Development of cellulose acetate based antimicrobial food packaging materials for controlled release of lysozyme

Antimicrobial packaging materials were obtained by incorporation of lysozyme into cellulose acetate (CA) films. In order to achieve controlled release of lysozyme, the structure of the films was changed from highly asymmetric and porous to dense by modulating the composition of the initial casting solution. The highest release rate, soluble lysozyme activity and antimicrobial activity were obtained with the film prepared from 5% CA solution including 1.5% lysozyme. Increasing CA content in the casting solution decreased the porosity of the films, hence, reduced the release rate, maximum released lysozyme activities and the antimicrobial activities of the films. In contrast, immobilized lysozyme activities and the tensile strength of the films increased. The incorporation of lysozyme did not cause significant reductions in tensile strength and elongation at break values except in films prepared with 15% CA. This study showed the good potential of asymmetric CA films to achieve controlled release in antimicrobial packaging.     

纳米二氧化钛抗菌食品包装复合膜的研究进展

纳米二氧化钛具有较好的抗菌作用,且在传统包装材料中有较好的分散性,添加了纳米二氧化钛的食品包装薄膜具有较好的抗菌效果,能在一定程度上延长食品的保质期。目前,有较多关于纳米二氧化钛食品包装复合膜的研究,主要是围绕抗菌性,机械性能和安全性等方面展开,研究表明：纳米二氧化钛复合膜的抗菌性受光照影响;复合膜的机械性能、热力学性能和阻隔性等随纳米二氧化钛的加入有所改变;复合膜中的纳米二氧化钛可能会迁移到包装的食品中,造成食品安全隐患;制备复合膜时需综合考虑以上因素。本文主要对纳米二氧化钛的抗菌机理、纳米二氧化钛抗菌食品包装薄膜的制备和应用、纳米二氧化钛的迁移研究进展进行概述,旨在扩展纳米二氧化钛复合膜更好更安全地应用于食品包装。     

食品包装用复合膜材质分析方法研究

目的 研究食品包装用复合膜材质的分析方法。方法 样品截面经包埋抛光后, 采用扫描电镜-能谱仪(scanning electron microscope-energy dispersive spectrometer, SEM-EDS)对样品层数及各层元素信息进行表征。样品经甲酸浸泡分层后, 采用傅里叶变换红外光谱仪(fourier transforminfrared spectroscopy, FT-IR)、差式扫描量热仪(differential scanning calorimetry, DSC)、SEM-EDS对分层后各层薄膜的红外特征吸收峰、熔点、元素信息进行表征。结果 确认该复合膜具有4层结构, 从外表面到内表面材质依次为PET层(厚度约13 μm)、PA层(厚度约16 μm)、铝层(厚度约10 μm)、PP/PE共混层(厚度约67 μm)。结论 通过溶剂剥离分层, SEM-EDS、FT-IR、DSC连用表征分析, 可以确认食品包装用复合膜的多层膜整体结构及每层薄膜材质。     

Development of mono and multilayer antimicrobial food packaging materials for controlled release of potassium sorbate

In this study, cellulose acetate (CA) based mono and multilayer films including potassium sorbate (Psb) as an antimicrobial agent were prepared using dry phase inversion technique. To achieve appropriate controlled release of Psb, the structure of the films was changed by manipulating the film preparation conditions. In particular, the initial casting composition, wet casting thickness and drying temperature were varied. Results indicate that Psb release rate decreased as the CA content in the casting solution, the wet casting thickness and the drying temperature for both mono and multilayer films were increased. Compared to the results for the monolayer films, a significant decrease of Psb release rate through the multilayer films was recorded. Drying-induced crystallization was observed in the monolayer films. As a consequence of this, a fast initial release of Psb, controlled by Fickian diffusion, was followed by a slower release controlled by dissolution of Psb crystals. In multilayer films, no crystals were detected in the structure and the release rate was regulated only by diffusion of Psb through the film. The results suggest that the films prepared in this study can be used as food packaging materials for achieving controlled and extended release of Psb.     

Effect of antioxidants and light stabilisers on silver migration from nanosilver-polyethylene composite packaging films into food simulants

The effect of exposure time, temperature and food simulants, especially additives, on the release of silver from nanosilver-polyethylene composite films to food simulants was studied. Two different type of nanosilver-polyethylene composite films (with or without additives) were chosen to conduct the experiment with the aim of exploring the behaviour of silver migration. It was shown that the migration of silver into 50% ethanol at 40 and 70°C was much less than that into 3% acetic acid. With the increase of exposure time and temperature, the release of silver increased. The migration even continued after a long exposure time (14 days at 20°C, 10 days at 40°C, and 6 days at 70°C respectively). Only about 0.15‰ of silver migrated from composite films with the additives into 3% acetic acid after 6 days of exposure at 70°C, while about 1.3% of silver migrated from composite films that did not contain additives under the same conditions. This could be because the addition of the antioxidants and light stabilisers prevents silver from being oxidised, which is an important way for the release of silver.     

Preparation of active antimicrobial methyl cellulose/carvacrol/montmorillonite nanocomposite films and investigation of carvacrol release

Methyl cellulose (MC)/carvacrol (CRV)/montmorillonite (MMT) nanocomposite films were prepared to obtain active antimicrobial packaging materials. The characterization of film samples by X-ray diffraction and transmission electron microscopy showed that composite films were of nano structures. CRV addition to the MC film and MC/MMT nanocomposite films led to a decrease in the thickness and opacity values of them, whereas MMT addition to the film matrix caused an increase in these values. Thermal stability of films slightly increased with increasing MMT concentration in film matrix. CRV release from films was investigated at different temperatures for 30 days. An increase in the MMT concentration matrix caused a decrease in CRV release at 25.0 ± 0.5 °C and in 60 ± 4% relative humidity (RH). CRV release increased with temperature at a constant RH. The antimicrobial activities of films were tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by the microatmosphere method and these organisms were completely inhibited on the nutrient broth/bacteriological agar medium when film samples containing 11.1 ± 0.2 mg CRV were present. MC/CRV film and MC/CRV/MMT-60% nanocomposite films on sausage reduced E. coli and S. aureus counts by 0.9 and 0.7 log cfu/mL, respectively, compared to the control film. The amount of CRV release from developed antimicrobial films can be controlled by MMT concentration within the film matrix and by the storage temperature of film.     

食品接触用再生纤维素薄膜的应用进展与法规研究

随着人们环保意识的加深以及再生纤维素薄膜生产加工工艺的进步,使再生纤维素薄膜作为一种绿色环保的、有着优良性能的包装材料在近年来再次得到关注,被越来越广泛地应用在食品接触材料及制品领域.然而该类材质目前并没有被包含在我国食品接触材料产品标准中,使得其无法可依,安全问题无法得到保障.因此,为推动我国食品接触用再生纤维素薄膜...     

Development of an active food packaging system with antioxidant properties based on green tea extract

A formula including green tea extract (GTE) was developed as an active food packaging material. This formula was moulded to obtain an independent component/device with antioxidant properties that could be easily coupled to industrial degassing valves for food packaging in special cases. GTE components (i.e., gallic acid, catechins and caffeine) were identified and quantified by HPLC-UV and UPLC-MS and migration/diffusion studies were carried out. Antioxidant properties of the formula alone and formula-valve were measured with static and dynamic methods. The results showed that the antioxidant capacity (scavenging of free radicals) of the new GTE formula was 40% higher than the non-active system (blank). This antioxidant activity increased in parallel with the GTE concentration. The functional properties of the industrial target valve (e.g., flexibility) were studied for different mixtures of GTE, and good results were found with 17% (w/w) of GTE. This new active formula can be an important addition for active packaging applications in the food packaging industry, with oxidative species-scavenging capacity, thus improving the safety and quality for the consumer and extending the shelf-life of the packaged food.     

Improvement of active chitosan film properties with rosemary essential oil for food packaging

Rosemary essential oil (REO) was used to develop an active film from chitosan. The effects of REO concentration (0.5, 1.0 and 1.5% v/v) on film properties were studied by measuring the physical, mechanical and optical properties of the REO‐loaded films. Scanning electron microscopy and Fourier transform infrared (FTIR) spectroscopy were used to study microstructure and the interaction of the chitosan‐based films. The solubility and water gain of the chitosan film decreased about 25% and 85%, respectively, by REO incorporation, up to 1.5% v/v, because of the interaction between hydrophilic groups of chitosan and REO as confirmed by FTIR. It was determined that REO improved the transparency of the films from 4.97 in neat chitosan up to 7.61; moreover, it reduced the films’ light transmission in UV light more than 25%. Films containing REO showed more antibacterial activity and total phenol content. The films containing REO showed potential to be used as active film in food preservation.     

Preparation of silver nanoparticles/polymethylmethacrylate/cellulose acetate film and its inhibitory effect on Cronobacter sakazakii in infant formula milk

Cronobacter sakazakii is a harmful foodborne pathogen, and its contaminated food will pose a huge threat to human health. Prevention of C. sakazakii contamination of food is valuable for food safety as well as for human health. In this study, silver nanoparticles (AgNP) were successfully immobilized on the surface of cellulose acetate (CA) and polymethylmethacrylate (PMMA) composite to obtain AgNP/PMMA/CA film. Through the inhibition zone and growth curve experiments, we found that AgNP/PMMA/CA films has excellent antibacterial activity on C. sakazakii. The AgNP/PMMA/CA film can prolong the lag phase of the growth curve of C. sakazakii from 2 to 8 h. The antibacterial films were found to reduce the survival of C. sakazakii in Luria-Bertani and infant formula by combining it with a mild heat treatment (45°C, 50°C, and 55°C). The AgNP/PMMA/CA film combined with 55°C water bath can completely inactivate C. sakazakii in infant formula within 120 min. Finally, the potential mechanism by which AgNP/PMMA/CA films reduce the heat tolerance of C. sakazakii was investigated by quantitative real-time PCR. The results showed that AgNP/PMMA/CA films could reduce the expression of environmental tolerance-related genes in C. sakazakii. The current research shows that AgNP/PMMA/CA film has strong antibacterial activity, and the antibacterial film combined with mild heat treatment can accelerate the inactivation of C. sakazakii and effectively reduce the harm of foodborne pathogens. The AgNP/PMMA/CA film can be used as a potential packaging material or antibacterial surface coating.     

普鲁兰多糖/槐糖脂抑菌保鲜膜的制备

目的:为替代传统不可再生塑料保鲜膜,采用经济环保原料制作性能优良的抑菌保鲜膜,并确定其最佳配方。方法:在最佳成膜条件下,采用单因素实验分析普鲁兰多糖、槐糖脂和甘油浓度对成膜性能的影响,并考察了槐糖脂的抑菌浓度。在此基础上设计正交实验,确定抗菌保鲜膜原料的最佳配比,并验证膜液及保鲜膜的保鲜性能。结果:槐糖脂对金黄色葡萄球菌抑制效果显著(p<0.01),2.4 g/L时达到100%抑制;对大肠杆菌和白色假丝酵母菌菌有不同程度的抑制作用,4.0 g/L时抑菌率分别为28.75%和14.53%。确定了膜液的最佳配方为普鲁兰多糖18 g/L、槐糖脂3.6 g/L、甘油8.75 g/L。该膜液及所成的抗菌保鲜膜对樱桃的保鲜效果与对照组相比效果显著(p<0.01)。结论:将槐糖脂生物表面活性剂作为可抗菌保鲜膜的原料,为绿色抗菌保鲜膜的制备工艺提供新的理论依据。     

Performance evaluation of a novel food packaging material based on clay/polyvinyl alcohol nanocomposite

The effectiveness of a novel, laminated clay/polyvinyl alcohol nanocomposite food-packaging film was examined by barrier analysis and food shelf-life monitoring. The effect of storage conditions on the film's oxygen permeability was studied and compared to commercial LLDPE/PET film as control. Additionally, pouches of 14 cm × 10.5 cm prepared from both films were filled with tomato paste as the food model, and stored at different temperatures (20–50 °C) and humidities (20–85% RH) for 10 days. Incorporating a coating layer containing 30 wt% (d.b.) of clay into polymer was found to improve its barrier properties, with drastic reduction of oxygen transmission rates (OTR) up to 99%, especially at 20% RH. While surrounding humidity affected the OTR of composite film significantly more than that of control film, the OTR of composite film was lower and less susceptible to temperature changes. The changes of food physical-chemical properties with time showed that the pouches of composite film significantly decreased ascorbic acid and lycopene oxidation of tomato paste by up to 88 and 37%, respectively. Furthermore, no discolouration occurred to the samples packaged by the nanocomposite film as compared to the control.Industrial relevanceA novel clay/polyvinyl alcohol nanocomposite film was developed with excellent barrier properties against oxygen. Evaluation of the performance of this food-packaging film indicated that incorporation of montmorillonite enhanced food preservation as suggested by decreased ascorbic acid and lycopene oxidation, and no discolouration of tomato paste. This new approach could be adopted by the food industry to assist commercial producers and retailers for preserving and extending the shelf-life of a variety of food products.     

Evaluation of antimicrobial and physical properties of edible film based on carboxymethyl cellulose containing potassium sorbate on some mycotoxigenic Aspergillus species in fresh pistachios

Active packaging is a relatively novel concept of packaging that changes the conditions of the packaged food to extend its shelf-life and improve its safety. In this study, antimicrobial effects of carboxymethyl cellulose based-edible film containing potassium sorbate as an antimicrobial agent were studied against Aspergillus flavus (PTCC-5004), Aspergillus parasiticus (PTCC-5286) and A. parasiticus (PTCC-5018) by using agar diffusion assay. Results showed suitable inhibition effects against A. parasiticus (PTCC-5286) and A. flavus (PTCC-5004) in comparison with A. parasiticus (PTCC-5018). Pistachios were coated with this edible antimicrobial film containing three concentrations of sorbate (1, 0.5 and 0.25 g/100 mL film solution); all concentrations showed no growth of molds. Tensile strength values of films with potassium sorbate, decreased when compared to control, and film’s flexibility, was 28.82 percent for 3 g/100 mL sorbate, while higher concentration of sorbate, decreased the flexibility. The water vapor permeability values (WVP) of films were determined to be 1.18 (g mm/m² day kPa) for films plasticized with glycerol, without sorbate while WVP values for the films containing 1 and 2 g/100 mL sorbate increased to 3.77 and 15.5 (g mm/m² day kPa), respectively. The observed glass transition temperature (T_G) depression for these polymer blends was related to the plasticizer content (water, polyethylene, and glycerol), especially water.     

快速分析食品包装复合膜材质结构的方法研究

目的 研究快速分析食品包装复合膜材质结构的方法.方法 将样品用夹具固定,切片机切片处理后获得材料横截面,并标记样品内外层,利用扫描电子显微镜仪(scanning electron microscope,SEM)对样品层数和由外到内厚度进行表征和测量.利用衰减全反射(attenuated total reflection...     

Development of cellulose nanofibrils reinforced polyvinyl alcohol films incorporated with alizarin for intelligent food packaging

Visual pH-sensing films were fabricated using cellulose nanofibrils (CNF) reinforced polyvinyl alcohol (PVA) and alizarin. The relationships between the ratio of PVA: CNF hydrogel (2:1, 1:1, 1:2) and the physical properties and colour response efficiency of indicator films were investigated. Fourier transform infrared spectroscopy of films evidenced alizarin and CNF was properly incorporated by physical interaction. A new weak X-ray diffraction peak appeared at 2θ = 22.4°, which was affected by the incorporation of CNF. The increase in the CNF content induced enhancements of thermal stability, tensile strength, water contact angle and colour sensitivity of the indicator films. The colourimetric films had a higher sensitivity to discolouration when exposed to acidic vapours than alkaline vapours. The films presented a remarkable colour change varied from purple in alkaline condition to yellow in acidic condition. Therefore, this colourimetric film can be used as a volatile acid sensor for intelligent packaging.     

Properties of low methoxyl pectin‐carboxymethyl cellulose based on montmorillonite nanocomposite films

In this study, the low methoxyl pectin‐carboxymethyl cellulose‐based montmorillonite (LMP‐CMC‐MMT, LCM) nanocomposite films with nine ratios of LMP:CMC (from 10:0 to 0:10) and different MMT contents (1–8 wt%) were prepared. The mechanical properties, colour, opacity and water vapour permeability (WVP) of composite films were investigated. The maximum of tensile strength (TS) of composite films was 39.85 ± 2.51 MPa at LMP:CMC ratio of 4:6 and 4 wt% MMT (LCM47), which indicated the formation of hydrogen bonds between MMT and LMP‐CMC. The reduction of WVP of the LCM47 composite film was 333% of that of the CMC film due to the tortuous path caused by MMT incorporation. LCM composite films had the higher b*‐ and ΔE*‐values and lower L*‐values in comparison with LMP‐CMC (LC) composite films. The LCM composite films showed a decrease in transparency as MMT content increased.     

食品金属包装材料中化学物的迁移研究进展

基于目前关于食品用金属包装材料中有毒有害物质迁移研究还基本空白的现状,本文介绍了金属包装材料中的潜在迁移情况,并着重介绍了重金属、双酚类物质和三聚氰胺等潜在迁移物及其研究现状,探讨了金属包装材料中化学物迁移研究的一般过程,为后期金属罐内有害物质的迁移研究和食品包装行业的危害分析和关键控制点(HACCP,Hazard Analysis and Critical Control Point)管理提供依据。      

Antioxidant edible film based on a carrot pectin-enriched fraction as an active packaging of a vegan cashew ripened cheese

An orange-coloured carrot pectin-enriched fraction (CPEF), with 50% uronic acids (42%-methylated), carrying lipophilic carotenoids and α-tocopherol, developed homogeneous calcium-crosslinked films at 0%, 25%, 50%, 75% and 100% CPEF proportions regarding a commercial pectin. CPEF gave higher relative elongation at break (65% for 50% CPEF film) when compared to 0% CPEF film (26% elongation). FTIR spectra showed a decreased intensity in the C = O group of the esterified carboxylate band as the CPEF content increased. CPEF maintained the orange colour (a* ≈ +37) and partly the carotenes (k ≈ 8.62 × 10⁻³ d⁻¹) in films, even under 25 °C light storage. Also, CPEF gave water resistance to dissolution (100% CPEF film: 50% solubility), maintaining film integrity after 24 h soaking. Surface wettability decreased (40° contact angle) when CPEF proportion increased. These characteristics made the 100% CPEF film an efficient antioxidant interface that preserved a vegan cashew ripened cheese of high water activity (0.952) for 60 days at 7 °C, as determined through the assay of thiobarbituric acid-reactive substances (TBARS).