Using photo-modification to compatibilize nano-ZnO in development of starch-kefiran-ZnO green nanocomposite as food packaging material

Cellulose nanocrystals in the development of biodegradable materials: A review on CNC resources, modification, and their hybridization

The escalating demand for sustainable materials has propelled cellulose into the spotlight as a promising alternative to petroleum-based products. As the most abundant organic polymer on Earth, cellulose is ubiquitous, found in plants, bacteria, and even a unique marine animal-the tunicate. Cellulose polymers naturally give rise to microscale semi-crystalline fibers and nanoscale crystalline regions known as cellulose nanocrystals (CNCs). Exhibiting rod-like structures with widths spanning 3 to 50 nm and lengths ranging from 50 nm to several microns, CNC characteristics vary based on the cellulose source. The degree of crystallinity, crucial for CNC properties, fluctuates between 49 and 95 % depending on the source and synthesis method. CNCs, with their exceptional properties such as high aspect ratio, relatively low density (≈1.6 g cm-3), high axial elastic modulus (≈150 GPa), significant tensile strength, and birefringence, emerge as ideal candidates for biodegradable fillers in nanocomposites and functional materials. The percolation threshold, a mathematical concept defining long-range connectivity between filler and polymer, governs the effectiveness of reinforcement in nanocomposites. This threshold is intricately influenced by the aspect ratio and molecular interaction strength, impacting CNC performance in polymeric and pure nanocomposite materials. This comprehensive review explores diverse aspects of CNCs, encompassing their derivation from various sources, methods of modification (both physical and chemical), and hybridization with heterogeneous fillers. Special attention is devoted to the hybridization of CNCs derived from tunicates (TCNC) with those from wood (WCNC), leveraging the distinct advantages of each. The overarching objective is to demonstrate how this hybridization strategy mitigates the limitations of WCNC in composite materials, offering improved interaction and enhanced percolation. This, in turn, is anticipated to elevate the reinforcing effects and pave the way for the development of nanocomposites with tunable viscoelastic, physicochemical, and mechanical properties.

Biodegradable nano-reinforced packaging with improved functionality to extend the freshness and longevity of Plums Oemleria cerasiformis

Food packaging reinforced with Zn-doped TiO2 nanoparticles with enhanced prerequisite film-forming and biodegradable traits was prepared to augment fresh food storage. Pure and tailored metal (Zinc, Copper, and Selenium) doped TiO2 nanoparticles were synthesized and analyzed through multiple characterization techniques (optical spectra, XRD patterns (X-Ray Diffraction), Dynamic Light Scattering, and Scanning Electron Microscopy). The synthesized nanoparticles were tested for their Minimum Inhibitory Concentrations, antimicrobial potential against common lethal food pathogens, and cytotoxicity. Compared to Cu- and Se-doped nanoparticles, Zn-doped TiO2 nanoparticles displayed the most potent antimicrobial activity with insignificant cytotoxicity and were incorporated into the food packaging materials. The developed nano-reinforced food packaging efficaciously augmented the freshness of plums (Oemleria cerasiformis) for 16 days (42 ± 2 °C). The physicomechanical characterization of the nano-reinforced packaging establishes its utility in food packaging applications. The developed biodegradable packaging undergoes complete decomposition within 12 days of storage in natural soil.

Biopolymer Based Multifunctional Films Loaded with Anthocyanin Rich Floral Extract and ZnO Nano Particles for Smart Packaging and Wound Healing Applications

There are significant societal repercussions from our excessive use of plastic products derived from petroleum. In response to the increasing environmental implications of plastic wastes, biodegradable materials have been proven to be an effective means of mitigating environmental issues. Therefore, protein- and polysaccharide-based polymers have gained widespread attention recently. In our study, for increasing the strength of a biopolymer (Starch), we used ZnO dispersed nanoparticles (NPs), which resulted in the enhancement of other functional properties of the polymer. The synthesized NPs were characterized using SEM, XRD, and Zeta potential values. The preparation techniques are completely green, with no hazardous chemicals employed. The floral extract employed in this study is Torenia fournieri (TFE), which is prepared using a mixture of ethanol and water and possesses diverse bioactive features and pH-sensitive characteristics. The prepared films were characterized using SEM, XRD, FTIR, contact angle and TGA. The incorporation of TFE and ZnO (SEZ) NPs was found to increase the overall nature of the control film. The results obtained from this study confirmed that the developed material is suitable for wound healing and can also be used as a smart packaging material.

Photo-degradable and recyclable starch/Fe3O4/TiO2 nanocomposites: feasibility of an approach to reduce the recycling labor cost in plastic waste management

In this research, a biodegradable starch/Fe₃O₄/TiO₂ bio-nanocomposites (SFT) were produced using different nano Fe₃O₄/TiO₂ (FT) (3, 5, and 10 (wt% dry based)) contents. Mechanical properties, visual properties, moisture-sensitive parameters, magnetic properties, and physical properties of the film specimens were investigated. Photodegradability of film specimens was also evaluated under UV-A irradiation. The FT content increased the hydrophobicity of the film specimens. Tensile strength (TS) of SFT films was increased by increasing FT up to 3%. Elongation at break (EB) and tensile energy to break (TEB) were decreased by adding FT content up to 3% simultaneously. The film specimens' water vapor permeability (WVP) was decreased with increasing FT content. The intrinsic viscosity of SFT was decreased by increasing FT content. It confirms the enhancement of photodegradability of the specimens by increasing FT content. It seems the compatibility of FT with biopolymer has had great effects on these properties. Use of FT-based nanocomposites is an appropriate approach to developing magnetic-recyclable and photodegradable packaging materials.

Comparison of Protein Content, Availability, and Different Properties of Plant Protein Sources with Their Application in Packaging

Plant-based proteins are considered to be one of the most promising biodegradable polymers for green packaging materials. Despite this, the practical application of the proteins in the packaging industry on a large scale has yet to be achieved. In the following review, most of the data about plant protein-based packaging materials are presented in two parts. Firstly, the crude protein content of oilseed cakes and meals, cereals, legumes, vegetable waste, fruit waste, and cover crops are indexed, along with the top global producers. In the second part, we present the different production techniques (casting, extrusion, and molding), as well as compositional parameters for the production of bioplastics from the best protein sources including sesame, mung, lentil, pea, soy, peanut, rapeseed, wheat, corn, amaranth, sunflower, rice, sorghum, and cottonseed. The inclusion of these protein sources in packaging applications is also evaluated based on their various properties such as barrier, thermal, and mechanical properties, solubility, surface hydrophobicity, water uptake capacity, and advantages. Having this information could assist the readers in exercising judgement regarding the right source when approving the applications of these proteins as biodegradable packaging material.

Multilayer photonic films based on interlocked chiral-nematic cellulose nanocrystals in starch/chitosan

In this study, a new approach to employ and control cellulose nanocrystal (CNC) chiral nematic structure as a biodegradable, intelligent material was investigated. Tuned CNC self-assembled films were interlocked between two layers of citric acid, cross-linked starch/chitosan (1:1) films through the solvent casting process. This method increased the mechanical properties of produced films and created a selective reflection band from UV to near-IR depending on the helical pitch of the chiral nematic CNC layer. The features of these intelligent films have potential for different applications, from UV protective packaging to biomedical uses. The water vapor permeability (WVP) of the produced films decreased considerably by adding a CNC layer into the cross-linked starch/chitosan structure. Also, the WVP was different for the different helical pitches of the CNC layer. The starch/chitosan (outer layer) also showed a remarkable antibacterial property against E. coli, P. fluorescens, S. Enteritidis, and S. aureus which could be useful for biomedical applications or antibacterial packaging.

Humidity-Responsive Photonic Films and Coatings Based on Tuned Cellulose Nanocrystals/Glycerol/Polyethylene Glycol

It has been extensively reported that cellulose nanocrystals (CNCs) can represent structural colors due to their unique chiral-nematic self-assembly. However, the application of this remarkable structure does need further investigation. It has been challenging to keep the selective reflection band (SRB) resulting from the CNC structure in the visible spectrum. Herein, composition of CNC colloidal suspensions with polyethylene glycol (PEG) and glycerol (Gly) have been studied to develop humidity-responsive sensors in the form of coatings and films. The fabricated samples were characterized for their mechanical properties, optical properties, water uptake capacity, water contact angle, and surface roughness. Additionally, the chemical structure of the samples was studied with FTIR spectroscopy. The produced humidity indicators on microbial glass slides were maintained and tested in a different relative humidity range from 20% to 98% with a different color response from blue to red, respectively. The color change of the humidity sensors was reversible for several cycles. It should be noted that the color change can be detected easily by the naked eye. The water uptake test showed that pure CNC and CNC/Gly had the lowest (34%) and highest (83%) water absorption levels. The mechanical tests for CNC/PEG composites showed the highest tensile strength (40.22 MPa). Moreover, microstructural characterizations confirmed the CNC pitch formation in all the samples. Addition of the fillers increased the CNC pitch, resulting in a mesoporous film formation. These produced humidity sensors are promising candidates in food and drug packaging due to their biodegradability, biocompatibility, and cost-effectiveness.

Polysaccharide-Based Nanocomposites for Food Packaging Applications

The article presents a review of the literature on the use of polysaccharide bionanocomposites in the context of their potential use as food packaging materials. Composites of this type consist of at least two phases, of which the outer phase is a polysaccharide, and the inner phase (dispersed phase) is an enhancing agent with a particle size of 1-100 nm in at least one dimension. The literature review was carried out using data from the Web of Science database using VosViewer, free software for scientometric analysis. Source analysis concluded that polysaccharides such as chitosan, cellulose, and starch are widely used in food packaging applications, as are reinforcing agents such as silver nanoparticles and cellulose nanostructures (e.g., cellulose nanocrystals and nanocellulose). The addition of reinforcing agents improves the thermal and mechanical stability of the polysaccharide films and nanocomposites. Here we highlighted the nanocomposites containing silver nanoparticles, which exhibited antimicrobial properties. Finally, it can be concluded that polysaccharide-based nanocomposites have sufficient properties to be tested as food packaging materials in a wide spectrum of applications.

Antimicrobial Biodegradable Food Packaging Based on Chitosan and Metal/Metal-Oxide Bio-Nanocomposites: A Review

Finding a practical alternative to decrease the use of conventional polymers in the plastic industry has become an acute concern since industrially-produced plastic waste, mainly conventional food packaging, has become an environmental crisis worldwide. Biodegradable polymers have attracted the attention of researchers as a possible alternative for fossil-based plastics. Chitosan-based packaging materials, in particular, have become a recent focus for the biodegradable food packaging sector due to their biodegradability, non-toxic nature, and antimicrobial properties. Chitosan, obtained from chitin, is the most abundant biopolymer in nature after cellulose. Chitosan is an ideal biomaterial for active packaging as it can be fabricated alone or combined with other polymers as well as metallic antimicrobial particles, either as layers or as coacervates for examination as functional components of active packaging systems. Chitosan-metal/metal oxide bio-nanocomposites have seen growing interest as antimicrobial packaging materials, with several different mechanisms of inhibition speculated to include direct physical interactions or chemical reactions (i.e., the production of reactive oxygen species as well as the increased dissolution of toxic metal cations). The use of chitosan and its metal/metal oxide (i.e., titanium dioxide, zinc oxide, and silver nanoparticles) bio-nanocomposites in packaging applications are the primary focus of discussion in this review.

Digital holographic microscopy for real-time investigation of 3D microstructural dynamics of starch-kefiran-based nanocomposite

Investigating real-time phenomena in bio-polymers has received much attention because of their increasing demands in polymer substitution. The 3D morphometry of polymer surfaces may be very impactful in such studies. Here, digital holographic microscopy (DHM) is applied for quantitative measurement of the rare morphological changes of UV-A and UV-C exposed nanocomposites during their incubation with excess water. By reconstructing the recorded successive digital holograms, the time evolution of the swelled regions of the samples is derived. Our results clearly show that the higher water swelling of UV-A irradiated starch/kefiran/ZnO may be attributed to its higher hydrophilicity.

Two Fascinating Polysaccharides: Chitosan and Starch. Some Prominent Characterizations for Applying as Eco-Friendly Food Packaging and Pollutant Remover in Aqueous Medium. Progress in Recent Years: A Review

The call to use biodegradable, eco-friendly materials is urgent. The use of biopolymers as a replacement for the classic petroleum-based materials is increasing. Chitosan and starch have been widely studied with this purpose: to be part of this replacement. The importance of proper physical characterization of these biopolymers is essential for the intended application. This review focuses on characterizations of chitosan and starch, approximately from 2017 to date, in one of their most-used applications: food packaging for chitosan and as an adsorbent agent of pollutants in aqueous medium for starch.

Antimicrobial activities of chitosan/titanium dioxide composites as a biological nanolayer for food preservation: A review

Packaging is an integral part of food industry that preserves the properties of food during storage. Food spoilage caused by foodborne microorganisms is a public health problem that imposes a significant burden on the healthcare systems. Moreover, packaging based on artificial and chemical materials such as plastic is destructive to the environment. Chitosan can be categorized as an active food packaging material because of its inherent antimicrobial properties and capacity to carry various active components. Combining chitosan and metallic nanoparticles can be used as a practical approach in antimicrobial packaging systems. This strategy has advantages of thermal stability, barrier properties, antioxidant and antimicrobial packaging. Titanium dioxide is one of these nanoparticles that plays a photocatalytic role by releasing reactive oxygen species, thereby leading to the destruction of microorganisms' cell wall and extension of food shelf life. This review elaborates on the antimicrobial applications of chitosan/titanium dioxide nanoparticles films in food packaging systems.

Effect of magnetic field alignment of cellulose nanocrystals in starch nanocomposites: Physicochemical and mechanical properties

The magnetic field (MF) induced alignment of cellulose nanocrystals (CNC) within a starch matrix is investigated and its effect on the physicochemical and mechanical properties of the nanocomposites are discussed in the paper. Two different kinds of CNC i.e. plant-CNC and tunicate-CNC and its hybrid combination are studied to understand the effect of aspect ratio of CNC on the properties of nanocomposite. Nanocomposites with tunicate sourced CNC showed higher tensile strength and modulus, and lower water vapor permeability as compared to plant sourced CNC. These properties are higher for nanocomposites prepared under MF. The modulus of starch nanocomposites increased from 0.26 GPa and 0.32 GPa to 0.38 GPa and 0.44 GPa, respectively for plant-CNC and tunicate-CNC when exposed to MF. The improved orientation and alignment of CNC in presence of MF is further supported by Raman and scanning electron micrographs studies.

Incorporation of quaternary ammonium chitooligosaccharides on ZnO/palygorskite nanocomposites for enhancing antibacterial activities

Quaternary ammonium chitooligosaccharides (QACOS) was incorporated onto the ZnO/palygorskite (ZnO/PAL) nanocomposite by a simple electrostatic self-assembly process to produce a new organic-inorganic nanocomposite (QACOS/ZnO/PAL) with excellent antibacterial activity. After loading QACOS, the Zeta potential of ZnO/PAL was changed from -26.7 to +30.3 mV, which facilitates to improve the targeting behavior of ZnO/PAL towards bacteria and its contact with bacteria, resulting in a significant improvement of antibacterial capability. The MIC values of QACOS/ZnO/PAL for inhibiting bacteria (0.5 mg/mL for E. coli and 1 mg/L for S. aureus) were superior to ZnO/PAL and QACOS, demonstrated an expected synergistic antibacterial effect between QACOS and ZnO/PAL. The improved contact and interface interaction between QACOS/ZnO/PAL and bacteria makes it easier to destroy the structural integrity of bacteria. As a whole, the incorporation of polysaccharide as regulators of surface charge opens up a new way to further enhance the antibacterial activity of inorganic antibacterial materials.

Investigation and preparation of biodegradable starch-based nanofilms for potential use of curcumin and garlic in food packaging applications

In this study, biodegradable starch-based nano films were developed by turmeric extract curcuma longa (CC), octaphenyl-polyhedral oligomeric silsesquioxane (POSS), garlic extract with antibacterial properties (GC) and clay nanoparticles. Ag⁺-Mt-POSS-CC-CS, Mt-CC-CS and Mt-GC-CS nanofilms were synthesized as the final products. The antibacterial and surface-active corn starch-based nanofilms that were synthesized were analyzed by using the methods of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM). After this, the antibacterial resistances of the corn starch nanofilms against the bacteria Salmonella and Staphylococcus aureus (S. aureus) and their surface-active properties against the bacteria S. aureus, E. coli, Listeria monocytogenes and Salmonella were examined. The synthesized nano films were subjected to migration analyses, which are an important criterion for food packaging films, and their results were compared.According to the results of the analysis, while the starch nanofilms containing garlic showed antibacterial resistance against salmonella and S. aureus bacteria, the starch nano films containing curcumin and octaphenyl-POSS did not form an inhibition zone. Comparing surface activity properties, curcumin and octaphenyl-POSS-containing nano films showed surface activity, while the garlic-containing nanofilms did not show surface activity. This result shows that the mechanical properties of nanofilm containing garlic have given stronger results. Migration analysis results show that the synthesized nanofilm has found to suitable for use in the packaging of all food products such as milk products, fatty foods, liquid, acidic and dry foods according to the results of all migration analyses.

Prospects of kefiran as a food-derived biopolymer for agri-food and biomedical applications

There is a huge demand for food-derived polysaccharides in the field of materials research due to the increasing concerns posed by synthetic biopolymers.

Prospect of Polysaccharide-Based Materials as Advanced Food Packaging

The use of polysaccharide-based materials presents an eco-friendly technological solution, by reducing dependence on fossil resources while reducing a product's carbon footprint, when compared to conventional plastic packaging materials. This review discusses the potential of polysaccharides as a raw material to produce multifunctional materials for food packaging applications. The covered areas include the recent innovations and properties of the polysaccharide-based materials. Emphasis is given to hemicelluloses, marine polysaccharides, and bacterial exopolysaccharides and their potential application in the latest trends of food packaging materials, including edible coatings, intelligent films, and thermo-insulated aerogel packaging.