Effect of box materials on the distribution of 1-MCP gas during cold storage: A CFD study

1-Methylcyclopropene (1-MCP) is a synthetic plant growth regulator used commercially to delay ripening of fruits. The substance is applied in gas form (as a fumigant) in the storage room. In long term postharvest cold storage, fruit are placed in boxes (usually plastic or wooden bins) and stacked in a specific pattern. The top of the boxes are frequently covered with a thin plastic sheet for the purpose of reducing fruit moisture loss. Wooden boxes, card linings and other plant based porous materials used in bins have 1-MCP adsorption capacity. Plastic covers affect the airflow and with that the 1-MCP transport. In this paper, the influence of box materials and plastic cover on the distribution of 1-MCP in cold storage was studied using validated CFD models. Reynolds Average Navier–Stokes equations with the SST k–ω turbulence model were used to calculate the airflow. Diffusion, convection and adsorption of 1MCP were modeled to obtain 3D spatial and temporal distributions of 1-MCP inside a storage container, boxes and fruit. Time dependent profiles of calculated 1-MCP concentrations in the air in the container agreed well with measurement data. The plastic cover imposed no effect on the adsorption of 1-MCP. Wooden boxes notably adsorbed 1-MCP from the treatment atmosphere and may reduce the efficacy and uniformity of the treatment.     

Modeling the diffusion-adsorption kinetics of 1-methylcyclopropene (1-MCP) in apple fruit and non-target materials in storage rooms

The purpose of this research was to model the kinetics of adsorption of 1-methylcyclopropene (1-MCP) in apple fruit and non-target solid materials found in apple storage rooms. The process was described by Fick’s second law of diffusion of the gas through the pores of the material coupled with adsorption kinetics of the gas on the material’s binding sites. A finite element formulation of the model, describing the diffusion and adsorption mechanisms separately, was first developed. The values of the relevant parameters were estimated based on headspace measurements of the decrease of 1-MCP in jars containing the different materials. The headspace concentration of 1-MCP was measured using gas chromatography. Apple fruit (Golden Delicious and Jonagold) and the following bin construction materials were investigated: high density polyethylene (HDPE), oak, poplar wood and card lining. The range in the magnitude of the diffusion coefficient, adsorption coefficient, and concentration of active sites in the various solids was 10,000-, 8-, and 30-fold, respectively.     

1-MCP处理对南果梨20℃贮藏期香气成分的影响

利用固相微萃取技术(solid phase micro extraction,SPME)与气相色谱- 质谱(gas chromatography-mass spectrometry,GC-MS)相结合对1-methylcyclopropene(1-MCP)处理南果梨20℃贮藏香气成分进行研究。结果表明：南果梨香气成分的释放与果实的后熟程度有很大的关系,总体上呈现先上升后略下降的趋势;1-MCP 处理延长了南果梨20℃贮藏期,但减少了香气成分种类;处理组检出果实香气的种类比对照组减少了27.8%,其中酯类香气种类比对照果减少了31.3%。     

1-MCP处理对“岳帅”苹果冷藏软化及相关生理指标的影响

研究1-甲基环丙烯(1-methylcyclopropene,1-MCP)处理对"岳帅"苹果低温贮藏期间与软化相关的主要物质含量及酶活性的影响,探讨1-MCP处理对"岳帅"苹果果实软化的调控机理,为"岳帅"苹果贮藏保鲜提供理论依据。以"岳帅"苹果为研究对象,使用0.0、0.5、1.0、2.0μL/L的1-MCP处理后,于(0.0±0.5)℃、相对湿度90%~95%的冷库内贮藏,定期测定果实硬度、呼吸强度、乙烯释放量、细胞壁组成成分及相关酶活性。"岳帅"苹果采后呼吸强度和乙烯释放量均于第30天时达到峰值,多聚半乳糖醛酸酶(polygalacturonase,PG)也在第30天达活力高峰,果胶甲酯酶、纤维素酶(cellulose,Cx)、β-葡萄糖苷酶第45天达活力高峰,同时果实可溶性果胶含量迅速上升,原果胶、纤维素含量不断下降。0.5μL/L 1-MCP处理可推迟果实呼吸强度高峰、乙烯释放量高峰、PG和Cx活力高峰的出现,对抑制可溶性果胶含量升高和原果胶含量的降低作用显著(P0.05),但对冷藏结束时果实硬度的降低抑制效果不显著(P0.05);1.0μL/L和2.0μL/L 1-MCP处理对果实呼吸强度、乙烯释放量、细胞壁降解酶、可溶性果胶含量均有显著抑制作用(P0.05),并且能显著抑制果实硬度下降(P0.05)。"岳帅"苹果在冷藏期间原果胶、纤维素不断被分解,可溶性果胶不断生成,果实硬度迅速下降;除PG外,各细胞壁降解酶活力高峰均出现在呼吸强度和乙烯释放量高峰之后。1-MCP处理通过改变"岳帅"苹果呼吸强度和乙烯释放量,抑制果实细胞壁降解酶活性并推迟活性高峰,从而减缓果实细胞壁组成成分降解,抑制果实软化。1.0μL/L和2.0μL/L的1-MCP处理效果较为显著。     

Postharvest application of 1-Methylcyclopropene modulates fruit ripening, storage life and quality of 'Tegan Blue' Japanese plum kept in ambient and cold storage

The role of postharvest application of 1-Methylcyclopropene (1-MCP) in modulating 'Tegan Blue' Japanese plum fruit ripening and quality under ambient and cold storage conditions was investigated. 1-MCP-treated fruit (0, 0.5, 1.0 and 2.0 μL L⁻¹) were allowed to ripen at ambient temperature in Experiment 1, while in the second experiment the fruit were kept in cold storage (0, 3 and 6 weeks) before ripening. In both experiments, 1-MCP treatment significantly delayed (2–8 days), suppressed (30–70%) the climacteric ethylene production, maintained higher fruit firmness (34–60%), titratable acidity, L* , chroma, hue angle of fruit skin and pulp, and reduced concentrations of soluble solids, ascorbic acid, total carotenoids and total anti-oxidants as compared to the control. 1-MCP (1.0 μL L⁻¹) treatment suppresses and delays the climacteric ethylene production with acceptable fruit quality during ripening at ambient temperature and is effective in extending the storage life up to 6 weeks with minimal loss of plum fruit quality.     

1-MCP结合冰温贮藏对葡萄采后品质及相关生理代谢的调控

以“乍娜”葡萄为试材,研究0.5μL/L和1.5μL/L 2个用量的1-MCP处理结合冰温贮藏(温度－0.3℃±0.3℃)对葡萄采后主要品质及相关生理指标的作用效果。结果表明：冰温贮藏结合2个浓度的1-MCP处理均可在不同程度上提高葡萄贮藏好果率并降低质量损失率和果梗褐变指数,抑制葡萄果穗呼吸强度和乙烯生成速率的增加,并能够有效抑制果实丙二醛(malondialdehyde,MDA)、超氧阴离子自由基(O2－ ·)、过氧化氢(H2O2)含量和脂氧合酶(lipoxygenase,LOX)活性的增加,保持或增大超氧化物歧化酶(superoxide dismutase,SOD)和过氧化物酶(peroxidase,POD)的活性;1μL/L 1-MCP处理结合冰温贮藏作用效果较好,使葡萄贮期较普通冷库对照延长20d。综上所述,适宜浓度的1-MCP处理结合冰温贮藏有利于提高葡萄采后贮藏品质和果实抗性、延缓果实衰老,在鲜食葡萄无硫保鲜方面具有非常好的应用前景。     

1-MCP处理结合冰温贮藏对磨盘柿果实软化衰老的影响

目的：探讨冷藏、冰温贮藏、1-甲基环丙烯（1-methylcyclopropene,1-MCP）处理结合冰温贮藏对采后柿果硬度和软化相关物质代谢的影响。结果：与冷藏处理相比,冰温贮藏有效抑制了乙烯生成,抑制了多聚半乳糖醛酸酶（PG）、纤维素酶（Cx）、淀粉酶活性的增加,抑制了可溶性果胶含量的升高,延缓了果肉硬度的降低,而1-MCP处理结合冰温贮藏对柿果实硬度的保持、抑制PG、Cx、淀粉酶活性升高的作用好于冰温单一贮藏,因此,1-MCP处理结合冰温贮藏是保持柿果实硬度较为适宜的贮藏方法。     

基于电子鼻分析1-MCP对‘香红’梨后熟进程的影响

香红’梨经1-甲基环丙烯（1-Methylcyclopropene,1-MCP）（1.0 μL·L-1）处理后,测定贮藏期（10 d）内果实的呼吸强度、乙烯释放速率变化,同时利用电子鼻对贮藏期内的果实挥发性气体变化进行分析。结果表明:与对照组相比,1-MCP处理抑制果实的呼吸强度和乙烯释放速率。电子鼻能区分对照组不同贮藏时期的果实挥发性气体,其中6、10 d的果实挥发性气体分别有明显变化。1-MCP处理组0、2、6、8 d的果实挥发性气体的响应值分布存在部分交叉,而4、10 d的挥发性气体分布区域相对独立。线性判别分析（linear discriminant analysis,LDA）结果中果实挥发性气体的分布区域更加集中,更能说明不同贮藏时期果实挥发性气体的分布情况。载荷（Loading）分析表明W5S、W2W和W2S三个传感器对区别不同处理的果实挥发性气体发挥了关键作用,1-MCP处理明显减少氮氧化合物（W5S）、有机硫化物和芳香族化合物（W2W）、醇类和部分芳香族化合物（W2S）三类物质的生成。总之,结合电子鼻分析,证明1-MCP明显抑制香红梨果实乙烯和部分挥发性气体的生成,因而延缓果实后熟进程。     

1-MCP处理结合激光微孔膜包装对采后水蜜桃的保鲜效果

以“霞辉8号”水蜜桃为试材,采用2 μL/L 1-甲基环丙烯(1-Methylcyclopropene, 1-MCP)熏蒸处理果实24 h后用激光微孔膜包装,研究1-MCP处理结合激光微孔膜(1-MCP+LMF)包装对水蜜桃保鲜效果的影响。结果表明,1-MCP+LMF包装处理显著降低了水蜜桃冷藏期间的呼吸强度和失重率（P<0.05）,贮藏35 d时分别比对照组低18.84 mg CO₂/kg·h和17.87%;可溶性固形物含量从贮藏时的7.92%上升到8.38%,对照组上升到10.04%;抗坏血酸含量贮藏结束时为对照组的3.39倍;超氧化物歧化酶、过氧化氢酶和抗坏血酸氧化酶活力显著高于对照（P<0.05）,从而减少了H₂O₂的积累,贮藏35 d后H₂O₂含量为对照组的78.86%;同时,1-MCP+LMF包装还抑制了多聚半乳糖醛酸酶和β-葡萄糖苷酶活力,进而延缓了原果胶含量的下降和可溶性果胶含量的上升,维持了桃果实较高的硬度,贮藏结束时硬度为贮藏时的42.88%,而对照组下降24.56%。以上结果表明,1-MCP处理结合激光微孔膜包装可显著减少水蜜桃冷藏期间失重和腐烂,延缓水蜜桃营养品质下降,抑制生理生化代谢活动,其货架寿命在5 ℃条件下可延长至28 d。     

1-MCP对净皮甜石榴的冷藏保鲜效果

对陕西临潼净皮甜石榴采后用不同浓度(0.25、0.5、1.0、1.5μL/L)1-MCP处理后于4℃冷藏,定期测定了部分采后生理指标并统计果实的腐烂情况。结果表明,1-MCP处理能维持果实相对较高水平的有机酸含量、出汁率和花青苷含量,抑制了石榴果皮相对电导率的上升速率,降低了石榴的乙烯释放速率,从而延缓果实的衰老,有效降低了冷藏期和货架期石榴的腐烂率与腐烂指数。在0.25～1.5μL/L的1-MCP浓度范围内,处理浓度越低,果实品质和保鲜效果越好。     

1-MCP对木纳格葡萄的保鲜效果

为寻找新型、无硫的鲜食葡萄保鲜方法,以新疆木纳格葡萄为试材,研究0.5、1.0和1.5 μL/L的1-MCP熏蒸处理对其在常温(25±0.5) ℃和冷藏(0~3) ℃贮藏期间果实的主要品质、生理指标及其作用效果的影响。结果表明:1-MCP熏蒸处理能在不同程度上降低常温贮藏条件下以及冷藏条件下葡萄的脱粒率、腐烂率、果穗失重率和果梗褐变,保持葡萄的硬度、可溶性固形物、V_C含量、可溶性糖含量以及可滴定酸含量。室温贮藏结束时,1.0 μL/L浓度1-MCP处理的葡萄可溶性糖含量为10.18%,比对照组高出29.36%,可溶性固形物比对照组高出20.65%,而失重率却比对照组低34.85%。冷藏贮藏结束时,1.0 μL/L浓度1-MCP处理的葡萄腐烂率为26.13%,比对照组低30.49%,而V_C含量比对照组高出34.38%。0.5 μL/L和1.5 μL/L的1-MCP处理对维持果实品质也有一定的作用,但是效果均不如1.0 μL/L处理的果实明显。综上所述,1.0 μL/L浓度的1-MCP处理的葡萄腐烂率最低,果实的外在品质和内在品质下降幅度最小,保鲜效果最好。     

1-MCP结合ClO2处理对冰温贮藏玫瑰香葡萄生理和品质的影响

以玫瑰香葡萄为试材,通过对不同处理方式果实在贮藏期间品质和生理生化指标的变化分析,探讨冰温贮藏(-0.5～-0.2℃)条件下,1-MCP和ClO2处理对果实的保鲜效果。结果表明,1.0μL/L1-MCP结合1.0μL/LClO2处理比1.0μL/L1-MCP、1.0μL/LClO2单独处理更能有效保持葡萄贮藏过程中的品质,并降低与衰老相关的生化反应,贮藏45d时1-MCP+ClO2处理的腐烂率和果梗褐变指数分别比对照低36.23%、12.50%,果实硬度仅下降了2.93kg/cm2,可溶性固形物含量和VC含量分别高于对照0.50%、2.52mg/100g;丙二醛含量低于对照5.86μmol.g-1,POD、SOD活性较对照增强,有效延缓了葡萄在贮藏过程中的衰老进程。     

不同处理对生鲜电商模式下“徐香”猕猴桃常温品质变化的影响

生鲜电商模式下,产品直接由冷库递送给消费者,传统的货架期概念转变为常温食用期。为探究该模式下"徐香"猕猴桃常温品质变化规律,确定适宜的贮藏及流通处理方式,首先通过感官评价和仪器测定,确定"徐香"猕猴桃的可食用硬度范围,进而研究1-MCP及不同包装处理对低温贮藏不同阶段果实常温食用品质影响,研究不同初始硬度果实食用期限。结果表明,"徐香"猕猴桃的可食用的硬度范围约为2.6~10.5 N,最佳的食用硬度范围为5.0~7.6 N;1-MCP可显著抑制猕猴桃软化,延长食用期,但不适于短期贮藏果实;纸箱加保鲜袋包装是常温食用期间最为适宜的包装方式,该包装方式均可显著延长短期低温贮藏及1-MCP处理长期贮藏果实的可食用期限及最佳可食用期限。常温食用期间,初始硬度不同果实可实现梯度软化,经不同时间达到可食用期和最佳可食用期,可满足消费者消费期内不同时段的食用要求。     

Quality improvement and extension of shelf life by 1-methylcyclopropene in plum as affected by ripening stage at harvest

Plum (Prunus domestica L. cv. ‘President’) fruits were harvested at two pre-climacteric stages of ripeness (stage 1 and stage 2), and then treated with 1-methylcyclopropene (1-MCP) at two doses (0.3 and 0.5 μl l⁻¹) followed by 1, 2, 3, 4 and 5 weeks of cold storage and their respective 7 days of shelf life at 20 °C. Both 1-MCP doses were effective in terms of ethylene inhibition during shelf life after cold storage, for both ripening stages. Similarly, lower weight losses, delayed colour changes, reduced softening rate and diminished ripening index were found in 1-MCP treated plums than in controls at both stages of ripeness. Hence, during cold storage and shelf life, the efficacy of 1-MCP on ethylene production, weight loss, pulp firmness and ripening index was dose-dependent, while for colour and respiration rate the dose-dependence was only found during shelf life. The storability of 1-MCP treated plums could be extended up to 4 weeks of cold storage plus 7 days at 20 °C, and only up to 1 week of cold storage plus 7 days at 20 °C for controls. Then, 1-MCP is an effective tool for quality improvement and extension of shelf life in plums, and fruit might be harvested in stage 2 of ripening, at which the most desirable organoleptic attributes had been developed on tree.     

不同处理对磨盘柿冷藏及货架期品质与生理的影响

以磨盘柿为试材,用浓度为1.0 μL/L的1-MCP处理,用高浓度CO2(85%~90%)处理24 h,探究不同处理方式(CO2脱涩、1-MCP处理后CO2脱涩、1-MCP与CO2脱涩同时处理)对冷藏及冷藏后货架期果实的品质与生理影响。结果表明,与CO2脱涩相比较,1-MCP处理后CO2脱涩可以有效降低柿果呼吸强度,抑制乙烯生成速率、柿果色泽的改变,延缓柿果质地的降低,维持果实营养物质(TSS、TA及Vc含量)在较高水平,有效减缓了挥发性香气成分的减弱。但1-MCP与CO2脱涩同时处理却加速了果实成熟且贮藏后期差异显著(P<0.05)。因此,柿果经1-MCP处理后再高浓度CO2脱涩不仅可脱涩还具有较好的保鲜效果。     

采后1-MCP和MAP处理对‘红富士’苹果冷藏和货架期品质的影响

对‘红富士’苹果进行1.0 μL/L 1-甲基环丙烯（1-methylcyclopropene,1-MCP）和自发气调包装（modified atmosphere package,MAP）处理,继而进行0 ℃冷藏和20 ℃货架贮藏。结果表明：贮藏期间,‘红富士’苹果果实硬度和可滴定酸含量下降,可溶性固形物含量升高,虎皮病和果心褐变增多。1-MCP处理能较好维持冷藏期间‘红富士’苹果果实硬度和可溶性固形物含量,降低了包装内CO2和乙烯含量。同时,1-MCP明显降低了冷藏期间虎皮病发病指数、果心褐变指数以及果柄端果肉褐变率,显著抑制果皮α-法尼烯及共轭三烯的生成。1-MCP＋MAP结合使用可较好维持果实可滴定酸含量和果皮色泽、抑制果柄端果肉褐变。综合分析认为,1-MCP＋MAP处理能较好维持‘红富士’果实冷藏和货架期间的品质,并显著抑制果实虎皮病的发生。     

纸片型1-MCP处理对安溪油柿果实采后生理和贮藏品质的影响

研究了纸片型1-甲基环丙烯（1-methylcyclopropene,1-MCP）处理对安溪油柿果实采后生理和贮藏品质的影响。采后安溪油柿果实用1.35 μL/L的1-MCP处理12 h后,在（20±1）℃、相对湿度85%下贮藏。结果表明：与对照相比,1-MCP处理能有效降低采后安溪油柿果实呼吸强度;抑制果实表面色度a*值、b*值、C*值、L*值和色调角h的变化,抑制果皮叶绿素含量下降和类胡萝卜素含量上升,降低果实转红指数,并保持较好的果实外观色泽;此外,1-MCP处理能保持较高的果实硬度及可溶性固形物、可滴定酸、总糖、蔗糖、还原糖质量分数和VC、单宁含量,减少果实质量损失。因此认为,1.35 μL/L纸片型1-MCP处理可有效延缓采后安溪油柿果实后熟衰老、改善果实贮藏品质。     

1-MCP可控缓释包装纸对杏果实贮藏品质的影响

本文以1-甲基环丙烯（1-Methylcyclopropene, 1-MCP）为保鲜剂,将其与不同比例的乙基纤维素（Ethyl cellulose ether,EC）和聚丙烯酸（Polyacrylic acid,PAA）混合匀浆后涂布至纸基上制成1-MCP可控缓释包装纸,研究其释放机制,并利用制作的1-MCP可控缓释包装纸处理在2 ℃下贮藏的赛买提杏,研究1-MCP可控缓释包装纸对杏果实贮藏过程中呼吸强度、硬度、可滴定酸、可溶性固形物、果皮颜色、商品率的影响,以期得到一种能有效延长杏果实贮藏期的保鲜纸。结果表明,在95% RH,2 ℃和80%聚丙烯酸的条件下,1-MCP粉末的颗粒塌陷使气体缓慢释放,释放机制参数为0.49,释放速率随着PAA含量的升高而增大。1-MCP可控缓释包装纸能抑制杏果实呼吸强度高峰的到来,延缓硬度、可滴定酸和可溶性固形物含量的降低,并保持果皮颜色。说明1-MCP可控缓释包装纸能有效保持在低温环境下贮藏的杏果实品质,并为1-MCP可控缓释包装纸运用到其它果蔬的贮藏中提供一定的参考。     

1-MCP和预贮对深州蜜桃采后生理和品质的影响

为保持深州蜜桃冷藏期间良好的品质, 延长贮藏时间, 采用1 . 0 μ L / L 1 - 甲基环丙烯
（1-methylcyclopropene,1-MCP）熏蒸和预贮（8 ℃、5 d转入0 ℃）的方法对采后深州蜜桃进行处理,测定0 ℃冷
藏期间果实呼吸速率、乙烯释放速率和品质的变化。结果表明,1-MCP处理能够明显抑制桃果实冷藏期间的呼吸速
率和乙烯释放速率,推迟呼吸高峰期的出现;同时延缓了果实软化,抑制可溶性固形物含量上升,降低了果实的褐
变指数和腐烂指数;预贮促进了果实后熟,但预贮和1-MCP处理均明显降低了贮藏期果实褐变度和酚类物质含量,
二者结合处理对抑制果实褐变效果最佳。