Food packaging plays a fundamental role in the modern food industry as a main process to preserve the quality of food products from manufacture to consumption. New food packaging technologies are being developed that are formulated with natural compounds by substituting synthetic/chemical antimicrobial and antioxidant agents to fulfill consumers’ expectations for healthy food. The strategy of incorporating natural antimicrobial compounds into food packaging structures is a recent and promising technology to reach this goal. Concepts such as “biodegradable packaging”, “active packaging”, and “bioactive packaging” currently guide the research and development of food packaging. However, the use of natural compounds faces some challenges, including weak stability and sensitivity to processing and storage conditions. The nano/microencapsulation of these bioactive compounds enhances their stability and controls their release. In addition, biodegradable packaging materials are gaining great attention in the face of ever-growing environmental concerns about plastic pollution. They are a sustainable, environmentally friendly, and cost-effective alternative to conventional plastic packaging materials. Ultimately, a combined formulation of nano/microencapsulated antimicrobial and antioxidant natural molecules, incorporated into a biodegradable food packaging system, offers many benefits by preventing food spoilage, extending the shelf life of food, reducing plastic and food waste, and preserving the freshness and quality of food. The main objective of this review is to illustrate the latest advances in the principal biodegradable materials used in the development of active antimicrobial and antioxidant packaging systems, as well as the most common nano/microencapsulated active natural agents incorporated into these food-packaging materials.

In this study, an antimicrobial plant-based film was developed using pectin which is incorporated by different percentages of nanoemulsified trans-cinnamaldehyde (TC). The nanoemulsion of TC was incorporated into pectin to form films containing TC at concentrations of 5.00%, 3.33%, 2.50% and 2.00% (w/w). The nanoemulsion of TC was formed by using soybean lecithin as an emulsifier and had a zeta potential of −57 mV and an average size of 106 nm. The analysis showed that the addition of emulsified TC enhanced the light barrier properties, but the opacity of films increased due to the increase in light absorption, coalescence, and light-scattering phenomena. Films containing the nanoemulsion of TC exhibited reduced tensile strength and elasticity due to structural discontinuities in the film network caused by the presence of the nanoemulsion of TC, while elongation at break increased for TC concentrations of 2.50% and 2.00%. The films retained their infrared spectra, but their thermal stability decreased slightly. The incorporation of TC nanoemulsion significantly reduced the glass transition temperature, as shown by the differential scanning calorimetry analysis. The active films showed antimicrobial activity against Listeria innocua and Escherichia coli, indicating their potential for various food applications.

This study aimed to improve the physical, mechanical, and biological properties of a monolayer pectin (P) film containing nanoemulsified trans-Cinnamaldehyde (TC) by incorporating it between inner and outer layers of ethylcellulose (EC). The nanoemulsion had an average size of 103.93 nm and a zeta potential of −46 mV. The addition of the nanoemulsion increased the opacity of the film, reduced its moisture absorption capacity, and improved its antimicrobial activity. However, the tensile strength and elongation at break of the pectin films decreased after the incorporation of nanoemulsions. Multilayer films (EC/P/EC) showed a higher resistance to breaking and better extensibility compared to monolayer films. The antimicrobial activity of both mono and multilayer films was effective in inhibiting the growth of foodborne bacteria during storage of ground beef patties at 8 °C for 10 days. This study suggests that biodegradable antimicrobial multilayer packaging films can be effectively designed and applied in the food packaging industry.

Several plants rich in phenolic compounds have many uses in the food and pharmaceutical fields. However, after extraction, these active biomolecules are susceptible to degradation. Microencapsulation is a possible solution to prevent this rapid degradation. In this study, phenolic compounds from the okra Abelmoschus esculentus L’s leaves, fruits and seeds were extracted using microwave-assisted extraction and then microencapsulated via the spray drying technique using maltodextrin combined with pectin (in a ratio of 10:1) as an encapsulation material. The total phenolic content, DPPH scavenging and antimicrobial activities of okra extracts and encapsulated samples were evaluated to verify the encapsulation efficiency. Particle size distribution determination and scanning electron microscopy of the microcapsules were also carried-out. The ethanolic leaf extract showed higher significant levels of total phenolic compounds (162.46 ± 4.48 mg GAE/g DW), and anti-oxidant (75.65%) and antibacterial activities compared to those of other aqueous and ethanolic extracts from fruits and seeds. Furthermore, the spray-dried ethanolic leaf extract had the highest total phenolic content. However, the encapsulated ethanolic fruit extract had the highest percentage of DPPH scavenging activity (30.36% ± 1.49). In addition, antibacterial activity measurements showed that the addition of ethanolic and aqueous seed microcapsules provided a significant zone of inhibition against the bacterium Brochotrix thermosphacta (38 mm and 30 mm, respectively). Okra aqueous leaf microcapsules showed the smallest Sauter mean diameter values (7.98 ± 0.12 µm). These data are applicable for expanding the use of okra leaves, fruits and seeds as food additives and/or preservatives in the food industry.

Two plant-based emulsifiers, soybean lecithin and pea protein isolate, were studied for their emulsifying and encapsulating capacities of an antimicrobial molecule, trans-cinnamaldehyde (TC), at two different pH values, three and seven, and after drying with two different techniques, spray-drying and freeze-drying. To characterize the obtained capsules, various physicochemical tests were conducted to examine particle size, encapsulation efficiency, thermal and moisture stability, and powder morphology. The spray-dried (SD) and freeze-dried (FD) powders had an average particle size of 8.35 µm and 144.49 µm, respectively. The SD powders showed similar encapsulation efficiency (EE) for soybean lecithin and pea protein isolate with an average value of 95.69%. On the other hand, the FD powders had lower EE compared to SD powders, with an average of 58.01% for lecithin-containing powders and 83.93% for pea-protein-containing powders. However, the water content of FD powders (2.83%) was lower than that of SD powders (4.72%). The powders prepared at pH 3 showed better thermal stability. Morphological analysis showed spherical particles for SD powders and irregular shapes for FD powders. Nanoemulsions as well as dried powders showed interesting antimicrobial activities against Escherichia coli and Listeria innocua, confirming their potential use as natural preservatives in foods.

Développement de Films Actifs Biodégradables à base de Nano/microcapsules pour la Biopréservation des Aliments: Les emballages alimentaires actifs biodégradables présentent un grand potentiel en tant que nouvelle solution d'emballage pour lutter contre la pollution plastique et les problèmes liés à l'utilisation de conservateurs alimentaires synthétiques. Dans cette thèse nous nous sommes intéressés au développement d'emballages actifs biodégradables à base de biopolymères contenant des nano/microcapsules d'huiles essentielles. La première partie de cette thèse a concerné la préparation de nanoémulsions stables de trans-cinnamaldéhyde (TC) comme agent antimicrobien en utilisant un émulsifiant d'origine végétale. Un film monocouche actif à base de pectine contenant la nanoémulsion de TC a ensuite été développé. La caractérisation a montré que ce film monocouche de pectine devait être modifié pour améliorer ses propriétés afin de répondre aux exigences généralement requises pour les emballages alimentaires. C'est pourquoi une technique multicouche a été appliquée dans la suite de ce travail pour isoler le film de pectine contenant la nanoémulsion à l’aide de deux couches d'éthylcellulose (EC) ce qui a permis d'améliorer les propriétés physiques et mécaniques du film. Les films monocouches et multicouches ont permis de prolonger la durée de conservation de la viande hachée de dix jours à 8 °C. Le film de pectine monocouche a eu tendance à se dégrader, tandis que le film multicouche est resté intact. L'effet de l'épaisseur des couches d’EC sur les propriétés des films a ensuite été étudié. Les résultats ont montré que l'augmentation de l'épaisseur améliorait la stabilité physique, mécanique et thermique, mais réduisait l'activité antimicrobienne. Enfin, le séchage (par atomisation et par lyophilisation) a été utilisé pour préparer des microcapsules déshydratées de TC avec une évaluation de l'effet du type d'émulsifiant (lécithine et protéine de pois) et du pH (3 et 7). Sur la base des résultats de l'analyse et de caractérisation, y compris l'efficacité d'encapsulation, la teneur en eau, les propriétés thermiques et l'activité antimicrobienne, la formulation optimale a été sélectionnée pour produire des microcapsules qui ont ensuite été utilisées pour développer un film actif. La couche intermédiaire de ce film a été conçue pour contenir des microcapsules sèches de TC et a été protégée par deux couches externes d'EC. Les propriétés physiques, mécaniques et thermiques de films contenant deux concentrations différentes de microcapsules de TC ont été étudiées. L'inhibition de la croissance bactérienne par les films a été observée sur des galettes de viande hachée inoculées et stockées à 8 °C pendant 12 jours ce qui démontre leur activité antimicrobienne. Aussi, des résultats prometteurs ont été obtenus en testant la biodégradabilité des films monocouches et multicouches dans le sol et dans l'eau douce, ainsi que dans le lombricompostage. Cette étude confirme que l'emballage sous forme de films multicouches puisse être utilisé pour prolonger la durée de conservation des produits alimentaires et présente un grand potentiel pour des applications pour l'emballage d’aliments frais.