Certain naturally occurring volatile organic compounds are able to mitigate food spoilage caused by microbial growth. Their considerable vapor pressure enables them to create an antimicrobial atmosphere within a package, and this property can be used for the development of active food-packaging technologies. The volatility of these molecules, however, makes their stabilization difficult and limits their effectiveness. Whilst much research is being undertaken on the use of natural antimicrobial volatiles for inhibiting microbial growth in food, less attention has been paid to the design of controlled-release mechanisms that permit the efficient application of these compounds. Most studies to date either spray the volatile directly onto the fresh product, immerse it in a solution containing the volatile, or embed the volatile in a paper disc to create a vapor in the headspace of a package. More sophisticated alternatives would be delivery systems for the sustained release of volatiles into the package headspace. Such systems are based on the encapsulation of a volatile in organic or inorganic matrices (cyclodextrins, electrospun non-wovens, polymer films, micelles, molecular frameworks, etc.). However, most of these devices lack an efficient triggering mechanism for the release of the volatile; most are activated by humidity. All of these techniques are revised in the present work, and the most recent and innovative methods for entrapping and releasing volatiles based on reversible covalent bonds are also discussed.

In this work, novel active films based on ethylene vinyl alcohol copolymer (EVOH) and cinnamaldehyde (CIN) were successfully obtained employing a hybrid technique consisting of a two-step protocol involving the preparation of a polymeric EVOH-CIN masterbatch by solvent-casting for its further utilization in the preparation of bioactive EVOH-based films by melt extrusion processing. The influence of CIN over the EVOH matrix was studied in terms of optical, morphological, thermal, and mechanical properties. Optically transparent films were obtained and the incorporation of cinnamaldehyde resulted in yellow-colored films, producing a blocking effect in the UV region. A decrease in the glass transition temperature was observed in the formulations containing cinnamaldehyde, indicating a plasticizing effect. This phenomenon was confirmed by an increase in the elongation at break values of the extruded films. Results from thermogravimetric analysis determined a slight decrease in the thermal stability of EVOH provoked by the vaporization of the bioactive compound. Bioactive properties of the films were also studied; the presence of residual cinnamaldehyde in EVOH after being subjected to an extrusion process conferred some radical scavenging activity determined by the DPPH assay whereas films were able to exert antifungal activity in vapor phase against Penicillium expansum. Therefore, the present work shows the potential of the hybrid technique employed in this study for the preparation of bioactive films by a ready industrial process technology for food packaging applications.

Strawberries are valuable because of their nutritional value, but they are also highly perishable fruits. Fungal decay is the overriding factor that alters the overall quality of fresh strawberries. Because no hygienic treatments to reduce the initial microbial load are feasible, molds develop during postharvest when using conventional packaging. In this study, an antifungal packaging system for strawberries was developed to improve safety and quality. Trans-2-hexenal (HXAL), a natural compound in strawberries, was incorporated into the modified atmosphere packaging (MAP) systems. Zero, 100, and 250 µL of HXAL were included in cellulosic pads and were covered with a polyamide coating to control its release. The pads were placed on the bottom of plastic trays; an amount of250 g of strawberries was added, flow packed in micro-perforated PP bags, and stored at 4 °C for 14 days. Fungal infection was monitored during the storage period, and the optical and textural properties of the strawberries were measured at days 0 and 14. Analysis of the package headspace was conducted to check for the HXAL concentration. HXAL was partially retained in the fruits and was converted into hexyl acetate and 2-hexen-1-ol acetate, but this was only measurably present in the headspace of the active systems. Mold growth was fully inhibited in active packaging although the strawberries were softer and darker than those in the control packages. The active package was not as efficient if the fruits were stored under thermal-abuse conditions (15 and 22 °C).

Two ZIF-8-based biocomposites were obtained by entrapping benzaldehyde and methyl anthranilate via direct impregnation with fast encapsulation kinetics and high molecule payloads, that incorporated in a zein film provided improved antifungal activity.

Antimicrobial packaging has emerged as an efficient technology to improve the stability of food products. In this study, new formulations based on ethylene vinyl alcohol (EVOH) copolymer were developed by incorporating the volatile methyl anthranilate (MA) at different concentrations as antifungal compound to obtain active films for food packaging. To this end, a twin-screw extruder with a specifically designed screw configuration was employed to produce films at pilot scale. The quantification analyses of MA in the films showed a high retention capacity. Then, the morphological, optical, thermal, mechanical and water vapour barrier performance, as well as the antifungal activity in vitro of the active films, were evaluated. The presence of MA did not affect the transparency or the thermal stability of EVOH-based films, but decreased the glass transition temperature of the copolymer, indicating a plasticizing effect, which was confirmed by an increase in the elongation at break values of the films. Because of the additive-induced plasticization over EVOH, the water vapour permeability slightly increased at 33% and 75% relative humidity values. Finally, the evaluation of the antifungal activity in vitro of the active films containing methyl anthranilate showed a great effectiveness against P. expansum and B. cinerea, demonstrating the potential applicability of the developed films for active food packaging.

The environmental impact of food waste and agro-industrial by-products has promoted the development of circular economy strategies for food applications. In this study, edible films were developed from biopolymers extracted from avocado peel and seeds (hemicellulose, pectin, lignin, and starch), incorporating ethyl lauroyl arginate (LAE^®) as an antifungal agent. The activity of LAE^® was evaluated against Colletotrichum gloeosporioides on inoculated avocados stored at 12 °C and 22 °C. Fruit shelf life was assessed through physiological, physicochemical and sensory parameters during cold storage and subsequent shelf life. Films containing 10% LAE^® exhibited strong antifungal activity, and their efficacy was higher at 12 °C than at 22 °C. Coated fruits exhibited a ripening delay of up to 2 days compared to controls. These findings highlight the potential use of avocado by-product-based LAE^® coatings as a sustainable strategy for preserve postharvest avocado quality.