Sustainable nanocomposite coating for moulded pulp with enhanced barrier properties for food packaging applications

Abstract

Due to poor barrier properties and high sensitivity to moisture, the applications of paper‐based food packaging remain limited. While gaining high barrier performance and surface durability, laminating papers with binders and other materials often leads to reduced recyclability and sustainability. Herein, we present a promising approach to improve the barrier properties and surface oil resistance of bagasse moulded pulp while preserving its green profile. A bio‐nanocomposite layer, combining nanocellulose and shellac (natural polyester), was coated on the surface of moulded pulp. This nanocomposite coating layer provides excellent gas barrier and water barrier performance simultaneously, thanks to the ester modification of nanocellulose to improve its hydrophobicity. With a good compatibility and dispersion in the shellac matrix phase, the modified nanofibrillated cellulose demonstrated an improved barrier performance compared with the unmodified nanofibrillated cellulose. Oxygen transmission rate and water vapour transmission rate of the coated pulps were in the range 60–300 cm3 m−2 day−1 and 10–30 g m−2 day−1, respectively, comparable to those of conventional food packaging materials. The surface resistance of the coated pulps was also greatly improved, indicated by the water contact angle, oil contact angle, Kit test and oil resistance test in a bowl model. The nanocomposite was able to enhance the tensile strength of the moulded pulp by 23%. In summary, the current sustainable nanocomposite coating layer demonstrated great potential in converting paper‐based materials to high barrier and sustainable food packaging. © 2022 Society of Industrial Chemistry.

The Effect of Cellulose Nanofibres on Dewatering during Wet-Forming and the Mechanical Properties of Thermoformed Specimens Made of Thermomechanical and Kraft Pulps

“…Presently, the demonstrators do not have any surface modification to provide a liquid barrier. Some strategies have been proposed recently in this respect, including using lignin in the bulk to reduce hydrophilicity [ 24 ] or surface coatings containing CNF or combinations with chitosan [ 29 , 30 , 31 ]. However, such strategies only seem to reduce the liquid absorption.…”

“…Kraft pulp fibres appeared to retain more water, which increased the dewatering time during wet-moulding and apparently increased the resistance of the pulp to be compressed during thermoforming. It is worth to keep in mind that the migration of substances, in the form of microplastics and nanoplastics, from packaging materials to food during storage or heating is known to occur for plastics, e.g., PP and PE [29]. Contrary to wood fibres that do not melt, the melting of PP and PE starts at approx.…”

“…Hence, it still seems challenging to compete with the liquid-resistant PE layer applied on some pulp fibre products. It is worth to keep in mind that the migration of substances, in the form of microplastics and nanoplastics, from packaging materials to food during storage or heating is known to occur for plastics, e.g., PP and PE [29]. Contrary to wood fibres that do not melt, the melting of PP and PE starts at approx.…”

Shellac: From Isolation to Modification and Its Untapped Potential in the Packaging Application

“…In one research work, Shellac failed to serve as a water barrier in some way [87]. In contrast, in another study, Shellac with nano-fibrillated cellulose (NFC) was coated on pulp cutlery, improving the water barrier and outperforming traditional polymers, such as polyethylene terephthalate (PET) [88]. With various biopolymers, including pea starch/guar gum [77], KGM [74], CMC [80], and SPI [79], Shellac has been used as reinforcement to strengthen the water barrier, oxygen barrier, and mechanical properties, which are crucial for the majority of food packaging applications.…”

Nurturing a global choir of perspective

“…Soykeabkaew et al . describe sustainable nanocomposite coatings for molded pulp with enhanced barrier properties for food packaging applications 9 . This recent manuscript speaks to our continued emphasis on sustainability and circular thinking for next generation products.…”