Composite films of sodium alginate and konjac glucomannan incorporated with tea polyphenols for food preservation

Reinforced Nacre-Like MXene/Sodium Alginate Composite Films for Bioinspired Actuators Driven by Moisture and Sunlight

MXene-based soft actuators have attracted increasing attention and shown competitive performance in various intelligent devices such as supercapacitors, bionic robots and artificial muscles. However, the development of robust MXene-based actuators with multi-stimuli responsiveness remains challenging. In this study, a nacre-like structure soft actuator based on MXene and sodium alginate (SA) composite films is prepared using a straightforward solvent casting self-assembly method, which not only enhances the mechanical performance (tensile strength of 72 MPa) but also diversifies the stimuli responsiveness of the material. The composite actuators can be powered by external stimuli from renewable energy sources, from moisture inducing a maximum bending angle of 190 degrees at a relative humidity (RH) of 91%, and sunlight irradiation generating a maximum curvature of 1.45 cm-1 under 100 mW cm-2. The feasibility of practical applications, including moisture-responsive flowers and walkers, sunlight-responsive oscillators, and smart switches, is demonstrated through comprehensive experimental characterization and performance evaluation. The work presented here provides insight into the design of robust actuators via the utilization and conversion of environmentally renewable energy sources.

Seaweed as a Valuable and Sustainable Resource for Food Packaging Materials

Plastic food packaging causes massive pollution in the environment via resource extraction, gas emissions, and the enduring plastic waste accumulation. Hence, it is of crucial importance to discover sustainable alternatives in order to protect ecosystems and conserve precious resources. Recently, seaweed has been emerging as a promising sustainable solution to plastic pollution. Seaweed is a fast-growing marine plant that is abundant in tropical coastlines and requires minimal resources to cultivate. In addition, seaweed is rich in valuable polysaccharides such as alginate, fucoidan, carrageenan, agar, and ulva, which can be extracted and processed into biodegradable films, coatings, and wraps. This ability allows the creation of an alternative to plastic food packages that are completely biodegradable, made from renewable resources, and do not linger in landfills or oceans for centuries. In this context, this review discusses the main classification of seaweed, their production and abundance in the world, and provides a summary of seaweed-based materials developed in the last 2-5 years for potential usage in the food packaging sector.

Fabricating active Egg Albumin/Sodium Alginate/Sodium Lignosulfonate Nanoparticles film with significantly improved multifunctional characteristics for food packing

In food packaging, sodium lignosulfonate nanoparticles (SLS NPs) showed significant antibacterial properties, antioxidant and UV barrier activities. Herein, the SLS NPs were synthesized via a sustainable green method and were added into egg albumin/sodium alginate mixture (EA/SA) to fabricate a safe, edible EA/SA/SNPs food packaging. A composite film EA/SA/SNP was examined microstructurally and physicochemically. The mechanical characteristics, UV protection, water resistance, and the composite film's thermal stability were all enhanced by the inclusion of SLS NPs, and water vapor permeability reduced by 44 %. This composite film exhibited robust antioxidative properties with DPPH and ABTS free radical scavenging rates reaching 76.84 % and 92.56 %, and effective antimicrobial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with antibacterial rates reaching 98.25 % and 97.13 % for the positively charged nanoparticles interacting with the cell membrane. Freshness tests showed that the EA/SA/SNPs packaging film could delay the quality deterioration of fresh tomatoes. This composite film can slow down spoilage bacteria proliferation and prolongs food's preservation period by eight days at ambient temperature.

Antibacterial Activity of Modified Sesbania Gum Composite Film and Its Preservation Effect on Wampee Fruit (Clausena lansium (Lour.) Skeels)

The primary challenges in fruit and vegetable preservation include extending storage duration while preserving sensory quality and nutritional value. In this study, sesbania gum (SG) was oxidized to prepare oxidized sesbania gum (OSG). An OSG/ZnO composite film was subsequently prepared, combining OSG, sodium carboxymethyl cellulose (CMC), and nano-zinc oxide (nano-ZnO). The preparation technology was determined via a response surface optimization experiment. When the addition amount of nano-ZnO exceeded 0.3 mg/mL, the composite films exhibited an antibacterial rate of over 90% against E. coli and S. aureus. For wampee (Clausena lansium (Lour.) Skeels) preservation, a OSG/ZnO-0.3 film was directly applied as a coating. The findings demonstrated favorable results in terms of the rate of rotting, soluble solids, and titrable acidity, effectively prolonging wampee fruit storage. This suggests the potential of an OSG composite film with nano-ZnO as a promising fruit packaging material, thereby expanding the application of SG and wampee fruit preservation.

Functional, Physical, and Volatile Characterization of Chitosan/Starch Food Films Functionalized with Mango Leaf Extract

Active packaging is one of the currently thriving methods to preserve highly perishable foods. Nonetheless, the integration of active substances into the formulation of the packaging may alter their properties-particularly mass transfer properties-and therefore, the active compounds acting. Different formulations of chitosan (CH), starch (ST), and their blends (CH-ST), with the addition of mango leaf extract (MLE) have been polymerized by casting to evaluate their food preservation efficiency. A CH-ST blend with 3% MLE using 7.5 mL of the filmogenic solution proved to be the most effective formulation because of its high bioactivity (ca. 80% and 74% of inhibition growth of S. aureus and E. coli, respectively, and 40% antioxidant capacity). The formulation reduced the water solubility and water vapor permeability while increasing UV protection, properties that provide a better preservation of raspberry fruit after 13 days than the control. Moreover, a novel method of Headspace-Gas Chromatography-Ion Mobility Spectrometry to analyze the volatile profiles of the films is employed, to study the potential modification of the food in contact with the active film. These migrated compounds were shown to be closely related to both the mango extract additions and the film's formulation themselves, showing different fingerprints depending on the film.