Improving the properties of starch-based antimicrobial composite films using ZnO-chitosan nanoparticles

Enhancing post-harvest quality of tomato fruits with chitosan oligosaccharide-zinc oxide nanocomposites: A study on biocompatibility, quality improvement, and carotenoid enhancement

In this study, a new composite with combination of chitosan oligosaccharide (COS) and zinc oxide nanoparticles (ZnO NPs), termed Chitosan Oligosaccharide-Zinc Oxide Nanocomposites (COS-ZnO NC), was designed to enhance the quality of tomato fruits during postharvest storage. SEM analysis showed a uniform distribution of COS-ZnO NC films on tomato surfaces, indicating high biocompatibility, while the FTIR spectrum confirmed the interaction of COS and ZnO NPs via hydrogen bonds. The COS-ZnO NC exerts positive effects on post-harvest quality of tomato fruits, including significantly reduced water loss, fewer skin wrinkles, increased sugar-acid ratio, and enhanced vitamin C and carotenoids accumulation. Furthermore, COS-ZnO NC induces transcription of carotenoid biosynthesis genes and promotes carotenoids storage in the chromoplast. These results suggest that the COS-ZnO NC film can significantly improve the quality traits of tomato fruits, and therefore is potential in post-harvest storage of tomato fruits.

Development of starch-cellulose composite films with antimicrobial potential

This study explored the structure and performance of starch-based antibacterial films reinforced with black tea cellulose nanocrystals (BT-CNCs). The optimal addition amount of BT-CNCs is 5 % (w/w Starch). This nanocrystal-infused film, incorporating chitosan (CS), ε-polylysine (ε-PL), and zinc oxide nanoparticles (ZnONP) as antibacterial agents, exhibited a smooth, continuous surface. The addition of BT-CNCs and antibacterial agents did not change the group characteristic peaks of the film, but changed the crystallinity slightly. The films, namely St, St/CNCs, St/CNCs/CS, and St/CNCs/ε-P, maintained high light transmittance (above 80 %), except for the St/CNCs/ZnONP film, which effectively shielded UV radiation. The combined use of antibacterial agents and BT-CNCs enhanced the water and oxygen barrier properties of the film. Notably, the St/CNCs/CS film exhibited the lowest solubility (17.74 % ± 0.36) and the highest tensile strength (14.23 ± 0.16 MPa). The antibacterial efficacy of the films decreased in the order of St/CNCs/ZnONP, St/CNCs/ε-PL, and St/CNCs/CS, with a more pronounced inhibitory effect on E. coli compared to S. aureus. This study marries natural waste recycling with cutting-edge food packaging technology, setting a new benchmark for the development of sustainable packaging materials.

Nanocomposite Films of Babassu Coconut Mesocarp and Green ZnO Nanoparticles for Application in Antimicrobial Food Packaging

In this work, novel nanocomposite films based on babassu coconut mesocarp and zinc oxide nanoparticles (ZnO NPs), synthesized by a green route, were produced for application as food packaging films. The films were prepared using the casting method containing different contents of ZnO NPs (0 wt%, 0.1 wt%, 0.5 wt%, and 1.0 wt%). The films were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), instrumental color analysis, and optical properties. The water vapor permeability (WVP) and tensile strength of films were also determined. The antimicrobial activity of the films against cooked turkey ham samples contaminated with Staphylococcus aureus was investigated. The results showed that incorporating ZnO NPs into babassu mesocarp matrices influenced the structure of the biopolymer chains and the color of the films. The BM/ZnO-0.5 film (0.5 wt% ZnO NPs) showed better thermal, mechanical, and WVP properties. Furthermore, the synergistic effect of babassu mesocarp and ZnO NPs in the BM/ZnO-0.5 film improved the antimicrobial properties of the material, reducing the microbial count of S. aureus in cooked turkey ham samples stored under refrigeration for 7 days. Thus, the films produced in this study showed promising antimicrobial packaging materials for processed foods.

Starch/chitosan nanoparticles bionanocomposite membranes for methylene blue dye removal

This research aims to develop relatively new membranes from starch biopolymer incorporated with different concentrations (0, 5, 10, 15, 20% w/w of solid starch) of chitosan nanoparticles (CNP) that can be used for water treatment. The membranes were fabricated using the solvent casting method while the CNP was produced using the ionic gelation method. The membranes were characterized in terms of morphology, porosity, water vapor permeability (WVP), and water contact angle. The application of the membranes to treat water was demonstrated on methylene blue solution because methylene blue is a commonly used dye in many industries. It was found that the starch/10% CNP membrane was the optimum membrane for methylene blue dye treatment because the membrane exhibits a smooth surface, high WVP (1.67 × 10-10g Pa-1h-1m-1), high porosity (59.92%), low water contact angle value (44.8°), and resulted in the highest percentage removal of methylene blue (94.0%) after the filtration. After filtration, the starch/10% CNP membrane was still in good condition without breakage. In conclusion, the starch/CNP membranes produced in this study are promising for sustainable and environmentally friendly water treatment, especially for water containing methylene blue dye. This research aligns with current thematic trends in bionanohybrid composite materials utilization, offering innovative solutions for addressing water pollution challenges.

Development and characterization of semi-refined iota carrageenan/fish gelatin-based biocomposite film incorporated with SiO2/ZnO nanoparticles

Food packaging based on natural polymers from polysaccharides and proteins can be an alternative to replace conventional plastics. In the present study, semi-refined iota carrageenan (SRIC) and fish gelatin (FG) were used as polymer matrix film with different concentration ratios (0.5:1.5 %, 1.0:1.0 % and 1.5:0.5 % w/w) and SiO2-ZnO nanoparticles were incorporated as fillers with the same concentration in all formulas (0.5:1.5 % w/w carrageenan-fish gelatin). This study aimed to develop films for food packaging applications with desirable physical, mechanical, optical, chemical, and microbiological properties. The results showed that incorporating SiO2-ZnO nanoparticles significantly (p < 0.05) improved the films' elongation at break, UV-screening properties, and antimicrobial activity. Also, the films' thickness, degradability, and transparency significantly (p < 0.05) increased with the higher concentration of fish gelatin addition in the SRIC matrix polymer. The best formula was obtained on the SRIC-FG film at the ratio of 1.5:0.5 % w/w, which performed excellent antimicrobial activity. Thus, semi-refined iota carrageenan/fish gelatin-based biocomposite film incorporated with SiO2-ZnO nanoparticles can be potentially developed as eco-friendly and intelligent food packaging materials to resolve traditional plastic-related issues and prevent food waste.

Starch-chitosan blends: A comprehensive review on the preparation, physicochemical properties and applications

Starch and chitosan, polysaccharides derived from natural sources, have significant potential across various domains. Starch is extracted from starch-bearing plants, such as potatoes, whereas chitosan is obtained from the exoskeletons of marine animals, fungi and insects. However, the original forms of starch and chitosan have several limitations, such as low solubility and weak mechanical strength. Interestingly, the combined effects of starch and chitosan resulted in the development of starch-chitosan blends with markedly improved functional properties. These blends demonstrated high tensile strength, improved hydrophilicity and increased adsorption capacity. Furthermore, modification of starch-chitosan blends by techniques such as crosslinking and incorporation of other functional materials contributes to diverse characteristics and functionalities. This review addresses a crucial gap in the literature by providing an overview and up-to-date analysis of starch-chitosan blends. The preparation methods and functional properties of these blends in various forms, such as films, beads and hydrogels, have been extensively discussed. Emphasis is placed on the versatile applications of these blends in research, development and industries such as pharmaceuticals, wastewater treatment, agriculture and food technology. This review aims to provide an insightful overview of starch-chitosan blends and stimulate broader interdisciplinary research interests. By providing concluding insights and prospects, this review highlights the potential for further exploration of the impact of starch-chitosan blends on consumers and the environment.

Structure and properties of starch - BaSO4 composite obtained using mechanical activation techniques

The aim of this study is to obtain and characterize starch films structurally modified by in situ precipitation of BaSO4 combined with mechanical activation of casting dispersion in a rotor-stator device. By the rheological method, it was found that the modification causes a decrease in the ability of casting dispersions to structure over time. Composite films with a filler content of 0 %-15 % (w/w) were characterized using optical and SEM microscopy, FT-IR spectroscopy, and tensile and moisture resistance testing data. The maximum increase in strength (by 70 %) and elongation at break (by 870 %) is achieved with a filler content of 5 % and 15 %, respectively. An increase in the filler content to 5 % causes an increase in starch recrystallization rate, but at concentrations above 5 % of BaSO4, it inhibits retrogradation. The films obtained by mechanical activation with optimized parameters were uniformly translucent, had lower water vapor permeability than films made from starch alone, had high flexibility, and did not warp or shrink. The developed high-performance, environmentally friendly method can be recommended for the large-scale production of starch-based composite materials.

Acetylated nanocellulose reinforced hydroxypropyl starch acetate realizing polypropylene replacement for green packaging application

The use of natural starch as a replacement for petroleum-based packaging materials is limited due to its poor processability, weak mechanical properties, and strong moisture sensitivity. To address these limitations, this study adopts molecular design of hydroxypropylation and acetylation to sequentially modify natural starch, and material design of introducing acetylated cellulose nanofibers (ACNF) into the starch matrix to reinforce the material. Hydroxypropylation decreased the interaction force between the starch molecular chains, thereby reducing the glass transition temperature. Subsequent acetylation introduced hydrophobic acetyl groups that disrupted intermolecular hydrogen bonds, enhancing the mobility of the starch molecular chain, and endowed the hydroxypropyl starch acetate (HPSA) with excellent thermoplastic processability (melt index of 7.12 g/10 min) without the need for plasticizers and notable water resistance (water absorption rate of 3.0 %). The introduction of ACNF generated a strong interaction between HPSA chains, promoting the derived ACNF-HPSA to exhibit excellent mechanical strength, such as high impact strength of 2.1 kJ/m2, tensile strength of 22.89 MPa, elasticity modulus of 813.22 MPa, flexural strength of 24.18 MPa and flexural modulus of 1367.88 MPa. Its overall performance even surpassed that of polypropylene (PP) plastic, making it a potential alternative material for PP-based packaging materials.

Enhancing physical characteristics and antibacterial efficacy of chitosan through investigation of microwave-assisted chemically formulated chitosan-coated ZnO and chitosan/ZnO physical composite

This study investigates the creation and analysis of chitosan-zinc oxide (CS-ZnO) nanocomposites, exploring their effectiveness in inhibiting bacteria. Two synthesis approaches, physical and chemical, were utilized. The CS-ZnO nanocomposites demonstrated strong antibacterial properties, especially against Staphylococcus aureus, a Gram-positive bacterium. Chemically synthesized nanocomposites (CZ10 and CZ100) exhibited larger inhibition zones (16.4 mm and 18.7 mm) compared to physically prepared CS-Z5 and CS-Z20 (12.2 mm and 13.8 mm) against Staphylococcus aureus. Moreover, CZ nanocomposites displayed enhanced thermal stability, with decomposition temperatures of 281°C and 290°C, surpassing CS-Z5 and CS-Z20 (260°C and 258°C). The residual mass percentages at 800°C were significantly higher for CZ10 and CZ100 (58% and 61%) than for CS-Z5 and CS-Z20 (36% and 34%). UV-Visible spectroscopy revealed reduced band gaps in the CS-ZnO nanocomposites, indicating improved light absorption. Transmission electron microscopy (TEM) confirmed uniform dispersion of ZnO nanoparticles within the chitosan matrix. In conclusion, this research underscores the impressive antimicrobial potential of CS-ZnO nanocomposites, especially against Gram-positive bacteria, and highlights their enhanced thermal stability. These findings hold promise for diverse applications in industries such as medicine, pharmaceuticals, and materials science, contributing to the development of sustainable materials with robust antimicrobial properties.

Carbon dot/g-C3N4-mediated self-activated antimicrobial nanocomposite films for active packaging applications

A novel carbon dot/g-C3N4 nanocomposite (CCN) exhibiting enhanced photocatalytic activity was developed and used as a photoactive nanofiller to construct corn starch/carboxymethyl cellulose (CS/CMC)-based functional films. The morphologies and structures of the CCN-CS/CMC composite films were investigated with scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The effects of the CCN on the physicochemical properties and antibacterial activities of the films were analyzed. The properties of the films were optimized with the addition of CCN (0.20 mg/mL), and the tensile strength of the film was increased to 11.9 MPa and the water contact angle was increased to 103.39°. The optimal active film showed > 99.9 % antibacterial efficiencies against Escherichia coli and Staphylococcus aureus under visible light and prolonged the shelf lives of bananas for more than four days compared to the 4-day shelf life of the control. This work provides a novel route for developing antimicrobial active packaging.

The influence of the combined impact of shear stress and cavitation on the structure and properties of starch-natural rubber composite

In this article, we examined a high-performance, environmentally friendly method for producing composite films based on starch and natural rubber latex (NR). To increase the compatibility of the components, the casting dispersions were subjected to short-term (10 s) mechanical activation in a rotor-stator device. Using the rotational viscosimetry method, it was found that mechanical activation reduces the structuring degree and the effective viscosity of the casting dispersions. The composite films with the NR content of 0-30 % were characterized using optical and SEM microscopy, X-ray diffraction, tensile, and moisture resistance testing data. When the NR content increases from 0 to 30 %, the elongation at break increased by 570 % and 950 % for films obtained using mechanical activation and without it, respectively. The extremely high increase in film tensile strength (on average by 155 %) and the decrease in the NR extractability with toluene due to the use of mechanical activation indicate the possibility of mechanically induced formation of an in situ copolymer at the starch-NR interface. The developed method can be recommended for large-scale production of composite starch-based materials.

Starch biopolymer films containing chitosan nanoparticles: A review

Starch biopolymer films incorporated with chitosan nanoparticles (CNP) or starch/CNP films are promising alternatives to non-degradable food packaging materials. The films can be utilized for active food packaging applications because CNP exhibits antimicrobial and antioxidant properties, which can improve food shelf-life. Nonetheless, knowledge of the effects of CNP inclusion on the properties of starch films is not fully elucidated. This paper reviews the influences of various concentrations of CNP, sizes of CNP, and other additives on the mechanical, thermal, barrier, antimicrobial, antioxidant, biodegradability, and cytotoxicity properties of starch/CNP films as well as the mechanisms involved in relation to food packaging applications. The usage of starch/CNP films for active food packaging can help to reduce environmental issues and contribute to food safety and security.

Physicochemical and photocatalytic properties of biogenic ZnO and its chitosan nanocomposites for UV-protection and antibacterial activity on coated textiles

The textiles for medical use and the purification of textile factory effluents have become the most crucial part of the human healthcare sector. In this study bioactive compounds produced by four distinct plant extracts were used for the synthesis of zinc oxide nanoparticles. The four different ZnO nanoparticles were comprehensively characterized by different analytical techniques. XRD analysis revealed the crystalline nature and phase purity of the ZnO nanoparticles. FTIR spectra provided information on the function of plant extracts in the stabilization or capping process. The size distribution and morphological diversity of the nanoparticles were further clarified by SEM and TEM images. The photocatalytic degradation activity of the four ZnO nanoparticles on two different dyes showed that ZnO nanoparticles prepared from A. indica were most effective for the degradation of 98 % and 91 % of Rhodamine B and Alizarin red dye respectively. The selected ZnO nanoparticles from A. indica were used to prepare ZnO-chitosan nanocomposites before coating on cotton fabrics. The hydrophobicity, UV protection factor, and antibacterial activity of ZnO-chitosan nanocomposites, when coated on cotton fabrics, were also examined. The overall results demonstrated the ZnO and ZnO-chitosan nanocomposite prepared in the present study as a promising material for environmental remediation application.

Polysaccharide mediated nanodrug delivery: A review

Polysaccharides have drawn a lot of attention due to their potential as carriers for drugs and other bioactive chemicals. In drug delivery systems, natural macromolecules such as polysaccharides are widely utilized as polymers. This utilization extends to various polysaccharides employed in the development of nanoparticles for medicinal administration, with the goal of enhancing therapeutic efficacy while minimizing side effects. This study not only offers an overview of the existing challenges faced by these materials but also provides detailed information on key polysaccharides expertly engineered into nanoparticles. Noteworthy examples include Bael Fruit Gum, Guar Gum, Pectin, Agar, Cellulose, Alginate, Chitin, and Gum Acacia, each selected for their distinctive properties and strategically integrated into nanoparticles. The exploration of these natural macromolecules illuminates their diverse applications and underscores their potential as effective carriers in drug delivery systems. By delving into the unique attributes of each polysaccharide, this review aims to contribute valuable insights to the ongoing advancements in nanomedicine and pharmaceutical technologies. The overarching objective of this review research is to assess the utilization and comprehension of polysaccharides in nanoapplications, further striving to promote their continued integration in contemporary therapeutics and industrial practices.

Starch-based antibacterial food packaging with ZnO nanoparticle

Starch-based biofilms with embedded nanoparticles (NPs) are used to wrap food in biodegradable packaging system that has high antibacterial action against a variety of microorganisms. In this study, ZnO NPs were synthesised using both a green synthesis approach utilising Azadirachta indica (Neem) and a chemical synthesis approach using the sol-gel technique. The structural and morphological properties of all synthesized NPs were characterized through XRD, UV-VIS, UV-DRS, FTIR, and FESEM analysis. Further, these NPs were employed in the development of starch-based biodegradable films. A meticulous comparative analysis was performed to evaluate the functional properties of the nanocomposites, encompassing crucial parameters such as film thickness, moisture content, swelling index, opacity, solubility, water vapor permeability, and tensile strength. In comparison to films embedded with chemically synthesised NPs (F1), nanocomposite with green synthesised NPs (F2) showed 15.27% greater inhibition against Escherichia coli growth and 22.05% stronger inhibition against Staphylococcus aureus bacterial strains. Based on the biodegradability analysis, the nanocomposite film-F2 showed a 53.33% faster degradation rate compared to the film-F1. The developed films were utilized to assess the quality of both wrapped and unwrapped grapes, leading to the generalization of the research for the development of starch-based antibacterial and environmentally friendly food packaging material.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05834-9.

Polysaccharides and proteins based bionanocomposites as smart packaging materials: From fabrication to food packaging applications a review

Food industry is the biggest and rapidly growing industries all over the world. This sector consumes around 40 % of the total plastic produced worldwide as packaging material. The conventional packaging material is mainly petrochemical based. However, these petrochemical based materials impose serious concerns towards environment after its disposal as they are nondegradable. Thus, in search of an appropriate replacement for conventional plastics, biopolymers such as polysaccharides (starch, cellulose, chitosan, natural gums, etc.), proteins (gelatin, collagen, soy protein, etc.), and fatty acids find as an option but again limited by its inherent properties. Attention on the initiatives towards the development of more sustainable, useful, and biodegradable packaging materials, leading the way towards a new and revolutionary green era in the food sector. Eco-friendly packaging materials are now growing dramatically, at a pace of about 10-20 % annually. The recombination of biopolymers and nanomaterials through intercalation composite technology at the nanoscale demonstrated some mesmerizing characteristics pertaining to both biopolymer and nanomaterials such as rigidity, thermal stability, sensing and bioactive property inherent to nanomaterials as well as biopolymers properties such as flexibility, processability and biodegradability. The dramatic increase of scientific research in the last one decade in the area of bionanocomposites in food packaging had reflected its potential as a much-required and important alternative to conventional petroleum-based material. This review presents a comprehensive overview on the importance and recent advances in the field of bionanocomposite and its application in food packaging. Different methods for the fabrication of bionanocomposite are also discussed briefly. Finally, a clear perspective and future prospects of bionanocomposites in food packaging were presented.

Preparation and Application of Active Bionanocomposite Films Based on Sago Starch Reinforced with a Combination of TiO2 Nanoparticles and Penganum harmala Extract for Preserving Chicken Fillets

The aim of this study was to develop sago starch-based bionanocomposite films containing TiO₂ nanoparticles and Penganum harmala extract (PE) to increase the shelf life of chicken fillets. First, sago starch films containing different levels of TiO₂ nanoparticles (1, 3, and 5%) and PE (5, 10, and 15%) were prepared. The barrier properties and antibacterial activity of the films against different bacteria strains were investigated. Then, the produced films were used for the chicken fillets packaging, and the physicochemical and antimicrobial properties of fillets were estimated during 12-day storage at 4 °C. The results showed that the addition of nano TiO₂ and PE in the films increased the antibacterial activity against gram-positive (S. aureus) higher than gram-negative (E. coli) bacteria. The water vapor permeability of the films decreased from 2.9 to 1.26 (×10^-11 g/m·s·Pa) by incorporating both PE and nano TiO₂. Synergistic effects of PE and nano TiO₂ significantly decreased the oxygen permeability of the sago starch films from 8.17 to 4.44 (cc.mil/m²·day). Application results of bionanocomposite films for chicken fillet storage at 4 °C for 12 days demonstrated that the films have great potential to increase the shelf life of fillets. The total volatile basic nitrogen (TVB-N) of chicken fillets increased from 7.34 to 35.28 after 12 days, whereas samples coated with bionanocomposite films increased from 7.34 to 16.4. For other physicochemical and microbiological properties of chicken fillets, similar improvement was observed during cold storage. It means that the bionanocomposite films could successfully improve the shelf life of the chicken fillets by at least eight days compared to the control sample.

Essential characteristics improvement of metallic nanoparticles loaded carbohydrate polymeric films - A review

Petroleum-based films have contributed immensely to various environmental issues. Developing green-based films from carbohydrate polymers is crucial for addressing the harms encountered. However, some limitations exist on their property, processibility, and applicability that prohibit their processing for further developments. This review discusses the potential carbohydrate polymers and their sources, film preparation methods, such as solvent-casting, tape-casting, extrusion, and thermo-mechanical compressions for green-based films using various biological polymers with their merits and demerits. Research outcomes revealed that the essential characteristics improvement achieved by incorporating different metallic nanoparticles has significantly reformed the properties of biofilms, including crystallization, mechanical stability, thermal stability, barrier function, and antimicrobial activity. The property-enhanced bio-based films made with nanoparticles are potentially interested in replacing fossil-based films in various areas, including food-packaging applications. The review paves a new way for the commercial use of numerous carbohydrate polymers to help maintain a sustainable green environment.

Recent advances and future challenges of the starch-based bio-composites for engineering applications

Starch is regarded as one of the most promising sustainable materials due to its abundant yield and excellent biodegradability. From the perspective of practical engineering applications, this paper systematically describes the development of starch-based bio-composites in the past decade. Packaging properties, processing characteristics, and current challenges for the efficient processing of starch-based bio-composites are reviewed in industrial packaging. Green coatings, binders, adsorbents, flocculants, flame retardants, and emulsifiers are used as examples to illustrate the versatility of starch-based bio-composites in chemical agent applications. In addition, the work compares the application of starch-based bio-composites in conventional spinning with emerging spinning technologies and describes the challenges of electrostatic spinning for preparing nanoscale starch-based fibers. In terms of flexible electronics, the starch-based bio-composites are regard as a solid polymer electrolyte and easily modified porous material. Moreover, we describe the applications of the starch-based gels in tissue engineering, controlled drug release, and medical dressings. Finally, the theoretical input and technical guidance in the advanced sustainable engineering application of the starch-based bio-composites are provided in the work.

Green Chitosan‐Flaxseed Gum Film Loaded with ZnO for Packaging Applications

The possibility of manufacturing edible packaging materials with tailored properties and low cost has attracted much interest. This work presents a new material for edible packaging made from flaxseed gum (FSG) and chitosan (Ch) loaded with zinc oxide nanoparticles (ZnO‐NPs). ZnO‐NPs are synthesized in situ during the preparation of the edible film. The Ch/FSG/ZnO‐NPs films are prepared by casting Ch in different ratios of FSG (12.5%, 25%, 37.5%, and 50%). The resulting films are evaluated for their physicochemical, mechanical, and barrier properties to determine their suitability for coating or packaging food or bioproducts. By studying the antimicrobial activities of the ZnO‐NPs loaded films, we can see that ZnO‐NP's concentration highly affects these activities. In addition, the FSG improves mechanical properties. Films developed by incorporating ZnO‐NPs are proposed to be appropriate for low‐moisture food and pharmaceutical products, which can reduce environmental problems associated with synthetic packaging. Consequently, Ch/FSG composite films have the potential to replace conventional packaging.

Antimicrobial Nano-Zinc Oxide Biocomposites for Wound Healing Applications: A Review

Chronic wounds are a major concern for global health, affecting millions of individuals worldwide. As their occurrence is correlated with age and age-related comorbidities, their incidence in the population is set to increase in the forthcoming years. This burden is further worsened by the rise of antimicrobial resistance (AMR), which causes wound infections that are increasingly hard to treat with current antibiotics. Antimicrobial bionanocomposites are an emerging class of materials that combine the biocompatibility and tissue-mimicking properties of biomacromolecules with the antimicrobial activity of metal or metal oxide nanoparticles. Among these nanostructured agents, zinc oxide (ZnO) is one of the most promising for its microbicidal effects and its anti-inflammatory properties, and as a source of essential zinc ions. This review analyses the most recent developments in the field of nano-ZnO–bionanocomposite (nZnO-BNC) materials—mainly in the form of films, but also hydrogel or electrospun bandages—from the different preparation techniques to their properties and antibacterial and wound-healing performances. The effect of nanostructured ZnO on the mechanical, water and gas barrier, swelling, optical, thermal, water affinity, and drug-release properties are examined and linked to the preparation methods. Antimicrobial assays over a wide range of bacterial strains are extensively surveyed, and wound-healing studies are finally considered to provide a comprehensive assessment framework. While early results are promising, a systematic and standardised testing procedure for the comparison of antibacterial properties is still lacking, partly because of a not-yet fully understood antimicrobial mechanism. This work, therefore, allowed, on one hand, the determination of the best strategies for the design, engineering, and application of n-ZnO-BNC, and, on the other hand, the identification of the current challenges and opportunities for future research.

Construction and application of nano ZnO/eugenol@yam starch/microcrystalline cellulose active antibacterial film

The goal of this study was to develop new biocomposite films that can better protect and prolong the shelf life of food. Here, a ZnO: eugenol@yam starch/microcrystalline cellulose (ZnO:Eu@SC) antibacterial active film was constructed. Because of the advantages of metal oxides and plant essential oils, codoping with these can effectively improve the physicochemical and functional properties of composite films. The addition of an appropriate amount of nano-ZnO improved the compactness and thermostability, reduced the moisture sensitivity, and enhanced the mechanical and barrier properties of the film. ZnO:Eu@SC exhibited good controlled release of nano-ZnO and Eu in food simulants. Nano-ZnO and Eu release was controlled by two mechanisms: diffusion (primary) and swelling (secondary). After loading Eu, the antimicrobial activity of ZnO:Eu@SC was significantly enhanced, resulting in a synergistic antibacterial effect. Z₄:Eu@SC film extended the pork shelf life by 100 % (25 °C). In humus, the ZnO:Eu@SC film was effectively degraded into fragments. Therefore, the ZnO:Eu@SC film has excellent potential in food active packaging.

Preparation, characterization, and antibacterial effect of bio-based modified starch films

There are several problems with common starch films, including strong water absorption and poor mechanical properties. To create a better starch film, octenyl succinate cassava starch ester (OSCS) was first blended with chitosan and nano ZnO to prepare an OSCS/CS/ZnO film. Then, the film was supplemented with different concentrations of ε-PL as a bacteriostatic agent to prepare a film that would resist bacterial invasion. The mechanical properties, barrier properties, optical properties, and color of the modified starch antibacterial films were investigated, and finally the antibacterial properties and cytotoxicity were tested. The results demonstrated that the modified starch antibacterial film had good mechanical properties, improved surface hydrophobicity, and had a UV-blocking effect. The modified starch antibacterial film with ε-PL of 8% had stable and long-lasting antibacterial properties, stable release, and good cytocompatibility. An active packaging material was successfully prepared using ε-PL and had a strong preservative effect on food.

Optimization and characterization of biodegradable film based on glutinous flour/glycerol/chitosan/ZnO using Response Surface Methodology (RSM) - Central Composite Design (CCD)

Starch-based films are considered more competitive than petroleum because they are renewable, environmentally friendly, and easily degraded. The film in this study was fabricated from white glutinous flour, glycerol, chitosan, and ZnO through a starch gelatinization process. Chitosan content ranges from 2-4% (w/v), ZnO 4-8% of the dry weight of solid, and glycerol 15-45% of the dry weight of solids with a mass of white glutinous flour as much as 3 g was determined. Optimization and determination of running variables based on Central Composite Design. Response variables such as tensile strength, elongation, and water absorption were observed as important parameters in applying film as packaging materials. The Design Expert program recommended 2 g of chitosan: 8 % ZnO: 36.02% glycerol as the best composition in film fabrication, which aims to obtain maximum tensile strength and elongation, as well as minimum water absorption with the maximum desirability value (0.660). The predicted response values under optimal conditions by RSM were 3.68 MPa for tensile strength, 86.79% for elongation, and 268.09% for water absorption. The actual response has a tensile strength of 3.31 MPa, elongation of 83.5%, and water absorption of 320%. On average, a white glutinous flour/glycerol/chitosan/ZnO-based film required ± 45 days to degrade in the soil completely.

Recent Advances and Applications in Starch for Intelligent Active Food Packaging: A Review

At present, the research and innovation of packaging materials are in a period of rapid development. Starch, a sustainable, low-cost, and abundant polymer, can develop environmentally friendly packaging alternatives, and it possesses outstanding degradability and reproducibility in terms of improving environmental issues and reducing oil resources. However, performance limitations, such as less mechanical strength and lower barrier properties, limit the application of starch in the packaging industry. The properties of starch-based films can be improved by modifying starch, adding reinforcing groups, or blending with other polymers. It is of significance to study starch as an active and intelligent packaging option for prolonging shelf life and monitoring the extent of food deterioration. This paper reviews the development of starch-based films, the current methods to enhance the mechanical and barrier properties of starch-based films, and the latest progress in starch-based activity, intelligent packaging, and food applications. The potential challenges and future development directions of starch-based films in the food industry are also discussed.

Composite cassava starch/chitosan/Pineapple Leaf Fiber (PALF)/Zinc Oxide (ZnO): Bioplastics with high mechanical properties and faster degradation in soil and seawater

Biopolymers based on starch, cellulose and proteins extracted directly from biomass with or without modification have been widely used as the natural resources to produce biodegradable plastic. Starch has several disadvantages: strong hydrophilic behavior and inferior mechanical properties when compared with synthetic polymers. Starch is also mostly soluble in water and will be decomposed before undergoing the gelatinization process. To provide resistance and mechanical strength of starch, several fillers (reinforcement) in the form of metal and natural materials are usually added to the polymer matrix. Zinc oxide (ZnO) nanoparticle and natural fiber as a lightweight material that is biocompatible, nontoxic, cost-effective and exhibit strong antibacterial activity can be considered as a reinforcement of starch-based bioplastic. The present study, the reinforcing effect of ZnO on the mechanical, antibacterial, and physical properties of bioplastic films in the form of cassava starch/chitosan/pineapple leaf fiber (PALF)/ZnO. The highest value of elongation at break is for 16 % ZnO-bioplastics which could be completely decomposed only 21 days in ordinary soil and only 18 days in seawater. The packaging tests using slice bread showed antimicrobial properties with no fungal growth for 30 days of bioplastic coatings with 10, 13, and 16 % ZnO NPs. The results in this study indicated that, the ZnO and PALF plays an important role in reinforcing the physical, mechanical, and antibacterial properties of starch/chitosan/PALF-based bioplastic.

Corn Starch-Based Bionanocomposite Film Reinforced With ZnO Nanoparticles and Different Types of Plasticizers

Corn starch var. Paragon from Indonesia and carboxymethyl cellulose (CMC) were used to develop bionanocomposite film containing different types of plasticizers [glycerol (G) or sorbitol (S)] incorporated with zinc oxide (ZnO) nanoparticles (NPs) (0, 3, 5 wt.%) via casting method. The main objective of this study was to improve the properties of the bionanocomposite film with incorporated different types of plasticizers and ZnO NPs. The physicochemical properties of the film were systematically characterized. The results showed that the incorporation of sorbitol could significantly enhance the value of tensile strength, elongation, and Young's modulus than glycerol. In general, a higher concentration of ZnO NPs in the film could increase the tensile strength, reduce the water vapor permeability, decrease the water solubility, and influence the morphology, crystallinity, functional groups, and thermal stability of the films. The data showed that corn starch bionanocomposite film containing sorbitol with 5 wt% ZnO NPs was the most optimal film as compared to other formulations as the solubility and water vapor transmission rate (WVTR) value significantly reduced, and also it increased the value of tensile strength, elongation, and Young's modulus. It can be concluded that the incorporation of glycerol or sorbitol plasticizers reinforced by ZnO NPs plays an important role in improving the properties of bionanocomposite film, hence the film has the potency to be used as sustainable and environmental friendly packaging.

Preparation and application of silver/chitosan-sepiolite materials with antimicrobial activities and low cytotoxicity

Antimicrobial materials can prevent microbial infection and affect the beauty and structure of interior walls. Herein, a hybrid material silver/chitosan-sepiolite (Ag/5CTs-Sep) with antimicrobial activities was prepared via impregnation. Its antimicrobial properties were investigated via the disk diffusion method. Results showed that the width of inhibition zone of Ag/5CTs-Sep against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Aspergillus niger reached 58.15, 32.95 and 35.18 mm, respectively. The Sep was a suitable carrier for increasing thermal stability and antimicrobial durability, and chitosan improved the dispersion of silver to enhance antimicrobial activities. In addition, characterization indicated that the modification of Sep by CTs can promote the formation of lattice oxygen in Ag/5CTs-Sep, which can induce a high reactive oxygen species (ROS) content, causing the death of microbials. The antifungal mechanism revealed that the death of Aspergillus niger was due to Ag/5CTs-Sep that induced the production of high ROS level and damaged cell membrane. Moreover, Ag/5CTs-Sep possessed low cytotoxicity, and an applied test of the water-based coatings showed that the addition of Ag/5CTs-Sep could both effectively inhibit microorganisms and meet the performance standards for water-based coatings. This work may provide new guidance for the design and application of antibacterial materials.

Tunable mechanical behavior of collagen-based films: A comparison of celluloses in different geometries

Collagen (Col) films were reinforced by celluloses in different geometries: microcrystalline cellulose (MCC), cellulosic fines (CF), cellulose nanofiber (CNF) and cellulose nanocrystals (CNC). The reinforcement mechanisms were investigated by the elastoplasticity and fracture appearance. Compared with the fracture stress of collagen film (67.5 MPa), the Col-CNF films effectively borne the stress (95.8 MPa) by intercrystalline fracture, ascribing the abundant hydrogen bonding and mechanical locking between cellulose and collagen. The toughness of Col-CF films was increased by the interfibrillar slippage of CF and pull-off of CF within the matrix, improving the strain-to-break from 8.37% to 12.13%. The films added with MCC and CNC weaken the mechanical behavior, due to the defects and lack of mechanical locking. Besides, the effects of celluloses' geometries on the thickness, density, water-tightness, thermal stability, crystallinity and FTIR of films were also investigated. These provide the evidence that the geometries of fillers diversely improve the behaviors of collagen film offering strategies for the film with adjustable mechanical properties.

Antimicrobial Nanomaterials for Food Packaging

Food packaging plays a key role in offering safe and quality food products to consumers by providing protection and extending shelf life. Food packaging is a multifaceted field based on food science and engineering, microbiology, and chemistry, all of which have contributed significantly to maintaining physicochemical attributes such as color, flavor, moisture content, and texture of foods and their raw materials, in addition to ensuring freedom from oxidation and microbial deterioration. Antimicrobial food packaging systems, in addition to their function as conventional food packaging, are designed to arrest microbial growth on food surfaces, thereby enhancing food stability and quality. Nanomaterials with unique physiochemical and antibacterial properties are widely explored in food packaging as preservatives and antimicrobials, to extend the shelf life of packed food products. Various nanomaterials that are used in food packaging include nanocomposites composing nanoparticles such as silver, copper, gold, titanium dioxide, magnesium oxide, zinc oxide, mesoporous silica and graphene-based inorganic nanoparticles; gelatin; alginate; cellulose; chitosan-based polymeric nanoparticles; lipid nanoparticles; nanoemulsion; nanoliposomes; nanosponges; and nanofibers. Antimicrobial nanomaterial-based packaging systems are fabricated to exhibit greater efficiency against microbial contaminants. Recently, smart food packaging systems indicating the presence of spoilage and pathogenic microorganisms have been investigated by various research groups. The present review summarizes recent updates on various nanomaterials used in the field of food packaging technology, with potential applications as antimicrobial, antioxidant equipped with technology conferring smart functions and mechanisms in food packaging.

Thermoplastic starch nanocomposites: sources, production and applications - a review

The development of materials based on thermoplastic starch (TPS) is an excellent alternative to replace or reduce the use of petroleum-derived polymers. The abundance, renewable origin, biodegradability, biocompatibility, and low cost of starch are among the advantages related to the application of TPS compared to other thermoplastic biopolymers. However, through the literature review, it was possible to observe the need to improve some properties, to allow TPS to replace commonly used polyolefins. The studies reviewed achieved these modifications were achieved by using plasticizers, adjusting processing conditions, and incorporating fillers. In this sense, the addition of nanofillers proved to be the main modification strategy due to the large number of available nanofillers and the low charge concentration required for such improvement. The improvement can be seen in thermal, mechanical, electrical, optical, magnetic, antimicrobial, barrier, biocompatibility, cytotoxicity, solubility, and swelling properties. These modification strategies, the reviewed studies described the development of a wide range of materials. These are products with great potential for targeting different applications. Thus, this review addresses a wide range of essential aspects in developing of this type of nanocomposite. Covering from starch sources, processing routes, characterization methods, the properties of the obtained nanocomposites, to the various applications. Therefore, this review will provide an overview for everyone interested in working with TPS nanocomposites. Through a comprehensive review of the subject, which in most studies is done in a way directed to a specific area of study.

The relationship between linear chain length distributions of amylopectin and the functional properties of the debranched starch-based films

The relationship between linear chain length distributions and the functional properties of the starch-based films after pullulanase debranching treatment of corn (CS), rice (RS) and wheat (WS) were investigated. The results indicated that the film thickness was negatively correlated with A chains content (r = -0.939) and apparent amylose content (r = -0.926), and was positively correlated with B3 chains content (r = 0.847). The tensile strength of the debranched starch-based films were positively correlated with apparent amylose content (r = 0.813), and the elongation at break were inversely proportional to B3 chains content (r = -0.817). The hydrophobicity of the starch-based films was positively and negatively correlated with the proportions of linear chains with DP 6-12 (r = 0.892) and DP 25-36 (r = -0.863), respectively. On the contrary, no significant correlation was noticed between chain length distribution of amylopectin and transparency and thermal stability.

Fabrication of highly transparent and multifunctional polyvinyl alcohol/starch based nanocomposite films using zinc oxide nanoparticles as compatibilizers

This work explored biodegradable polyvinyl alcohol/starch (PVA/ST) film compatibilized by rod-like ZnO nanofillers as multifunctional food packaging materials. The influence of rod-like ZnO nanofillers on the microstructural, UV-shielding, antibacterial, mechanical, thermal, together with water barrier performances of PVA/ST composite films was fully studied. Results revealed that rod-like ZnO nanofillers could be uniformly distributed into the PVA/ST matrix, playing the role of compatibilizers to provide compact and dense nanocomposite films. The resulting nanocomposite films presented greatly improved mechanical and water vapor barrier properties as compared to virgin PVA/ST film. Moreover, the well distributed ZnO endowed PVA/ST film with excellent antimicrobial activity against both E. coli and S. aureus, together with outstanding UV-shielding capability meanwhile retaining highly optical transparency (approximately 90%). The developed PVA/ST/ZnO films were tested for packaging fresh-cut carrot slices to prevent microbial infection and prolong their shelf life. These results indicated that the developed highly transparent and multifunctional PVA/ST/ZnO nanocomposite films possess broad application prospects in active food packaging field.

Deciphering molecular interaction and digestibility in retrogradation of amylopectin gel networks

The impact of the internal part of aewx amylopectin on the gel network and digestibility during retrogradation was investigated using wx amylopectin as a reference. After β-amylolysis for 60 min (aewx-60), greater shifts in both λ_max value and absorbance of iodine binding profiles were observed, accompanied by an increment of short chains (DP 3-5) with reducing the external long chains (DP 17.2). For the amylopectin gels aged 7 days at 4 °C, aewx had greater intermolecular aggregation of double helices to form junction zones, resulting in remarkably higher G', which was significantly greater than that of wx amylopectin or aewx-60. Moreover, aewx amylopectin had a greater RS accompanied by a reduction in RDS after retrogradation. The gel network models of retrograded amylopectins were built to interpret more molecular interactions for aewx than those of wx. The results revealed that aewx amylopectin with a higher proportion of longer external chains prompted the flexibility to align and interact for the formation of double helices and enzyme-resistant structures.

Novel Bio-Based Materials and Applications in Antimicrobial Food Packaging: Recent Advances and Future Trends

Food microbial contamination not only poses the problems of food insecurity and economic loss, but also contributes to food waste, which is another global environmental problem. Therefore, effective packaging is a compelling obstacle for shielding food items from outside contaminants and maintaining its quality. Traditionally, food is packaged with plastic that is rarely recyclable, negatively impacting the environment. Bio-based materials have attracted widespread attention for food packaging applications since they are biodegradable, renewable, and have a low carbon footprint. They provide a great opportunity to reduce the extensive use of fossil fuels and develop food packaging materials with good properties, addressing environmental problems and contributing significantly to sustainable development. Presently, the developments in food chemistry, technology, and biotechnology have allowed us to fine-tune new methodologies useful for addressing major safety and environmental concerns regarding packaging materials. This review presents a comprehensive overview of the development and potential for application of new bio-based materials from different sources in antimicrobial food packaging, including carbohydrate (polysaccharide)-based materials, protein-based materials, lipid-based materials, antibacterial agents, and bio-based composites, which can solve the issues of both environmental impact and prevent foodborne pathogens and spoilage microorganisms. In addition, future trends are discussed, as well as the antimicrobial compounds incorporated in packaging materials such as nanoparticles (NPs), nanofillers (NFs), and bio-nanocomposites.

Development of a novel starch-based dietary fiber using glucanotransferase

In this study, a glucanotransferase from prokaryotic Azotobacter chroococcum NCIMB 8003 was recombinantly expressed and its biochemical characteristics and bioconversion ability for starch were investigated. The purified enzyme has the optimum activity at 55 °C and pH 6.5-7.0, as well as a melting temperature of 62 °C. The double-charged ion Ca2+ stimulated the activity of the enzyme by approximately 2.4 times. The kinetic parameters and specificity analysis revealed that this glucanotransferase had a higher affinity for high-amylose starch. During the transglycosylation reaction, the starch molecule was converted into a relatively small polymer with a narrow size distribution. For the enzyme modification of high-amylose starch for 72 h, the amount of α-1,6 linkages increased from 1.9% to 22.7% and the content of resistant starch (RS) increased from 3.18% to 17.83%. In addition, the fine structure displayed the reuteran-like highly branched glucan linked by single linear α-1,6 linkages and α-1,4/6 branching points. These results revealed that a promising prebiotic dietary fiber was synthesized from starch with glucanotransferase modification.