This study focuses on the development of polyvinyl alcohol-chitosan-tragacanth gum composite films enriched with rosehip extract and seed oil for the packaging of active foods. The films were tested for their antioxidant activity, transparency, biodegradability, water vapor permeability and effectiveness in preserving sweet cherries under seasonal high temperature conditions. The addition of tragacanth, rosehip extract and rosehip seed oil significantly influenced the mechanical properties by increasing elongation at break and tensile strength. Films enriched with rosehip seed oil effectively reduced weight loss and preserved the sensory properties of the cherries, while films based on rosehip extract exhibited superior antioxidant properties with increased free radical scavenging activity. Biodegradability tests showed that all films degraded under soil conditions, with the rate of degradation depending on the concentration of tragacanth gum. The water vapor permeability results showed that the addition of rosehip extract and seed oil significantly reduced the water vapor permeability and improved the barrier properties of the films. Preservation tests showed that these films minimized titratable acidity, oxidative stress and moisture loss, effectively extending the shelf life of sweet cherries under highly stressful conditions. These results highlight the potential of rosehip-enriched biopolymer films as a sustainable and environmentally friendly packaging alternative to extend the shelf life of perishable fruits.

The objective of the current study was to evaluate the feasibility of Aloe vera gel as a plasticizer and crosslinker in improving the properties of starch-polyvinyl alcohol blends that could find applications in packaging. The concentration of Aloe vera gel was varied (1%, 3%, 5% and 7% wt/wt) to produce SPA-1, SPA-3, SPA-5 and SPA-7 films, respectively. The plasticizing and crosslinking characteristics associated with Aloe vera gel had a positive influence on the mechanical properties of the films. Addition of Aloe vera gel increased the tensile strength of films from 27.45 MPa (control) to 32.98, 32.53 and 32.32, for SPA-1, SPA-3 and SPA-5 films, respectively. Among all the films, highest elongation at break (20.62%) was observed for SPA-3 films. Due to crosslinking, degree of swelling, water solubility and water vapour permeability for SPA-3 films decreased by 5.58%, 38.29% and 21.44%, respectively, compared to control films. The contact angle of the SPA-3 film significantly increased by 49.25% when compared to control samples. Scanning electron microscope images revealed compact and smooth surface microstructure of control films, and crosslinking was evident in presence of Aloe vera gel. The rate of degradation for SPA-3 films in soil after 40 days was enhanced by 32.25% compared to control films. SPA-1 and SPA-3 films were tested for use as packaging material for storage of green chillies. Chillies under unpacked conditions, in control and SPA-1 films, turned red in 3 days. Those stored in films with 3% Aloe vera gel began to change colour later (after 5 days) with no visual evidence of microbial or fungal growth. In summary, starch-polyvinyl alcohol matrix films with 3% Aloe vera gel (SPA-3) were effective as a sustainable alternative in increasing shelf life of foodstuff.

Oxalate esters and isosorbide serve as intriguing polymer building blocks, as they can be sourced from renewable resources, such as CO2 and glucose, and the resulting polyesters offer outstanding material properties. However, the low reactivity of the secondary hydroxyl groups makes it difficult to generate high-molecular-weight polymers from isosorbide. Combining diaryl oxalates with isosorbide appears to be a promising approach to produce high-molecular-weight isosorbide-based polyoxalates (PISOX). This strategy seems to be scalable, has a short polymerization time (<5 h), and uniquely, there is no need for a catalyst. PISOX demonstrates outstanding thermal, mechanical, and barrier properties; its barrier to oxygen is 35 times better than PLA, it possesses mechanical properties comparable to high-performance thermoplastics, and the glass transition temperature of 167 degrees C can be modified by comonomer incorporation. What makes this high-performance material truly exceptional is that it decomposes into CO2 and biomass in just a few months in soil under home-composting conditions and it hydrolyzes without enzymes present in less than a year in 20 degrees C water. This unique combination of properties has the potential to be utilized in a range of applications, such as biomedical uses, water-resistant coatings, compostable plastic bags for gardening and agriculture, and packaging plastics with diminished environmental impact.

With an increase in environmental pollution and microplastic problems, it is more urgent now to replace non-biodegradable films with biodegradable films that are low-cost and from renewable resources. Cotton gin motes (GM), a type of cellulosic waste that is generated from cotton ginning, is an excellent candidate for fabricating biodegradable films due to its properties and abundance. In this study, GM was first mechanically milled into a fine powder, followed by compounding with polycaprolactone (PCL) and extruded to produce composite pellets which were then compress-moulded into composite films. This environmentally friendly process used physical processing and all the materials were consumed in the process without generating any waste residue. To improve the compatibility and mixing properties between GM and PCL, the use of a plasticiser (polyethylene glycol) was considered. A high content of GM powder (up to 50%) was successfully compounded with the polymer. The SEM images of the composite films showed smooth surface morphology and well-distributed GM powder in the PCL matrix. The added advantage of compounding GM with the polymer matrix was that the composite film developed UV-shielding properties due to the presence of lignin in the GM powder. This property will be critical for films used in UV-resistance applications. Furthermore, the composite even with high GM content (50%), showed good mechanical properties, with 9.5 MPa yield strength and 442% elongation, which was only a 50% decrease in elongation when compared with clear PCL film. The soil biodegradation of GM composite films under controlled temperature (20 degrees C) and humidity (50%) for 1 month showed around 41% weight loss. Overall, this study demonstrates the potential of GM to be used as a biodegradable and UV-protective composite film for a wide array of applications, such as packaging and UV-protective coverings.