Recent developments in multifunctional and nanoreinforced polymers have provided the opportunity to produce high barrier, active and intelligent food packaging which can help ensure, or even enhance, ...the quality and safety of packaged foods. This book provides a comprehensive review of novel polymers and polymer nanocomposites for use in food packaging. Part One and Two discuss nanofillers for plastics in food packaging and investigate high barrier plastics. Part Three investigates silver-based antimicrobial polymers, the incorporation of antimicrobial/antioxidant natural extracts into polymeric films, and biaoctive food packaging strategies. Part Four examines nanotechnology in sustainable plastics with chapters examining the food packaging applications of polylactic acid (PLA) nanocomposites, polyhydroxyalkanoates (PHAs), starch-based polymers, chitosan and carragenan polysaccharides and protein-based resins for packaging gluten (WG)-based materials. This book proves a valuable resource for researchers in packaging in the food industry and polymer scientists interested in multifunctional and nanoreinforced materials.
Fiber–matrix interfacial adhesion is one of the key factors governing the final properties of natural fiber-based polymer composites. In this work, four extrusion reactive agents were tested as ...potential compatibilizers in polyhydroxylbutyrate (PHB)/cellulose composites: dicumyl peroxide (DCP), hexamethylene diisocyanate (HMDI), resorcinol diglycidyl ether (RDGE), and triglycidyl isocyanurate (TGIC). The influence of the fibers and the different reactive agents on the mechanical properties, physical aging, and crystallization behavior were assessed. To evaluate the compatibilization effectiveness of each reactive agent, highly purified commercial cellulose fibers (TC90) were used as reference filler. Then, the influence of fiber purity on the compatibilization effect of the reactive agent HMDI was evaluated using untreated (U_RH) and chemically purified (T_RH) rice husk fibers, comparing the results with the ones using TC90 fibers. The results show that reactive agents interact with the polymer matrix at different levels, but all compositions showed a drastic embrittlement due to the aging of PHB. No clear compatibilization effect was found using DCP, RDGE, or TGIC reactive agents. On the other hand, the fiber–polymer interfacial adhesion was enhanced with HMDI. The purity of the fiber played an important role in the effectiveness of HMDI as a compatibilizer, since composites with highly purified fibers showed the greatest improvements in tensile strength and the most favorable morphology. None of the reactive agents negatively affected the compostability of PHB. Finally, thermoformed trays with good mold reproducibility were successfully obtained for PHB/T_RH/HMDI composition.
In the present study, a new poly(3-hydroxybutyrate-
-3-hydroxyvalerate-
-3-hydroxyhexanoate) P(3HB-
-3HV-
-3HHx) terpolyester with approximately 68 mol% of 3-hydroxybutyrate (3HB), 17 mol% of ...3-hydroxyvalerate (3HV), and 15 mol% of 3-hydroxyhexanoate (3HHx) was obtained via the mixed microbial culture (MMC) technology using fruit pulps as feedstock, a processing by-product of the juice industry. After extraction and purification performed in a single step, the P(3HB-
-3HV-
-3HHx) powder was melt-mixed, for the first time, in contents of 10, 25, and 50 wt% with commercial poly(3-hydroxybutyrate-
-3-hydroxyvalerate) (PHBV). Thereafter, the resultant doughs were thermo-compressed to obtain highly miscible films with good optical properties, which can be of interest in rigid and semirigid organic recyclable food packaging applications. The results showed that the developed blends exhibited a progressively lower melting enthalpy with increasing the incorporation of P(3HB-
-3HV-
-3HHx), but retained the PHB crystalline morphology, albeit with an inferred lower crystalline density. Moreover, all the melt-mixed blends were thermally stable up to nearly 240 °C. As the content of terpolymer increased in the blends, the mechanical response of their films showed a brittle-to-ductile transition. On the other hand, the permeabilities to water vapor, oxygen, and, more notably, limonene were seen to increase. On the overall, this study demonstrates the value of using industrial biowaste derived P(3HB-
-3HV-
-3HHx) terpolyesters as potentially cost-effective and sustainable plasticizing additives to balance the physical properties of organic recyclable polyhydroxyalkanoate (PHA)-based food packaging materials.
Electrospinning of uniform biohybrid fibers with concealed cellulose microfibrils (CMF) is reported as a promising and environmentally sound concept for reinforcement of polymer nonwoven fiber ...systems of fine dimensions. The extraction and refinement of the high-strength crystalline microfibril bundles (15−20 nm thick) from bacterial cellulose networks is presented, as well as their morphology prior to and post electrospinning, Nanofibers composed of a poly(methyl methacrylate) (PMMA) matrix with cellulose contents reaching 20 wt % were repeatedly obtained. A high degree of dispersion of the microfibrils was obtained for a variety of CMF contents and the aggregation of the CMF was greatly suppressed as the microfibrils were aligned and rapidly sealed inside the acrylate matrix during the continuous formation of the fibers. The limited CMF aggregation up to 7 wt % was related to a suppressed phase separation caused by the rapid solidification of the polymer solutions during spinning. The fibers’ diameters decreased significantly from ∼1.8 μm (1 wt %) to ∼100 nm (20 wt %) with increasing cellulose contents, resulting in CMF agglomerations and percolating architectures within the acrylate host, which was consistent with microscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) evaluations. The nominal content of cellulose in the fibers was assessed by Lorentzian profile fit assignment of the crystalline vs amorphous fractions of the fibers’ X-ray diffractograms. TGA of fibers with low CMF content revealed that both CMF and PMMA showed a significantly improved thermal stability in the composite material. The biohybrid fibers were continuously aligned into an anisotropic nanocomposite yarns from a liquid support during spinning. The strategy described herein may allow for new mechanically robust nonwoven fiber systems, or be used as implemented on existing electrospun formulations that are lacking mechanical integrity. It is envisioned that the cellulose microfibrils may be of importance in biomedical applications where biocompatibility is a requirement.
•The effect of a zein interlayer on PHA with different valerate content was analyzed.•PLA and PET multilayer systems were also prepared and used as reference materials.•Zein nanofibers improved ...oxygen permeability of the multilayer structures.•PHA’s-zein multilayers can be postulated as potential substitutes of PET.
This paper compares the effect of incorporating high barrier self-adhesive nanostructured interlayers of zein between layers of other polyhydroxyalkanoate materials (a PHB homopolymer and a PHBV5 copolymer with 5% valerate content). Furthermore, similar reference multilayer structures based on both a polylactide (PLA) and a polyethylene terephthalate (PET) were also prepared, retaining high levels of transparency. The results indicate significant differences of the effect of the interlayer between different materials. Thus, while the oxygen and limonene barrier properties were significantly improved by the presence of a zein nanostructured interlayer, the water vapour permeability of these multilayer systems were seem to vary among materials since the zein interlayer was only efficient as a barrier element in the PHA materials as compared to PLA. Flexibility of PHB and PHBV multilayer structures were also greatly improved by the addition of zein interlayers whereas minor changes were observed in PLA and PET multilayer systems. These results provide complementary insight into the use of electrospun nanostructured zein to generate fully renewable solutions in multilayer form to enhance the barrier performance of polyhydroxyalcanoates.
Nowadays, the interest on nanofibrillated cellulose (CNF) has increased owing to its sustainability and its capacity to improve mechanical and barrier properties of polymeric films. Moreover, this ...filler shows some drawbacks related with its high capacity to form aggregates, hindering its dispersion in the matrix. In this work, an improved procedure to optimize the dispersability of CNF in a thermoplastic starch was put forward. On the one hand, CNF needs a hydrophilic dispersant to be included in the matrix, and on the other, starch needs a hydrophilic plasticizer to obtain a thermoformable material. Glycerol was used to fulfil both targets at once. CNF was predispersed in the plasticizer before nanofibrillation and later on was included into starch, obtaining thin films. The tensile strength of these CNF-starch composite films was 60% higher than the plain thermoplastic starch at a very low 0.36%
/
percentage of CNF. The films showed a noticeable correlation between water uptake, and temperature and humidity. Regarding permeability, a ca. 55% oxygen and water vapor permeability drop was found by nanofiller loading. The hydrolytic susceptibility of the composite was confirmed, being similar to that of the thermoplastic starch.
•Quercetin and ferulic acid were encapsulated using electrospinning.•Blends of amaranth protein isolate and pullulan were used as encapsulating matrices.•Sustained release of the antioxidants from ...the electrospun fibers was observed.•Encapsulation improved antioxidant capacity of bioactives during in-vitro digestion.
Two bioactive compounds, quercetin and ferulic acid, were encapsulated using the electrospinning technique within hybrid amaranth protein isolate (API):pullulan ultrathin fibers. Initially, the composition of the encapsulation structures was optimized, both in terms of matrix components ratio and to maximize the bioactive loading. The morphology and thermal stability of the developed encapsulation structures were evaluated, as well as the encapsulation efficiency and distribution within the fibers of both antioxidant compounds. Moreover, the release characteristics and protection ability of the encapsulation structures during an in-vitro digestion study were investigated. Smooth ultrathin electrospun fibers were obtained in which the antioxidants were homogeneously distributed. Through this methodology, it was possible to incorporate within the API:pullulan fibers up to 10 and 20% (by weight) of quercetin and ferulic acid, respectively, which were released in a sustained manner during in-vitro digestion, keeping to a greater extent their antioxidant capacity in comparison with the non-encapsulated compounds.
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