Edible films and coatings containing bioactives

Essential oils as additives in active food packaging

Food packaging can be considered as a passive barrier that protects food from environmental factors such as ultraviolet light, oxygen, water vapour, pressure and heat. It also prolongs the shelf-life of food by protecting from chemical and microbiological contaminants and enables foods to be transported and stored safely. Active packaging (AP) provides the opportunity for interaction between the external environment and food, resulting in extended shelf-life of food. Chemoactive packaging has an impact on the chemical composition of the food product. The application of natural additive such as essential oils in active packaging can be used in the forms of films and coatings. It has been observed that, AP helps to maintain temperature, moisture level and microbial and quality control of the food. This review article provides an overview of the active packaging incorporated with essential oils, concerns and challenges in industry, and the effect of essential oil on the packaging microstructure, antioxidant and antimicrobial properties.

Covalent linkage of bioactive volatiles to a polysaccharide support as a potential approach for preparing active edible coatings and delivery systems for food products

In this study, a potential of covalent linkage approach for developing active edible coatings was examined. Vanillin and trans-cinnamaldehyde were bound to chitosan by Schiff base reaction and reductive amination. The modified polysaccharides were comprehensively characterized and applied as active coatings on fresh-cut melon. The covalent linkage allowed overcoming solubility problems with the lipophilic vanillin and cinnamaldehyde and neutralizing their volatility, producing well-adhered coatings that enhanced fruit quality and storability without sensorial impairment. The attached hydrophobic moieties also provided new polysaccharides with self-assembling ability. Their aggregates were loaded with antimicrobial citral and added to mandarin juice, resulting in up to 6 log CFU/mL microbial count reduction. Thus, the covalent linkage concept offers several advantages, especially when hydrophobic or volatile active agents are used. Further developed, it may become a safe and effective tool for the formation of advanced active edible coatings and delivery vehicles for direct applications on food products.

Effect of the application of an edible film with turmeric (Curcuma longa L.) on the oxidative stability of meat

The aim of this study was to develop an edible alginate-based film produced with turmeric (EFT), as an active compound, and evaluate its antioxidant capacity for application in fresh pork loin, beef loin, and chicken breast. The EFT was characterized by barrier parameters, color, and mechanical, structural, and antioxidant properties. Meat samples with and without EFT were stored at 4°C and analyzed at 2-day intervals. The meat samples with EFT showed significant differences (p < .05) in color (CIE L*a*b*) and exhibited lower TBARS values compared with those without EFT. The addition of turmeric in the film, besides affecting its physicochemical and structural properties, contributed an important antioxidant effect for the meat.

Novel Materials in the Preparation of Edible Films and Coatings—A Review

The development of edible films and coatings has seen remarkable growth in recent decades and is expected to have an important impact on the quality of food products in the coming years. This growth is attributed to the increasing knowledge of edible films and edible coating technology, as well as advances in material science and processing technology. Packaging is used in order to reduce synthetic packaging and can play a role as an eco-friendly biodegradable package or a protective coating on the food surface. A large amount of bio-based polymers have been used in the production of edible films and coatings. Novel sources of edible materials, as well as the novel processing techniques, are a subject of great interest due to their promising potential as innovative food packaging systems. This paper presents the concept and potential for application of new film-forming materials and management of food wastes from the fruit and vegetable industry, which can encounter problems in appropriate disposal. It summarizes the extensive knowledge about the new film-forming materials such as plant residues, flours and gums to show their protective effectiveness and suitability in various types of foods.

Functionalizing and bio-preserving processed food products via probiotic and synbiotic edible films and coatings

Edible films and coatings constitute an appealing concept of innovative, cost-effective, sustainable and eco-friendly packaging solution for food industry applications. Edible packaging needs to comply with several technological pre-requisites such as mechanical durability, low permeability to water vapor and gases, good optical properties, low susceptibility to chemical or microbiological alterations and neutral sensory profile. Over the past few years, functionalization of edible films and coatings via the inclusion of bioactive compounds (antioxidants, micronutrients, antimicrobials, natural coloring and pigmentation agents) and beneficial living microorganisms has received much attention. As for living microorganisms, probiotic bacterial cells, primarily belonging to the Lactobacilli or Bifidobacteria genera, have been exploited to impart bespoke health and biopreservation benefits to processed food. Given that the health benefit conferring and biopreservation potential of probiotics is dependent on several extrinsic and intrinsic parameters, the development of probiotic and synbiotic edible packaging concepts is a quite challenging task. In the present chapter, we aimed at a timely overview of the technological advances in the field of probiotic, symbiotic and synbiotic edible films and coatings. The individual or combined effects of intrinsic (matrix composition and physical state, pH, dissolved oxygen, water activity, presence of growth stimulants or inhibitors) and extrinsic (film forming method, food processing, storage time and conditions, exposure to gastrointestinal conditions) factors on maintaining the biological activity of probiotic cells were addressed. Moreover, the impact of living cells inclusion on the mechanical, physicochemical and barrier properties of the edible packaging material as well as on the shelf-life and quality of the coated or wrapped food products, were duly discussed.

Characterization of fish collagen from blue shark skin and its application for chitosan- collagen composite coating to preserve red porgy (Pagrus major) meat

Pepsin soluble collagen (PSC) was extracted from blue shark (Prionace glauca) skin and was used for chitosan-collagen composite coating to investigate coating effects on fresh red porgy (Pagrus major) fillet quality during storage at 4°C. Total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), pH, K value, drip loss, and sensory evaluation scores were measured as deterioration indexes. Results show that coating by 1% of chitosan solutions containing 0.0%-0.8% of PSC significantly improved most deterioration indexes. Coating by 1% of chitosan solution containing 0.8% of PSC yielded the best results for K value, drip loss, and sensory evaluation, although the other indexes show no clear PSC concentration dependence. These results indicate 1% of chitosan solution containing 0.8% of PSC as the best coating formulation examined in this study. PRACTICAL APPLICATIONS: Aquatic products have high contents of water and protein. Their qualities are likely to decline because of endogenous chemical and enzyme reactions, and also because of the role of spoilage and pathogenic microorganisms during storage. The edible collagen and chitosan coating suggested by this research is biodegradable, biocompatible, cost effective, and is able to meet the requirements for food quality and storage duration. Pepsin soluble collagen (PSC) is an aquatic product processing by-product that makes the maximum use of resources. As described herein, a composite formulation comprising collagen and chitosan improves preservation effects of different types of coatings. A more high-quality and effective edible coating formulation was obtained, thereby extending the red porgy fillet shelf life.

Biodegradable films based on fruit puree: a brief review

The production of fruit-film packaging has attracted increasing attention in scientific research due to the packaging's environmentally friendly, nontoxic, and edible characteristics. The development of alternative packaging contributes to both minimizing the environmental impacts caused by the large consumption of non-biodegradable plastics and favoring the reduction of postharvest loss/waste of fruit. In addition, these fruit films have the potential to be functional packages due the presence of antioxidant and antimicrobial compounds that can migrate to the food matrix, acting as natural additives. The use of fruit puree to develop biodegradable films can be simpler and more practical than the developed of films from fruit flour or extracts, reducing the time, energy, and resources necessary to prepare the film-forming solution. A better understanding of the mechanical properties, bioactive compounds, and potential applications is interesting in terms of prospecting new specific ways to produce and use these films. In this study, we briefly review the general aspects of fruit puree films, highlighting their characterization for use as food packaging.

Chemical and Physical Characteristics of Edible Films, Based on κ- and ι-Carrageenans with the Addition of Lapacho Tea Extract

The aim of the study was to characterize antioxidant and textural property differences of edible films prepared with the addition of lapacho extract (LE). The experimentally produced edible films also contained different carrageenans (ι- and κ-carrageenan). The κ- and ι-carrageenan, glycerol and the different addition of LE (5%, 10%, 20%) were used as ingredients for forming films. The pH and viscosity were measured for film forming solutions (before drying). The following analyses were performed on films: the total polyphenol content (TPC), Ferric Reducing Antioxidant Power (FRAP) and 2-Diphenyl–1-Picrylhydrazyl (DPPH). Optical parameters were analyzed by the determination of UV-Vis spectra. The structure of films was characterized by scanning electron microscopy. The gained results indicated that the use of different gelling agents (ι- and κ-carrageenan) resulted in statistically significant (p < 0.05) differences in textural properties (strength and breaking strain) of produced edible films. The highest antioxidant properties and TPC had a κ film with 20% LE (DPPH: 87.63 ± 0.03%; TPC: 233.75 ± 0.104 mg gallic acid/g). According to these results, it can be concluded that edible films with the highest concentrations of added lapacho extract can serve as a good source of antioxidant compounds. Certainly, these properties can be usefully incorporated into the wrapped food commodity.

New Tricks for Old Guys: Recent Developments in the Chemistry, Biochemistry, Applications and Exploitation of Selected Species from the Lamiaceae Family

Lamiaceae is one of the largest families of flowering plants comprising about 250 genera and over 7,000 species. Most of the plants of this family are aromatic and therefore important source of essential oils. Lamiaceae are widely used as culinary herbs and reported as medicinal plants in several folk traditions. In the Mediterranean area oregano, sage, rosemary, thyme and lavender stand out for geographical diffusion and variety of uses. The aim of this review is to provide recent data dealing with the phytochemical and pharmacological studies, and the more recent applications of the essential oils and the non-volatile phytocomplexes. This literature survey suggests how the deeper understanding of biomolecular processes in the health and food sectors as per as pest control bioremediation of cultural heritage, or interaction with human microbiome, fields, leads to the rediscovery and new potential applications of well-known plants.

Design and preparation of antimicrobial meat wrapping nanopaper with bacterial cellulose and postbiotics of lactic acid bacteria

Lyophilized postbiotics of Lactobacillus plantarum was prepared and impregnated in bacterial nanocellulose (BNC) by ex-situ method to develop an antimicrobial ground meat wrapping nanopaper. The postbiotics incorporated BNC (P-BNC) films were optimized by response surface methodology and their antimicrobial activity against Listeria monocytogenes were examined. The BNC with postbiotics at 21.21% concentration and 28 min impregnation time was chosen as an optimized P-BNC film. The FTIR results confirmed the immobilization of postbiotics in BNC. The P-BNC film represented a significant reduction (~5 log cycles) in L.monocytogenes counts in ground meat at the end of the storage period (9 days at 4 °C). Meat wrapped by P-BNC film displayed a significant decrease in total mesophilic and psychrophiles count and TBA values than the controls. BNC can be considered as a proper carrier for development of antimicrobial film using postbiotics of LAB for food application.

Edible coatings in post-harvest papaya: impact on physical-chemical and sensory characteristics

The aim of the present study was to characterize the physical-chemical and sensory attributes of two papaya varieties (Aliança and Golden THB) (Carica papaya L.) coated with different solutions of manioc starch and clove essential oil (Syzygium aromaticum L. Merr. et Perry). Four different treatments were studied in papaya fruits at ripening stage 1: T0 (control); T1 (fruits coated with a solution of manioc starch); T2 (fruits coated with clove essential oil at 0.175 mL L^-1); T3 (solution of manioc starch with clove essential oil-0.175 mL L^-1). The physical-chemical and sensory analyses were conducted in the fruits at ripening stage 5. The edible coatings did not influence the physical-chemical characteristics of the two varieties. Those fruits coated with manioc starch reported a good sensory acceptance not differing statistically from the control fruits in the majority of the attributes studied. By evaluating the purchase intention regarding the variety Aliança, all the treatments reported good levels of acceptance, with higher scores in the option "would certainly buy". After the sensory evaluation, treatment T3 reported a purchase intention of 80%. It was concluded that the edible coatings did not influence the physical-chemical characteristics of the fruits, however, they influenced the sensory acceptance of the tasters. For the variety Aliança, the application of treatment T3 is recommended, while for Golden THB, treatments T1 and T2 are recommended due to their similarity to the control.

Edible Films and Coatings Functionalization by Probiotic Incorporation: A Review

Edible coatings and films represent an alternative packaging system characterized by being more environment- and customer-friendly than conventional systems of food protection. Research on edible coatings requires multidisciplinary efforts by food engineers, biopolymer specialists and biotechnologists. Entrapment of probiotic cells in edible films or coatings is a favorable approach that may overcome the limitations linked with the use of bioactive compounds in or on food products. The recognition of several health advantages associated with probiotics ingestion is worldwide accepted and well documented. Nevertheless, due to the low stability of probiotics in the food processing steps, in the food matrices and in the gastrointestinal tract, this kind of encapsulation is of high relevance. The development of new and functional edible packaging may lead to new functional foods. This review will focus on edible coatings and films containing probiotic cells (obtaining techniques, materials, characteristics, and applications) and the innovative entrapment techniques use to obtained such packaging.

Physicochemical and bioactive properties of edible methylcellulose films containing Rheum ribes L. extract

Methylcellulose (MC) polymer was used to prepare the edible films. Then, the Rheum ribes L. ethanol extract (RE) was added to the films in order to act as a natural antimicrobial agent. All the methylcellulose films were characterized for bioactivity and the physicochemical analysis were carried out to define functional group interactions between the polymer and RE. The strongest antimicrobial effect was obtained with MC films enriched with 2% (w/w) RE against to Listeria monocytogenes with 20.3 ± 2.5 mm zone diameter. In the presence of RE, the tensile strength of film decreased, whereas the extract concentration significantly increased. The elongation at break and the water vapor permeability (WVP) values of the films were found to have decreased significantly in parallel with the increase in RE content. Moreover, the increase in the concentration of RE caused an increment in the hydrophilic properties, especially contact angle values of the films.

Structural, Physical, and Antifungal Characterization of Starch Edible Films Added with Nanocomposites and Mexican Oregano (Lippia berlandieri Schauer) Essential Oil

The aim of this study was to evaluate the structural, physical, and antifungal characteristics of starch edible films added with nanocomposites and Mexican oregano (Lippia berlandieri Schauer) essential oil (EO). Starch edible films were formulated with Mexican oregano EO (0%, 1%, or 2% v/v) and bentonite or halloysite (2%). Physical properties such as L* (luminosity), hue, film thickness, and O₂ and CO₂ permeability were determined. Structural analysis was carried out via atomic force microscopy (AFM). Antifungal activity against Aspergillus niger, Fusarium spp., and Rhizopus spp. was evaluated. The addition of EO and nanocomposites reduced luminosity, providing color to the edible films. Film thickness increased through the addition of EO concentration. O₂ and CO₂ permeability was increased by bentonite/EO films, and for halloysite films, CO₂ permeability decreased as EO concentration increased. The addition of EO with both nanocomposites shows an evident morphological change in film structure, decreasing pore density and increasing pore size. In general, Mexican oregano EO added to edible starch films has an adequate fungicidal effect. The most sensitive microorganism tested was A. niger. Edible films added with Mexican oregano EO and nanocomposites show better physical and antifungal properties due to an adequate structural change in the biopolymer matrix.

Furcellaran/gelatin hydrolysate/rosemary extract composite films as active and intelligent packaging materials

The study investigated the active and intelligent properties of films based on furcellaran (FUR), gelatin hydrolysate (GELH) and rosemary extract (from fresh leaves (FRE) and dry leaves (DRE)). Rosemary extracts were blended with FUR/GELH film forming solution at different three concentrations (5, 10, 20%). Analyzing the ζ-potential dependences of complexation polysaccharide-protein hydrolysate, we selected optimal ratio for the film formation. The introduction of rosemary extracts into FUR/GELH films increased thickness, water content and tensile strength. The UV barrier properties of tested films improved with the addition of rosemary extracts into FUR/GELH matrix. The antioxidant activity (DPPH and FRAP) did not improved with the addition of FRE but significantly increased with the addition of DRE, reaching 88% of DPPH inhibition and 207 of μmol Trolox/g of dried film of FRAP value. The color changes in different pH were observed, however, the fish spoilage test showed that those films are not suitable as intelligent films for monitoring freshness of this type of food product. Among all films tested, FUR/GELH film with 20% DRE exhibited the best performance. The obtained results suggested that FUR/GELH films with 20% DRE could be used as a promising active food packing material.

The influence of Aloe vera gel incorporation on the physicochemical and mechanical properties of banana starch-chitosan edible films

BACKGROUND

Aloe vera (AV) gel is a promising material in food conservation, given its widely reported antimicrobial and antioxidant activity; however, its application in the formation of edible films and coatings has been small owing its low film-forming capability. The aim of this study was to investigate the physicochemical properties of film-forming solutions and films prepared using unripe banana starch-chitosan and AV gel at different AV gel concentrations.

RESULTS

Our results showed that AV gel considerably affected the rheological and optical properties of the edible coatings, mainly due to increased amounts of solids brought by the AV gel. Film-forming capacity and physicochemical properties were also studied; most of the film properties were affected by the inclusion of AV gel, with decreased water vapor permeability, tensile strength and elongation at break. Fourier transform infrared studies showed that the inclusion of AV gel disrupts the interaction between starch and chitosan molecules; however, further studies are needed to fully understand the specific interactions between the components of AV gel and both starch and chitosan molecules.

CONCLUSION

Our results suggest that the addition of AV gel creates a crosslinking effect between the phenolic compounds in AV gel and starch molecules, which disrupts the starch-chitosan interaction and greatly affects the properties of both the film-forming solution and edible films. © 2018 Society of Chemical Industry.

Mechanical, barrier, and color properties of banana starch edible films incorporated with nanoemulsions of lemongrass ( Cymbopogon citratus) and rosemary ( Rosmarinus officinalis) essential oils

Edible films are among the most promising fields in food science over the last decade due to their versatility (they can be made from a wide array of materials) and because they can be used as carriers of different active substances, like antioxidants, antimicrobial agents, and essential oils from plants. In the case of the essential oils, their inclusion in edible films is limited by their low water solubility. Nanoemulsions are thermodynamically stable and transparent systems that can be used as a way of incorporating essential oils into edible film matrices. In this paper, we developed lemongrass and rosemary essential oil nanoemulsions by using a low-energy method, observing the effect of the surfactant/oil ratio in their physicochemical properties. Then we studied the effect of the nanoemulsions concentration incorporated into banana starch edible films. We observed that essential oils' nanoemulsions have a plasticizing effect increasing the film's water vapor permeability, transparency, and elongation at break, while the hydrophobic nature of the essential oils lead to a decrease in their water solubility.

Application of Bacteriocins and Protective Cultures in Dairy Food Preservation

In the last years, consumers are becoming increasingly aware of the human health risk posed by the use of chemical preservatives in foods. In contrast, the increasing demand by the dairy industry to extend shelf-life and prevent spoilage of dairy products has appeal for new preservatives and new methods of conservation. Bacteriocins are antimicrobial peptides, which can be considered as safe since they can be easily degraded by proteolytic enzymes of the mammalian gastrointestinal tract. Also, most bacteriocin producers belong to lactic acid bacteria (LAB), a group that occurs naturally in foods and have a long history of safe use in dairy industry. Since they pose no health risk concerns, bacteriocins, either purified or excreted by bacteriocin producing strains, are a great alternative to the use of chemical preservatives in dairy products. Bacteriocins can be applied to dairy foods on a purified/crude form or as a bacteriocin-producing LAB as a part of fermentation process or as adjuvant culture. A number of applications of bacteriocins and bacteriocin-producing LAB have been reported to successful control pathogens in milk, yogurt, and cheeses. One of the more recent trends consists in the incorporation of bacteriocins, directly as purified or semi-purified form or in incorporation of bacteriocin-producing LAB into bioactive films and coatings, applied directly onto the food surfaces and packaging. This review is focused on recent developments and applications of bacteriocins and bacteriocin-producing LAB for reducing the microbiological spoilage and improve safety of dairy products.

Antimicrobial edible coatings and films from micro-emulsions and their food applications

This study focused on the use of antimicrobial edible coatings and films from micro-emulsions to reduce populations of foodborne pathogens in foods. Corn-Bio-fiber gum (C-BFG) was used as an emulsifier with chitosan. Allyl isothiocyanate (AIT) and lauric arginate ester (LAE) served as antimicrobials. Micro-emulsions were obtained from a solution consisting of 1% chitosan, 0.5% C-BFG, and 1-4% AIT or LAE which was subject to high pressure homogenization (HPH) processing at 138MPa for 3cycles. Coatings and films produced from the micro-emulsions had micro-pores with sizes ranging from 100 to 300nm and micro-channels that hold antimicrobials effectively and facilitate the release of antimicrobials from the center to the surface of the films or coatings, thus enhancing their antimicrobial efficacy. The coatings and films with 1% AIT reduced populations of Listeria innocua by over 5, 2, and 3 log CFU in culture medium (Tryptic soy broth, TSB), ready-to-eat meat, and strawberries, respectively. The coatings and films with 1% LAE reduced populations of Escherichia coli O157:H7 and Salmonella spp. by over 5 and 2 log CFU in TSB and strawberries, respectively. This study provides an innovative approach for the development of effective antimicrobial materials to reduce food borne pathogenic contaminants on ready-to-eat meat, strawberries, or other food.

Active nanocomposite films based on soy proteins-montmorillonite- clove essential oil for the preservation of refrigerated bluefin tuna (Thunnus thynnus) fillets

This manuscript evaluates the potential application of active nanocomposite films based on soy protein isolate (SPI)-montmorillonite (MMT)-clove essential oil (CEO) to the preservation of muscle fillets of bluefin tuna (Thunnus thynnus) during refrigerated storage, and furthermore analyzes whether the clay diffuses from the package to food. SPI films with: CEO (SPI-CEO), MMT (SPI-MMT), or both CEO and MMT (SPI-MMT-CEO), were prepared and used to cover tuna fillets during 17days of storage at 2°C. Polyethylene films were also used as control. Protein films nanoreinforced with 10g MMT/100g SPI and activated with CEO were able to decrease microbial growth (evaluated by TVBN and microorganism counts) and lipid autooxidation (evaluated according to the TBA index, FTIR and color parameters) of tuna fillets during the storage period studied. The presence of clay seemed to favor the release of the active principles of clove oil by prolonging its antimicrobial (especially effective to inhibit Pseudomonas spp.) and antioxidant activity over time without observing the diffusion of the clay's own metals (Si and Al) from the nanocomposite materials to the muscle of fish. These results are encouraging for the use of nanocomposite films in food packaging.