Films and edible coatings containing antioxidants - a review

Development of gelatin/agarose active coatings functionalized with Ocimum gratissimum L. essential oil for enhancing storability of 'Booth 7' avocado

Novel active coating from gelatin/agarose (GA) functionalized with Ocimum gratissimum L. essential oil (OGO) had been developed as a medium to evaluate their properties before being applied for avocado preservation. The resultant coating films showed enhanced mechanical, water-barrier, bactericidal, antioxidant, and UV-shielding properties by adding OGO. The best tensile strength (2.91 MPa) and flexibility (45.82 %) was found in the GA film containing 5 % (w/w) of OGO (GA-OGO-5). Furthermore, this coating formulation presented moderate antibacterial activities against Listeria, Pseudomonas, Salmonella, and Escherichia. The GA-OGO-5 coating film also divulged the highest hydrophobicity and adequate antioxidant function (30.75 μg/mL) and thus, was chosen to coat on 'Booth 7' avocados by dipping method. The GA-OGO-5 coating layers were to be efficient to decline the respiration rate of avocado during 6-day storage at 25 °C and 64 %RH. Peel color, weight loss (5.22 %), total soluble solids (8.14 %), and solution pH (6.79) at the end of storage also indicated that the GA-OGO-5 coating presented the best effectiveness for enhancing the storability of avocado as compared to uncoated and GA-treated fruit. Therefore, the GA-OGO coating has been considered as an alternative post-harvest technique to enhance the avocado storability and could be further commercialized for industry application.

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.

Bioactive Edible Films and Coatings Based in Gums and Starch: Phenolic Enrichment and Foods Application

Edible films and coatings allow preserving fresh and processed food, maintaining quality, preventing microbial contamination and/or oxidation reactions and increasing the shelf life of food products. The structural matrix of edible films and coatings is mainly constituted by proteins, lipids or polysaccharides. However, it is possible to increase the bioactive potential of these polymeric matrices by adding phenolic compounds obtained from plant extracts. Phenolic compounds are known to possess several biological properties such as antioxidant and antimicrobial properties. Incorporating phenolic compounds enriched plant extracts in edible films and coatings contribute to preventing food spoilage/deterioration and the extension of shelf life. This review is focused on edible films and coatings based on gums and starch. Special attention is given to bioactive edible films and coatings incorporating plant extracts enriched in phenolic compounds.

Corn starch and methylcellulose edible films incorporated with fireweed (Chamaenerion angustifolium L.) extract: Comparison of physicochemical and antioxidant properties

The properties of edible films derived from corn starch (CS) and methylcellulose (MC) supplemented with fireweed extract (FE; 0.0125-0.05% w/w) were analyzed. Due to their more crystalline structure, the MC films were significantly stronger (~26 MPa) than the CS films (~4 MPa). In turn, CS produced films with lower water vapor permeability (WVP, 50.12-51.74 vs. 56.52-59.10 g mm m^-2 d^-1 kPa^-1). The hydrothermally-disrupted starch granules contributed to high roughness and opacity of the CS films. The FE-supplemented films exhibited an intensive yellow color and improved the UV-absorbing effect. FE delayed starch retrogradation, as indicated by the reduced crystallinity and slightly improved transparency of the CS films. Incorporation of FE significantly enhanced the released radical scavenging activity (RSA) of the films, while did not affect the WVP and mechanical properties. Due to better FE-trapping capacity, the CS-based films exhibited lower antioxidant activity (RSA_60min = 2.21-19.75%) as compared to the MC counterparts (RSA_60min = 4.87-38.31%).

Wheat Biocomposite Extraction, Structure, Properties and Characterization: A Review

Biocomposite materials create a huge opportunity for a healthy and safe environment by replacing artificial plastic and materials with natural ingredients in a variety of applications. Furniture, construction materials, insulation, and packaging, as well as medical devices, can all benefit from biocomposite materials. Wheat is one of the world’s most widely cultivated crops. Due to its mechanical and physical properties, wheat starch, gluten, and fiber are vital in the biopolymer industry. Glycerol as a plasticizer considerably increased the elongation and water vapor permeability of wheat films. Wheat fiber developed mechanical and thermal properties as a result of various matrices; wheat gluten is water insoluble, elastic, non-toxic, and biodegradable, making it useful in biocomposite materials. This study looked at the feasibility of using wheat plant components such as wheat, gluten, and fiber in the biocomposite material industry.

The impact of essential oils on the qualitative properties, release profile, and stimuli-responsiveness of active food packaging nanocomposites

Food industries attempt to introduce a new food packaging by blending essential oils (EOs) into the polymeric matrix as an active packaging, which has great ability to preserve the quality of food and increase its shelf life by releasing active compounds within storage. The main point in designing the active packaging is controlled-release of active substances for their enhanced activity. Biopolymers are functional substances, which suggest structural integrity to sense external stimuli like temperature, pH, or ionic strength. The controlled release of EOs from active packaging and their stimuli-responsive properties can be very important for practical applications of these novel biocomposites. EOs can affect the uniformity of the polymeric matrix and physical and structural characteristics of the composites, such as moisture content, solubility in water, water vapor transmission rate, elongation at break, and tensile strength. To measure the ingredients of EOs and their migration from food packaging, chromatographic methods can be used. A head-space-solid phase micro-extraction coupled to gas chromatography (HS-SPME-GC-MS) technique is as a good process for evaluating the release of Eos. Therefore, the aims of this review were to evaluate the qualitative characteristics, release profile, and stimuli-responsiveness of active and smart food packaging nanocomposites loaded with essential oils and developing such multi-faceted packaging for advanced applications.

The influence of edible coatings and natural antioxidants on fresh-cut potato quality, stability and oil uptake after deep fat frying

The effect of four edible hydrocolloid coatings (carboxymethyl cellulose, chitosan, pectin and gum arabic) on fresh-cut potato's colour, pH and moisture content during storage was studied. Possibility of coating enrichment with natural olive leaf extract and sodium ascorbate was also evaluated. Coatings scored as the best ones straight after coating or during storage for 7 days at 10 ± 1 °C, were used for deep fat frying of potato. Chitosan was shown to cause significant decrease in pH and browning of potato strips. Pectin was classified as good coating alone but in combination with olive leaf extract showed lower quality parameters of fresh-cut samples compared to control. Only carboxymethyl cellulose and gum arabic itself or enriched with olive leaf extract or sodium ascorbate were shown not to affect colour, pH and moisture during storage. Moreover, these coatings significantly reduced fat content in deep fat fried potato strips, without influence on L*, b*, whiteness index (WI), and ΔE.

Application of Antioxidants as an Alternative Improving of Shelf Life in Foods

Oxidation is the main problem in preserving food products during storage. A relatively novel strategy is the use of antioxidant-enriched edible films. Antioxidants hinder reactive oxygen species, which mainly affect fats and proteins in food. At present, these films have been improved by the addition of micro- and nanoliposomes coated with carbohydrate polymers, which are not hazardous for human health and can be ingested without risk. The liposomes are loaded with different antioxidants, and their effects are observed as a longer storage time of the food product. The synergy of these methodologies and advances can lead to the displacement of the protective packaging used currently, which would result in food products with functional properties added by the films, an increase in shelf life, and an improvement to the environment by reducing the amount of waste.

Chitosan Edible Films Enhanced with Pomegranate Peel Extract: Study on Physical, Biological, Thermal, and Barrier Properties

In the present study, pomegranate peel extract was used as a reinforcing agent in developing chitosan-based edible film. Different concentrations (0.2 g/mL, 0.4 g/mL, 0.6 g/mL, 0.8 g/mL, and 1.0 g/mL) of pomegranate peel extract were incorporated in chitosan-based edible film. A neat chitosan film was used as a control. This work covers the effect of pomegranate peel extract on the physical, biological, mechanical, thermal, and barrier properties of enriched chitosan-based edible film. The results showed that the thickness (0.142-0.159 mm), tensile strength (32.45-35.23 MPa), moisture (11.23-15.28%), opacity (0.039-0.061%), water (1.32-1.60 g·mm/m2), gas barrier properties (93.81-103.45 meq/kg), phenolic content (5.75-32.41 mg/g), and antioxidant activity (23.13-76.54%) of the films increased with increasing volume fraction of pomegranate peel extract. A higher concentration of incorporated pomegranate peel extracts significantly (p < 0.05) reduced the thermal stability of the film, along with its transparency, solubility, swelling, and color. This work revealed that the incorporation of a higher portion of pomegranate peel extract in chitosan film holds significant (p < 0.05) potential for the increase in biological activities of such films in terms of antioxidant and antimicrobial behavior. The properties of pomegranate peel extract-enriched chitosan films could be an excellent cure for free radicals, whereas they could also inhibit the growth of the foodborne pathogens during the processing and preservation of the food. Further studies are needed for the application of pomegranate peel extract-enriched edible films on food products such as fruits and vegetables in order to extend their storage life and improve the quality and safety of preserved food products.

Development of biopolymeric films with addition of vitamin C and catuaba extract as natural antioxidants

Sustainability has been an important issue in cosmetic industry, resulting in increasing concerns about environmental impacts, starting by the selection of raw materials. The aim of this work was the production of biopolymeric films based on a cassava starch and gelatin mixture (1:1) with the incorporation of natural antioxidants, such as vitamin C and catuaba extract aiming its future use as an eco-friendly cosmetic. Films were produced by casting (2.0 g polymer/100 g filmogenic solution) employing glycerol (20 g/100 g polymer) as plasticizer, and vitamin C (0-10.0 g/100 g polymer) and catuaba extract (0-1.5 g/100 g polymer) were added as bioactive compounds. All formulations resulted in films with good appearance and homogeneity. All films produced with vitamin C and catuaba extract had their antioxidant capacity demonstrated, the catuaba extract films presented an antioxidant capacity values between 6.65% and 57.56%, and the vitamin C films presented values between 75.62% and 100%, even in those produced with low concentrations. Films loaded with vitamin C (10 g/100 g polymer) presented the highest antioxidant capacity (93.33%). Films prepared with 1.5 g catuaba extract/100 g polymer and all vitamin C formulations are promising alternatives for use as sustainable cosmetic products.

Recent Developments in Smart Food Packaging Focused on Biobased and Biodegradable Polymers

Food packaging has a crucial function in the modern food industry. New food packaging technologies seek to meet consumers and industrial's demands. Changes related to food production, sale practices and consumers' lifestyles, along with environmental awareness and the advance in new areas of knowledge (such as nanotechnology or biotechnology), act as driving forces to develop smart packages that can extend food shelf-life, keeping and supervising their innocuousness and quality and also taking care of the environment. This review describes the main concepts and types of active and intelligent food packaging, focusing on recent progress and new trends using biodegradable and biobased polymers. Numerous studies show the great possibilities of these materials. Future research needs to focus on some important aspects such as possibilities to scale-up, costs, regulatory aspects, and consumers' acceptance, to make these systems commercially viable.

Characterization of Food Packaging Films with Blackcurrant Fruit Waste as a Source of Antioxidant and Color Sensing Intelligent Material

Chitosan and pectin films were enriched with blackcurrant pomace powder (10 and 20% (w/w)), as bio-based material, to minimize food production losses and to increase the functional properties of produced films aimed at food coatings and wrappers. Water vapor permeability of active films increased up to 25%, moisture content for 27% in pectin-based ones, but water solubility was not significantly modified. Mechanical properties (tensile strength, elongation at break and Young’s modulus) were mainly decreased due to the residual insoluble particles present in blackcurrant waste. FTIR analysis showed no significant changes between the film samples. The degradation temperatures, determined by DSC, were reduced by 18 °C for chitosan-based samples and of 32 °C lower for the pectin-based samples with blackcurrant powder, indicating a disturbance in polymer stability. The antioxidant activity of active films was increased up to 30-fold. Lightness and redness of dry films significantly changed depending on the polymer type. Significant color changes, especially in chitosan film formulations, were observed after exposure to different pH buffers. This effect is further explored in formulations that were used as color change indicators for intelligent biopackaging.

Propriedades químicas e mecânicas de filme bioativo de amido de mandioca com adição de extrato de jamelão (Syzygium cumini L.)

Resumo O jamelão é uma fruta encontrada nas regiões Norte, Sudeste e Nordeste do Brasil. O extrato dos frutos apresenta atividade antioxidante, devido à presença de compostos bioativos, como carotenoides e compostos fenólicos. Este estudo objetivou elaborar filmes comestíveis, compostos por amido de mandioca como matriz principal, com a adição de extrato de jamelão. A polpa de jamelão foi concentrada em roto-evaporador para a obtenção do extrato aquoso. Os ensaios para a elaboração dos filmes foram realizados segundo um delineamento composto central 22 com três repetições no ponto central, para avaliar o efeito das concentrações de glicerol (7,95% a 22,05%) e de extrato de jamelão (15,9 a 44,1%) sobre as propriedades mecânicas do filme (força na perfuração e deformação na ruptura) e sobre o teor de compostos fenólicos. As maiores concentrações do plastificante glicerol e do extrato de jamelão influenciaram positivamente nas propriedades mecânicas do filme, provocando diminuição da força na perfuração de 3,61 N para 2,55 N e aumento da deformação na ruptura de 1,44% para 76,33%. Os efeitos lineares e quadráticos das concentrações de glicerol e de extrato de jamelão e suas interações foram significativas sobre as respostas: força na perfuração e deformação na ruptura, no nível de 95% de confiança. A concentração de extrato de jamelão teve efeito significativo sobre o teor de compostos fenólicos, com coeficiente de determinação R2=0,9782. A interação entre glicerol e extrato de jamelão auxilia na obtenção de filmes de amido de mandioca com boas propriedades mecânicas e bioativas.

Comparison of Polysaccharides as Coatings for Quercetin-Loaded Liposomes (QLL) and Their Effect as Antioxidants on Radical Scavenging Activity

Liposomes are microstructures containing lipid and aqueous phases employed in the encapsulation and delivery of bioactive agents. Quercetin-loaded liposomes (QLLs) were coated with three different polysaccharides and then tested as radical scavengers. Lactose (LCQLL), chitosan (CCQLL), and inulin (ICQLL) were employed as coating materials. Particle size determined by light scattering, showed primary size of 200 nm for all samples, while a secondary particle size of 600 nm was observed for CCQLL. Scanning electron microscopy (SEM) evidenced particle aggregation with the addition of the polysaccharide coating. Transmission electron microscopy (TEM) revealed the layered microstructure of liposomes composed of at least two layers, and primary particle size below 100 nm. QLL showed higher antioxidant activity than the coated liposomes. This behavior was attributed to the chemical interaction between quercetin and the corresponding coating polysaccharide in the layered structure, which traps the quercetin and keeps it unavailable for radical scavenging. From the three polysaccharides, lactose showed a better performance as coating material in the antioxidant activity, which suggested that the smaller size of the disaccharide molecule resulted in a faster releasing of the quercetin in the solution. Thus, LCQLL is an advantageous way to deliver quercetin for antioxidant purposes, where the low stability in delivered media of quercetin loaded liposomes is commonly compromised.

Trends and advances in edible biopolymer coating for tropical fruit: A review

Nowadays, many of the tropical fruits have been commercialized worldwide due to increasing demand. In 2018, global tropical fruit has reached an unprecedented peak of 7.1 million tonnes. As such, a lot of large scale farming has been initiated to cultivate the fruit for commercialization. The nature of tropical fruit is perishable make the fruit easily undergo post-harvest losses especially when the fruit travels in a long distance for distribution. Losses of tropical fruit is estimated around 18-28% after harvesting. Then, the losses will continually develop during the trading process. Applying fruit coating on the fruit can minimize substantial privation. This article compendiously reviews the needs of coating and discuss different types of coating materials. The efficiency of different coating materials; polysaccharide, protein, lipid and composite based coating on tropical fruit is highlighted. There are various types of coating available for major fruit such as banana, mango, pineapple and avocado that can effectively extend the post-harvest life, minimize water loss, reduce chilling injuries and fight against post-harvest disease. Coating from minor fruit such as durian, rambutan, passion-fruit and mangosteen are still limited especially made from lipid and protein coating. In choosing the most appropriate coating for tropical, the nature of fruit needs to be understood. In addition, the chemistry of coating components and techniques of application is important in modulating the fruit quality.

Self-Assembled Carbohydrate Polymers for Food Applications: A Review

The self-assembled natural and synthetic polymers are booming. However, natural polymers obtained from native or modified carbohydrate polymers (CPs), such as celluloses, chitosan, glucans, gums, pectins, and starches, have had special attention as raw material in the manufacture of self-assembled polymer composite materials having several forms: films, hydrogels, micelles, and particles. The easy manipulation of the architecture of the CPs, as well as their high availability in nature, low cost, and being sustainable and green polymers have been the main positive points in the use of them for different applications. CPs have been used as building blocks for composite structures, and their easy orientation and ordering has given rise to self-assembled CPs (SCPs). These macromolecules have been little studied for food applications. Nonetheless, their research has grown mainly in the last 5 years as encapsulated food additive wall materials, food coatings, and edible films. The multifaceted properties (systems sensitive to pH, temperature, ionic strength, types of ions, mechanical force, and enzymes) of these devices are leading to the development of advanced food materials. This review article focused on the analysis of SCPs for food applications in order to encourage other research groups for their preparation and implementation.

Development of a poly(vinyl alcohol)/lysine electrospun membrane-based drug delivery system for improved skin regeneration

Nanofiber-based wound dressings are currently being explored as delivery systems of different biomolecules for avoiding skin infections as well as improve/accelerate the healing process. In the present work, a nanofibrous membrane composed of poly(vinyl alcohol) (PVA) and lysine (Lys) was produced by using the electrospinning technique. Further, anti-inflammatory (ibuprofen (IBP)) and antibacterial (lavender oil (LO)) agents were incorporated within the electrospun membrane through blend electrospinning and surface physical adsorption methods, respectively. The obtained results demonstrated that the PVA_Lys electrospun membranes incorporating IBP or LO displayed the suitable morphological, mechanical and biological properties for enhancing the wound healing process. Moreover, the controlled and sustained release profile attained for IBP was appropriate for the duration of the wound healing inflammatory phase, whereas the initial burst release of LO is crucial to prevent wound bacterial contamination. Indeed, the PVA_Lys_LO electrospun membranes were able to mediate a strong antibacterial activity against both S. aureus and P. aeruginosa, without compromising human fibroblasts viability. Overall, the gathered data emphasizes the potential of the PVA_Lys electrospun membranes-based drug delivery systems to be used as wound dressings.

Recent Advances in Edible Polymer Based Hydrogels as a Sustainable Alternative to Conventional Polymers

The over increasing demand of eco-friendly materials to counter various problems, such as environmental issues, economics, sustainability, biodegradability, and biocompatibility, open up new fields of research highly focusing on nature-based products. Edible polymer based materials mainly consisting of polysaccharides, proteins, and lipids could be a prospective contender to handle such problems. Hydrogels based on edible polymer offer many valuable properties compared to their synthetic counterparts. Edible polymers can contribute to the reduction of environmental contamination, advance recyclability, provide sustainability, and thereby increase its applicability along with providing environmentally benign products. This review is highly emphasizing on toward the development of hydrogels from edible polymer, their classification, properties, chemical modification, and their potential applications. The application of edible polymer hydrogels covers many areas including the food industry, agricultural applications, drug delivery to tissue engineering in the biomedical field and provide more safe and attractive products in the pharmaceutical, agricultural, and environmental fields, etc.

Bioactive Compounds Incorporation into the Production of Functional Biodegradable Films - A Review

The bioactive compounds incorporation for the production of biodegradable food packagings comes as a viable and environmentally friendly substitute in order to improve the nutritional value as well as extend the shelf life of highly perishable food products. Moreover, the use of bioactive compounds has been directly associated with the promotion of health aspects; the ingestion of bioactive compounds is related with minimizing risks of some diseases such as hypertension, diabetes, and coronary heart diseases. Therefore, the present study carried out a review of the current scenario in the film's production with natural antioxidants addition. The prebiotics and probiotics compound addition in films properties produced were also discussed in this work. Additionally, the film biodegradation properties should also be taken into account for their right disposal in the environment. Some factors that can to affect the biodegradation process are the nature of the polymer, the interactions among the blend components, its crystallinity, and the environmental conditions (light, temperature, O2 concentrations; and humidity). Therefore, the evaluation of relationships between structure and the polymers biodegradability is the extreme importance.

Gelatine-Based Antioxidant Packaging Containing Caesalpinia decapetala and Tara as a Coating for Ground Beef Patties

The development of antioxidant-active packaging has numerous advantages, such as the reduction of synthetic additives in food, the reduction of plastic waste and food protection against oxidation reactions. Different concentrations of extracts of the plants Caesalpinia decapetala (CD) and Caesalpinia spinosa "Tara" (CS) were incorporated into gelatine films as natural antioxidants. The physical, mechanical and antioxidant properties of these films were studied. Films containing plant extracts at a high concentration had lower tensile strength with higher elongation at break points, compared to the control film (p < 0.05). Films exhibited antioxidant activity in the oxygen radical absorbance capacity (ORAC) and Trolox equivalence antioxidant capacity (TEAC) assays when added at 0.2%. The application of gelatine film containing CD and CS was found to be effective in delaying lipid oxidation and deterioration of beef patty quality during storage. Therefore, the films prepared in this study offered an alternative edible coating for the preservation of fresh food.

Chemical and Sensory Quality Preservation in Coated Almonds with the Addition of Antioxidants

Almonds provide many benefits such as preventing heart disease due to their high content of oleic fatty acid-rich oil and other important nutrients. However, they are susceptible to oxidation reactions causing rancidity during storage. The objective of this work was to evaluate the chemical and sensory quality preservation of almonds coated with carboxymethyl cellulose and with the addition of natural and synthetic antioxidants during storage. Four samples were prepared: almonds without coating (C), almonds coated with carboxymethyl cellulose (CMC), almonds coated with CMC supplemented with peanut skins extract (E), and almonds coated with CMC and supplemented with butylhydroxytoluene (BHT). Proximate composition and fatty acid profile were determined on raw almonds. Almond samples (C, CMC, E and BHT) were stored at 40 °C for 126 d. Lipid oxidation indicators: peroxide value (PV), conjugated dienes (CD), volatile compounds (hexanal and nonanal), and sensory attributes were determined for the stored samples. Samples showed small but significant increases in PV, CD, hexanal and nonanal contents, and intensity ratings of negative sensory attributes (oxidized and cardboard). C had the highest tendency to deterioration during storage. At the end of storage (126 d), C had the highest PV (3.90 meqO2 /kg), and BHT had the lowest PV (2.00 meqO2 /kg). CMC and E samples had similar intermediate PV values (2.69 and 2.57 meqO2 /kg, respectively). CMC coating and the addition of natural (peanut skin extract) and synthetic (BHT) antioxidants provide protection to the roasted almond product.

Enhancing mechanical properties of chitosan films via modification with vanillin

The vanillin/chitosan composite films were prepared using the solvent evaporation method. The properties of the films including optical property, water vapor permeability (WVP), tensile strength (TS) and elongation at break (%E) were studied to investigate the effect of cross-linking agent of vanillin on chitosan films by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectrum (FT-IR). Results showed that the TS of composite films increased by 53.3% and the WVP decreased by 36.5% compared with pure chitosan film that were due to the formation of the dense network structure by FT-IR spectra. There were almost no changes of the thermal stability of the composite films compared with the pure chitosan film by TGA analysis. In addition, from the SEM images, it could be seen that the film with addition of vanillin with 0.5-10% concentration exhibited good compatibility.

In vitro toxicological evaluation of essential oils and their main compounds used in active food packaging: A review

Essential oils (EOs) and their main constituent compounds have been extensively investigated due to their application in the food industry for improving the shelf life of perishable products. Although they are still not available for use in food packaging in the market in Europe, considerable research in this field has been carried out recently. The safety of these EOs should be guaranteed before being commercialized. The aim of this work was to review the scientific publications, with a primary focus on the last 10 years, with respect to different in vitro toxicological aspects, mainly focussed on mutagenicity/genotoxicity. In general, fewer genotoxic studies have been reported on EOs in comparison to their main components, and most of them did not show mutagenic activity. However, more studies are needed in this field since the guidelines of the European Food Safety Authority have not always been followed accurately. The mutagenic/genotoxic activities of these substances have been related to metabolic activation. Therefore, in vivo tests are required to confirm the absence of genotoxic effects. Considering the great variability of the EOs and their main compounds, a case-by-case evaluation is needed to assure their safe use in food packaging.