Development and oxygen scavenging performance of three-layer active PET films for food packaging

Active Flexible Films for Food Packaging: A Review

Active food packaging is a dynamic area where the scientific community and industry have been trying to find new strategies to produce innovative packaging that is economically viable and compatible with conventional production processes. The materials used to develop active packaging can be organized into scavenging and emitting materials, and based on organic and inorganic materials. However, the incorporation of these materials in polymer-based flexible packaging is not always straightforward. The challenges to be faced are mainly related to active agents' sensitivity to high temperatures or difficulties in dispersing them in the high viscosity polymer matrix. This review provides an overview of methodologies and processes used in the production of active packaging, particularly for the production of active flexible films at the industrial level. The direct incorporation of active agents in polymer films is presented, focusing on the processing conditions and their effect on the active agent, and final application of the packaging material. Moreover, the incorporation of active agents by coating technologies and supercritical impregnation are presented. Finally, the use of carriers to help the incorporation of active agents and several methodologies is discussed. This review aims to guide academic and industrial researchers in the development of active flexible packaging, namely in the selection of the materials, methodologies, and process conditions.

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.

Oxygen absorption data of multilayer oxygen scavenger-polyester films with different layouts

Oxygen absorption measurements in continuous regard active multilayer films with different layouts, all incorporating a PET/Oxygen scavenger (OS) layer, operating as active O₂ barrier, inserted between two PET inert layers, acting as passive O₂ barrier. The data set is related to “Transport properties of multilayer active PET films with different layers configuration” by Apicella et al. (2018) [1].

A set of four multilayer films, with different relative thickness of the active and inert layers, was produced using a laboratory scale co-extrusion cast-film equipment and was analyzed in terms of oxygen scavenging performance. Single layer active and inert layers were also produced for comparison. The results have shown a longer exhaustion time for all the active multilayer films, respect to the active monolayer one. Moreover, at constant thickness of the active layer, the exhaustion time increases by increasing the thickness of the inert layers, whereas, at constant thickness of the inert layers, the residual oxygen concentration decreases by increasing the thickness of the active layer.

Active Packaging Applications for Food

The traditional role of food packaging is continuing to evolve in response to changing market needs. Current drivers such as consumer's demand for safer, "healthier," and higher-quality foods, ideally with a long shelf-life; the demand for convenient and transparent packaging, and the preference for more sustainable packaging materials, have led to the development of new packaging technologies, such as active packaging (AP). As defined in the European regulation (EC) No 450/2009, AP systems are designed to "deliberately incorporate components that would release or absorb substances into or from the packaged food or the environment surrounding the food." Active packaging materials are thereby "intended to extend the shelf-life or to maintain or improve the condition of packaged food." Although extensive research on AP technologies is being undertaken, many of these technologies have not yet been implemented successfully in commercial food packaging systems. Broad communication of their benefits in food product applications will facilitate the successful development and market introduction. In this review, an overview of AP technologies, such as antimicrobial, antioxidant or carbon dioxide-releasing systems, and systems absorbing oxygen, moisture or ethylene, is provided, and, in particular, scientific publications illustrating the benefits of such technologies for specific food products are reviewed. Furthermore, the challenges in applying such AP technologies to food systems and the anticipated direction of future developments are discussed. This review will provide food and packaging scientists with a thorough understanding of the benefits of AP technologies when applied to specific foods and hence can assist in accelerating commercial adoption.

Gallic Acid as an Oxygen Scavenger in Bio-Based Multilayer Packaging Films

Oxygen scavengers are used in food packaging to protect oxygen-sensitive food products. A mixture of gallic acid (GA) and sodium carbonate was used as an oxygen scavenger (OSc) in bio-based multilayer packaging films produced in a three-step process: compounding, flat film extrusion, and lamination. We investigated the film surface color as well as oxygen absorption at different relative humidities (RHs) and temperatures, and compared the oxygen absorption of OSc powder, monolayer films, and multilayer films. The films were initially brownish-red in color but changed to greenish-black during oxygen absorption under humid conditions. We observed a maximum absorption capacity of 447 mg O₂/g GA at 21 °C and 100% RH. The incorporation of GA into a polymer matrix reduced the rate of oxygen absorption compared to the GA powder because the polymer acted as a barrier to oxygen and water vapor diffusion. As expected, the temperature had a significant effect on the initial absorption rate of the multilayer films; the corresponding activation energy was 75.4 kJ/mol. Higher RH significantly increased the oxygen absorption rate. These results demonstrate for the first time the production and the properties of a bio-based multilayer packaging film with GA as the oxygen scavenger. Potential applications include the packaging of food products with high water activity (a_w > 0.86).

Responsive Food Packaging: Recent Progress and Technological Prospects

Responsive food packaging is an emerging field in food packaging research and the food industry. Unlike active packaging, responsive packaging systems react to stimuli in the food or the environment to enable real time food quality and food safety monitoring or remediation. This review attempts to define and clarify the different classes of food packaging technologies. Special emphasis is given to the description of responsive food packaging including its technical requirements, the state of the art in research and the current expanding market. The development and promises of stimuli responsive materials in responsive food packaging are addressed, along with current challenges and future directions to help translate research developments into commercial products.