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The present study reports on the development by thermoforming of highly sustainable trays based on a bilayer structure composed of paper substrate and a film made of a blend of partially bio-based poly(butylene succinate) (PBS) and poly(butylene succinate-co-adipate) (PBSA). The incorporation of the renewable succinic acid derived biopolyester blend film slightly improved the thermal resistance and tensile strength of paper, whereas its flexural ductility and puncture resistance were notably enhanced. Furthermore, in terms of barrier properties, the incorporation of this biopolymer blend film reduced the water and aroma vapor permeances of paper by two orders of magnitude, while it endowed the paper structure with intermediate oxygen barrier properties. The resultant thermoformed bilayer trays were, thereafter, originally applied to preserve non-thermally treated Italian artisanal fresh pasta, "fusilli calabresi" type, which was stored under refrigeration conditions for 3 weeks. Shelf-life evaluation showed that the application of the PBS–PBSA film on the paper substrate delayed color changes and mold growth for 1 week, as well as reduced drying of fresh pasta, resulting in acceptable physicochemical quality parameters within 9 days of storage. Lastly, overall migration studies performed with two food simulants demonstrated that the newly developed paper/PBS–PBSA trays are safe since these successfully comply with current legislation on plastic materials and articles intended to come into contact with food. [ABSTRACT FROM AUTHOR]

High-resistance paper was manufactured by laccase-grafting of carboxymethyl cellulose (CMC) and chitosan (CPX) on Kraft pulp fiber. The reaction was mediated in the presence of laccase by one of the following polyphenols in the presence of air: gallic acid (GA), vanillic acid (VA) and catechol (1,2-DHB). Enzyme was added at constant loading (24 kg ton-1), 1% pulp consistency, 0.005% CMC, pH = 6.3 ± 0.5 and 2 mM of mediator. CPX content was assessed at two levels (0% and 0.005%). Treated pulps were analyzed by different mechanical tests (ring crush, mullen, corrugating medium test (CMT) flat crush of corrugating medium test and tension). An improvement in these parameters was obtained by biopolymer coupling and selected mediator. When using GA, three parameters increased more than 40%, while ring crush increased 120%. For the case of VA, properties were enhanced from 74% to 88% when CPX was added. For 1,2-DHB, there was not found a statistically significant difference between the results in the presence of CPX. Scanning electron microscopy, confocal microscopy, FTIR and 13C NMR were used in all papers in order to evaluate grafting. Hence, it was possible to correlate polymerization with an improvement of paper's mechanical properties. [ABSTRACT FROM AUTHOR]

There is increasing research towards the substitution of petrochemicals by sustainable components. Biopolymers such as proteins, polysaccharides, and lipids derive from a variety of crop sources and most promisingly from waste streams generated during their processing by the agro food industry. Among those, proteins of different types such as whey, casein, gelatin, wheat gluten, soy protein or zein present a potential beyond the food and feed industry for the application in packaging. The general protein hydrophilicity promotes a good compatibility to polar surfaces, such as paper, and a good barrier to apolar gases, such as oxygen and carbon dioxide. The present review deals with the development of protein-based coatings and films. It includes relevant discussion for application in paper or board products, as well as an outlook on its future industrial potential. Proteins with suitable functionalities as food packagingmaterials are described as well as the different technologies for processing the coatings and the current state of the art about the coating formulations for selectively modulating barrier, mechanical, surface and end of life properties. Some insights onto regulations about packaging use, end of life and perspectives of such natural coating for decreasing the environmental impact of packages are given. [ABSTRACT FROM AUTHOR]

The barrier resistance and wettability of papers are commonly controlled by the application of petroleum-based derivatives such as polyethylene, waxes and/or fluor-derivatives as coating. While surface hydrophobicity is improved by employing these polymers, they have become disfavored due to limitations in fossil-oil resources, poor recyclability, and environmental concerns on generated waste with lack of biodegradation. Alternatively, biopolymers including polysaccharides, proteins, lipids and polyesters can be used to formulate new pathways for fully bio-based paper coatings. However, difficulties in processing of most biopolymers may arise due to hydrophilicity, crystallization behavior, brittleness or melt instabilities that hinder a full exploitation at industrial scale. Therefore, blending with other biopolymers, plasticizers and compatibilizers is advantageous to improve the coating performance. In this paper, an overview of barrier properties and processing of bio-based polymers and their composites as paper coating will be discussed. In particular, recent technical advances in nanotechnological routes for bio-based nano- composite coatings will be summarized, including the use of biopolymer nanoparticles, or nanofillers such as nanoclay and nanocellulose. The combination of biopolymers along with surface modification of nanofillers can be used to create hierarchical structures that enhance hydrophobicity, complete barrier protection and functionalities of coated papers. [ABSTRACT FROM AUTHOR]

As one of the most abundant natural polymers in nature, polysaccharides have the potential to replace petroleum-based polymers that are difficult to degrade in paper coatings. Polysaccharide molecules have a large number of hydroxyl groups that can bind strongly with paper fibers through hydrogen bonds. Chemical modification can also effectively improve the mechanical, barrier, and hydrophobic properties of polysaccharide-based coating layers and thus can further improve the related properties of coated paper. Polysaccharides can also give paper additional functional properties by dispersing and adhering functional fillers, e.g., conductive particles, catalytic particles or antimicrobial chemicals, onto paper surface. Based on these, this paper reviews the application of natural polysaccharides, such as cellulose, hemicellulose, starch, chitosan, and sodium alginate, and their derivatives in paper coatings. This paper analyzes the improvements and influences of chemical structures and properties of polysaccharides on the mechanical, barrier, and hydrophobic properties of coated paper. This paper also summarizes the researches where polysaccharides are used as the adhesives to adhere inorganic or functional fillers onto paper surface to endow paper with great surface properties or special functions such as conductivity, catalytic, antibiotic, and fluorescence. [ABSTRACT FROM AUTHOR]