Nowadays, food packaging systems have shifted from a passive to an active role in which the incorporation of antimicrobial compounds into biopolymers can promote a sustainable way to reduce food spoilage and its environmental impact. Accordingly, composite materials based on oxidized-bacterial cellulose (BC) and poly(vinyl alcohol)-chitosan (PVA-CH) nanofibers were produced by needleless electrospinning and functionalized with the bacterial pigment prodigiosin (PG). Two strategies were explored, in the first approach PG was incorporated in the electrospun PVA-CH layer, and TEMPO-oxidized BC was the substrate for nanofibers deposition (BC/PVA-CH_PG composite). In the second approach, TEMPO-oxidized BC was functionalized with PG, and afterward, the PVA-CH layer was electrospun (BC_PG/PVA-CH composite). The double-layer composites obtained were characterized and the nanofibrous layers displayed smooth fibers with average diameters of 139.63 ± 65.52 nm and 140.17 ± 57.04 nm, with and without pigment incorporation, respectively. FTIR-ATR analysis confirmed BC oxidation and revealed increased intensity at specific wavelengths, after pigment incorporation. Moreover, the moderate hydrophilic behavior, as well as the high porosity exhibited by each layer, remained mostly unaffected after PG incorporation. The composites’ mechanical performance and the water vapor transmission rate (WVTR) evaluation indicated the suitability of the materials for certain food packaging solutions, especially for fresh products. Additionally, the red color provided by the bacterial pigment PG on the external surface of a food packaging material is also a desirable effect, to attract the consumers’ attention, creating a multifunctional material. Furthermore, the antimicrobial activity was evaluated and, PVA-CH_PG, and BC_PG layers exhibited the highest antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa. Thus, the fabricated composites can be considered for application in active food packaging, owing to PG antimicrobial potential, to prevent foodborne pathogens (with PG incorporated into the inner layer of the food packaging material, BC/PVA-CH_PG composite), but also to prevent external contamination, by tackling the exterior of food packaging materials (with PG added to the outer layer, BC_PG/PVA-CH composite).

A Bacterial Cellulose (BC) film was developed and characterized as a potential functional bioactive material. BC films, obtained from a microbial consortium of bacteria and yeast species, were functionalized with the bacterial pigment prodigiosin, produced by Serratia plymuthica, and flexirubin-type pigment, from Chryseobacterium shigense, which exhibit a wide range of biological properties. BC was successfully functionalized at 15% over the weight of the fiber at 40 °C during 60 min, and a color strength of 1.00 ± 0.01 was obtained for BC_prodigiosin and 0.38 ± 0.02 for BC_flexirubin-type pigment. Moreover, the BC films showed moderate hydrophilic character following alkaline treatment, which was maintained after both pigments were incorporated. The porosity and mechanical performance of the functionalized BC samples also remained unaffected. Furthermore, the BC samples functionalized with prodigiosin presented antibacterial activity and were able to inhibit the growth of pathogenic bacteria Staphylococcus aureus and Pseudomonas aeruginosa, with inhibition rates of 97.89 ± 0.60% and 85.12 ± 0.17%, respectively, while BC samples functionalized with flexirubin-type pigment exhibited the highest antioxidant activity, at 38.96 ± 0.49%. This research provides an eco-friendly approach to grant BC film-based material with color and advantageous bioactive properties, which can find application in several fields, especially for medical purposes.

In response to escalating concerns about environmental pollution from conventional plastic packaging, there is a growing interest in ecological and sustainable materials for food packaging. Consequently, biopolymer-based electrospun materials, particularly polysaccharides such as chitosan (CH), starch, and cellulose, have emerged as promising alternatives to synthetic ones due to their remarkable barrier properties and mechanical strength. Moreover, following the trend of employing polysaccharides as ecological and sustainable solutions for packaging materials, natural colorants have also been recognized as safer alternatives to synthetic dyes, addressing concerns about potential adverse effects on human health and the environment. These natural colorants add color to food packaging and enhance food freshness, possibly extending shelf life and promoting consumers' perception of food quality and safety. Therefore, this review summarizes recent advancements in fabricating and characterizing electrospun materials based on polysaccharides and natural colorants for sustainable food packaging. It explores various electrospinning techniques and highlights the incorporation of natural colorants, including bacterial pigments, for active and intelligent packaging applications. Moreover, it emphasizes the increasing role of the biobased industry in developing sustainable packaging materials with bioactive coloration. Lastly, the review addresses challenges, opportunities, and future research directions. Graphical Abstract

Nowadays, worldwide challenges such as global warming, pollution, unsustainable consumption patterns, and scarcity of natural resources are key drivers toward future-oriented bioeconomy strategies, which rely on renewable biobased resources, such as bacterial pigments and bacterial cellulose (BC), for materials production. Therefore, the purpose of this study was to functionalize bacterial cellulose with violacein, flexirubin-type pigment, and prodigiosin and test their suitability as pH indicators, due to the pigments’ sensitivity to pH alterations. The screening of the most suitable conditions to obtain the BC-pigment indicators was achieved using a full factorial design, for a more sustainable functionalization process. Then, the pH response of functionalized BC to buffer solutions was assessed, with color changes at acidic pH (BC-violacein indicator) and at alkaline pH (BC-violacein, BC-prodigiosin, and BC-flexirubin-type pigment indicators). Moreover, the indicators also revealed sensitivity to acid and base vapors. Furthermore, leaching evaluation of the produced indicators showed higher suitability for aqueous foods. Additionally, color stability of the functionalized BC indicators was carried out, after light exposure and storage at 4 °C, to evaluate the indicators’ capacity to maintain color/sensitivity. Thus, BC membranes functionalized with bacterial pigments have the potential to be further developed and used as pH indicators.

In this study, needleless electrospinning technology was used to obtain flexirubin (F)‐loaded polyvinyl alcohol (PVA)_kefiran (KF)/polycaprolactone (PCL) electrospun nanofibers. The SEM images of PVA_KF_ F and PCL_F nanofibers displayed beadless morphology with average diameters of 211.90 ± 96.08 and 1610.71 ± 996.68 nm, respectively. FTIR‐ATR analysis revealed increased intensity at specific wavelengths, after pigment incorporation. The high porosity exhibited by each layer and the mechanical properties of the double‐layered nanofibrous material remained unaffected after flexirubin‐type pigment incorporation. In addition, PVA_KF_F/PCL_F nanofibers showed antioxidant activity of 41.03 ± 0.29%, evaluated by the scavenging of the ABTS radical as well as the ability to reduce enzymatic browning of apple slices. Thus, we believe that the fabricated PVA_KF_F/PCL_F double‐layered material can be considered for application in active food packaging systems.