Chitosan application for active bio-based films production and potential in the food industry: Review

During the past decade, there was an increasing interest to develop and use bio-based active films which are characterized by antimicrobial and antifungal activities in order to improve food preservation and to reduce the use of chemical preservatives. Biologically active bio-molecules such as chitosan and its derivatives have a significant potential in the food industry in view of contaminations associated with food products and the increasing concerns in relation with the negative environmental impact of conventional packaging materials such as plastics. Chitosan offers real potential for applications in the food industry due to its particular physico-chemical properties, short time biodegradability, biocompatibility with human tissues, antimicrobial an antifungal activities, and non-toxicity. Thus, chitosan-based films have attracted serious attention in food preservation and packaging technology. This is mainly due to a fact that chitosan exhibits high antimicrobial activity against pathogenic and spoilage micro-organisms, including fungi, and both Gram-positive and Gram-negative bacteria. The aim of the present review was to summarize the most important information on chitosan from its bioactivity point of view and to highlight various preparative methods used for chitosan-based active bio-films and their potential for applications in the food preservation and packaging technology.     

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。     

壳聚糖对于肉类食品防腐和保鲜的应用研究进展

壳聚糖是1种来源于蟹、虾等甲壳类动物贝壳的天然高分子聚合物.对于多种食源性丝状真菌、酵母、细菌等具有广谱抗性,并且具有很好的抗脂质过氧化作用.以壳聚糖为材料制成的包装膜,具有透气屏障的作用,可以延缓被包裹物与外界的气体交换以及包裹物自身营养成分的流失.这些特性使壳聚糖作为潜在的食品防腐剂或食品包裹材料具有很高的市场应用潜力和应用价值.本文主要对近年来壳聚糖作为食品防腐剂在延长生鲜肉、鱼、火腿制品保存期方面的研究和应用情况进行了综述.     

Applications of chitosan for improvement of quality and shelf life of foods: a review

ABSTRACT:  Chitosan is a modified, natural biopolymer derived by deacetylation of chitin, a major component of the shells of crustacean. Recently, chitosan has received increased attention for its commercial applications in the biomedical, food, and chemical industries. Use of chitosan in food industry is readily seen due to its several distinctive biological activities and functional properties. The antimicrobial activity and film-forming property of chitosan make it a potential source of food preservative or coating material of natural origin. This review focuses on the applications of chitosan for improvement of quality and shelf life of various foods from agriculture, poultry, and seafood origin.     

Characterization of antimicrobial properties on the growth of S. aureus of novel renewable blends of gliadins and chitosan of interest in food packaging and coating applications

The biocide properties of chitosan-based materials have been known for many years. However, typical antimicrobial formulations of chitosan, mostly chitosonium salts, are known to be very water sensitive materials which may impair their use in many application fields such as food packaging or food coating applications. This first work reports on the development and characterization of the antimicrobial properties of novel fully renewable blends of chitosan with more water-resistant gliadin proteins isolated from wheat gluten. Chitosan release to the nutrient broth from a wide range of blends was studied making use of the ninhydrin method. The results indicated that both pure chitosan and its blends with gliadins presented significant antimicrobial activity, which increased with increasing the amount of chitosan in the composite formulation as expected. The gliadins-chitosan blends showed good transparency and film-forming properties and better water resistance than pure chitosan. The release tests revealed that dissolution of the biocide glucosamine groups, i.e. the chitosan water soluble fractions, also increased with the amount of chitosan present in the formulation. The release of these groups was for the first time directly correlated with the antimicrobial properties exhibited by the blends. Thus, incorporation of chitosan into an insoluble biopolymer matrix was revealed as a very feasible strategy to generate novel chitosan-based antimicrobial materials with potential advantages, for instance active food packaging applications.     

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。     

Antimicrobial edible films and coatings

Increasing consumer demand for microbiologically safer foods, greater convenience, smaller packages, and longer product shelf life is forcing the industry to develop new food-processing, cooking, handling, and packaging strategies. Nonfluid ready-to-eat foods are frequently exposed to postprocess surface contamination, leading to a reduction in shelf life. The food industry has at its disposal a wide range of nonedible polypropylene- and polyethylene-based packaging materials and various biodegradable protein- and polysaccharide-based edible films that can potentially serve as packaging materials. Research on the use of edible films as packaging materials continues because of the potential for these films to enhance food quality, food safety, and product shelf life. Besides acting as a barrier against mass diffusion (moisture, gases, and volatiles), edible films can serve as carriers for a wide range of food additives, including flavoring agents, antioxidants, vitamins, and colorants. When antimicrobial agents such as benzoic acid, sorbic acid, propionic acid, lactic acid, nisin, and lysozyme have been incorporated into edible films, such films retarded surface growth of bacteria, yeasts, and molds on a wide range of products, including meats and cheeses. Various antimicrobial edible films have been developed to minimize growth of spoilage and pathogenic microorganisms, including Listeria monocytogenes, which may contaminate the surface of cooked ready-to-eat foods after processing. Here, we review the various types of protein-based (wheat gluten, collagen, corn zein, soy, casein, and whey protein), polysaccharide-based (cellulose, chitosan, alginate, starch, pectin, and dextrin), and lipid-based (waxes, acylglycerols, and fatty acids) edible films and a wide range of antimicrobial agents that have been or could potentially be incorporated into such films during manufacture to enhance the safety and shelf life of ready-to-eat foods.     

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.     

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.     

壳聚糖复合膜在果蔬保鲜中的应用

壳聚糖具有良好的生物相容性、可生物降解性、安全性、成膜性、抗菌性等,常用于果蔬保鲜。但由于机械性能和生物活性不足,为了增强其理化性能和生物活性,常添加生物聚合物、抗菌剂、抗氧化剂等功能成分以提高膜综合性能。综述了壳聚糖膜和壳聚糖/多糖、壳聚糖/蛋白质、壳聚糖/脂质、壳聚糖/抗菌剂、壳聚糖/抗氧化剂等壳聚糖基复合膜在果蔬保鲜中的应用进展,从壳聚糖的诱导活性、成膜特性和抗菌活性三个方面总结了壳聚糖膜的保鲜机理,分析了壳聚糖基复合膜目前在果蔬保鲜实际应用中存在的问题,并对未来发展方向进行了展望,以期为开发安全、高效、绿色、经济的壳聚糖基果蔬保鲜膜提供一定的理论指导。     

Physical Characterization and Pork Packaging Application of Chitosan Films Incorporated with Combined Essential Oils of Cinnamon and Ginger

Combinations of essential oils (EOs) can be an effective approach to reinforce their antimicrobial effects. In this sense, incorporation of two EOs into edible films may have supplementary utilizations in food packaging. Chitosan films containing combined EOs of cinnamon and ginger (1:1) at levels of 0.00, 0.05, 0.20, and 1.00% were developed and preliminarily characterized in the current study. The effect of the resulting materials on the antimicrobial and antioxidant properties of pork was then investigated during refrigerated storage (4 °C) over 9 days. Results showed that the presence of EOs markedly increased the thickness and opacity of the chitosan films, but did not modify the film solubility and water vapor permeability. When applied to the preservation of pork slices, these films were effective in retarding total microbial growth, increases in pH as well as lipid oxidation. The highest antioxidant and antimicrobial activities were observed in chitosan films incorporated with 1.00% EOs. These results suggest that chitosan-EO films have potential for application in pork packaging.     

Chitosan-based biodegradable functional films for food packaging applications

Chitin is the structural material of crustaceans, insects, and fungi, and is the second most abundant biopolymer after cellulose on earth. Chitosan, a deacetylated derivative of chitin, can be obtained by deacetylation of chitin. It is a functionally versatile biopolymer due to the presence of amino groups responsible for the various properties of the polymer. Although it has been used for various industrial applications, the recent one is its use as a biodegradable antimicrobial food packaging material. Much research has been focused on chitosan-based flexible food packaging and edible food coatings to compete with conventional non-biodegradable plastic-based food packaging materials. Various strategies have been used to improve the properties of chitosan - using plasticizers and cross-linkers, embedding the polymer with fillers such as nanoparticles, fibers, and whiskers, and blending the polymer with natural extracts and essential oils and also with other natural and synthetic polymers. However, much research is still needed to bring this biopolymer to industrial levels for the food packaging applications.Industrial relevanceAs a major by-product of the seafood industry, a massive amount of crustacean shell waste is generated each year, which can be used to produce value-added chitin, which can be converted to chitosan using a relatively simple deacetylation process. Being extracted from a bio-waste product using many energy-efficient methods, chitosan is much cheaper as compared to other biopolymers. Nevertheless, the exceptional properties of chitosan make it a relatively stronger candidate for food packaging applications. Chitosan has already been used in various industries, such as biomedical, agriculture, water treatment, cosmetics, textile, photography, chromatography, electronics, paper industry, and food industry. This review article compiles all the essential literature up to the latest developments of chitosan as a potential food packaging material and the outcomes of its practical utilization for this purpose.     

Postharvest Quality of Fresh-Cut Carrots Packaged in Plastic Films Containing Silver Nanoparticles

Active food packaging containing antimicrobial additive goes beyond traditional functions of packaging, once it can extend food shelf life maintaining its quality, safety and reducing postharvest losses by controlling food spoilage. Among several antimicrobial additives employed in polymeric films for packaging, metallic nanoparticles outstand due to its facility for synthesis, low-cost of production, and intense antimicrobial properties. In this work, extruded plain films of low-density polyethylene (LDPE) containing silver nanoparticles (AgNPs) embedded in SiO₂ and TiO₂ carriers (namely MS and MT, respectively) were produced and used as active packaging for maintaining the physicochemical and microbiological quality of carrots (Daucus Carota L. cv. Brasília). The neat (LDPE) and composite films containing MS and MT were characterized by scanning electron microscopy and permeability to oxygen and used for packaging fresh-cut sliced carrots stored at 10 °C for 10 days. After the storage time, the physicochemical properties of carrots were characterized, while the antimicrobial properties of films and AgNP migration were investigated. Our results revealed that both MT and MS packages showed antimicrobial activity even for films containing low concentration of AgNP. In addition, AgNP antimicrobial activity demonstrated to be carrier-dependent, once MT-LDPE showed improved performance compared to MS-LDPE. Regarding the physicochemical properties of packaged carrot, lower soluble solids and weight loss and higher levels of ascorbic acid were observed for carrots packaged with MT-LDPE films (compared to MS-LDPE), leading to a better postharvest quality conservation. Such differences observed in physicochemical properties of carrots are related to the distinct antimicrobial and film permeability properties for each composite film. In addition, under the conditions employed in this study, AgNP migration from the packages to fresh-cut carrot was not observed, which is highly desirable for food packaging safety, indicating the potential of such active packages for food preservation application.     

壳聚糖基复合膜的成膜机理和特性研究进展

壳聚糖通过分子内和分子间氢键连接形成具有粘性的成膜溶液,流延干燥后可形成高透明度的可食膜。又因壳聚糖膜具有一定的机械性能、阻气性和抑菌性,已广泛应用于食品贴体包装,来提高食品质量。纯壳聚糖膜的力学性能、阻水性等不能满足理想包装的高保护性、高防潮性的要求,限制了其在食品包装方面的应用。在实际生产中,壳聚糖常与其他成膜材料、抗菌物质复合,改善其机械性能、阻隔性及抑菌性能,延长食品货架期。本文概述了壳聚糖的制备、纯壳聚糖膜的成膜机理和特性;重点综述了壳聚糖分子上的氨基、羟基等与多糖类（如淀粉、果胶）、蛋白质类（如明胶）、脂质（如甘油、植物精油）等聚合物分子上的羰基、羟基、乙酰基等通过氢键、静电相互作用,形成抗拉强度高、阻气性好、抑菌能力强的复合膜,为壳聚糖复合膜的开发和应用、提高食品安全性提供技术支持。     

金属有机框架材料在食品包装中的应用

随着食品工业的发展,食品安全问题引起人们的广泛关注。金属有机框架（metal-organic frameworks,MOFs）是一类具有独特物理和化学性质的功能材料,其具有多孔结构以及显著的抗菌性能,因此在食品保鲜方面显示出良好的应用前景。在食品包装领域,MOFs可以延长食品的保质期并延缓贮藏期食品品质的劣变,提高食品包装材料的性能。本文综述MOFs作为抗菌剂、氧清除剂和乙烯清除剂在食品包装中的应用,介绍MOFs在食品包装领域的应用前景及面临的问题,旨在为MOFs在食品包装中的应用提供参考。     

Chitosan coatings enriched with essential oils: Effects on fungi involved in fruit decay and mechanisms of action

BackgroundPesticides have a negative impact on the health of consumers and on the environment, and as a consequence, the use of naturally occurring antimicrobial agents have become more popular to prevent food spoilage. An alternative is the use of chitosan, because of its antimicrobial, antioxidant activities and its capacity to form films having good mechanical properties. Chitosan has been used in the preparation of films and coatings for the preservation of different food products, and the addition of essential oils have been shown to be a good strategy to improve its antimicrobial activity in situ.Scope and approachThis review compiles information related to studies and research that employ chitosan as matrix for films, coatings and nanogels with essential oils extracted from plants, as antifungal agent. A special emphasis has been addressed to the effect exerted on the most pathogenic fungi for crops, also highlighting the mechanisms of action that researchers attribute to the composite, together with inhibition data.Key Findings and ConclusionEffective natural treatments, using chitosan-essential oils films or nano-emulsions, improve the preservation of fruit in terms of fungal decay. The effect is particularly dependent on the ability to release the antimicrobial compounds from the polymer matrix, the type of essential oils, the fungal species, and the incubation temperature. Several efforts are still required to understand in detail the mechanism of degradation of perishable food, how the chitosan-essential oils composites control or inhibit food decay, the effects on other pathogenic and non-pathogenic moulds as well as on the production of mycotoxins.     

Antimicrobial effectiveness of bioactive packaging materials from edible chitosan and casein polymers: assessment on carrot, cheese, and salami

Antimicrobial packaging is one of the most promising active packaging systems for controlling spoilage and pathogenic microorganisms. In this work, the intrinsic antimicrobial properties of chitosan (CH) were combined with the excellent thermoplastic and film-forming properties of sodium caseinate (SC) to prepare SC/CH film-forming solutions and films. The antimicrobial effectiveness of SC, CH, and SC/CH coatings on the native microfloras of cheese, salami, and carrots was evaluated. In vitro assays through the test tube assay indicated that the most significant antimicrobial effect was achieved by CH and SC/CH solutions on carrot and cheese native microfloras. SC film-forming solutions did not exert antimicrobial activity on any of the native microflora studied. SC, CH, and SC/CH films stored in controlled environments showed that the retention of the antimicrobial action was observed until 5-d storage, at 65% relative humidity in both temperatures (10 °C and 20 °C). In vivo assays were also performed with SC, CH, and SC/CH applied as coatings or wrappers on the 3 food substrates. CH and SC/CH applied at both immersion and wrapper exerted a significant bactericidal action on mesophilic, psychrotrophic, and yeasts and molds counts, showing the 3 microbial populations analyzed a significant reduction (2.0 to 4.5 log CFU/g). An improvement of the bactericidal properties of the CH/SC blend respect to those of the neat CH film is reported. The ionic interaction between both macromolecules enhances its antimicrobial properties. Practical Application: The continuous consumer interest in high quality and food safety, combined with environmental concerns has stimulated the development and study of biodegradable coatings that avoid the use of synthetic materials. Among them, edible coatings, obtained from generally recognized as safe (GRAS) materials, have the potential to reduce weight loss, respiration rate, and improve food appearance and integrity. They can be used in combination with other food preservation techniques in order to extend the effectiveness of the food preservation chain. Moreover, antimicrobial films and coatings have innovated the concept of active packaging and have been developed to reduce, inhibit, or delay the growth of microorganisms on the surface of food in contact with the package. The use of antimicrobials packaging films to control the growth of microorganisms in food can have a significant impact on shelf-life extension and food safety. In addition, antimicrobial films can be prepared by the combination of inherent antimicrobial materials (that is, CH), with good film-forming protein-based ones (that is, SC). Therefore, the objective of this work is to study the performance of 2 biodegradable and edible biopolymers and their combination as natural packages for selected food products.     

Characterization and antimicrobial analysis of chitosan-based films

Chitosan-based films for food packaging applications were prepared by casting and dried at room temperature or heat-treated in order to study functional properties and antimicrobial activity. In all cases, films were flexible and transparent, regardless of chitosan molecular weight, glycerol content, and temperature. Regarding antimicrobial activity, chitosan film forming solutions showed antimicrobial behaviour against Escherichia coli and Lactobacillus plantarum. It was also observed that the bacteriostatic property of chitosan-based films against bacteria employed in this study was notably affected by temperature. Moreover, temperature produced significant variation in the functional properties of chitosan-based films, such as colour, wettability, resistance against UV light and mechanical properties. In good agreement with this behaviour, total soluble matter (TSM), fourier transform infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD) results suggested a change in the chemical structure of chitosan films, possibly due to Maillard reaction when heat treatment was used.     

The antimicrobial,mechanical, physical and structural properties of chitosan–gallic acid films

Chitosan films incorporated with various concentrations of gallic acid were prepared and investigated for antimicrobial, mechanical, physical and structural properties. Four bacterial strains that commonly contaminate food products were chosen as target bacteria to evaluate the antimicrobial activity of the prepared gallic acid–chitosan films. The incorporation of gallic acid significantly increased the antimicrobial activities of the films against Escherichia coli, Salmonella typhimurium, Listeria innocua and Bacillus subtilis. Chitosan films incorporated with 1.5 g/100 g gallic acid showed the strongest antimicrobial activity. It was also found that tensile strength (TS) of chitosan film was significantly increased when incorporating 0.5 g/100 g gallic acid. Inclusion of 0.5 g/100 g gallic acid also significantly decreased water vapor permeability (WVP) and oxygen permeability (OP). Microstructure of the films was investigated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) and it was found that gallic acid was dispersed homogenously into the chitosan matrix.     

壳聚糖的生产及其在食品工业中的应用

壳聚糖是一种丰富的天然资源.近年来,壳聚糖的开发应用受到国内外的重视,越来越多的产品从实验室走向市场.概述了壳聚糖的研究现状和最新进展,并介绍了壳聚糖的性质和生产方法;着重讨论了其在食品工业中的应用.