit storage at 1.5 degrees C. PAL activity increased in response to cold stress and was higher in fruit held under ethylene than under air during the whole storage period, whereas CAT was temporarily higher in ethylene-treated fruit. In contrast, the activities of the other enzymes were not increased by ethylene. The global results suggest that the ethylene-induced chilling tolerance in Fortune mandarins might be due to increased PAL and CAT activities.     

Electron beam ionization induced oxidative enzymatic activities in pepper (Capsicum annuum L.), associated with ultrastructure cellular damages

Mature green pepper fruits (Capsicum annuum L.) were subjected to ionizing radiation, in the range of 1-7 kGy, with accelerated electrons. Ultrastructural changes by electron microscopy, and the activity of several oxidative metabolism-related enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaicol peroxidase (POX), and lipoxygenase (LOX), were determined in pericarp tissue just after the ionization treatment and during postionization storage at 7 degrees C followed by 3 days at 20 degrees C. Changes in oxidative stress during the ionization treatment was assessed by the accumulation of malondyaldehide (MDA), a lipid peroxidation product. The ionization induced modifications in the cell ultrastructure, a moderate separation of the plasma membrane from the cell wall being observed for all doses. At 5 and 7 kGy, peroxisomes were not detected and the structures of the chloroplast and vacuoles were seriously damaged. Lipid peroxidation and lipoxygenase activity increased with the ionization dose, staying constant and decreasing, respectively, during the storage period. Conversely, catalase, ascorbate peroxidase, and superoxide dismutase had lower values than in nonionized fruits and, in general, their values did not change or diminished slightly from the seventh day of storage. Peroxidase exhibited an increase in activity with the ionization dose, although these was not a linear relationship, with higher values at 3kGy. Ionization of pepper, especially at doses of 5 and 7 kGy, caused a significant oxidative damage in the fruit, since it increased oxidation and decreased the antioxidant enzymatic defense systems causing ultrastructural changes at cell level.     

高湿贮藏对茄子冷害及抗氧化系统的影响

为探讨高湿贮藏对减轻茄子冷害的作用及其与抗氧化系统的关系,本试验将茄子果实分别放置于4℃的干雾控湿高湿冷库(相对湿度96%~99%)和低湿冷库(相对湿度70%~75%)中贮藏15 d,每隔3 d进行取样测定,比较分析相关指标的变化。结果表明,与低湿贮藏相比,高湿贮藏能显著抑制茄子果实冷害指数、相对电导率和失重率的上升(P<0.05),保持茄子果实较高的硬度及总酚和花青素含量。同时,高湿贮藏能显著提高茄子果实中超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)和过氧化物酶(POD)等抗氧化酶的活性(P<0.05),抑制过氧化氢(H₂O₂)和超氧阴离子( {\mathrm{O}}_2^{\frac{-}{·}} )的产生,保持更高的1,1-二苯基-2-三硝基苯肼(DPPH)和羟基自由基清除能力。上述结果表明,高湿贮藏可维持茄子果实较高的抗氧化系统活性,从而抑制活性氧对茄子的伤害,减轻果实冷害。本研究为高湿贮藏在茄子果实采后保鲜中的应用提供了一定的依据。     

麦秸、稻壳及菌渣还田对设施菜地的青椒品质及产量的影响

针对设施菜地长期连作带来的土壤退化问题,研究不同种类农业废弃物(麦秸、稻壳及菌渣)还田对设施青椒光合色素含量、产量及品质的影响,以了解农业废弃物利用的可行性。结果表明:麦秸、稻壳及菌渣还田可以有效提高光合色素含量和抗氧化酶(超氧化物歧化酶、过氧化物酶、过氧化氢酶)活性,降低丙二醛含量,其中叶绿素含量以菌渣处理(T3)最高,为1.045 3 mg/g FW;类胡萝卜素含量以稻壳+麦秸处理(T4)最高,为0.257 8 mg/g FW;Chl.a/Chl.b值、Chl.(a+b)/Car.值均以菌渣处理(T3)最大,分别为3.22、4.12。此外,农业废弃物还田可以有效抑制青椒果实中类黄酮和花青素色素的形成。菌渣处理(T3)下的果实可溶性糖与Vc含量最高,分别较对照处理(T7)增加81.20%、15.84%,可溶性蛋白质和游离氨基酸蛋白质含量分别以稻壳+麦秸处理(T4)、稻壳处理(T1)最高。结果还显示,多种农业废弃物配施的青椒产量低于单一施入;菌渣单施处理(T3)产量最高,达48 255.75 kg/hm~2。     

Protein changes in the albedo of citrus fruits on postharvesting storage

In this work, major protein changes in the albedo of the fruit peel of Murcott tangor (tangerine x sweet orange) during postharvest ageing were studied through 2D PAGE. Protein content in matured on-tree fruits and in fruits stored in nonstressing [99% relative humidity (RH) and 25 degrees C], cold (99% RH and 4 degrees C), and drought (60% RH and 25 degrees C) conditions was initially determined. Protein identification through MS/MS determinations revealed in all samples analyzed the occurrence of manganese superoxide dismutase (Mn SOD), actin, ATP synthase beta subunit (ATPase), citrus salt-stress associated protein (CitSap), ascorbate peroxidase (APX), translationally controlled tumor protein (TCTP), and a cysteine proteinase (CP) of the papain family. The latter protein was identified in two different gel spots, with different molecular mass, suggesting the simultaneous presence of the proteinase precursor and its active form. While Mn SOD, actin, ATPase, and CitSap were unchanged in the assayed conditions, TCTP and APX were downregulated during the postharvest ageing process. Ageing-induced APX repression was also reversed by drought. CP contents in albedo, which were similar in on- and off-tree fruits, were strongly dependent upon cold storage. The active/total CP protein ratio significantly increased after cold exposure. This proteomic survey indicates that major changes in protein content in the albedo of the peel of postharvest stored citrus fruits are apparently related to the activation of programmed cell death (PCD).     

The impact of selenium application on enzymatic and non-enzymatic antioxidant systems in Zea mays roots treated with combined osmotic and heat stress

Selenium (Se), regarded as an antioxidant, has been found beneficial for plants growing under stressed conditions. To investigate whether the Se application helps to improve stress tolerance, sodium selenite (Na₂SeO₃ · 5H₂O, 5–15 μM) was hydroponically applied to Zea mays variety OSSK-713-roots under heat and/or PEG-induced osmotic stress (25% PEG-6000) for 8 h. The individual/combined stress caused accumulation of reactive oxygen species (ROS). While only superoxide dismutase (SOD) increased with heat stress alone, the activities of SOD, catalase (CAT) and ascorbate peroxidase (APX) increased under PEG exposure. The combination of these stresses resulted in an induction of both SOD and CAT activities. Lipid peroxidation (TBARS) levels were also high in all the stress treatments, especially under the combination treatment. Addition of Se not only improved the activities of SOD, APX and glutathione reductase (GR) in stress-treated roots, but it also changed the activities of monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR). The findings reveal that Se has a positive effect on heat and/or osmotic stress mitigation mainly by regulating the ascorbate-glutathione cycle, especially in PEG-treated plants. Under the combined stress treatment, addition of 5 µM of exogenous Se was most effective.     

高压电场处理对贮藏番茄活性氧代谢的调节

为探讨高压电场调控采后果实成熟衰老的作用机理,研究了交变电场和稳恒电场处理对采后番茄活性氧代谢的影响。试验结果表明：交变电场处理可诱导贮藏前期番茄超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性,延缓贮藏后期SOD活性上升和CAT活性下降;稳恒电场处理对酶活性的诱导不显著。两种电场处理均延缓了过氧化物酶（POD）活性高峰出现的时间。稳恒电场处理果实整个贮藏过程中保持了高水平的抗坏血酸（AsA）以及还原型谷胱甘肽（GSH）含量。整个贮藏期间高压电场处理均显著抑制了番茄过氧化氢含量以及超氧阴离子的产生。     

酸铝胁迫对栝楼根系生长及铝积累的影响

针对南方酸性红壤对作物的生长造成的不利影响,采用水培方式,研究酸铝环境0、100、300、500、1000μmol·L-1Al3＋pH4.5,处理7d对长兴栝楼根系生长及铝积累的影响。测定指标包括根系活力、质膜透性、抗氧化酶类活性（过氧化物酶POD、过氧化氢酶CAT、抗坏血酸过氧化物酶APX、愈创木酚过氧化物酶GPX、超氧化物歧化酶SOD）及其同工酶、过氧化氢（H2O2）含量、根尖铝含量的影响。结果表明：随着铝处理浓度升高,根系活力增大,根系质膜透性无显著变化;POD、CAT、APX酶活升高,GPX和SOD活性降低,多种抗氧化酶都有多条同工酶谱带出现;根尖相对铝含量升高,桑色素染色情况显示,荧光梯度与铝含量测定结果一致,并观察到根尖以上根毛处细胞凸起较之平整排列的根细胞更容易积累铝。栝楼对南方酸性红壤具有较强的适应能力,其体内抗氧化酶系统及根尖吸收、积累铝的机制对缓解铝毒害起着重要作用。     

红壤水分条件对柑橘叶片质膜透性以及活性氧代谢和保护酶活性的影响

通过盆栽柑橘控制盆内红壤不同含水量处理,研究了不同红壤水分条件对柑橘叶片质膜透性以及活性氧代谢和保护酶活性的影响.结果表明,柑橘叶片相对电导率在红壤相对含水量75% 处理时最低,并与红壤相对含水量呈显著负相关(R2 = 0.8236*,n=50);柑橘叶片丙二醛(MDA)含量随土壤水分含量的减少而显著增加,并与红壤相对含水量呈显著负相关(R2 = 0.9051*,n=50).柑橘叶片超氧阴离子自由基(O2.-)生成速率与过氧化氢(H2O2)含量在不同红壤水分条件下具有相近的变化曲线,在红壤相对含水量60% 的处理下达最大值后,随红壤水分减少或增加均呈下降趋势;O2.-、H2O2并不是引起柑橘在红壤水分亏缺或盈余胁迫状况下氧化伤害的单一原因.随着红壤含水量的变化,柑橘叶片抗氧化系统处于动态的平衡中,柑橘叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)酶活性在红壤干旱条件下都保持了较高的活性,但过氧化氢酶(CAT)活性随土壤水分减少却显著降低.     

甜菜M14品系与二倍体栽培甜菜耐盐性的比较研究

【目的】甜菜属于耐盐碱作物,通过比较两个优质甜菜材料的耐盐性,为甜菜育种提供科学依据。【方法】本试验以甜菜M14品系(18+1条染色体)和来自同一亲本分离得到的二倍体栽培甜菜(18条染色体)为试验材料,在正常和200 mmol/L NaCl胁迫条件下进行水培试验。在处理0、1、3、5、7天后,采集幼苗样品,测定株高、根长,分析K^+、Na^+、丙二醛(MDA)和甜菜碱含量,测定主要抗氧化物酶基因(SOD、CAT、APX、GR)和甜菜碱合成基因(CMO、BADH)的转录水平及以上6个基因编码酶活性。【结果】1)正常条件下,两个甜菜材料的株高和根长均无明显差异;200 mmol/L NaCl胁迫条件下,M14品系的株高和根长均优于二倍体。2)正常条件下,M14品系与二倍体的根吸收K^+和Na^+的能力相似,代谢过程中产生甜菜碱的量相当;200 mmol/L NaCl胁迫条件下,两个甜菜材料根中的K^+、Na^+含量差异不显著,而M14品系根中的甜菜碱含量高于二倍体。3)正常条件下,两个甜菜材料根中的SOD、CAT、APX、GR、CMO和BADH基因转录水平差异均不显著;200 mmol/L NaCl胁迫条件下,M14品系根中的SOD和GR基因转录水平均在第1天时高于二倍体,CAT、APX、CMO和BADH基因转录水平在第3~5天显著高于二倍体。4)正常条件下,两个甜菜材料根中SOD、CAT、APX、GR、CMO和BADH活性差异不显著;200 mmol/L NaCl胁迫条件下,M14品系根中各酶活性均显著高于二倍体。【结论】在200 mmol/L NaCl胁迫条件下,甜菜M14品系根部的甜菜碱含量较高,抗氧化物酶基因转录水平及酶活性均显著高于二倍体,表现出更高的耐盐性。     

小麦幼苗对氧乐果胁迫的生理学响应

通过溶液培养研究了不同浓度(0、0.1、1.0、5.0和10.0 g/L)氧乐果处理后小麦幼苗叶绿素含量、类胡萝卜素含量、可溶性糖含量及保护酶活性的动态变化。结果表明:在氧乐果胁迫下,高浓度的氧乐果(5.0和10.0 g/L)处理显著降低了小麦幼苗的叶绿素含量和类胡萝卜素含量,且随着处理时间的延长其差异尤为显著;小麦叶片中可溶性糖含量随着氧乐果浓度和处理天数的增加而显著增加。超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性均先上升后下降;抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)活性在0.1 g/L氧乐果处理的第1d时略有上升,然后下降。小麦响应氧乐果胁迫并上调SOD、POD、CAT等保护酶的活性和可溶性糖的含量,降低叶片光合作用,籍此维持小麦免受低浓度氧乐果的胁迫以维持小麦的正常生长;但高浓度氧乐果处理对小麦根系产生了明显的毒害作用,致使5.0 g/L氧乐果胁迫的小麦根系SOD、POD、CAT活性显著下降。APX和GR可能在低浓度氧乐果处理初期起主要保护作用,而在高浓度氧乐果胁迫下则受到明显抑制作用。     

Controlled-atmosphere effects on postharvest quality and antioxidant activity of cranberry fruits

The effects of controlled-atmosphere (CA) storage on the firmness, respiration rate, quality, weight loss, total phenolics and flavonoids contents, and total antioxidant activities of the Pilgrim and Stevens cultivars of cranberries (Vaccinium macrocarpon Aiton) have been studied during storage in atmospheres of 2, 21, and 70% O(2) with 0, 15, and 30% CO(2) (balance N(2)); and 100% N(2) at 3 degrees C. Elevated CO(2) concentrations decreased bruising, physiological breakdown, and decay of berries, thereby reducing fruit losses. Respiration and weight loss of fruits decreased, but fruit softening increased, at higher CO(2) concentrations. Accumulations of acetaldehyde, ethanol, and ethyl acetate varied by cultivar and storage atmosphere but were generally highest in the 2 and 70% O(2) and 100% N(2) atmospheres and increased in response to elevated CO(2) concentrations. Overall, the 30% CO(2) plus 21% O(2) atmosphere appeared optimal for the storage of cranberries. Sensory analysis is required, however, to confirm that accumulations of fermentation products at this atmosphere are acceptable for consumers. Stevens fruits had a higher phenolics content and total antioxidant activity than Pilgrim fruits. The storage atmosphere did not affect the content of total phenolics or flavonoids. However, the total antioxidant activity of the fruits increased overall by about 45% in fruits stored in air. This increase was prevented by storage in 30% CO(2) plus 21% O(2).     

Antioxidant activity of the main phenolic compounds isolated from hot pepper fruit (Capsicum annuum L)

Four cultivars (Bronowicka Ostra, Cyklon, Tornado, and Tajfun) of pepper fruit Capsicum annuum L. were studied for phenolics contents and antioxidant activity. Two fractions of phenolics, flavonoids (with phenolic acids) and capsaicinoids, were isolated from the pericarp of pepper fruit at two growth stages (green and red) and were studied for their antioxidant capacity. Both fractions from red fruits had higher activities than those from green fruits. A comparison of the capsaicinoid fraction with the flavonoid and phenolic acid fraction from red fruit with respect to their antioxidant activity gave similar results. Phenolic compounds were separated and quantified by LC and HPLC. Contents of nine compounds were determined in the flavonoid and phenolic acid fraction: trans-p-feruloyl-beta-d-glucopyranoside, trans-p-sinapoyl-beta-d-glucopyranoside, quercetin 3-O-alpha-l-rhamnopyranoside-7-O-beta-d-glucopyranoside, trans-p-ferulyl alcohol-4-O-[6-(2-methyl-3-hydroxypropionyl] glucopyranoside, luteolin 6-C-beta-d-glucopyranoside-8-C-alpha-l-arabinopyranoside, apigenin 6-C-beta-d-glucopyranoside-8-C-alpha-l-arabinopyranoside, lutoeolin 7-O-[2-(beta-d-apiofuranosyl)-beta-d-glucopyranoside], quercetin 3-O-alpha-l-rhamnopyranoside, and luteolin 7-O-[2-(beta-d-apiofuranosyl)-4-(beta-d-glucopyranosyl)-6-malonyl]-beta-d-glucopyranoside. The main compounds of this fraction isolated from red pepper were sinapoyl and feruloyl glycosides, and the main compound from green pepper was quercetin-3-O-l-rhamnoside. Capsaicin and dihydrocapsaicin were the main components of the capsaicinoid fraction. A high correlation was found between the content of these compounds and the antioxidant activity of both fractions. Their antioxidant activities were elucidated by heat-induced oxidation in the beta-carotene-linoleic acid system and the antiradical activity by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) decoloration test. The highest antioxidant activity in the beta-carotene-linoleic acid system was found for trans-p-sinapoyl-beta-d-glucopyranoside, which was lower than the activity of free sinapic acid. Quercetin 3-O-alpha-l-rhamnopyranoside had the highest antiradical activity in the DPPH system, which was comparable to the activity of quercetin. The activities of capsaicin and dihydrocapsaicin were similar to that of trans-p-feruloyl-beta-d-glucopyranoside in the DPPH model system.     

适宜1-MCP处理保持采后菠萝常温贮藏品质

为了探索1-MCP处理对采后菠萝生理及品质的影响,为菠萝贮藏保鲜措施提供理论依据。以‘巴厘’品种的菠萝果实为试材,采用适宜0.45μL/L体积分数的1-MCP对菠萝进行处理,置于25℃条件下贮藏,采用气相色谱定期测定乙烯释放量,并采用常规理化分析方法测定菠萝品质及相关生理指标。结果表明,1-MCP处理能延缓果实贮藏过程中乙烯的合成速率,与相同贮藏条件下的对照(未处理)果实相比,乙烯释放高峰推迟4 d;1-MCP处理可以延缓果实丙二醛(malondialdehyde,MDA)含量的快速升高,同时对脂氧合酶(lipoxygenase,LOX)酶活性起到抑制作用;与对照相比,1-MCP处理推迟了过氧化物酶(peroxidase,POD)、过氧化氢酶(catalase,CAT)等酶活性高峰的出现,并使POD、CAT、过氧化物歧化酶(superoxide dismutase,SOD)等保持较高的活性,可以有效延缓菠萝在贮藏期间的衰老进程,在贮藏14 d时,分别比对照高出22.30%、32.35%、36.67%,差异显著(P0.05);1-MCP还可减缓果实可滴定酸、维生素C等含量的下降,有助于保持果实的良好品质。1-MCP处理可抑制菠萝贮藏期的果实衰老进程,有利于保持果实品质,提高贮藏效果。研究结果将为菠萝贮藏保鲜措施提供参考。