包装材料透氧性对蛋糕油脂氧化程度的影响研究

分别采用KNY/CPP,OPP/VMCPP和PET(SiO2)/CPP 3种材料对蛋糕进行包装,研究了3种包装材料透氧性对蛋糕油脂氧化程度的影响,并对包装材料下的氧化速率进行了表征,分别得到了3种包装材料酸价氧化速率拟合方程和过氧化值氧化速率拟合方程,证实了包装材料的透氧率与蛋糕的油脂氧化速率不能建立明确的数学关系。     

Spin-Related Electron Transfer and Orbital Interactions in Oxygen Electrocatalysis

Oxygen evolution and reduction reactions play a critical role in determining the efficiency of the water cycling (H₂O ⇔ H₂ + $\frac{1}{2}$O₂), in which the hydrogen serves as the energy carrier. That calls for a comprehensive understanding of oxygen electrocatalysis for efficient catalyst design. Current opinions on oxygen electrocatalysis have been focused on the thermodynamics of the reactant/intermediate adsorption on the catalysts. Because the oxygen molecule is paramagnetic, its production from or its reduction to diamagnetic hydroxide/water involves spin-related electron transfer. Both electron transfer and orbital interactions between the catalyst and the reactant/intermediate show spin-dependent character, making the reaction kinetics and thermodynamics sensitive to the spin configurations. Herein, a brief introduction on the spintronic explanation of the catalytic phenomena on oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is given. The local spin configurations and orbital interactions in the benchmark transition-metal-based catalysts for OER and ORR are analyzed as examples. To further understand the spintronic oxygen electrocatalysis and to develop more efficient spintronic catalysts, the challenges are summarized and future opportunities proposed. Spin electrocatalysis may emerge as an important topic in the near future and help integrate a comprehensive understanding of oxygen electrocatalysis.     

Development of Palladium‐based Oxygen Scavenger: Optimization of Substrate and Palladium Layer Thickness

Oxygen scavenging films based on vacuum deposited palladium layers were developed to remove residual oxygen remaining in food packages after modified atmosphere packaging. Palladium (Pd) was coated on to a range of packaging films and in different thicknesses using magnetron sputtering technology. To improve the substrate surface, an additional silicon oxide (SiO_x) layer was also applied to the films before Pd deposition. To determine the oxygen scavenging activity, the scavenger films were placed into an airtight cell, which was flushed with a gas mixture containing 2 vol.% oxygen and 5 vol.% hydrogen. The results showed that the oxygen scavenging rate was strongly dependent on the coating substrate as well as on the Pd deposition thickness. Packaging films such as polyethylene terephthalate, aluminium oxide‐coated polyethylene terephthalate, oriented polypropylene and polylactic acid were found to be the most suitable substrates for Pd‐based oxygen scavengers. Moreover, it was demonstrated that the intermediate SiO_x layer between the substrate and the Pd layer led to a substantial increase in the oxygen scavenging activity rate (up to 33‐fold) for all applied packaging films. Additionally, it was shown that the optimal Pd layer thickness for the investigated oxygen scavenging films lies between 0.7 and 3.4 nm. The resulting scavenger films have the potential to scavenge residual headspace oxygen of sensitive foods within a matter of minutes leading to shelf life extension and overall quality improvements. Copyright © 2015 John Wiley & Sons, Ltd.     

化学链制氧技术铜基氧载体的性能研究

在STA409PC热重分析仪上对Cu/Si氧载体的脱氧-吸氧性能加以研究, 并利用BET、SEM和XRD对所制备氧载体的比表面积、表面形貌和物相组成进行分析。结果表明, 在N₂氛围中, 当温度高于850℃时Cu/Si氧载体脱氧反应进入快速反应阶段; 氧载体在空气氛围中再生的快速反应温度高于400℃; 氧载体脱氧和吸氧的反应速率随颗粒直径的减小及气体流量的增大, 而增大但变化不明显, 而随反应温度的升高, 氧载体脱氧和吸氧反应速率都会急剧增大; 23次循环实验中, 氧载体脱氧-吸氧性能稳定, 经循环之后的氧载体, 颗粒表面变得光滑, 空隙率增加, 但机械强度降低。物相分析结果表明氧载体脱氧后的成分主要有Cu₂O和SiO₂, 吸氧后的成分主要有CuO和SiO₂, 氧载体的制备方法和循环性能有很好的稳定性和适应性。     

抗氧化活性包装阻氧性与活性剂应用研究进展

目的 为抗氧化活性包装阻氧性与抗氧化活性剂应用的研究提供相应的理论基础,以期为解决抗氧化活性包装目前存在的问题提供更新颖的解决思路.方法 对抗氧化活性包装的阻氧性不同影响因素进行分析,表述抗氧化活性包装的抗氧化评价方式,按照作用方式对抗氧化活性剂进行分类,并阐述其作用机理与应用进展.结果 包装中抗氧化活性剂的包埋方式单一,缓释性能和安全性能需进一步提高,还需探究含特殊气味的抗氧化活性剂对食品风味的影响.结论 抗氧化活性包装可以有效减缓食品因氧化造成的风味及品质劣变,在食品保鲜领域拥有更广大的发展前景.     

PEN啤酒瓶的开发应用

研究了2,6-萘二甲酸二甲酯(DMN)缩聚为聚2,6-萘二甲酸二乙酯(PEN)共聚物的合成工艺,讨论了PEN化学性质和气体阻隔性能。结果表明:PEN共聚物的合成工艺与普通聚酯切片的合成工艺相近,PEN的啤酒瓶可耐100℃高温,对O2、CO2气体的阻隔性比普通PET瓶提高6倍以上。     

Toward New Polymeric Oxygen Scavenging Systems: Formation of Poly(vinyl alcohol) Oxygen Scavenger Film

Active packaging is a term that refers to the use of package to do more than merely protect the food from the outside environment. Amongst active packaging, oxygen scavengers can prevent oxidative damage to flavour and colour in a wide range of foods. They offer advantages in maintaining quality and extending shelf life. We thus present the use of a cobalt(II) complex with the ligand l ‐threonine as a new oxygen scavenger. This complex, in addition to its high reactivity with oxygen after water activation, can be obtained easily in large amounts and does not react with oxygen in solid state. Thus, the incorporation of the Co(II)(l ‐Thr)₂(OH₂)₂ natural complex in organic polar polymer (poly(vinyl alcohol)) by casting process was conducted. The reactivity towards oxygen of the obtained films was evaluated by oxidation kinetics monitoring using ultraviolet–visible spectrophotometry as a function of time and relative humidity. Oxygen consumption of the active film was found equal to the complex alone (2.5 mg of O₂ per gramme of complex) after water activation (90.5% relative humidity). Copyright © 2014 John Wiley & Sons, Ltd.     

无菌包装袋的透氧性研究

目的研究无菌包装袋的透氧率与其厚度、材质及温湿度的关系。方法用厚度测试仪测量无菌包装袋厚度,用红外光谱仪检测材质、用氧气渗透测试仪测试透氧率,并比较厚度、材质和温湿度对透氧率的影响。结果无菌包装袋的透氧率随厚度的增加而减小;材质对无菌包装袋的透氧率影响较大;无菌包装袋的透氧率随着温度的增加而增加,阻氧性能下降。结论无菌包装袋的厚度、材质和环境温度对其透氧率均有影响,而相对湿度对透氧率无显著影响。     

Designing Efficient Oxygen Scavenging Coating Formulations for Food Packaging Applications

Modified atmosphere packaging is widely used to prolong the shelf life of many oxygen‐sensitive items including food, pharmaceuticals, work of art and so on. For food packaging applications, we investigated the effectiveness of oxygen scavenging coatings and flexographic printing ink formulations made using water soluble and water insoluble ascorbate enzyme systems. The present study summarizes the effects of various parameters on the oxygen scavenging rates and other performance aspects of the formulations. It is shown that; the initial oxygen scavenging rate can be increased by increasing the surface area of Calcium Ascorbate crystals and addition of catalyst or edible oil; addition of a catalyst like TiO₂ or Alumina and an edible oil in Ascorbate and laccase‐based formulations induces a synergistic effect upon the rate of scavenging oxygen from the packages; an efficient oxygen scavenging coating formulation can be made using water soluble Calcium Ascorbate and insoluble Ascorbate Palmitate containing enzyme and substrate; designing an efficient oxygen scavenging formulation using water insoluble Ascorbate Palmitate can reduce or eliminate formation of effluent which has potential to change the aperral of food items inside the package; an adverse effect of some binders which cause a reduction in the oxygen scavenging rate can be eliminated by making blends of different binders. Copyright © 2013 John Wiley & Sons, Ltd.     

Development of an Active Thermoplastic Film with Oxygen Scavengers Made of Activated Carbon and Sodium Erythorbate

An active thermoplastic film made of low‐density polyethylene (LDPE) filled with oxygen scavengers made of powdered activated carbon (PAC) impregnated with sodium erythorbate (SE) was developed for packaging applications. Initial tests indicated that the impregnation of PAC with SE enhanced the heat resistance of SE, thereby allowing processing at temperatures typical of LDPE manufacturing. Subsequently, LDPE films with PAC/SE particles were manufactured in coupons that represented a typical juice package, and experiments indicated that these films absorbed 3.57 mg of oxygen in 11 days. This amount corresponded to 80% the concentration of oxygen in the headspace of the package. Furthermore, findings indicated that active particles alone have 10 times higher oxygen absorption capacity than the active LDPE film. Finally, the physical properties of the film were characterized by microscopy where oxygen scavengers showed a good dispersion within the matrix. However, 20 wt.% of these active particles decreased tensile strength of the film by 53%. Copyright © 2014 John Wiley & Sons, Ltd.     

Biosorption of copper and lead ions by waste beer yeast

Locally available waste beer yeast, a byproduct of brewing industry, was found to be a low cost and promising adsorbent for adsorbing copper and lead ions from wastewater. In this work, biosorption of copper and lead ions on waste beer yeast was investigated in batch mode. The equilibrium adsorptive quantity was determined to be a function of the solution pH, contact time, beer yeast concentration, salt concentration and initial concentration of copper and lead ions. The experimental results were fitted well to the Langmuir and Freundlich model isotherms. According to the parameters of Langmuir isotherm, the maximum biosorption capacities of copper and lead ions onto beer yeast were 0.0228 and 0.0277 mmol g(-1) at 293 K, respectively. The negative values of the standard free energy change (DeltaG degrees ) indicate spontaneous nature of the process. Competitive biosorption of two metal ions was investigated in terms of sorption quantity. The amount of one metal ion adsorbed onto unit weight of biosorbent (q(e)) decreased with increasing the competing metal ion concentration. The binding capacity for lead is more than for copper. Ion exchange is probably one of the main mechanism during adsorptive process.     

软包装材料透氧率对食用油氧化特性的影响

通过恒温加速实验,运用分光光度法测定不同透氧率的软包装材料中的食用油的过氧化值,分析了不同透氧率的软包装材料对食用油氧化特性的影响,理论上含铝箔或镀铝材料的氧化速率较小。结果表明:不同透氧率的包装材料对食用油的氧化影响是显著的;在进行盒中袋内袋材料的选择时,选择透氧率低的包装材料是合理的。     

Compensation of Pinhole Defects in Food Packages by Application of Iron‐based Oxygen Scavenging Multilayer Films

To protect sensitive food products from oxidative deterioration, multilayer barrier film systems and also modified atmosphere packaging are widely applied. However, the preservation of food quality in such packaging systems may be compromised by the presence of defects in the sealing layer of the films, especially when these are below a critical size, typically the detection limit of standard leak testers of 10 µm. The addition of an oxygen scavenger (OS) layer in barrier film structures could therefore provide extended protection against O₂ penetration through such defects. In this study, O₂ absorption of different multilayer film structures including an iron‐based OS were investigated under defined gas atmospheres. Measurement cells were thereby covered with plastic films of defined O₂ permeability to simulate conditions in a food package during storage with pinhole defect sizes of 10 and 17 µm. The results indicated that the OS film structures applied could only compensate for a defect size of 10 µm in the sealing layer. Analysis of the O₂ absorption of different multilayer film structures at 85% and 100% relative humidity showed that higher humidity accelerates the activation of the scavenger. After full activation, the scavenger kinetics are the same for 85% and 100% relative humidity. Long‐term storage experiments using the most effective film structure from the preliminary experiments were carried out to compare O₂ absorption of a snack food product in packages with and without an OS. The analyzed linear gradient of the reaction of the OS film and food product, respectively, indicated first‐order reaction kinetics with corresponding reaction constants calculated to be K (food product) 0.021 mg (O₂) mbar (O₂)^?1 day^?1 and K (OS film) 0.066 mg (O₂) mbar (O₂)^?1 day^?1. The reaction velocity of the OS was thus three times faster than that of the food. The applicability of OS multilayer film systems to compensate a critical pinhole defect size of 10 µm for sensitive food products could therefore be confirmed. The measurement of quality parameters for the status of lipid oxidation processes would help to verify this result. Copyright © 2012 John Wiley & Sons, Ltd.     

啤酒包装容器设计

从啤酒市场状况的分析出发,抓住其地域性强、季节性强、家庭消费能力强、文化品位高这些特点,理解啤酒包装在其销售中所起的重要作用.并且就玻璃瓶、易拉罐、啤酒桶这3种形式讨论具体的啤酒包装容器改进方案.     

系统选择钙钛矿型透氧膜材料

提出了一套系统选择具有高透氧能力、结构稳定性及热化学稳定性的钙钛矿型混合氧离子电子导体透氧膜材料的策略,在此策略指导下开发出了若干新的导体膜材料．采用了标准陶瓷法、络合法等对材料进行了合成,采用色谱法及Ｘ射线粉末衍射法分别对其透氧性能与稳定性进行了测定与表征,并将其与几种典型透氧膜材料进行了比较．结果表明此系列新材料确实具有预期的透氧性能与结构和热化学稳定性．典型材料,Ｂａ０．5Ｓｒ０．５Ｃｏ０．８Ｆｅ０．２Ｏ３－δ导体膜在８５０℃下透氧量达１．１６ｍＬ［ＳＴＰ］·ｃｍ－２·ｍｉｎ－１,并在长达１０００多小时的测定中保持稳定的透氧能力．     

微型变压吸附制氧与氧疗保健

微型变压吸附制氧具有方便、灵活以及可长期连续供氧等特点,是家庭氧疗保健的最佳供氧方法。随着微型制氧技术的发展,微型变压吸附制氧机的各项性能指标逐步提高。微型变压吸附制氧应用于氧疗保健可以治疗病理性缺氧疾病,可以缓解生理性缺氧症状、环境性缺氧症状。随着人们对氧疗保健认识的深入和供氧设备的发展,氧疗保健将得到快速发展。     

系统选择钙钛矿型透氧膜材料

提出了一套系统选择具有高选氧能力、结构稳定性及热化学稳定性的钙钛矿型混合氧离子电子导体透氧膜材料的策略,在此策略指导下开发出了若干新的导体膜材料,采用了标准陶瓷法、络合法等对材料进行了合成,采用色谱法及X射线粉末衍射法分别对其透氧性能与稳定性进行了测定与表征,并将其与几种典型透氧膜材料进行了比较。结果表明此系列材料确实具有预期的透氧性能与结构和热化学稳定性。典型材料,Ba0.5Sr0.5Co0.8Fe0.2O3-δ导体膜在850℃下透氧量达1.16mL[STP],cm^-2.min^-1,并在长达1000多小时的测定中保持稳定的透氧能力。     

Effect of Surface Preparation of Zirconia on its Reactivity with Oxygen

This paper reports surface electrical properties of zirconia studied using work function measurements in the temperature range 297–1173 K during oxidation. It was found that surface preparation procedures, such as grinding and polishing, result in a change of its reactivity with oxygen. The effects produced by the preparation can be removed during thermal treatment at 1473 K.     

Inactivation of Palladium‐based Oxygen Scavenger System by Volatile Sulfur Compounds Present in the Headspace of Packaged Food

An oxygen scavenger based on a catalytic system with palladium (CSP) was recently developed to remove oxygen in food packagings. Although the CSP worked with various types of food, with some foods, an inhibition of the CSP was observed. Because such catalytic systems are susceptible to poisoning by sulfur‐containing compounds, the aim of this study was to understand the inactivation of palladium‐based catalysts in presence of foods containing volatile sulfur compounds (VSCs). To achieve this, the oxygen scavenging activity (OSA) of the CSP was evaluated in presence of selected food products. Afterwards, VSCs mainly present in these foods were exposed to the CSP, and the influence on the OSA was evaluated. Finally, headspace analysis was performed with the diluted VSCs and with the packaged food products using proton transfer reaction time‐of‐flight mass spectrometry. It was found that the catalytic activity of the CSP was inhibited when VSCs were present in the headspace in concentrations ranging between 10.8–36.0 ppbv (dimethyl sulfide, DMS), 1.2–7.2 ppbv (dimethyl disulfide), 0.7–0.9 ppbv (dimethyl trisulfide), 2.1–5.8 ppbv (methional) and 4.6–24.5 ppbv (furfuryl thiol). It was concluded that in packaged roast beef and cheese, DMS may be the compound mainly responsible for the inactivation of the CSP. In packagings containing ham, the key compounds were hydrogen sulfide and methanethiol; in peanuts, it was methanethiol; and in par‐baked buns, an accumulation of methional, DMS, butanethiol and methionol. When potato chips were packaged, it was demonstrated that when VSCs are present in low concentrations, oxygen can still be scavenged at a reduced OSA.     

工业氧及医用氧中痕量乙炔的检测

生产氧气的空分装置中如果乙炔含量超标,极易引发爆炸,须通过定期检测工业氧或医用氧中的乙炔含量进行预防.经过色谱条件优化,用FID检测器与三氧化二铝毛细柱配合,可检测出氧气中痕量级别的乙炔含量.