Edible films and coatings: Structures, active functions and trends in their use

Study of Hybrid Modification with Humic Acids of Environmentally Safe Biodegradable Hydrogel Films Based on Hydroxypropyl Methylcellulose

The possibility of increasing the complexity of the operational properties of environmentally safe biodegradable polymer hydrogel materials based on hydroxypropyl methylcellulose due to modification by humic acids from lignite is considered. As a result of this research, environmentally safe hybrid hydrogel films with antibacterial properties were received. In the framework of physicochemical studies, it was determined by IR spectroscopy that hydroxypropyl methylcellulose modified with humic acids hybridmaterials are received by the mechanism of matrix synthesis, which is accompanied by hydroxypropyl methylcellulose crosslinking through multipoint interaction with the carboxyl group of humic acids. Regularities in terms of changes in water absorption, gelation time, and mold emergence time regarding the environmentally safe biodegradable polymer hydrogel materials based on hydroxypropyl methylcellulose depending on the humic acid content were revealed. It was established that the optimal humic acid content in environmentally safe biodegradable hydrogel films with bactericidal properties based on hydroxypropyl methylcellulose is 15% by mass. It was also established that the hybrid modification of hydroxypropyl methylcellulose with humic acids allows them to preserve their biodegradation properties while giving them antibacterial properties. The environmentally safe biodegradable hydrogel films with bactericidal properties based on hydroxypropyl methylcellulose and humic acids are superior in their operational characteristics to known similar biodegradable hydrogel films based on natural biopolymers.

Polysaccharide-Based Biodegradable Films: An Alternative in Food Packaging

Packaging can mitigate the physical, chemical, and microbiological phenomena that affects food products’ quality and acceptability. However, the use of conventional packaging from non-renewable fossil sources generates environmental damage caused by the accumulation of non-biodegradable waste. Biodegradable films emerge as alternative biomaterials which are ecologically sustainable and offer protection and increase food product shelf life. This review describes the role of biodegradable films as packaging material and their importance regarding food quality. The study emphasizes polysaccharide-based biodegradable films and their use in foods with different requirements and the advances and future challenges for developing intelligent biodegradable films. In addition, the study explores the importance of the selection of the type of polysaccharide and its combination with other polymers for the generation of biodegradable films with functional characteristics. It also discusses additives that cause interactions between components and improve the mechanical and barrier properties of biodegradable films. Finally, this compilation of scientific works shows that biodegradable films are an alternative to protecting perishable foods, and studying and understanding them helps bring them closer to replacing commercial synthetic packaging.

Structure and properties of gelatin edible film modified using oxidized poly(2-hydroxyethyl acrylate) with multiple aldehyde groups

BACKGROUND

Pure gelatin film usually exhibits characteristics of being brittle and hydrophilic, which limit its wide use in food packing fields. In this study gelatin/oxidized poly(2-hydroxyethylacrylate) (G/OP) composite films were prepared using casting techniques, the aim of this research was to investigate the effects of OP on the structures and properties of the G/OP composite films.

RESULTS

The Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy results indicated that the G/OP films retained their original secondary structure and random coiled conformation. However, the surface and cross-sectional morphologies of the G/OP films were rougher than those of pure gelatin films, cracks and agglomerates appeared with increasing OP dosage. The remarkable transparency of the G/OP film at 280 nm indicated excellent ultraviolet (UV) light barrier properties of the film, which inhibited UV-light-induced food oxidation. Moreover, the addition of OP decreased the water content and water solubility and considerably increased the water contact angle of pure gelatin films from 78.8° to 116.2° (a maximum increase of 37.5°). This suggested that OP modification improved the hydrophobicity of gelatin films. Furthermore, the inclusion of OP significantly promoted the flexibility of gelatin films, thereby improving their brittleness.

CONCLUSIONS

The UV light barrier properties, hydrophobicity, and flexibility of gelatin films were improved via OP modification, thus the produced G/OP composite films have the potential to be used in food packaging. © 2022 Society of Chemical Industry.

A Green Film-Forming Investigation of the Edible Film Based on Funoran: Preparation, Characterization, and the Investigation of the Plasticizer Effects

In this study, an edible film based on funoran was developed. Moreover, the effects of plasticizers (glycerol, xylitol, and sorbitol) on the physicochemical properties of the funoran films were also investigated. The interactions between plasticizers and funoran molecules of the film-forming system were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The results showed that the addition of plasticizers altered and broke the initial complex entangled structures of funoran molecular chains. Funoran films containing plasticizers were compatible, homogeneous, and dense, exhibiting good thermal stability below 100 °C. With the addition of plasticizers, the elongation at break, oxygen permeability, light transmittance, and water vapor permeability increased, but the tensile strength decreased. It was found that a glycerol addition of 40% was most suitable for commercial applications. All the results revealed the excellent film-forming properties of funoran, indicating that the prepared funoran films have tremendous potential for packaging applications.

An insight to potential application of synbiotic edible films and coatings in food products

Edible films and coatings have gained significant consideration in recent years due to their low cost and decreasing environmental pollution. Several bioactive compounds can be incorporated into films and coatings, including antioxidants, antimicrobials, flavoring agents, colors, probiotics and prebiotics. The addition of probiotics to edible films and coatings is an alternative approach for direct application in food matrices that enhances their stability and functional properties. Also, it has been noted that the influence of probiotics on the film properties was dependent on the composition, biopolymer structure, and intermolecular interactions. Recently, the incorporation of probiotics along with prebiotic compounds such as inulin, starch, fructooligosaccharide, polydextrose and wheat dextrin has emerged as new bioactive packaging. The simultaneous application of probiotics and prebiotics improved the viability of probiotic strains and elevated their colonization in the intestinal tract and provided health benefits to humans. Moreover, prebiotics created a uniform and compact structure by filling the spaces within the polymer matrix and increased opacity of edible films. The effects of prebiotics on mechanical and barrier properties of edible films was dependent on the nature of prebiotic compounds. This review aims to discuss the concept of edible films and coatings, synbiotic, recent research on synbiotic edible films and coatings as well as their application in food products.

A comprehensive review of food gels: formation mechanisms, functions, applications, and challenges

Gels refer to the soft and flexible macromolecular polymeric materials retaining a large amount of water or biofluids in their three-dimensional network structure. Gels have attracted increasing interest in the food discipline, especially proteins and polysaccharides, due to their good biocompatibility, biodegradability, nutritional properties, and edibility. With the advancement of living standards, people's demand for nutritious, safe, reliable, and functionally diverse food and even personalized food has increased. As a result, gels exhibiting unique advantages in food application will be of great significance. However, a comprehensive review of functional hydrogels as food gels is still lacking. Here, we comprehensively review the gel-forming mechanisms of food gels and systematically classify them. Moreover, the potential of hydrogels as functional foods in different types of food areas is summarized, with a special focus on their applications in food packaging, satiating gels, nutrient delivery systems, food coloring adsorption, and food safety monitoring. Additionally, the key scientific issues for future food gel research, with specific reference to future novel food designs, mechanisms between food components and matrices, food gel-human interactions, and food gel safety, are discussed. Finally, the future directions of hydrogels for food science and technology are summarized.

Edible Polymers and Secondary Bioactive Compounds for Food Packaging Applications: Antimicrobial, Mechanical, and Gas Barrier Properties

Edible polymers such as polysaccharides, proteins, and lipids are biodegradable and biocompatible materials applied as a thin layer to the surface of food or inside the package. They enhance food quality by prolonging its shelf-life and avoiding the deterioration phenomena caused by oxidation, humidity, and microbial activity. In order to improve the biopolymer performance, antimicrobial agents and plasticizers are also included in the formulation of the main compounds utilized for edible coating packages. Secondary natural compounds (SC) are molecules not essential for growth produced by some plants, fungi, and microorganisms. SC derived from plants and fungi have attracted much attention in the food packaging industry because of their natural antimicrobial and antioxidant activities and their effect on the biofilm's mechanical properties. The antimicrobial and antioxidant activities inhibit pathogenic microorganism growth and protect food from oxidation. Furthermore, based on the biopolymer and SC used in the formulation, their specific mass ratio, the peculiar physical interaction occurring between their functional groups, and the experimental procedure adopted for edible coating preparation, the final properties as mechanical resistance and gas barrier properties can be opportunely modulated. This review summarizes the investigations on the antimicrobial, mechanical, and barrier properties of the secondary natural compounds employed in edible biopolymer-based systems used for food packaging materials.

Natural alternatives for processed meat: Legislation, markets, consumers, opportunities and challenges

Consumers' interest in food with less and/or free from synthetic additives has increased considerably in recent years. In this context, researchers and industries have concentrated efforts on developing alternatives to these compounds. Replacing synthetic additives in meat products is a challenge, given their importance for sensory characteristics and food safety. Complementary technologies combined with the replacement and/or reduction of synthetic additives (hurdle technologies) has been studied focusing on the protection and extension of the shelf life of meat products. This review reports alternatives for replacing and/or reducing the use of synthetic additives in meat derivatives, aiming at the development of more natural and simpler meat products, familiar to consumers and considered clean labels.

Edible Bioactive Film with Curcumin: A Potential "Functional" Packaging?

Edible packaging has been developed as a biodegradable and non-toxic alternative to traditional petroleum-based food packaging. Biopolymeric edible films, in addition to their passive protective function, may also play a bioactive role as vehicles for bioactive compounds of importance to human health. In recent years, a new generation of edible food packaging has been developed to incorporate ingredients with functional potential that have beneficial effects on consumer health. Curcumin, a bioactive compound widely used as a natural dye obtained from turmeric rhizomes (Curcuma longa L.), has a broad spectrum of beneficial properties for human health, such as anti-inflammatory, anti-hypertensive, antioxidant, anti-cancer, and other activities. To demonstrate these properties, curcumin has been explored as a bioactive agent for the development of bioactive packaging, which can be referred to as functional packaging and used in food. The aim of this review was to describe the current and potential research on the development of functional-edible-films incorporating curcumin for applications such as food packaging.

Migration and Distribution of PAH4 in Oil to French Fries Traced Using a Stable Isotope during Frying

Isotope-labeled four polycyclic aromatic hydrocarbons (PAH4-d12) were applied to study the migration and distribution of PAH4 in oil to French fries during frying. The results showed that the mobilities of PAH4-d12 showed a downtrend within 0-6 h and then an uptrend, and PAH4-d12 were mainly distributed in the crust of the French fries, especially five-ring PAHs-d12. The correlation analysis showed that PAH4-d12 migration was mainly caused by oil absorption of French fries. The low fluidity of the oil slowed down the PAH4-d12 migration, which was accelerated as the total polar component increased (higher than 15-20%). Additionally, higher frying temperature enhanced the crust ratio and porous structure of French fries, which explained the abundant five-ring PAHs-d12 distributed in the crust. This study provided references for optimizing the frying parameters: the exposure of PAH4 in French fries to humans can be reduced by controlling the oil quality and weakening the crust of the French fries.

Recent Advancements of Polysaccharides to Enhance Quality and Delay Ripening of Fresh Produce: A Review

The freshness of fruits and vegetables plays a significant role in consumers' decision to purchase a product at the supermarket. Fresh-cut products are the latest trend in fulfilling society's restless needs, and the food industry is faced with the challenge of maintaining the quality of fresh produce. The food industry is concerned with the natural maturation and degradation of fruits and vegetables, primarily due to enzymatic reactions. It has been demonstrated that polysaccharide coatings effectively preserve the freshness of these products, extending their shelf life depending on the preservation method used. This review informs readers about the different types of polysaccharides and their novel applications as natural food preservatives in the past five years (2018-2022). The key findings summarized the properties of the antimicrobial agent, the molecular mechanism of action, coating methods, and formulation for the preservation approach. Additionally, we discuss the scientific factors influencing polysaccharide processing and preservation efficacy, allowing it to be used in post-harvest management.

A review of multilayer and composite films and coatings for active biodegradable packaging

Active biodegradable packaging are being developed from biodegradable biopolymers which may solve the environmental problems caused by petroleum-based materials (plastics), as well as improving the shelf life, quality, nutritional profile, and safety of packaged food. The functional performance of active ingredients in biodegradable packaging can be extended by controlling their release profiles. This can be achieved by incorporating active ingredients in sandwich-structured packaging including multilayer and composite packaging. In multilayer materials, the release profile can be controlled by altering the type, structure, and thickness of the different layers. In composite materials, the release profile can be manipulated by altering the interactions of active ingredients with the surrounding biopolymer matrix. This article reviews the preparation, properties, and applications of multilayer and composite packaging for controlling the release of active ingredients. Besides, the basic theory of controlled release is also elaborated, including diffusion, swelling, and biodegradation. Mathematical models are presented to describe and predict the controlled release of active ingredients from thin films, which may help researchers design packaging materials with improved functional performance.

Natural-Fiber-Reinforced Chitosan, Chitosan Blends and Their Nanocomposites for Various Advanced Applications

There has been much effort to provide eco-friendly and biodegradable materials for the next generation of composite products owing to global environmental concerns and increased awareness of renewable green resources. This review article uniquely highlights the use of green composites from natural fiber, particularly with regard to the development and characterization of chitosan, natural-fiber-reinforced chitosan biopolymer, chitosan blends, and chitosan nanocomposites. Natural fiber composites have a number of advantages such as durability, low cost, low weight, high specific strength, non-abrasiveness, equitably good mechanical properties, environmental friendliness, and biodegradability. Findings revealed that chitosan is a natural fiber that falls to the animal fiber category. As it has a biomaterial form, chitosan can be presented as hydrogels, sponges, film, and porous membrane. There are different processing methods in the preparation of chitosan composites such as solution and solvent casting, dipping and spray coating, freeze casting and drying, layer-by-layer preparation, and extrusion. It was also reported that the developed chitosan-based composites possess high thermal stability, as well as good chemical and physical properties. In these regards, chitosan-based "green" composites have wide applicability and potential in the industry of biomedicine, cosmetology, papermaking, wastewater treatment, agriculture, and pharmaceuticals.

Recent Advances in Novel Packaging Technologies for Shelf-Life Extension of Guava Fruits for Retaining Health Benefits for Longer Duration

Guava (Psidium guajava L.) fruit is also known as the apple of tropics, belongs to the family of genus Psidium, and is widely cultivated in tropical zones of the world. Recently, the importance of guava fruit has increased due to its inherent nutritional content, pleasant aroma, excellent flavor, and delicious taste. It is considered an excellent source of nutrients and phytochemicals. Guava is a climacteric fruit that continues to mature or ripen even after harvest, showing an increase in the rate of respiration and metabolic activities within a short period, leading to rapid senescence or spoilage of fruit. It has limitations in terms of commercialization due to short storage life after harvest and sensitivity to diseases and chilling injury during the storage period. Many postharvest technologies such as edible packaging, modified atmosphere packaging (MAP), composite packaging, controlled atmosphere packaging (CAP), antimicrobial/antifungal packaging, and nano packaging have been used to retard the chilling injury and enhance the keeping quality of guava fruits during the storage period to control respiration rate, reduce weight loss, minimize lipid oxidation, and maintain organoleptic properties. However, these packaging technologies have varied effects on the internal and external quality attributes of guava fruits. This review, therefore, discusses the physiology, mechanism of ripening, oxidation, and ethylene production of guava fruits. The review also discusses the packaging technologies and their effect on the postharvest characteristics of guava fruits during the storage period.

Effects of Gum Arabic Coatings Enriched with Lemongrass Essential Oil and Pomegranate Peel Extract on Quality Maintenance of Pomegranate Whole Fruit and Arils

The effects of gum arabic coatings combined with lemongrass oil and/or pomegranate peel extract on freshly harvested mature 'Wonderful' pomegranate fruit were studied. Fruit were coated with gum arabic (GA) (1.5% w/v) alone or enriched with lemongrass oil (LM) (0.1% v/v) and/or pomegranate peel extract (PP) (1% w/v). Fruit were packed into standard open top ventilated cartons (dimensions: 0.40 m long, 0.30 m wide and 0.12 m high), and stored for 6 weeks at 5 ± 1 °C (90% RH). Evaluations were made every 2 weeks of cold storage and after 5 d of shelf life (20 °C and 65% RH). Fruit coated with GA + PP (4.09%) and GA + PP + LM (4.21%) coatings recorded the least cumulative weight loss compared to the uncoated control (9.87%). After 6 weeks, uncoated control and GA + PP + LM recorded the highest (24.55 mg CO2Kg-1h-1) and lowest (10.76 mg CO2Kg-1h-1) respiration rate, respectively. Coating treatments reduced the incidence of decay and treatments GA + LM + PP and GA + PP recorded the highest total flavonoid content between 2 and 6 weeks of storage. The findings suggest that GA coatings with/without LM and PP can be a beneficial postharvest treatment for 'Wonderful' pomegranates to reduce weight loss and decay development during cold storage.

Biodegradation behavior and digestive properties of starch-based film for food packaging - a review

Non-degradable plastic places a serious burden on the environment, so consumers and researchers are working to develop biodegradable, safe, and sustainable food packaging materials. The starch-based film has become emerging material for food packaging. Not only does it shows excellent physicochemical properties, but also provides the desired degradation characteristics after use or the digestive properties after consumption, thus needing to comprehensively evaluate the quality of starch-based food packaging materials. This review summarizes the degradation behavior of the starch-based film in different degradation environments, and compares the suitability of degradation environments. Besides, the physicochemical properties of the composite or blend film during the degradation process were further discussed. The factors affecting the digestibility of starch-based edible film were reviewed and analyzed. Finally, the application and the future trend of the biodegradable starch-based film in the food packaging field were proposed. Future studies should combine and evaluate the physical properties and biodegradability of the composite/blend film, to develop food packaging materials with good characteristics and biodegradability.

Increased shelf life of Oncorhynchus mykiss (Rainbow trout) through Cu-Clay nanocomposites

Microbial growth is widely responsible for shortened shelf life of cold water-living fish products. So, it seems that current chemical-based food packaging has no acceptable efficacy, and food industrialists tend to the usage of more novel approaches like active food packaging. Among them, there is a great research interest in nanotechnology-emerging approaches. This study aimed to investigate the anti-microbial efficacies of Polyethylene/CuNP/nanoclay nanocomposites to enhance the shelf life and physiochemical features of rainbow trout. Three main nanocomposites with various concentrations of Cu and clay nanoparticles were examined. SEM, XRD, and EDX (as physiochemical analysis), disk diffusion (as antimicrobial assays), total volatile nitrogen (TVB-N), and peroxide value (PV) (as biochemical parameters) were measured. Based on the results, nanocomposites could reduce the microorganism growth rate by reducing the number of colonies (33.3%), inhibitory activities against both gram-positive (8 mm) and gram-negative bacteria (10 mm), maintenance of TVB-N (42% reduction), and PV (44% reduction) below the standard range. To sum up, these new nanocomposites can be a good candidate to enhance the shelf life of Rainbow Trout.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01031-0.

Biodegradability of Polyolefin-Based Compositions: Effect of Natural Rubber

Recently, environmental problems caused by the overproduction and consumption of synthetic polymer materials led to an urgent need to develop efficient methods for processing plastics. The accumulation of polymer waste for their subsequent incineration does not solve the problem due to the limited areas of landfills for waste storage. In addition, the incineration of polymer waste can cause toxic air pollution, which, in turn, does not contribute to an improvement in the environmental situation. Recycling plastics, although a more environmentally friendly waste disposal method, requires significant labor and energy costs and can be performed a limited number of times. Thus, the most promising solution to this problem is the creation of biodegradable polymers capable of degradation with the formation of simpler chemical structures (water, carbon dioxide, biomass, etc.), which are easily included in the metabolic processes of natural biological systems. The article provides an overview of the main trends in the creation of biodegradable composites for the needs of agriculture. Also, the article proposes a new composition based on polyethylene with natural rubber that surpasses existing biodegradable materials in a number of physical and mechanical characteristics and has the ability to complete biodegradation in 60 months. It is shown that the studies carried out to date indicate that these composites are highly promising for the creation of biodegradable packaging materials with good performance characteristics. Thus, it was concluded that further research on composites based on polyethylene and natural rubber is important.

Effects of storage temperature on the quality of eggs coated by cassava starch blended with carboxymethyl cellulose and paraffin wax

A blend of cassava starch (CS), carboxymethyl cellulose (CMC), and paraffin was prepared as a coating material to maintain the quality of eggs during 4 wk of storage at different temperatures. The efficacy of the CS/CMC/paraffin (6/1/0.5% w/v) coating was investigated in terms of the Haugh unit (HU), weight loss, pH, and microbial load at the end of storage. The best egg storage temperature was 4°C, which maintained an HU of grade AA in coated and uncoated eggs for 4 wk. Lower weight loss (2.14%) was observed in coated eggs at 4°C storage than at 30°C storage (3.26%). The pH in the albumen of coated and uncoated eggs at 4°C increased from 6.84 to 6.88 and 7.01 to 7.03, respectively, after 4 wk of storage. No microbes were detected in the coated and uncoated eggs at 4°C. The maximum microbial count was 728 ± 35 cfu/mL in uncoated eggs at 30°C storage. Egg coating prevented microbial contamination of eggs stored at 30°C for 4 wk. The freshness of the eggs did not affect the nutrient content. The egg-coating material effectively maintained egg quality, prevented microbial contamination of eggs, and increased the shelf life of eggs at storage temperatures of 25 and 30°C.

Alginate with citrus pectin and pterostilbene as healthy food packaging with antioxidant property

A new type of film packaging made from natural polysaccharide materials, with its environmental safety and friendliness, is considered as a potential substitute for plastics. Novel polysaccharide composite films based upon citrus pectin (CP) and sodium alginate (SA) were successfully prepared and characterized, containing pterostilbene (PTE) at various concentrations (0.2, 0.4, 0.8, 1.6, 3.2 mM). The rheological analysis displayed that all film-forming liquids performed no gelation behavior with G" > G' at low frequency and weak gelation with G" < G' at high frequency. The SA-CP films had good tensile strength (TS) and elongation at break (EB), while adding PTE as an antioxidant to the film reduced both the values. Of note, the SA-CP films with PTE had better moisture resistance than that of the pure SA-CP films, which was related to the changes of its microstructure. The increased roughness of the films containing PTE was observed by microscope. After calcium chloride cross-linking, the water solubility of the films was reduced, while its thermal stability was improved. Notably, the accretion of PTE expressively enhanced the antioxidant properties of the SA-CP films. Thus, the SA-CP composite films containing PTE could be utilized as an excellent antioxidant packaging material.

Sustainable edible packaging systems based on active compounds from food processing byproducts: A review

The global food processing industries represent a challenge and a risk to the environment due to the poor handling of residues, which are often discarded as waste without being used in further sidestreams. Although some part of this biomass is utilized, large quantities are, however, still under- or unutilized despite these byproducts being a rich resource of valuable compounds. These biowastes contain biopolymers and other compounds such as proteins, polysaccharides, lipids, pigments, micronutrients, and minerals with good nutritional values and active biological properties with applications in various fields including the development of sustainable food packaging. This review offers an update on the recent advancement of food byproducts recycling and upgrading toward the production of food packaging materials, which could be edible, (bio)degradable, and act as carriers of biobased active agents such as antimicrobials, antioxidants, flavoring additives, and health-promoting compounds. This should be a global initiative to promote the well-being of humans and achieve sustainability while respecting the ecological boundaries of our planet. Edible films and coatings formulations based on biopolymers and active compounds extracted from biowastes offer great opportunities to decrease the devastating overuse of plastic-based packaging. It has become evident that a transition from a fuel-based to a circular bio-based economy is potentially beneficial. Therefore, the exploitation of food discards within the context of a zero-waste biorefinery approach would improve waste management by minimizing its generation, reduce pollution, and provide value-added compounds. Most importantly, the development of edible packaging materials from food byproducts does not compete with food resources, and it also helps decrease our dependency on petroleum-based products. Practical Application Almost 99% of current plastics are petroleum-based, and their continuous use has been devastating to the planet as plastic-derived components have been detected in all trophic levels. Besides, the increasing amounts of food by-products are a socioeconomic and environmental challenge, and halving food loss and waste and turning it into valuable products has become necessary to achieve sustainability and economic circularity. The development of new packaging systems such as edible materials could be one of the solutions to limit the use of persistent plastics. Edible films and coatings by-products-based could also enhance food packaging performance due to their compounds' bioactivities.