In vitro antibacterial and antioxidant properties of chitosan edible films incorporated with Thymus moroderi or Thymus piperella essential oils

Impact of Olive Extract Addition on Corn Starch-Based Active Edible Films Properties for Food Packaging Applications

Active edible films based on corn starch containing glycerol as a plasticizer and an olive extract obtained from Spanish olive fruit (Olea europaea) by-products (olive extract; OE) at different concentrations (0, 0.05, 0.1 and 0.2 wt%) were prepared by using the casting technique and further solvent-evaporation. OE showed high total phenolic and flavonoids contents and antioxidant activity, which was evaluated by using three different methods: free radical scavenging assay by (1, 1-Dipheny l-2-picrylhydrazyl) DPPH, 2, 2-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) ABTS radical inhibition and ferric reducing antioxidant power (FRAP). The incorporation of OE into the corn starch/glycerol matrix underlined the antioxidant potential and antimicrobial effect against E. coli and S. aureus of these novel active films, being noticeable for films added with 0.2 wt% OE. The developed active films showed a clear thermo-oxidative stability improvement with OE incorporation, in particular at 0.2 wt% loading with an increase of around 50 °C in the initial degradation temperature (Tini) and oxidation onset temperature (OOT). The functional properties of control films were also improved with OE addition resulting in a decrease in Young's modulus, elongation at break, shore D hardness and water vapor permeability. The present work suggested the potential of the developed corn starch-based edible films as low-price and sustainable food packaging systems to prevent the oxidative deterioration of packaged foodstuff while reducing also the generation of olive by-products.

Study on Biodegradable Chitosan-Whey Protein-Based Film Containing Bionanocomposite TiO2 and Zataria multiflora Essential Oil

In our research, a composite film of whey protein isolate (WPI)/chitosan incorporated with TiO2 nanoparticles (NPs) and essential oil of Zataria multiflora (ZEO) was developed. The resulting composite films were evaluated by FTIR, SEM, and XRD, and also the physicochemical characteristics including color, mechanical properties, swelling ratio, and water vapor permeability (WVP) were studied. SEM graphs exhibited that the samples had a uniform and homogeneous structure where TiO2 NPs and ZEO were well dispersed. FTIR and XRD findings also show that the hydrogen bonds and hydrophobic interactions are the main interactions between the composite WPI/chitosan and TiO2. The crystalline nature of the composite samples increased with the increase of NP content. Nevertheless, ZEO had an insignificant effect on the functional groups and the crystallinity of composite samples. The film visual characterization revealed that, by adding and increasing the TiO2 and TiO2-ZEO, sample lightness and opacity significantly increased. Additions of TiO2 remarkably (p<0.05) improved the water vapor and mechanical properties of composite samples, although the loading of ZEO, regardless of TiO2 incorporation, led to a considerable decrement of these properties. Furthermore, composite films containing ZEO combined with 2% of TiO2 compared with 1% of NPs blended with ZEO had strong antimicrobial properties against Staphylococcus aureus, Escherichia coli, and Listeria monocytogenes. Generally, the findings proposed that the addition of TiO2 reinforces the properties of composite films with a synergistic effect of ZEO loading on the antibacterial ability, by which the resulting biodegradable composite samples can be used as a food active packaging material.

Chitosan Films Incorporated with Exopolysaccharides from Deep Seawater Alteromonas Sp

Two Alteromonas sp. strains isolated from deep seawater were grown to promote the production of exopolysaccharides (EPS, E611 and E805), which were incorporated into chitosan solutions to develop films. The combination of the major marine polysaccharides (chitosan and the isolated bacterial EPS) resulted in the formation of homogenous, transparent, colorless films, suggesting good compatibility between the two components of the film-forming formulation. With regards to optical properties, the films showed low values of gloss, in the range of 5-10 GU, indicating the formation of non-glossy and rough surfaces. In addition to the film surface, both showed hydrophobic character, with water contact angles higher than 100 º, regardless of EPS addition. Among the two EPS under analysis, chitosan films with E805 showed better mechanical performance, leading to resistant, flexible, easy to handle films.

Development and Characterization of Citrus Junos Pomace Pectin Films Incorporated With Rambutan (Nephelium Lappaceum) Peel Extract

New packaging materials using biopolymers have been studied to substitute synthetic packaging materials that lead to environmental pollution. In this study, a new biodegradable packaging material was developed using the pectin extracted from Citrus junos pomace, which is considered a food processing byproduct. Rambutan peel extract (RPE), at different concentrations (0.25%, 0.5%, and 1.0%), was added as an active material, and the functional properties of the C. junos pectin (CJP) films were evaluated. The incorporation of RPE enhanced the extensibility of the CJP films and their light-blocking ability by decreasing light transmittance. As the concentration of RPE increased, antioxidant activities of the CJP films increased, along with an increase in total phenolic content. Subsequently, the CJP prepared in this study can be used as a low-cost active biodegradable film material, and RPE can be added as a natural antioxidant for the CJP films to confer antioxidant activity.

Individual and Combined Coatings of Chitosan and Carnauba Wax with Oregano Essential Oil to Avoid Water Loss and Microbial Decay of Fresh Cucumber

The objective of the present study is to evaluate the effect of individual and combined coatings of chitosan (0.008 g·mL−1) and carnauba wax (0.1 g·mL−1) with oregano essential oil (OEO, 0.08 g·mL−1) to reduce dehydration and microbial decay of fresh cucumbers stored at 10 °C. Chitosan-OEO-wax films showed the lowest water vapor transmission rate (0.141 g·m−2·h−1), compared to single chitosan films (0.257 g·m−2·h−1). While chitosan-OEO films completely inhibited the in vitro growth of Alternaria alternata and reduced the growth of Salmonella Typhimurium, Escherichia coli O157:H7, mesophilic bacteria, and fungi isolated from decayed cucumbers. Besides, the infrared analysis of chitosan-OEO-wax films showed shifts in O–H and N–H absorption bands, indicating possible hydrogen bonding between the components. Wax and wax-OEO were the most effective coatings to prevent weight loss in cucumbers during 15 days of storage at 10 °C, while the most effective antimicrobial treatments were chitosan and chitosan-OEO. Therefore, these results showed that carnauba wax and carnauba wax-OEO coatings were the most effective in weight loss, whereas chitosan and chitosan-OEO were the most effective to reduce the microbial load of the treated fresh cucumber.

Polysaccharide and Protein Films with Antimicrobial/Antioxidant Activity in the Food Industry: A Review

From an economic point of view, the spoilage of food products during processing and distribution has a negative impact on the food industry. Lipid oxidation and deterioration caused by the growth of microorganisms are the main problems during storage of food products. In order to reduce losses and extend the shelf-life of food products, the food industry has designed active packaging as an alternative to the traditional type. In the review, the benefits of active packaging materials containing biopolymers (polysaccharides and/or proteins) and active compounds (plant extracts, essential oils, nanofillers, etc.) are highlighted. The antioxidant and antimicrobial activity of this type of film has also been highlighted. In addition, the impact of active packaging on the quality and durability of food products during storage has been described.

From waste/residual marine biomass to active biopolymer-based packaging film materials for food industry applications – a review

Waste/residual marine biomass represents a vast and potentially underexplored source of biopolymers chitin/chitosan and alginate. Their isolation and potential application in the development and production of bio-based food packaging are gaining in attractiveness due to a recent increment in plastic pollution awareness. Accordingly, a review of the latest research work was given to cover the pathway from biomass sources to biopolymers isolation and application in the development of active (antimicrobial/antioxidant) film materials intended for food packaging. Screening of the novel eco-friendly isolation processes was followed by an extensive overview of the most recent publications covering the chitosan- and alginate-based films with incorporated active agents.

Chitosan from crustacean shell waste and its protective role against lead toxicity in Oreochromis mossambicus

In the current study heavy metal removing capability and antioxidant properties of chitosan supplemented diet tested in lead poisoning induced Oreochromis mossambicus in comparison with and standard fish diet. O. mossambicus fishes weighed (20 ± 2gm) were purchased from a local commercial fish pond and acclimated to the laboratory conditions for 10 days. After that fish were dived into four groups, each group received respective feed throughout the experimental period. The fish fed with standard diet exhibited drastic weakening of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GR), glutathione peroxidase (GPx), ascorbic acid, α- tocopherol and β-carotene and also displayed abnormal histological changes in gills, liver, and intestine. The fish fed with a chitosan supplemented diet for 10 days showed substantial enhancements in antioxidant levels and also normal histological structures of organs in the fish.

Application of Protein-Based Films and Coatings for Food Packaging: A Review

As the IV generation of packaging, biopolymers, with the advantages of biodegradability, process ability, combination possibilities and no pollution to food, have become the leading food packaging materials. Biopolymers can be directly extracted from biomass, synthesized from bioderived monomers and produced directly by microorganisms which are all abundant and renewable. The raw materials used to produce biopolymers are low-cost, some even coming from agrion dustrial waste. This review summarized the advances in protein-based films and coatings for food packaging. The materials studied to develop protein-based packaging films and coatings can be divided into two classes: plant proteins and animal proteins. Parts of proteins are referred in this review, including plant proteins i.e., gluten, soy proteins and zein, and animal proteins i.e., casein, whey and gelatin. Films and coatings based on these proteins have excellent gas barrier properties and satisfactory mechanical properties. However, the hydrophilicity of proteins makes the protein-based films present poor water barrier characteristics. The application of plasticizers and the corresponding post-treatments can make the properties of the protein-based films and coatings improved. The addition of active compounds into protein-based films can effectively inhibit or delay the growth of microorganisms and the oxidation of lipids. The review also summarized the research about the storage requirements of various foods that can provide corresponding guidance for the preparation of food packaging materials. Numerous application examples of protein-based films and coatings in food packaging also confirm their important role in food packaging materials.

Synergistic inhibition effect of citral and eugenol against Aspergillus niger and their application in bread preservation

Consumers' preferences for cleaner label products require the food industry to replace synthetic preservatives with natural substitutes. Therefore, the synergistic inhibitory effect of eugenol and citral (S_EC) on Aspergillus niger was explored. On this basis, the antimicrobial sachet containing S_EC was developed and its application potential in bread preservation was evaluated. The content of reactive oxygen species (ROS) and malondialdehyde (MDA) showed that S_EC could significantly induce lipid peroxidation in cell membranes, in which citral played a leading role. The permeation experiments of SEM, TEM, propyl iodide and fluorescein diacetate showed that S_EC could destroy the integrity of the cell membrane. Eugenol contributed more than citral. The OD₂₆₀ and the relative conductivity of the S_EC group increased by 5.2 and 4.1 times, respectively, after 8 h. Finally, the shelf life experiment of bread showed that the antimicrobial sachets containing S_EC could significantly prolong the shelf life of bread without producing unpleasant odour.

Antimicrobial Activity of Oregano Essential Oil Incorporated in Sodium Alginate Edible Films: Control of Listeria monocytogenes and Spoilage in Ham Slices Treated with High Pressure Processing

The aim of the study was to evaluate the efficacy of oregano essential oil (OEO) incorporated in Na-alginate edible films when applied to sliced ham inoculated with a cocktail of Listeria monocytogenes strains, with or without pretreatment by high pressure processing (HPP). Microbiological, physicochemical and sensory analyses (in Listeria-free slices) were performed, while, the presence/absence and the relative abundance of each Listeria strain, was monitored by pulsed field gel electrophoresis (PFGE). The OEO incorporation in the films, caused approximately 1.5 log reduction in Listeria population at 8 and 12 °C at the end of the storage period, and almost 2.5 log reduction at 4 °C. The HPP treatment caused 1 log reduction to the initial Listeria population, while levels kept on decreasing throughout the storage for all the tested temperatures. The pH of the samples was higher in the cases where HPP was involved, and the samples were evaluated as less spoiled. Furthermore, the presence of OEO in the films resulted in color differences compared to the control samples, whilst the aroma of these samples was improved. In conclusion, the combined application of HPP and OEO edible films on the slices, led to a significant reduction or absence of the pathogen.

Development of antioxidant chitosan film with banana peels extract and its application as coating in maintaining the storage quality of apple

In the present study, the antioxidant chitosan (CS)-banana peels extract (BPE) composite film was developed. The different content of BPE (4%, 8% and 12%) was added to the CS film not only as the antioxidant but also as the cross-linking. The CS, CS-4% BPE, CS-8% BPE and CS-12% BPE films were characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD) and thermogravimetric analysis (TGA). The physical and mechanical properties possessed by the CS and CS-BPE films were compared as well, and the CS-4 %BPE composite film exhibited the most excellent properties. The decline in moisture contents, water solubility and water vapor permeability of CS-BPE composite film indicated the reduced hydrophilicity. Moreover, the CS-BPE composite film exhibited excellent antioxidant activity in different food simulants. Finally, the optimal concentration of CS-BPE coating treatment was identified and applied to apple fruit, and the results showed that CS-BPE coating was more capable of improving the postharvest quality of apple fruit than CS coating. This study evidences the promising nature of CS-BPE composite film and coating as a desirable alternative for active packaging and it is believed as conducive to valorization of banana peel by-products for allied applications.

Antioxidant and antibacterial chitosan film with tea polyphenols-mediated green synthesis silver nanoparticle via a novel one-pot method

In the present study, the antioxidant and antibacterial chitosan/tea polyphenols-silver nanoparticles composite film (CS/TP-AgNPs) was developed via a novel one-pot method. The TP was added to the CS film not only as the reducing agent of AgNPs but also as the cross-linking agent and antioxidant. The AgNPs and nanocomposite films developed were characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Besides, the physical, mechanical, antioxidant and antibacterial properties of the nanocomposite films were also analyzed. As the content of TP-AgNPs incorporation increased, the color of CS/TP-AgNPs nanocomposite film gradually shifted to brown, accompanied by an increase in opacity and thickness. The decrease in moisture contents and water vapor permeability of CS/TP-AgNPs nanocomposite film indicated that the TP-AgNPs varied the original bond between the CS-CS and CS-water. The denser cross-section of CS/TP-AgNPs nanocomposite film confirmed the enhanced mechanical properties. It is worth noting that CS/TP-AgNPs nanocomposite film exhibited more excellent antioxidant and antibacterial activity than CS film. This study developed the multi-functionality chitosan film by the simultaneous incorporation of AgNPs and TP and revealed the multiple effects of TP acting as reducing agent for AgNPs, cross-linking agent and antioxidant on chitosan film.

Active film incorporated with clove essential oil on storage of banana varieties

Purpose

Banana is an important tropical fruit with high demand in the market. The ripe fruits are less resistant to transport making logistics difficult. Moreover, as a climacteric fruit, it has a short post-harvest shelf life. Edible coatings/films, including active substances, have been used as an alternative for preserving fruits and vegetables during post-harvest period. The purpose of this study was to evaluate the incorporating clove essential oil on the properties of cassava starch films and their effect on the post-harvest quality of different banana varieties.

Design/methodology/approach

Cassava starch films incorporating clove essential oil were developed and the films were characterized with respect to moisture, thickness, solubility, water vapor permeability (WVP), biodegradability, color and in vitro antifungal activity. Cultivars such as Prata-Anã, Grand Nine, BRS Tropical and BRS Conquista were coated with cassava starch, cassava starch film with clove essential oil (CSEO) and polyvinyl polychloride (PVC). The quality of fruits was monitored during eight storage days using mass loss, total soluble solids content (TSS) and titratable acidity (TTA).

Findings

Incorporation of clove essential oil significantly increased film thickness, reduced moisture content, solubility and WVP (p < 0.05) and did not affect the biodegradability and color of the films. The essential oil incorporated films showed antifungal activity against the fungi Colletotrichum gloeosporioides and Colletotrichum musae, but not against the yeast Saccharomyces bourladii. CSEO and PVC coating were more efficient in reducing the mass loss, SS content and TTA of the coated fruits in all varieties studied. Both CSEO and PVC coatings improve the quality attributes such as TSS and TTA and reduced mass loss, of the banana varieties such as Prata-Anã, Grand Nine, BRS Tropical and BRS Conquista during storage.

Originality/value

The active film with essential oil showed antifungal activity and essential oil can be incorporated into other food systems. This study approaches a new possibility of film coating with essential oil for a banana that showed minimum weight loss and satisfactory quality and increased shelf life. This film coating demonstrates biodegradable characteristics that could be eco-friendly and sustainable to consumers.

Evaluation of antimicrobial and antioxidant activities for cellulose acetate films incorporated with Rosemary and Aloe Vera essential oils

Enhancement of natural based polymeric membranes for active packaging takes the attention of scientists. Their biological activities can be obtained by adding essential oils, which are natural extracts with antimicrobial and antioxidant properties. The target of current work aimed to produce bio-active membranes from cellulose acetate incorporated with Rosemary and Aloe Vera oil. The developed film's chemical structures and morphologies were investigated using FT-IR and SEM characterization tools. The impact of essential oils incorporation on water uptake, wettability behavior, and mechanical properties were explored. The results displayed that antimicrobial activity against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) increased as Rosemary and Aloe Vera oil percentage increases in cellulose acetate membranes. In addition, higher activity against B. subtilis compared to E. coli was also observed. Moreover, free radical scavenger activity (ABTS and DPPH) of cellulose acetate membranes, improved by increasing the essential oil content in the feed mixture. The obtained results provide a high potential for production of an efficient food packaging membrane from cellulose acetate containing Rosemary and Aloe Vera oil.

Mango leaf extract incorporated chitosan antioxidant film for active food packaging

Health hazards associated with usage of plastic films for food preservation demands for development of active films from non-toxic and antioxidant rich bio-sources. The reported work highlights the development, characterization and application studies of chitosan films enhanced for their antioxidant activity by mango leaf extract (MLE) incorporation. Effect of MLE variation (1-5%) on the morphology, optical nature, water exposure and mechanical characteristics of the chitosan-MLE composite films was studied. Increase in the MLE concentration resulted in films with increased thickness and decreased moisture content. Contact angle, water solubility and vapor permeability analysis demonstrated the reduced hydrophilicity and water vapor penetrability of the films due to MLE inclusion. MLE films possessed better tensile strength (maximum of 23.06 ± 0.19 MPa) with reduced elongation ratio than the pure chitosan film (18.14 ± 0.72 MPa). Antioxidants assessment in terms of total phenolic content, DPPH radical scavenging, ferric reducing power and ABTS radical scavenging showed improved antioxidant activity with the incremental amounts of MLE in the chitosan films. Microscopic studies revealed the smooth, compact and dense nature of the MLE-chitosan films favouring low oxygen transport rates. Application studies to cashew nuts preservation for 28 days storage indicated 56% higher oxidation resistance for the 5% MLE film than a commercial polyamide/polyethylene film. Results highlight the potential and promising nature of MLE impregnated chitosan films as suitable alternative for active packaging films for food preservation.

The Effect of Edible Chitosan Coatings Incorporated with Thymus capitatus Essential Oil on the Shelf-Life of Strawberry (Fragaria x ananassa) during Cold Storage

The strawberry is a fruit appreciated in the food industry for its high content of bioactive compounds. However, it is considered a highly perishable fruit, generally attacked by pests of phytopathogenic origin, which decreases its shelf-life. Normally, to diminish the losses caused by pathogenic microbes, coatings of polysaccharides in combination with natural products like essential oils are applied. In this work, we describe the effect of edible coatings from chitosan (CT) incorporating Thymus capitatus essential oil (TCEO), applied to strawberries stored under refrigeration conditions (5 ± 0.5 °C). Different concentrations of TCEO were applied to chitosan coatings, with different effects on the physical and microbiological properties of the strawberries. All the products had greater acceptance and quality than the controls, being more effective those with essential oil incorporation. It is noteworthy that all the essential oil treatments lead to an increase in the shelf-life of strawberries of up to 15 days. Scanning electron microscopy (SEM) analysis of the microstructure showed a decrease in compactness with TCEO introduction, but without compromising food preservation after 15 days. In addition, treated strawberries delayed the loss of physicochemical and antioxidant properties, due to protection against the microbial development of aerobic mesophylls, molds, and yeasts.

Quality and sensory acceptability of fish fillet (Oreochromis niloticus) with alginate-based coating containing essential oils

The quality and sensory acceptability of fish fillet (Oreochromis niloticus) with alginate-based coating containing ginger and oregano essential oils (EO) were evaluated. The antioxidant activity of essential oil, coating, and fish were also investigated. In relation to lipid oxidation, a decrease was observed in fish with the edible coatings compared to the control being the coating with oregano EO the most effective and also with the highest antioxidant activity. Loss in color and weight were significantly lower with coating. Fish with coating maintained firmness whereas fish without coating became softer. Fish with edible coating and oregano essential oils showed higher sensory acceptability regarding to odor evaluated by consumers. Thus, edible coatings with essential oils as natural antioxidant improved the product quality and sensory acceptability.

Antioxidant Activity and Release Kinetics of Caffeic and p-Coumaric Acids from Hydrocolloid-Based Active Films for Healthy Packaged Food

Sustainable hydrocolloid-based films containing natural antioxidants, caffeic and p-coumaric acids at different concentrations of 0.5%, 1%, 5%, and 10% w/w of polymers, were designed for packing fatty foods. Antioxidant activities and kinetics for all film formulations were assessed using radical scavenging activity (DPPH), reducing power, and iron chelating ability. Release kinetics of the antioxidants from the films into a food simulant (96% ethanol) were analyzed. The intermolecular interactions between antioxidants and polymers chains were assessed by Fourier transform infrared attenuated total reflectance (FTIR-ATR) and related to the film properties. Antioxidant activity of pure compounds (powder), showed that caffeic acid (IC₅₀ = 4 μg/mL) had higher activity than p-coumaric acid (IC₅₀ = 33 μg/mL). Films containing caffeic acid exhibited higher antioxidant activity, reducing power, and iron chelating ability than p-coumaric acid films. The antioxidant activity is concentration dependent. However, the percentage of release (PR) in ethanol (96%) is not influenced by the initial concentration. PR is 88% ± 9% and 82% ± 5%, respectively, for caffeic and p-coumaric acids. Determination of the partition ( K_p) and the apparent diffusion ( D) coefficients allowed better characterization of the release kinetic mechanisms. The partition coefficients of caffeic acid ( K_p = 454) and p-coumaric acid ( K_p = 480) are not influenced by the initial concentration. The diffusion coefficients ( D) of caffeic and p-coumaric acids were of same order, but they slightly increased with the antioxidant concentration and probably related to antioxidant activity. FTIR displayed that amide B and amide-III are involved in the interactions occurring between polymer chains and antioxidants. However, interactions are of only low energy and unable to significantly affect the structure of films and consequently the release kinetics.