Perspectives for chitosan based antimicrobial films in food applications

Recently, increasing attention has been paid to develop and test films with antimicrobial properties in order to improve food safety and shelf life. Active biomolecules such as chitosan and its derivatives have a significant role in food application area in view of recent outbreaks of contaminations associated with food products as well as growing concerns regarding the negative environmental impact of packaging materials currently in use. Chitosan has a great potential for a wide range of applications due to its biodegradability, biocompatibility, antimicrobial activity, non-toxicity and versatile chemical and physical properties. Thus, chitosan based films have proven to be very effective in food preservation. The presence of amino group in C2 position of chitosan provides major functionality towards biotechnological needs, particularly, in food applications. Chitosan based polymeric materials can be formed into fibers, films, gels, sponges, beads or even nanoparticles. Chitosan films have shown potential to be used as a packaging material for the quality preservation of a variety of food. Besides, chitosan has widely been used in antimicrobial films to provide edible protective coating, in dipping and spraying for the food products due to its antimicrobial properties. Chitosan has exhibited high antimicrobial activity against a wide variety of pathogenic and spoilage microorganisms, including fungi, and Gram-positive and Gram-negative bacteria. The present review aims to highlight various preparative methods and antimicrobial activity including the mechanism of the antimicrobial action of chitosan based films. The optimisation of the biocidic properties of these so called biocomposites films and role of biocatalysts in improvement of quality and shelf life of foods has been discussed.     

Development of Antimicrobial Gelatin-Based Edible Films by Incorporation of <Emphasis Type="Italic">Trans</Emphasis>-Anethole/β-Cyclodextrin Inclusion Complex

Antimicrobial activity is an attractive property for packaging materials which can extend the shelf life of products and provide microbial safety for consumers. The study aimed to analyze the physicochemical and antimicrobial properties of gelatin-based edible films containing trans-anethole as the active additive. Encapsulation with β-cyclodextrin was used as an effective way to introduce trans-anethole into gelatin matrix. The results showed that the trans-anethole/β-cyclodextrin inclusion complex could be evenly dispersed in the gelatin-based edible films with appropriate addition. The incorporation of trans-anethole conferred the edible films with good antimicrobial activity as expected, which increased with the content of trans-anethole increasing. Moreover, the addition of inclusion complex improved the tensile strength and surface hydrophobicity and reduced the moisture content of the edible films. It was interesting that the edible films presented great UV light barrier property and it was increased by the addition of inclusion complex. Overall, the antimicrobial gelatin-based edible films showed great potential as bioactive packaging materials to extend food shelf life.     

可食性降解抗菌保鲜膜的研究进展

食品贮藏过程中微生物引起的腐败是影响食品货架期的最重要的因素之一。为此,作为食品流通领域的重要成员,食品包装材料不仅应具有美观商品、便于运输等优点,对一些包装材料还要求具有抗菌、延长食品货架期的功能,并且本身具有安全性和可食用性,这就推动了人们对食品抗菌保鲜膜领域的研究。本文主要介绍了可食性、可降解性(抗菌)保鲜膜的概念、种类(多糖类、蛋白质类、脂类、复合膜类),抗菌剂的种类(有机抗菌剂、无机抗菌剂、天然抗菌剂、细菌素等);阐述了可食性、可降解抗菌保鲜膜的国内外研究现状;展望了可食性降解抗菌保鲜膜的未来发展趋势。本文期望为抗菌保鲜膜领域的研究提供一些新的思路。     

啤酒花浸膏对壳聚糖/聚乙烯双层膜的性能影响及释放行为

为抑制食品中有害微生物的生长繁殖,同时延缓食品品质变化、延长食品货架期,对储存食品进行适当包装尤为重要。本实验制备了含有啤酒花浸膏的壳聚糖/聚乙烯（polyethylene,PE）双层抑菌膜,研究了啤酒花浸膏添加量对抑菌膜表面结构、物理性能和抑菌活性的影响,以及在不同温度（4、25、35 ℃）和不同食品模拟体系（体积分数10%、50%、95%乙醇）中的释放行为。结果表明：啤酒花浸膏的加入使双层抑菌膜的耐水性增强,且对紫外光具有更高的屏障活性,同时赋予薄膜良好的抗氧化及抑菌活性,且含0.2 g/100 mL啤酒花浸膏的双层抑菌膜性能最佳。在相同条件下,啤酒花浸膏添加量越高,释放率也越高,且释放量随着温度和食品模拟液中乙醇体积分数的升高而增加,表明含啤酒花浸膏的壳聚糖/PE双层膜抑菌膜可用于高脂类食品的包装。因此,含有啤酒花浸膏的壳聚糖/PE双层抑菌膜既可弥补可食性单层膜阻水性差的不足,又能赋予聚乙烯包装膜所不具备的抑菌功能。     

可食用抗菌膜在食品包装领域的应用及研究进展

保鲜贮藏技术在延长易腐食品的保质期方面具有重要作用,随着消费者环保和安全意识的增强,可食用抗菌包装膜因具有天然、无毒的良好特性而逐渐受到青睐。本文详细介绍可食用抗菌膜的基材、制备方法与抗菌剂的种类,并总结可食用抗菌膜在食品包装领域的实际应用,同时阐述未来抗菌功能食品包装的发展趋势。以期为减少白色塑料污染并为对工农业产生的废物进行回收和开发利用提供参考,同时为食品保鲜贮藏提供科学依据和理论基础。     

活性包装薄膜的功能特性表征及对食品保鲜作用的研究进展

本文综述了活性包装薄膜的功能特性表征与对食品保鲜作用的研究进展,归纳总结了薄膜抗菌和抗氧化功能的表征方法,并从这两个方面介绍了薄膜对食品的保鲜作用,旨在为今后的研究提供参考。活性包装薄膜抗菌功能的表征方法主要有抑菌圈法、抑菌率法、微生物生长曲线法和包装食品直接测定法等,抗氧化功能的表征方法主要有自由基清除法、铁离子还原/抗氧化能力法和包装食品直接测定法等。薄膜对食品的保鲜作用主要体现在薄膜对所包装食品中微生物生长的抑制,对脂类、蛋白质氧化进程的减缓以及食品货架期的延长。     

Controlled release of thymol from zein based film

Active packaging materials, able to release antimicrobial compounds into foodstuffs, can be used in order to inhibit or slow down bacterial growth during storage. Zein-based mono and multilayer films were loaded with spelt bran and thymol (35% w/w) to obtain edible composite polymeric materials. Various composite systems were developed to control the release of thymol. In particular, the thickness of the layers and the biodegradable fibres amount were varied. Results highlight that thymol release rate decreased with the increase of the film thickness for both mono and multilayer films, without spelt bran addition. Conversely, a significant increase of thymol release rate with the increase of the bran concentration is recorded for both mono and multilayer films.Industrial relevanceIn recent years, food safety is an important area of concern to the food industry. This fact requires packaging to be an integral part of the preservation concept. Consequently additional antimicrobial activity from the packaging material can aid in shelf life extension. The present work is focused on the development of controlled release systems based on zein incorporated with an active compound, thymol and natural fibres. Release rate of thymol from the developed mono and multilayer films, as affected by layers thickness and fibres amount, was evaluated.     

抗菌材料在食品包装中的研究进展

食品抗菌包装可以有效抑制被包装食品所处环境中微生物的生长,延长食品的货架期,保证食品品质,在食品领域的地位越发重要。本文阐述了抗菌材料作用机理,介绍了常用的有机抗菌剂、无机抗菌剂和天然抗菌剂,并对食品抗菌包装的5 种实现方式进行了比较。对国内外近年来抗菌材料的研究进展,特别是对天然抗菌剂的应用做了详细说明。最后,结合目前抗菌包装膜和抗菌纸的生产现状,对食品抗菌包装的未来发展趋势和研究重点进行展望。     

A Review of Poly(Lactic Acid)‐Based Materials for Antimicrobial Packaging

Poly(lactic acid) (PLA) can be synthesized from renewable bio‐derived monomers and, as such, it is an alternative to conventional petroleum‐based polymers. Since PLA is a relatively new polymer, much effort has been directed toward its development in order to make it an acceptable and effective option to the more traditional petroleum‐based polymers. Commercially, PLA has received considerable attention in food packaging applications with a focus on films and coatings that are suitable for short shelf life and ready‐to‐eat food products. The potential for PLA to be used in active packaging has also been recognized by a number of researchers. This review focuses on the use of PLA in antimicrobial systems for food packaging applications and explores the engineering characteristics and antimicrobial activity of PLA films incorporated and/or coated with antimicrobial agents.     

Potential of Immobilization Technology in Bacteriocin Production and Antimicrobial Packaging

Globalization of food trade, increasing demand for ready to eat fresh food products, and awareness among consumers towards side effects of chemical preservatives have led to research and development in the area of biopreservation. Biopreservation basically involves inhibition or killing of food spoilage microorganisms by the application of other microbes or their antimicrobial products. Bacteriocins are ribosomally synthesized peptides having potential as biopreservatives. The enhanced, stable, continuous, and economically viable production of these preservatives can be carried out by employing immobilization technology. Various matrices, operational conditions, and fermentation systems have been explored for achieving maximum bacteriocin production through immobilization; besides these, immobilization can be used for the application of bacteriocins in various packaging materials or films for their functional effects at the surface of different food products. Efficiency of an antimicrobial packaging system can be increased by its application in combination with other methods, including high-pressure processing (HPP), which in turn can improve the shelf life of food products. These antimicrobial packaging systems can play a significant role in extending shelf life of food products by reducing the risk of foodborne pathogens, thereby enhancing their quality and safety.     

Characterization of Edible Active Coating Based on Alginate–Thyme Oil–Propionic Acid for the Preservation of Fresh Chicken Breast Fillets

Chicken meat presents serious problems of processing and storage. Edible coatings are used commercially to improve the shelf life of fresh foods. The aim of this study is to develop an effective antimicrobial edible coating to improve the shelf life and safety of fresh chicken meat. The effect of propionic acid and thyme essential oils as antimicrobial and antioxidant compounds incorporated into alginate‐based edible coating was evaluated. Physical, antimicrobial and sensorial analyses were performed in coated and uncoated samples. Sensorial analysis showed no significant differences between coated and uncoated samples, which do not influence the buying decisions of consumers. The pH of the meat surface, color and sensorial analysis changed during storage time, showing similar behavior between coatings, the principal parameters to determine the shelf life of this product were weight loss and microbiological deterioration, where coatings had different behaviors. The selected coating increased the shelf life by about 33% with the lowest dehydration.     

Effectiveness of antimicrobial food packaging materials

Antimicrobial additives have been used successfully for many years as direct food additives. The literature provides evidence that some of these additives may be effective as indirect food additives incorporated into food packaging materials. Antimicrobial food packaging is directed toward the reduction of surface contamination of processed, prepared foods such as sliced meats and Frankfurter sausages (hot dogs). The use of such packaging materials is not meant to be a substitute for good sanitation practices, but it should enhance the safety of food as an additional hurdle for the growth of pathogenic and/or spoilage microorganisms. Studies have focused on establishing methods for coating low-density polyethylene film or barrier films with methyl cellulose as a carrier for nisin. These films have significantly reduced the presence of Listeria monocytogenes in solutions and in vacuum packaged hot dogs. Other research has focused on the use of chitosan to inhibit L. monocytogenes and chlorine dioxide sachets for the reduction of Salmonella on modified atmosphere-packaged fresh chicken breasts. Overall, antimicrobial packaging shows promise as an effective method for the inhibition of certain bacteria in foods, but barriers to their commercial implementation continue to exist.     

Potassium Sorbate Permeability of Methylcellulose and Hydroxypropyl Methylcellulose Coatings: Effect of Fatty Acids

Surface microbial stability is a major determinant of the shelf life of refrigerated meat products. Surface microbial growth has also been noticed in intermediate moisture foods exposed to temperature fluctuations. One solution to this problem is to apply edible coatings to the food surface which control diffusion of antimicrobial agents into the food. Films with such properties were identified using a permeability cell. Methyl- and hydroxypropyl methylcellulose mixed with lauric, palmitic, stearic and arachidic acid significantly lowered the potassium sorbate permeation rate relative to cellulose ether films containing no fatty acids. Permeability determinations at 5, 24, 32 and 40°C showed excellent agreement with the Arrhenius activation energy model for the permeation process.     

Prevention of fungal spoilage in food products using natural compounds: A review

The kingdom Fungi is the most important group of microorganism contaminating food commodities, and chemical additives are commonly used in the food industry to prevent fungal spoilage. However, the increasing consumer concern about synthetic additives has led to their substitution by natural compounds in foods. The current review provides an overview of using natural agents isolated from different sources (plants, animals, and microorganisms) as promising antifungal compounds, including information about their mechanism of action and their use in foods to preserve and prolong shelf life. Compounds derived from plants, chitosan, lactoferrin, and biocontrol agents (lactic acid bacteria, antagonistic yeast, and their metabolites) are able to control the decay caused by fungi in a wide variety of foods. Several strategies are employed to reduce the drawbacks of some antifungal agents, like their incorporation into oil-in-water emulsions and nanoemulsions, edible films and active packaging, and their combination with other natural preservatives. These strategies facilitate the addition of volatile agents into food products and, improve their antifungal effectiveness. Moreover, biological agents have been investigated as one of the most promising options in the control of postharvest decay. Numerous mechanisms of action have been elucidated and different approaches have been studied to enhance their antifungal effectiveness.     

我国预制菜行业的发展现状及趋势

预制菜是将可食用原料经预加工制成的半成品或成品产品,具有一定的保质期,近年来该行业快速发展。该研究对预制菜的定义、分类、发展现状、技术难点、市场规模及主要企业进行了综述,并对预制菜的发展趋势进行了展望。目前的主要产业大省包括广东、山东、福建、江苏、河南等。预制菜技术难点主要有食品安全、感官品质、营养品质与保健功能、原材料质量控制及溯源体系、速冻及解冻技术、包装材料与技术、智能装备成套设备等方面。标准化、细分市场和高质量专业技术人才的培养与输送,将成为预制菜行业的发展方向。该综述可为预制菜领域科研攻关的方向、产业的发展提供参考。     

Wheat gluten–based coatings and films: Preparation,properties, and applications

Effective food packaging that can protect foodstuffs from physical, chemical, and biological damage and maintain freshness and quality is essential to the food industry. Wheat gluten shows promise as food packaging materials due to its edibility, biodegradability, wide availability, low cost, film-forming potential, and high resistance to oxygen. The low mechanical properties and poor water permeability of wheat gluten coatings and films limit their wide applications; however, some inferior properties can be improved through various solutions. This work presents a comprehensive review about wheat gluten–based coatings and films, including their formulation, processing methods, properties, functions, and applications. The mechanical and water resistance properties of coatings and films can be reinforced through wheat gluten modification, combinations of different processing methods, and the incorporation of reinforcing macromolecules, antioxidants, and nanofillers. Antioxidants and antimicrobial agents added to wheat gluten can inhibit microbial growth on foodstuffs, maintain food quality, and extend shelf life. Performances of wheat gluten–based coatings and films can be further improved to expand their applications in food packaging. Current research gaps are identified. Future research is needed to examine the optimal formulation and processing of wheat gluten–based coatings and films and their performance.     

Ethylene vinyl alcohol: a review of barrier properties for packaging shelf stable foods

Ethylene vinyl alcohol (EVOH) is one of the best known flexible thermoplastic oxygen barrier materials in use today. It is especially important for refrigerated and shelf-stable foods where oxygen deteriorates the quality of packaged products and reduces their shelf life. EVOH accounts for a majority of thermoplastic barrier materials used for rigid or semi-rigid retortable food containers. However. it is of limited use in flexible packages or lid films for rigid trays used for packaging thermally processed shelf-stable low acid foods due to its moisture sensitivity. Nevertheless, current use of other oxygen barrier materials such as polyvinylidene chloride and aluminum foil creates environmental concerns. Innovations in food processing technologies provide opportunities for increased use of EVOH in food packaging. The aim of this review is to give an overview of research on the oxygen barrier properties of EVOH from the perspective of structure-barrier property relationships and the consequences of food processing conditions.     

Edible Films and Coatings as Carriers of Living Microorganisms: A New Strategy Towards Biopreservation and Healthier Foods

Edible films and coatings have been extensively studied in recent years due to their unique properties and advantages over more traditional conservation techniques. Edible films and coatings improve shelf life and food quality, by providing a protective barrier against physical and mechanical damage, and by creating a controlled atmosphere and acting as a semipermeable barrier for gases, vapor, and water. Edible films and coatings are produced using naturally derived materials, such as polysaccharides, proteins, and lipids, or a mixture of these materials. These films and coatings also offer the possibility of incorporating different functional ingredients such as nutraceuticals, antioxidants, antimicrobials, flavoring, and coloring agents. Films and coatings are also able to incorporate living microorganisms. In the last decade, several works reported the incorporation of bacteria to confer probiotic or antimicrobial properties to these films and coatings. The incorporation of probiotic bacteria in films and coatings allows them to reach the consumers’ gut in adequate amounts to confer health benefits to the host, thus creating an added value to the food product. Also, other microorganisms, either bacteria or yeast, can be incorporated into edible films in a biocontrol approach to extend the shelf life of food products. The incorporation of yeasts in films and coatings has been suggested primarily for the control of the postharvest disease. This work provides a comprehensive review of the use of edible films and coatings for the incorporation of living microorganisms, aiming at the biopreservation and probiotic ability of food products.     

壳聚糖/植物精油可食性抗菌膜研究进展

壳聚糖包埋植物精油制备的可食性抗菌膜具有原料来源广泛、可食、可降解,抗菌效果强等优势,在食品保鲜领域显示了重要的应用价值。本文综述了壳聚糖和精油各自的结构、性质、壳聚糖/精油复合膜及添加了其它天然高分子如蛋白质、淀粉等的复合可食性抗菌膜的研究进展,同时指出了目前该研究领域中存在的问题,并对未来的研究方向进行了展望,为壳聚糖/植物精油复合可食性抗菌膜研究的进一步开发利用提供参考。