醋酸酯淀粉抗菌材料的性质

以疏水性的醋酸酯淀粉为基材,壳聚糖为抗菌剂制备了醋酸酯淀粉抗菌材料。通过考察醋酸酯淀粉取代度对壳聚糖分散性、材料力学性质、热性质和抗菌活性的影响,发现醋酸酯淀粉的取代度由1.9增加到2.9,抗菌材料表面和断面越均一,壳聚糖的分散性越好;但高取代度会削弱淀粉分子与壳聚糖分子间的相互作用力,使抗菌材料的断裂伸长率由33.7%降低至8.9%,玻璃化转变温度由74.8℃升高至86.4℃,拉伸模量由205 MPa增至260 MPa。同时过高的取代度又会影响壳聚糖的溶出,降低材料的抗菌活性。     

抗菌活性包装膜研究进展

活性包装是食品包装发展的新方向,其中的抗菌包装得到了人们的高度重视和广泛研究。在查阅有关文献的基础上,本文全面论述了抗菌包装膜目前的发展现状和趋势,对抗菌活性包装膜的机理、分类以及使用的关键抗菌物质进行重点阐述,也提出了抗菌包装膜今后值得研究的几个问题。     

Extruded Blends of Chitosan and Ethylene Copolymers for Antimicrobial Packaging

Chitosan was melt‐processed with an ethylene methyl acrylate copolymer ionomer and with an ethylene vinyl acetate copolymer to create antimicrobial extruded films. The key to obtaining a successful antimicrobial blend was the use of solid chitosonium acetate that remained after evaporation of water from the chitosan solution. When solid free‐flowing powders of chitosonium acetate were formed by spray drying chitosan solutions, blended in an extruder (at 2.5% and 4% chitosan) with Elvax® 3175 ethylene vinyl acetate copolymer, and extruded through a film die onto a chill roll to form films, the films exhibited antimicrobial activity against Escherichia coli 25922, Salmonella enterica serovar Enteritidis Nal^R, and Listeria monocytogenes Scott A. The log₁₀ reductions in CFU/ml after 24 h in a shake‐flask test were near 2 for films containing 4% chitosan. This melt‐blending/extrusion approach is expected to open applications for chitosan‐based antimicrobial packages and articles that were impossible or impractical with chitosan coatings. Copyright © 2011 John Wiley & Sons, Ltd.     

Physico‐Mechanical Properties of Starch‐Based Films Containing Naturally Derived Antimicrobial Agents

Thermoplastic starch (TPS) films containing relatively low [0.75 ± 0.08% (w/w)], intermediate [1.08 ± 0.04% (w/w)] and high [3.20 ± 0.29% (w/w)] levels of the antimicrobial (AM) agents carvacrol, linalool and thymol were prepared, and their physico‐mechanical and optical properties were evaluated. Addition of these AM agents to TPS film reduced the tensile strength with increasing AM agent content, with a significant effect observed at the highest AM agent concentration. The Young's modulus and elongation at break increased with increasing AM agent concentration, especially at the highest formulation concentration of AM agent. Films having a low or intermediate formulation concentration of AM agent exhibited no significant effect on their water vapour permeability, transparency and thermal properties when compared to the control film. Although scanning electron microscope imaging suggested a significant and progressive change in the surface morphologies of the films with AM agent concentration, the overall effects on the tested properties were not significant. This suggests that the direct incorporation of AM agents into TPS films did not adversely affect the films, particularly at lower AM agent concentrations. Copyright © 2013 John Wiley & Sons, Ltd.     

Conservation of Bakery Products Through Cinnamaldehyde Antimicrobial Films

In this study, an antimicrobial film containing cinnamaldehyde was developed to pack bread and pastry made without preservatives. These products were wrapped with the antimicrobial films and packaged in low‐density polyethylene bags. The antimicrobial activity of the films, the migration of the cinnamaldehyde in the films to the products and product acceptance by consumers were evaluated. Samples of bread and pastry packaged with films without the antimicrobial were used as controls. When samples of bread packaged with the cinnamaldehyde films were analysed, the films were found to be effective in inhibiting the growth of aerobic mesophiles, yeast and mould. The control sample was observed to have twice as much growth (four log cycles) compared with the other treatments after 12 days of storage. After 60 days, the samples of pastry dough showed a reduction of two and three log cycles of growth for aerobic mesophiles and Staphylococcus spp. for the 5 and 10% films, respectively. However, the amounts of yeast and mould in samples packed in either 5 or 10% antimicrobial films did not increase over the storage period. In all evaluations, water activity did not influence the microbiological results. The content of cinnamaldehyde that migrated from the film (5%) to the pastry dough and bread were 0.005 g/g and 0.0025 g/g, respectively, after 3 days of storage at 23 ± 2 °C. This amount of the antimicrobial influenced the acceptance of the pastry dough compared with the control but did not influence the acceptance of the bread, possibly due to the smaller amount of cinnamaldehyde detected in samples of bread in relation to the samples of pastry dough. Copyright © 2013 John Wiley & Sons, Ltd.     

Natural Antimicrobial – Containing EVOH Coatings on PP and PET Films: Functional and Active Property Characterization

Natural antimicrobials are currently being tested by many researchers for active packaging applications as a response to consumer demands for safer food products. In previous work, several packaging materials consisting of ethylene vinyl alcohol (EVOH)‐coated polypropylene (PP) films containing essential oils or their constituents as active agents were successfully developed and tested for antimicrobial activity. In this work, selected films from those materials, namely EVOH coatings with carvacrol, citral, marjoram essential oil, or cinnamon bark essential oil, on PP and polyethylene terephthalate (PET) substrates, were subjected to diverse physicochemical analyses in order to assess their suitability for food packaging applications. Concretely, the investigated properties were the stability of EVOH coatings on PP and PET substrates, the retainability of EVOH matrices for active compounds, the mechanical, optical, surface and barrier properties of the final active films and the effects of a matrix modification based on the addition of bentonite nanoclay on the performance of PP/EVOH active packages studied in actual working conditions. Results showed that the application of corona discharge followed by a polyethyleneimine‐based primer was the best anchorage treatment available to stabilize EVOH coatings on PP and PET substrates. Furthermore, they demonstrated that the retention of active agents into EVOH matrices ranged from low to moderate, depending on the embedded substance, and that their presence into an EVOH coating in the final multilayer films did not noticeably affect their mechanical, optical or barrier properties, although it considerably improved their wettability. They also indicated that the inclusion of bentonite nanoparticles into their carrier layers substantially enhanced the performance of the final packages, while maintaining or slightly improving their other physical properties. Hence, as a conclusion, all the assayed multilayer films were considered perfectly valid for food packaging applications, and the incorporation of bentonite nanoclay to their carrier layers was also highly recommended. Copyright © 2014 John Wiley & Sons, Ltd.     

胶原、壳聚糖及其共混膜对红细胞的影响

利用原子力显微镜高分辨、低损伤的成像能力,研究比较了壳聚糖膜(CSF)、胶原膜(COF)、胶原/壳聚糖共混膜(COF/CSF)对红细胞的影响。结果显示,壳聚糖膜对红细胞的粘附、聚集作用明显,导致红细胞形态异常甚至碎裂。胶原膜上的红细胞外形不规则,但细胞无碎裂。共混膜对红细胞有一定的粘附作用,对细胞形态的影响程度界于两种单组分膜之间。     

Immobilization of Lysozyme on Food Contact Polymers as Potential Antimicrobial Films

The objective of this work was to investigate the feasibility of incorporating an antimicrobial enzyme (lysozyme) into polymers which are suitable for food contact. Hen egg white lysozyme was immobilized on polyvinyl alcohol (PVOH) beads, nylon, 6,6 pellets and cellulose triacetate (CTA) films. Polyvinyl alcohol and nylon 6,6 yielded low activity against a suspension of dried Micrococcus lysodeikticus cells, while CTA yielded the highest activity; 1.25 cm²/ml (CTA film area to substrate volume ratio) fully hydrolyzed a 0.015% (w/v) suspension of dried cells in 30 min. The activity retention of lysozyme immobilized on CTA was 90% after one use and 60% after 20 repeated uses. The amount of enzyme added to the film during immobilization affected the activity of the immobilized lysozyme; highest activities were obtained when CTA films were formed by adding 150–250 mg lysozyme per g polymer. No significant effect of CTA film thickness on lysozyme activity was observed. Viability of M. lysodeikticus grown on tripticase soy broth (TSB) at 30°C was decreased in the presence of CTA film containing lysozyme. The film (0.01 cm²/ml TSB) was inhibitory and bactericidal against 10³ and 10⁸ c.f.u./ml M. lysodeikticus respectively. © 1997 John Wiley & Sons, Ltd.     

壳聚糖季铵盐/有机累托石纳米复合材料的抗菌性能研究

合成了壳聚糖季铵盐, 并通过溶液插层法将其插层进入有机累托石层间制备纳米复合材料, 研究表明, 当壳聚糖季铵盐与有机累托石的质量比为2∶1时, 其获得了4.8nm的最大层间距. 抗菌结果显示, 在偏酸、中性及偏碱性条件下, 所有的纳米复合材料都具有较好的抗菌性能, 且与有机累托石的含量和层间距成正比. 与壳聚糖季铵盐及有机累托石相比, 纳米复合材料对革兰氏阳性菌、革兰氏阴性菌及真菌的抗菌性能大大提高, 对金黄色葡萄球菌和枯草芽孢杆菌的最小抑制浓度仅为0.00313% (W/V), 且能在30min内杀死90%以上的金黄色葡萄球菌, 80%以上的大肠杆菌. 最后, 通过TEM和SEM结果探讨了其抗菌机理.     

壳聚糖/无机物纳米复合材料在抗菌方面的研究进展

壳聚糖作为一种天然高分子有机物,具有良好的生物相容性、可降解性和抗菌性,在抗菌方面已有一定的应用,但其抗菌性能易受自身因素和外界条件的影响,因此如何巩固和加强壳聚糖的抗菌性能并进行应用成为了研究的热点。将壳聚糖与无机物纳米材料复合,有机和无机组分协同互补,能显著提高材料的抗菌性能,复合材料还具有优异的机械强度和生物相容性,可广泛应用于水处理、食品、纺织、化妆品和医学等领域,引起了科研人员的密切关注。本文总结了壳聚糖的抗菌机理和影响抗菌性能的因素,详细介绍了壳聚糖与金属、金属氧化物、层状硅酸盐和碳材料等无机物复合后的纳米材料在抗菌方面的应用,同时对其在抗菌领域的发展前景进行了展望。     

Development and evaluation of antimicrobial natamycin‐incorporated film in gorgonzola cheese conservation

Conservation of food products depends on product quality and packaging suitability. The objective of this work was to develop and evaluate the antimicrobial efficiency of natamycin‐incorporated film in the production process of Gorgonzola cheese. It aims to optimize the production process and increase shelf‐life and food safety for the consumer. Films with different concentrations of natamycin were produced and tested in Gorgonzola cheeses to evaluate its efficiency against Penicillium roqueforti on the cheese surface. Films with 2 and 4% natamycin presented satisfactory results for fungus inhibition and the amount of natamycin released to the cheese was below that allowed by the legislation. Copyright © 2006 John Wiley & Sons, Ltd.     

壳聚糖的抗菌性能研究

本文考察了不同分子量壳聚糖对大肠杆菌和金黄色葡萄球菌的抗菌抑菌性能 ,初步找出了壳聚糖分子量和浓度对抗菌抑菌作用的影响 ,提出了壳聚糖的抗菌机理。研究发现 :分子量在 3 0万以下时 ,壳聚糖对金黄色葡萄球菌的抗菌作用随分子量减小而逐渐减弱 ;对大肠杆菌分子量越小 ,抗菌作用越明显。     

LiOH/尿素溶剂体系制备高强度壳聚糖水凝胶膜

本文采用冷冻爆破法,将壳聚糖在LiOH/尿素溶液中溶胀,-60℃冷冻结冰,解冻搅拌后得到澄清壳聚糖溶液。壳聚糖碱溶液在硫酸/乙醇凝固浴中反相沉析,得到壳聚糖凝胶膜。此碱性溶剂体系法能避免壳聚糖降解,提高力学强度。力学测试结果表明,壳聚糖水凝胶膜拉伸强度为2.28MPa,最大拉伸应变(ε)达到226%。SEM观测到水凝胶微观结构类似蜂窝状,孔径均匀、致密,大小分布为50nm～5μm;XRD分析结果表明,碱溶液体系处理后壳聚糖晶型由α型转变成β型,结晶度降低。致密的结构和低结晶度是壳聚糖凝胶膜透明性和力学强度提高的重要原因。该性能优异的壳聚糖凝胶膜在关节软骨、创口敷料等方面有良好的应用前景。     

壳聚糖/纳米TiO2杂化材料的制备及抗菌性能表征

制备了壳聚糖/纳米TiO2杂化膜,表征了其抗菌性能,分析了影响TiO2纳米粒子在壳聚糖溶液中分散性的影响因素。FT-IR、AFM分析了杂化膜的结构与形态。表明促进TiO2颗粒良好分散有四个主要因素:(1)表面电荷的重新分布;(2)空间保护作用;(3)化学键的相互作用;(4)超声分散。抗菌实验表明壳聚糖/纳米TiO2杂化膜具有很强的抗菌性能,细菌的形态学变化具有两个显著的特点:(1)细胞内物质渗漏,在细胞周围形成了环状结构;(2)细胞表面囊泡的形成。     

抗菌食品包装研究进展

综述了抗菌高分子食品包装的原理、检测方法、相关法规以及未来的发展方向,并对各种抗菌技术作了详细的论述。指出开发新型生物活性抗菌剂,通过物理、化学方法改性高分子使之具有杀菌能力,尤其是纳米抗菌技术的应用,将是抗菌包装最具前景的发展方向。     

Release of Thymol,Cinnamaldehyde and Vanillin from Soy Protein Isolate Films into Olive Oil

This study investigates the release of thymol, cinnamaldehyde and vanillin from soy protein isolate (SPI) films into olive oil. The SPI‐based films were casted with thymol, cinnamaldehyde and vanillin to obtain antimicrobial packaging films. The release of thymol, cinnamaldehyde and vanillin from the SPI films into olive oil at temperatures of 5°C, 20°C, 40°C and 60°C was determined by high‐performance liquid chromatography. The partition coefficients of thymol, cinnamaldehyde and vanillin between the SPI film and the olive oil were obtained. They decreased linearly with the increase of temperature. The diffusion coefficients of thymol, cinnamaldehyde and vanillin were determined by fitting the mathematical model to the experimental data. The Arrhennius equation could adequately describe the relationship between the temperature and the diffusion coefficients of thymol, cinnamaldehyde and vanillin, respectively. The activation energies for the release of thymol, cinnamaldehyde and vanillin were obtained, and they were respectively 55.92, 57.34 and 18.32 kJ mol^?1. Copyright © 2011 John Wiley & Sons, Ltd.     

Evaluation of Antifungal Activity of Antimicrobial Agents on Cheddar Cheese

The antifungal activity against Aspergillus niger of the antimicrobial (AM) agents linalool, carvacrol and thymol incorporated in the coatings of starch‐based films was investigated. The activity was initially determined on a solid medium using the modified microatmosphere method and then examined on Cheddar cheese. On the solid media, all the AM films demonstrated a significant inhibitory effect against A. niger growth. The inhibitory effect of the AM films containing 2.38% (w/w) AM agents is reflected by the colony diameters that were 29.3, 25.4 and 21.3 mm for linalool, carvacrol and thymol, respectively, at 25°C after 7 days incubation compared with the control sample where the colony diameter was 85.3 mm. The AM films containing 2.38% (w/w) linalool, carvacrol or thymol reduced the population of A. niger on the surface of Cheddar cheese by 1.8, 2.0 and 2.2 log CFU/g, respectively, after 35 days of storage at 15°C. The results suggest that starch‐based film coated with an AM agent has the potential for being used as a fungicidal packaging system. Copyright © 2012 John Wiley & Sons, Ltd.     

Development and evaluation of an edible antimicrobial film based on yam starch and chitosan

Edible antimicrobial films are an innovation within the biodegradable active packaging concept. They have been developed in order to reduce and/or inhibit the growth of microorganisms on the surface of foods. This study developed an edible antimicrobial film based on yam starch (Dioscorea alata) and chitosan and investigated its antimicrobial efficiency on Salmonella enteritidis. A solution of yam starch (4%) and glycerol (2%) was gelatinized in a viscoamilograph and chitosan added at concentrations of 1%, 3% and 5%. Films with and without chitosan were produced by the cast method. To evaluate the antimicrobial activity of the films, two suspensions of S. enteritidis were used in BHI medium, corresponding to counts of 2 × 10⁸ and 1.1 × 10⁶ CFU/ml. The suspensions (50 ml) were poured into flasks. The films were cut into 5 × 5 and 5 × 10 cm rectangles to be used at ratios of 1 : 1 (1 cm²/ml microorganism suspension) and 2 : 1 (2 cm²/ml). The film 30 µm thick on average. As a control, pure chitosan at an amount corresponding to that contained in the 3% and 5% films (5 × 10 cm) was added to flasks containing the microorganism suspension. Also, flasks containing only a suspension of S. enteritidis were used as control. The suspensions, in flasks, were kept at 37°C in a waterbath with agitation. Suspension aliquots were removed every hour for reading the optic density (OD₅₉₅) and plating onto PCA medium. The results showed that chitosan has a bactericidal effect upon S. enteritidis. Films treated with chitosan at different concentrations showed similar antimicrobial efficiency, in addition to being dependent on diffusion. The chitosan‐treated films caused a reduction of one to two log cycles in the number of microorganisms, whereas the pure chitosan presented a reduction of four to six log cycles compared with the control and starch film. The films showed good flexibility. Copyright © 2005 John Wiley & Sons, Ltd.     

纳米氯化银/壳聚糖抗菌敷料的制备及功能评价

以壳聚糖纤维为基底材料,经表面处理,采用硝酸银多步浸渍和快速氯化反应的方法,制备均匀嵌合纳米氯化银颗粒的壳聚糖纤维复合抗菌敷料。银负载量小于60mg/10*10cm2时,壳聚糖纤维表面可观察到均匀的氯化银纳米粒子,粒径分布20~80nm。氯化银纳米粒子结构和抑菌性具良好的稳定性,对大肠杆菌、金黄色葡萄球菌和绿脓杆菌的抑菌率均可达到99.99%。氯化银纳米粒子在经预处理的壳聚糖纤维表面具有良好的固着性。纳米氯化银/壳聚糖纤维供试样品对深二度烧伤伤口愈合没有不良作用,相对于生理盐水/纱布和磺胺吡啶银/纱布对照组,供试样品组的愈合率更高。本研究成果为新型氯化银抗菌敷料研发提供了重要依据。     

壳寡糖修饰的纳米银作为抗菌材料的合成与制备

制备了一种壳寡糖(CSO)修饰的纳米银抗菌材料。将含有羧基和二硫键的硫辛酸(LA)共价接枝到壳寡糖上合成了壳寡糖-接枝-硫辛酸共聚物(CSO-g-LA)。利用硫辛酸分子上的二硫键与纳米银的共价螯合作用,将壳寡糖修饰到纳米银表面。这种经壳寡糖共价修饰后的纳米银,其粒径大小为96.4nm,分散均匀没有团聚现象,且在广泛p H值和高盐浓度条件下能够保持良好的稳定性,能够应用于环境复杂的工业领域。这种具有良好稳定性的复合材料,有机地将壳寡糖和纳米银各自的优良抗菌能力协同起来,使得其在抗菌领域中将具有潜在的应用价值。