Physicochemical impact of cellulose nanocrystal on oxidation of starch and starch based composite films

Sustainable microcrystalline cellulose extracted from biowaste Albezia lebeck L. leaves: Biomass exfoliation and physicochemical characterization

There is a focus on sustainability when manufacturing materials. Utilizing biobased materials and replacing fossil-based products is the main research focus. Bio-composite materials are applied to packaging, filler coatings, and pharmaceuticals. Here, we used the leaves of the agro-waste plant Albizia lebeck L. to extract cellulose. Chemical treatment causing strong acid hydrolysis successfully extracted the cellulose content from the leaves. The cellulose obtained was then strengthened with polylactic acid to make a biobased film for future applications. Fourier transform spectroscopy, scanning electron microscopy, thermal analysis, particle size analysis, visible UV and elemental analysis were all used to characterize the extracted cellulose. SEM and mechanical property analysis were used to check and describe the quality of the reinforced biofilm. The greatest cellulose yield from this raw material was 50.2%. The crystallinity index and crystallite size (CI 70.3% and CS 11.29 nm) were high in the extracted cellulose. The TG (DTG) curve analysis derivative revealed cellulose particle breakdown was initiated around 305.2°C and can endure temperatures up to 600°C. Biofilms reinforced with polylactic acid cellulose (1, 2, 3, and 5% by weight %) exhibited a smooth and parallel surface. As the filler concentration increased, minor agglomeration occurred. The tensile strength of pure polylactic acid (PLA) (34.72 MPa) was extended up to 38.91 MPa for 5% filler. Similarly, Young's modulus also increased to 5.24 MPa. However, the elongation break decreases with the increase of filler content, and the least value of decrease is 7.5 MPa. Concerning prospective implementations, it is expected that the biobased film and cellulose particles will prove to be more functional.

Comprehensive Evaluation of the Physicochemical Attributes, Antioxidant Capacity, and pH-Responsive Behavior of Starch Films Enhanced by Laver Incorporation

Herein, a new starch film incorporating laver was developed to address issues related to inadequate water resistance and suboptimal preservation quality in food packaging. The integration of laver into starch film formulations offers a compelling avenue for creating biodegradable, active, and smart food packaging. Scanning electron microscope (SEM) analysis revealed that the starch film with a laver concentration of 70% exhibited a uniformly flat microstructure, as expected. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of intermolecular interactions and hydrogen bonding between the starch and laver. Viscoelastic tests demonstrated the superior film-forming performance of the starch/laver composite films. Moreover, it was found that the most favorable concentration of incorporated laver was 10%. Specifically, the S7-3 film emerged as a promising candidate for food packaging applications, boasting the highest contact angle (CA) value of 114.98 ± 1.28°, the lowest water solubility (WS) value of 15.38%, and a reduced water vapor transmission rate (WVTR) value of 2.52 g/m2 × h. Additionally, the S3-7 film displayed an extraordinary tensile strength of 32.47 MPa, an elongation at break of 19.04%, and a Young's modulus of 606.83 MPa. Furthermore, the starch/laver composite films exhibited outstanding UV-blocking capabilities, exceptional pH-responsive behavior, and significant antioxidant activity, underscoring their potential for packaging applications with laver integration.

A review of starch-based biocomposites reinforced with plant fibers

Renewable and biodegradable resources have gained increasing attention as promising alternatives to synthetic plastics. Among the diverse raw materials employed in bioplastics production, starch emerges as an attractive, low-cost, and largely available source. However, the inherent properties of starch-based materials often limit their utility across various applications, necessitating strategic modifications to enhance their performance. A common approach to boost these materials involves incorporating natural fillers into biopolymer matrices. Incorporating natural fibers within starch matrices enables the development of biocomposites with improved properties while retaining their renewable and biodegradable characteristics. This review briefly addresses fundamental aspects of starch structure, obtention, and processing, as well as the main pre-treatments of natural fibers and processing methods currently applied to produce starch-based composites. It also highlights the most recent advances in this field, elucidates the effect of the incorporation of fibers on the biocomposite properties, and discusses the critical parameters affecting the synergic combination between starch and fibers.

Functionalization Methods of Starch and Its Derivatives: From Old Limitations to New Possibilities

It has long been known that starch as a raw material is of strategic importance for meeting primarily the nutritional needs of people around the world. Year by year, the demand not only for traditional but also for functional food based on starch and its derivatives is growing. Problems with the availability of petrochemical raw materials, as well as environmental problems with the recycling of post-production waste, make non-food industries also increasingly interested in this biopolymer. Its supporters will point out countless advantages such as wide availability, renewability, and biodegradability. Opponents, in turn, will argue that they will not balance the problems with its processing and storage and poor functional properties. Hence, the race to find new methods to improve starch properties towards multifunctionality is still ongoing. For these reasons, in the presented review, referring to the structure and physicochemical properties of starch, attempts were made to highlight not only the current limitations in its processing but also new possibilities. Attention was paid to progress in the non-selective and selective functionalization of starch to obtain materials with the greatest application potential in the food (resistant starch, dextrins, and maltodextrins) and/or in the non-food industries (hydrophobic and oxidized starch).

Effect of rosin based quaternary ammonium salt on mechanical, hydrophily, antibacterial of cornstarch/polydopamine film for food packaging

Food packaging made of biobased materials is environmentally friendly, among which starch film is a type of biobased packaging with great development value. Some existing studies have attempted to add polydopamine (PDA) to enhance cross-linking, but there are still problems such as weakness and hydrophilicity, which greatly limit its application. Therefore, this study synthesized rosin based quaternary ammonium salt-modified cornstarch (ST-B), which was used to replace part of unmodified cornstarch (ST). In the prepared ST/PDA0.5/ST-B5 film, the introduction of a rigid rosin structure increased the stress and water contact angle of the ST/PDA0.5 film by 62 % and 26 %, respectively, while reducing its wettability and WVP; thus, further enhancing its antioxidant activity. Due to the antibacterial ability of rosin quaternary ammonium cations, the packaging film containing 7 wt% ST-B can kill >94.6 % of S. aureus and 99.9 % of E. coli, and can also extend the shelf life of strawberries. In addition, it is proven that the packaging film has good biocompatibility and high safety within cytotoxicity tests and 30-day gavage tests in mice. Therefore, the prepared ST/PDA/ST-B film has more potential for application in food preservation.

Plant-based Biomass/Polyvinyl Alcohol Gels for Flexible Sensors

Flexible sensors show great application potential in wearable electronics, human-computer interaction, medical health, bionic electronic skin and other fields. Compared with rigid sensors, hydrogel-based devices are more flexible and biocompatible and can easily fit the skin or be implanted into the body, making them more advantageous in the field of flexible electronics. In all designs, polyvinyl alcohol (PVA) series hydrogels exhibit high mechanical strength, excellent sensitivity and fatigue resistance, which make them promising candidates for flexible electronic sensing devices. This paper has reviewed the latest progress of PVA/plant-based biomass hydrogels in the construction of flexible sensor applications. We first briefly introduced representative plant biomass materials, including sodium alginate, phytic acid, starch, cellulose and lignin, and summarized their unique physical and chemical properties. After that, the design principles and performance indicators of hydrogel sensors are highlighted, and representative examples of PVA/plant-based biomass hydrogel applications in wearable electronics are illustrated. Finally, the future research is briefly prospected. We hope it can promote the research of novel green flexible sensors based on PVA/biomass hydrogel.

Development of chitosan/rice protein hydrolysates/ZnO nanoparticles films reinforced with cellulose nanocrystals

In the present work, the composite films were obtained by the solution casting method from chitosan and rice protein hydrolysates, reinforced with cellulose nanocrystals (CNC) of different contents (0 %, 3 %, 6 % and 9 %). The influence of different CNC loadings on the mechanical, barrier and thermal properties was discussed. SEM showed the formation of intramolecular interactions between the CNC and film matrices, leading to more compact and homogeneous films. These interactions had a positive influence on the mechanical strength properties, which was reflected in higher breaking force of 4.27 MPa. The elongation dwindled from 132.42 % to 79.37 % with increasing CNC levels. The linkages formed between the CNC and film matrices reduced the water affinity, leading to a reduction in their moisture content, water solubility and water vapor transmission. Thermal stability of the composite films was also improved in the presence of CNC, by increasing maximum degradation temperature from 311.21 to 325.67 °C with increasing CNC contents. The strongest DPPH inhibition of the film was 45.42 %. The composite films exhibited the highest inhibition zone diameter against E. coli (12.05 mm) and S. aureus (12.48 mm), and the hybrid of CNC and ZnO nanoparticles exhibited stronger antibacterial activity than their single existent forms. The present work shows the possibility of obtaining CNC-reinforced films with improved mechanical, thermal and barrier properties.

Reduced graphene oxide/cellulose nanocrystal composite films with high specific capacitance and tensile strength

Due to the environmental degradation and energy depletion, the strategy for fabricating high-performance supercapacitor electrode materials based on graphene and nanocellulose has received great attention. Herein, an environmentally friendly reduced graphene oxide (RGO)/cellulose nanocrystal (CNC) composite conductive film was prepared using L-ascorbic acid (L-AA) as the reductant of graphene oxide (GO). Based on chemical structure analysis, L-AA was proved to be an effective reductant to remove oxygen containing groups of GO. Through microstructure observation, a unique stacking structure of CNC and RGO was observed, which could be largely attributed to the hydrogen bond interaction. Furthermore, the effect of CNC amount on the performance of RGO/CNC composite films was also systematically investigated. Particularly, the addition of CNC was found to exert a positive effect on the tensile strength, which might be mainly due to a mass of hydrogen bonds between the CNCs. Meanwhile, the RGO/CNC composite conductive film featured ideal electrical double-layer capacitive (EDLC) behavior, exhibiting a gravity specific capacitance of 222.5 F/g and tensile strength of 32.17 MPa at 20 wt% CNC content. Therefore, the RGO/CNC composite conductive films may hold great promise for environmentally friendly electrode materials of supercapacitors and flexible electrical devices.