a b s t r a c tMost materials currently used for food packaging are non-degradable, generating environmental problems. Several biopolymers have been exploited to develop materials for eco-friendly food packaging. However, the use of biopolymers has been limited because of their usually poor mechanical and barrier properties, which may be improved by adding reinforcing compounds (fillers), forming composites. Most reinforced materials present poor matrix-filler interactions, which tend to improve with decreasing filler dimensions. The use of fillers with at least one nanoscale dimension (nanoparticles) produces nanocomposites. Nanoparticles have proportionally larger surface area than their microscale counterparts, which favors the filler-matrix interactions and the performance of the resulting material. Besides nanoreinforcements, nanoparticles can have other functions when added to a polymer, such as antimicrobial activity, enzyme immobilization, biosensing, etc. The main kinds of nanoparticles which have been studied for use in food packaging systems are overviewed, as well as their effects and applications.

Consumers are increasingly avoiding foods containing synthetic colourants, which lead food industries to replace them by natural pigments, such as carotenoids, betalains, anthocyanins and carminic acid. Betalains are water-soluble nitrogen-containing pigments, composed of two structural groups: the red-violet betacyanins and the yellow-orange betaxanthins. This review synthesises the published literature on basic chemistry of betalains, their sources and chemical stability. Moreover, several works are mentioned which have demonstrated the potent antioxidant activity of betalains, which has been associated with protection against degenerative diseases.

Food packaging materials are traditionally expected to contain foodstuffs and protect them from deteriorating agents. Although petroleum-derived polymers have been widely used for this purpose, the rising concern with their nonrenewable and/or nonbiodegradable nature paves the route for the development of greener alternatives, including polysaccharides and polypeptides. The use of these food-grade biomacromolecules, in addition to fruits and vegetables, provides edible packaging with suitable physical-mechanical properties as well as unique sensory and nutritional characteristics. This text reviews the chronological development pathway of films based on fruit and vegetable purees, pomaces, and extracts. Recent advances are extensively reviewed with an emphasis on the role that each film component plays in the resulting materials, whose production methods are examined from a technical standpoint and essential properties are compiled and contrasted to their conventional, synthetic counterparts. Finally, this comprehensive review discusses advantages and limitations of edible films based on fruits and vegetables.

Bacterial cellulose (BC) has been produced for a number of applications, mainly focused on the biomedical area. Although there is a variety of interesting applications of BC for food and food packaging, only a few have been explored to the moment, since the high cost of BC production is usually considered as a limiting factor. On the other hand, several cost-effective culture media have been proposed, contributing to reduce BC production costs. This article overviews the bioprocess conditions that affects BC production and the main possible applications of BC for food and food packaging purposes.

Cellulose nanoreinforcements have been used to improve mechanical and barrier properties of biopolymers, whose performance is usually poor when compared to those of synthetic polymers. Nanocomposite edible films have been developed by adding cellulose nanofibers (CNF) in different concentrations (up to 36 g/100 g) as nanoreinforcement to mango puree based edible films. The effect of CNF was studied in terms of tensile properties, water vapor permeability, and glass transition temperature (T(g)) of the nanocomposite films. CNF were effective in increasing tensile strength, and its effect on Young's modulus was even more noticeable, especially at higher concentrations, suggesting the formation of a fibrillar network within the matrix. The addition of CNF was also effective to improve water vapor barrier of the films. Its influence on T(g) was small but significant. The study demonstrated that the properties of mango puree edible films can be significantly improved through CNF reinforcement.

Cellulose nanostructures have been widely studied as components of materials for a variety of applications including food packaging. They are usually incorporated as a reinforcement phase in nanocomposites (as cellulose nanocrystals or cellulose nanofibrils). In other cases, cellulose nanostructures have been used as matrices for films-bacterial cellulose (BC) deserving a special attention in this context, since it is produced as naturally nanostructured membranes, which may grow in a medium containing other biopolymers (producing bottom-up built bionanocomposites), be impregnated with other components, or be disintegrated into nanofibribils or even nanocrystals. This review summarizes findings and prospective applications of nanocellulose for bio-based materials to be used in food packaging (including active packaging).

Chitosan is a biodegradable polymer which may be used to elaborate edible films or coatings to enhance shelf life of foods. This study demonstrates how cellulose nanofibers (CNF) can improve the mechanical and water vapor barrier properties of chitosan films. A nanocomposite film with 15% CNF and plasticized with 18% glycerol was comparable to some synthetic polymers in terms of strength and stiffness, but with poorer elongation and water vapor barrier, indicating that they can be used for applications that do not require high flexibility and/or water vapor barrier. The more important advantage of such films when compared to synthetic polymer films is their environmentally friendly properties.

Nanocellulose-based nanocomposite hydrogels are promising materials in different fields of application such as medicine, food, and agriculture.