1-MCP处理对蓝莓冷藏保鲜效果的影响

以'蓝丰'蓝莓(Vaccinium corymbosum L.'Bluecrop')果实为试材,采用1.0μL/L1-甲基环丙烯(1-MCP)处理蓝莓24 h,研究1-MCP处理对蓝莓果实冷藏保鲜效果的影响。对蓝莓果实贮藏进程中的硬度、弹力、黏力等质构特性,以及相关生理指标失重率、VC含量、花青苷含量和抗氧化能力等进行测定。结果表明:1-MCP处理可以有效地保持果实水分含量,延缓果实硬度下降,保持果实中VC含量。1-MCP处理的蓝莓果实颜色比对照果实颜色浅,能够延缓果实贮藏前期的花青苷形成。另外,1-MCP处理抑制了果实贮藏后期总抗氧化能力的下降,维持了果实较高的营养价值。     

Modelling Cooling of Packaged Fruit Using 3D Shape Models

This study presents a novel methodology to model the cooling processes of horticultural produce using realistic product shapes rather than commonly used simplified 3D shapes, such as spheres. Variable 3D apple and pear models were created by means of a validated geometric model generator based on X-ray computed tomography images. The fruit were randomly stacked into a geometrical model of a corrugated fibreboard box using the Discrete Element Method. A forced-air cooling process was simulated for three such apple filling patterns using CFD and the results were compared to those obtained with fruit represented by equivalent spheres. No significant difference in average aerodynamic resistance between the real apple shape and its spherical representation was found. The main contributor to the overall pressure drop was the package design rather than product shape. However, large differences in local air velocity and convective heat transfer coefficients were found between the two representations. The degree of cooling uniformity between individual fruit was overestimated when using simplified product shapes: real apple fruit shapes cooled less uniform. This difference between real and simplified product shapes was even larger for a box filled with pear fruit that are more different from a spherical shape. These results demonstrate that improved computer-aided design approaches help in simulating more accurate convective cooling processes. In a next step, such simulations will be used for multi-objective optimization of packaging in terms of cold chain efficiency and cooling uniformity.     

Evolution of Moisture Distribution During Storage in a Composite Food Modelling and Simulation

In order to predict moisture transfer in a composite food, a mathematical model was developed and tested on a 2‐components system constituted of a sponge‐cake in contact with a fresh wet filling. Using independent sorption kinetic experiment, a power law was found as representative of the effect of moisture content on water effective diffusivity of sponge‐cake. The parameters of power law was then adjusted using the model optimization procedure on moisture profiles measurements of sponge‐cake in contact with a 0.99 water activity agar gel at 20°C. The model was validated with 0.95 and 0.90 water activity agar gels and successfully used to predict moisture transfer in a real food (processed cheese/sponge‐cake system).     

梨质地变化规律与动力学模型

为了研究梨在采后贮藏过程中质地变化规律以对可食用期评估,实验测定了‘黄金’、‘玉冠’和‘丰水’3 个品种梨在贮藏过程中泰勒（Magness-Taylor,MT）硬度、果肉硬度、果肉弹性率和感官总体可接受度的变化,并建立了质地参数变化的动力学模型。结果表明：MT硬度、果肉硬度、果肉弹性率总体上均随贮藏时间延长逐渐降低,但果肉弹性率对贮藏时间变化的灵敏性优于MT硬度和果肉硬度,且果肉弹性率与感官总体可接受度的相关性更强;采用零级和一级动力学模型、Logistic模型和威布尔模型对各质地参数拟合,结果均是威布尔模型的拟合结果最佳;通过威布尔模型和感官评定,得到‘黄金’、‘玉冠’和‘丰水’梨的MT硬度分别低于14.762、10.411 N和7.255 N,果肉硬度分别低于8.215、7.438 N和5.181 N,果肉弹性率分别低于4.571、5.572 N/mm和3.609 N/mm后不具备商品价值,不建议食用。研究结果可为梨的贮藏和食用提供指导依据。     

应用DGGE技术研究玉米储藏过程中的霉菌群落时空分布特征

研究储粮过程中霉菌污染的发生规律,旨在减少霉菌及真菌毒素的污染,提高我国粮食安全。利用变性梯度凝胶电泳研究粮库中不同储藏时间和空间的玉米样品中霉菌群落的特点。结果表明,本研究中储藏玉米的霉菌污染以青霉、曲霉和毛霉为主,其霉菌群落的变化与储藏时间具有较强的相关性,而与其在粮库中的空间位置相关性较小。在储藏时间方面,储藏1a和3a的样品中霉菌群落具有较大的差异,而储藏2a样品的霉菌群落处于过渡期状态。本实验探究储藏玉米中霉菌群落的时空分布特征,可以为建立准确可靠的霉菌群落模型提供理论支持和数据支持。     

1-MCP处理对杨桃果实采后生理和贮藏品质的影响

该文探讨1-甲基环丙烯（1-MCP）处理对“香蜜”甜杨桃果实采后生理和贮藏品质的影响。采后‘香蜜’甜杨桃果实用0.6 μL/L的1-MCP处理12 h后,在(15±1） ℃、相对湿度90%下贮藏。贮藏期间测定果实呼吸强度、细胞膜相对渗透率、果皮叶绿素和类胡萝卜素含量、果实硬度、可溶性固形物和可滴定酸含量、果实好果率、失重率及感官品质等指标的变化。结果表明：与对照果实相比,1-MCP处理能有效降低杨桃果实的呼吸强度和呼吸峰值,抑制果实外观颜色转变,保持较高的果实硬度和可滴定酸含量,延缓果实细胞膜相对渗透率升高,减少果实失重和腐烂。经1-MCP处理的果实在(15±1) ℃、相对湿度90%下贮藏20 d时的好果率为78%,而对照果实只有63%。因此认为,0.6 μL/L 1-MCP处理可延缓采后‘香蜜’甜杨桃果实成熟衰老和保持果实贮藏品质。     

猪胴体冷却过程中表面微生物的时空分布研究

为了研究在猪胴体冷却过程中风速、温湿度及微生物数量的变化情况,建立猪胴体在冷却期间微生物的时空变化的模型,从而为冷库防治污染提供依据,本文采用热敏式风速仪测量夏季冷库内的风速、温湿度,利用擦拭法测定猪胴体表面微生物菌落总数,最终得到猪胴体冷却过程中微生物的时空变化情况,结果表明:在冷却前期(冷却时间0~8 h),由于冷库门的开启、猪胴体本身散热等原因导致冷库内的风速并非均匀分布,温湿度也逐渐上升,从而导致冷库内不同位置处猪胴体表面微生物的菌落总数均有不同程度的增加,其中冷库中间位置的猪胴体表面菌落总数显著增加(P<0.05),其余位置的猪胴体表面菌落总数增加不显著(P>0.05);在冷却后期(冷却时间8~14 h),冷库门关闭,不再有猪胴体进入冷库,冷库内的温湿度迅速下降,使猪胴体表面微生物的菌落总数显著减少(P<0.05)并趋于稳定;猪胴体迎风面的菌落总数略高于背风面,其中前腿、胸腹腔的微生物较多;相关性分析结果表明猪胴体表面菌落总数与温度、湿度、冷却时间、采样部位有极显著的相关关系(P<0.01),与风速有显著的相关关系(P<0.05)。总之,随着冷却时间的延长,猪胴体表面菌落总数有显著差异(P<0.05),冷库内不同位置的猪胴体表面菌落总数不同,同一猪胴体的不同部位之间也有差异,这为冷库的改进布局和污染控制奠定了基础。     

Fruit quality and physiological responses of litchi cultivar McLean's Red to 1-methylcyclopropene pre-treatment and controlled atmosphere storage conditions

The effect of 1-MCP pre-treatment and two different controlled atmosphere storage conditions (CA-1, 17% O₂ + 6% CO₂; CA-2, 7% O₂ + 3% CO₂) on fruit quality parameters and physiological changes with respect to pericarp browning in ‘McLean's Red’ litchi were investigated. Fruits were pre-treated with 1-MCP (500 nl/l) and held at CA-1 or CA-2 for 21 d at 2 °C and at 90% RH. Stand-alone CA-1 or stand-alone CA-2 and the commercially adopted sulphur dioxide (SO₂) treatment were included in this study for comparison. Of the five treatments 1-MCP + CA-1 was most effective in preventing browning, loss of red colour (colour value a*) of the pericarp, ascorbic acid content; and retaining acceptable SSC/TA and taste. Fruit from 1-MCP + CA-1 showed higher overall acceptance after 21 d storage without any off-flavour according to the sensory panel data.1-MCP + CA-1 reduced the polyphenol oxidase (PPO) and peroxidase (POD) activity, retained membrane integrity and anthocyanin content during storage. Although SO₂ treatment prevents browning it showed negative effects on SSC/TA, taste and membrane integrity. Stand-alone CA-2 condition indicated higher pericarp browning, PPO, POD activity and loss of membrane integrity. Therefore, 1-MCP pre-treatment and CA-1 retains overall fruit quality for up to 21 d.     

1-MCP对黄金百香果贮藏品质及风味变化的影响

为明确1-甲基环丙烯（1-MCP）对百香果采后品质及风味变化的影响,果实采后用1-MCP（0.8 μL·L?1,12 h）处理后,评测常温贮藏过程中果面色泽、果汁糖酸和维生素C（V_C）含量变化,并采用气相色谱-离子迁移谱联用（Gas Chromatography-Ion Mobility Spectrometry, GC-IMS）技术分析挥发性风味组分差异。结果表明,1-MCP处理后常温贮藏4 d可延缓果面色泽转黄,对果实可溶性固形物（TSS）无显著影响,一定程度上提高了可滴定酸（TA）含量,而对V_C含量的影响在不同贮藏期略有不同。1-MCP处理的果实常温贮藏4 d挥发性风味组分种类和含量均显著降低,包含GC-IMS检测出的35种已知和11种未知化合物,1-MCP处理的黄金百香果风味接近与刚采摘及常温贮藏2 d的果实。     

高新技术在果蔬贮藏中的应用

本文介绍减压贮藏、辐照处理、电离处理、生物技术保鲜、冰温贮藏等几种高新技术在果蔬贮藏中的应用。     

论三维水墨动画角色造型的虚与实

三维水墨动画是传统文化与现代技术的完美结合。数字水墨动画汲取了传统水墨画的精神要素,突出特点是将水墨画的虚实特性展现在动画中。表现为动画角色造型的虚实处理,从角色设计稿到三维模型到材质模型到渲染输出合成,整个过程都使用虚实艺术处理手法。     

Modelling and simulation of 3D orthogonal fabrics for composite applications

The present paper focuses on geometric and micromechanical modelling of 3D orthogonal fabrics for composite applications and employs meso-finite element (FE) modelling for it. FE modelling of textile composites is a powerful tool for the homogenisation of mechanical properties, study of stress–strain fields inside the unit cell, determination of damage initiation conditions and sites and simulation of damage development and associated deterioration of the homogenised mechanical properties of the composite. Meso-FE can be considered as a part of the micro-meso–macro-multi-level modelling process, with micromodels (fibres in the matrix) providing material properties for homogenised impregnated yarns and fibrous plies, and macromodel (structural analysis) using results of meso-homogenisation.     

1-甲基环丙烯结合水杨酸处理维持百香果果实贮藏品质

为延长百香果的贮藏期并保持贮藏过程中的品质,对比研究2 mmol∕L 水杨酸（salicylic acid,SA）、1 mmol∕L 1-甲基环丙烯（1-methylcyclopropene,1-MCP）、1-MCP 结合SA 处理对紫色百香果果实采后贮藏期间品质、活性氧、抗氧化酶指标的影响。百香果果实经SA、1-MCP 和1-MCP 结合SA 处理后,一定程度抑制乙烯的释放和脂氧合酶（lipoxygenase,LOX）活性,促进几丁质酶（chitinase,CHI）和β-1,3-葡聚糖酶（β-1,3-glucanase,GLU）的活性,增强抗氧化和抗病性作用,降低腐烂率。但因SA 可以增强呼吸,故导致凹陷和失重,加快总酸流失;1-MCP 抑制呼吸作用,增强超氧化物歧化酶（superoxide dismutase,SOD）活性,有利于控制失重和凹陷,但其对过氧化物酶（peroxidase,POD）活性的影响不利于控制衰老。1-MCP 结合SA 对POD 活性,CHI 活性以及GLU 活性的正向影响强于单独使用1-MCP 或SA 处理。因此,1-MCP 结合SA 通过提高百香果果实的抗氧化能力和抗病能力,降低百香果果实的凹陷、失重和腐烂率,且可有效避免单独使用1-MCP 或SA 处理的不良作用,协同维持百香果果实采后贮藏品质。     

Influence of 1-Methylcyclopropene (1-MCP) on Postharvest Storage Quality in Green Bell Pepper Fruit

The goal of this research was to evaluate the efficiency of 1-methylcyclopropene (1-MCP) on maintaining the quality parameters and antioxidant activity of bell pepper cv. Selika (an original red cultivar) and cv. H1530 (??ever-green?? line) after 18?days storage at 7°C and 3?days at 20°C. Fruits were harvested at green color, from a commercial shade net house in the desert region in Israel. In both cultivars, 600?nL?L^?1 1-MCP reduced weight loss and maintained firmness more than control or 900?nL?L^?1 1-MCP. Overall, 1-MCP treatment had a pronounced effect on delaying ripening processes as shown by inhibiting color changes, decreasing decay, and maintaining quality of non-climacteric green pepper fruit. 1-MCP treatment reduced the lipophilic antioxidant activity of this fruit, but the hydrophilic antioxidant activity remained similar to that observed at harvest.     

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。     

ClO_2和1-MCP对青皮核桃二步贮藏的效应

为了探究高效、无公害的核桃保鲜方法,以"辽宁2号"青皮核桃为试材,分别采用80 mg/L二氧化氯(Cl O2)和0.5μL/L 1-甲基环丙烯(1-MCP)处理,将青皮核桃(湿鲜坚果)二步贮藏于0~1℃,相对湿度70%~80%条件下,并以清水浸泡为对照。贮藏期间观测果实的保鲜效果、核仁抗氧化特征及品质的变化。结果表明:Cl O2处理延迟青皮果实腐烂6 d,延迟脱青皮坚果霉变5 d。第1步贮藏结束时(60 d)Cl O2、1-MCP和对照果实的腐烂指数分别为14.2%,20.1%,18.7%;第2步贮藏40 d,二步贮藏结束时(60+40)d,三者坚果的霉变率分别为11.6%,30.3%,24.8%。种皮、核仁的总酚和类黄酮含量分别于(60+20)d,(60+30)d前上升,之后下降,Cl O2处理的峰值均显著高于其他处理(P0.05)。三者的核仁抗氧化活性与其总酚变化一致。Cl O2处理的核仁感官品质下降以及酸价、过氧化值、可溶性蛋白含量、丙二醛(MDA)含量和脂氧合酶(LOX)活性增加均显著慢于对照,而1-MCP处理的上述变化居中。Cl O2处理明显延缓了青皮核桃腐烂和湿鲜坚果霉变,保持了较高的核仁品质。1-MCP仅延缓了核仁品质下降。     

Investigating the Effects of Table Grape Package Components and Stacking on Airflow, Heat and Mass Transfer Using 3-D CFD Modelling

The flow phenomenon during cooling and handling of packed table grapes was studied using a computational fluid dynamic (CFD) model and validated using experimental results. The effects of the packaging components (bunch carry bag and plastic liners) and box stacking on airflow, heat and mass transfer were analysed. The carton box was explicitly modelled, grape bunch with the carry bag was treated as a porous medium and perforated plastic liners were taken as a porous jump. Pressure loss coefficients of grape bunch with the carry bag and perforated plastic liners were determined using wind tunnel experiments. Compared with the cooling of bulk grape bunch, the presence of the carry bag increased the half and seven eighth cooling time by 61.09 and 97.34 %, respectively. The addition of plastic liners over the bunch carry bag increased the half and seven eighth cooling time by up to 168.90 and 185.22 %, respectively. Non-perforated liners were most effective in preventing moisture loss but also generated the highest condensation of water vapour inside the package. For perforated plastic liners, cooling with a high relative humidity (RH) air minimised fruit moisture loss. Partial cooling of the grape bunch inside the carry bag before covering it with a non-perforated plastic liner maintained the required high RH inside the package without condensation. The stacking of packages over the pallet affected the airflow pattern, the cooling rate and moisture transfer. There was a good agreement between measured and predicted results. The result demonstrated clearly the applicability of CFD models to determine optimum table grape packaging and cooling procedures.     

龙眼果实品质劣变和贮藏保鲜技术研究进展

龙眼是中国南方重要的亚热带特色水果,其果实成熟于高温季节,采后极易发生果皮褐变、果肉自溶及病原菌侵染所致果实腐烂等品质劣变,是限制龙眼果实采后保鲜期的主要因素。本文就龙眼果实采后品质劣变(果皮褐变、果肉自溶、病原菌侵染导致果实变质腐烂),热处理、紫外线-强效应波长(UV-B)辐照处理、二氧化氯处理、壳聚糖处理、低温贮藏、气调冷藏、微生物生物保鲜等龙眼果实采后处理及保鲜技术的国内外研究进展进行综述,旨在为延缓采后龙眼果实品质劣变、延长龙眼果实保鲜期提供技术参考。     

橄榄果实采后病害和保鲜技术研究进展

橄榄果实易发生采后病害而导致果实失水皱缩和不耐贮藏,严重影响橄榄产业的发展。为延长橄榄果实贮藏期提供理论依据和实践指导,对国内外橄榄煤烟病、炭疽病、焦腐病、果腐病、灰斑病、疫病、青霉病等橄榄果实主要采后侵染性病害的症状及其病原特征,采后生理性病害如低温冷害,及橄榄果实采后贮藏保鲜技术的研究进展进行了综述。