Biodegradable, UV-blocking, and antioxidant films from lignocellulosic fibers of spent coffee grounds

Food packaging solutions in the post-per- and polyfluoroalkyl substances (PFAS) and microplastics era: A review of functions, materials, and bio-based alternatives

Food packaging (FP) is essential for preserving food quality, safety, and extending shelf-life. However, growing concerns about the environmental and health impacts of conventional packaging materials, particularly per- and polyfluoroalkyl substances (PFAS) and microplastics, are driving a major transformation in FP design. PFAS, synthetic compounds with dual hydro- and lipophobicity, have been widely employed in food packaging materials (FPMs) to impart desirable water and grease repellency. However, PFAS bioaccumulate in the human body and have been linked to multiple health effects, including immune system dysfunction, cancer, and developmental problems. The detection of microplastics in various FPMs has raised significant concerns regarding their potential migration into food and subsequent ingestion. This comprehensive review examines the current landscape of FPMs, their functions, and physicochemical properties to put into perspective why there is widespread use of PFAS and microplastics in FPMs. The review then addresses the challenges posed by PFAS and microplastics, emphasizing the urgent need for sustainable and bio-based alternatives. We highlight promising advancements in sustainable and renewable materials, including plant-derived polysaccharides, proteins, and waxes, as well as recycled and upcycled materials. The integration of these sustainable materials into active packaging systems is also examined, indicating innovations in oxygen scavengers, moisture absorbers, and antimicrobial packaging. The review concludes by identifying key research gaps and future directions, including the need for comprehensive life cycle assessments and strategies to improve scalability and cost-effectiveness. As the FP industry evolves, a holistic approach considering environmental impact, functionality, and consumer acceptance will be crucial in developing truly sustainable packaging solutions.

Use of alfalfa cellulose for formulation of strong, biodegradable film to extend the shelf life of strawberries

Plastic packaging has increased concerns about human health and the ecosystem due to non-biodegradability. Several biopolymers, such as cellulose, starch, and proteins, are being explored, and cellulosic residue from agricultural biomass is suitable to overcome this predicament. Herein, cellulosic residue fibers (ACR) extracted from alfalfa were used to prepare biodegradable films by solubilizing them in ZnCl2 solution and crosslinking the chains with calcium ions (Ca2+) and sorbitol. Box Behnken Design optimized the ACR, CaCl2, and sorbitol amounts against the responses of water vapor permeability (WVP), tensile strength (TS), and elongation at break (EB). The optimized film combination was found to be 0.5 g ACR, 461.3 mM CaCl2, and 1.05 % sorbitol, making a 12 × 12 cm2 film, with a TS of 16.9 ± 0.4 MPa, EB of 10.1 ± 0.3 %, and WVP of 0.47 ± 0.11×10-10 g.m-1.s-1.Pa-1. It was translucent, blocked UVB light, followed Peleg's water absorption kinetics, displayed anti-oxidant activity, and biodegraded within 35 days at 24 % soil moisture. The ACR film extends the shelf life of strawberries by two more days compared to polystyrene film. The outcome offers a novel path to utilize and conserve natural resources and mitigate plastic perils, promoting a circular bioeconomy and sustainability and a win-win situation between the environment and farmers.

Biodegradable films from soyhull cellulosic residue with UV protection and antioxidant properties improve the shelf-life of post-harvested raspberries

Post-harvest loss of fruits and vegetables, and health risks and environmental impact of current plastic packaging warrant new biodegradable packaging. To this end, cellulosic residue from agricultural processing byproducts is suitable due to its renewability and sustainability. Herein, soyhulls cellulosic residue was extracted, solubilized in ZnCl2 solution, and crosslinked with calcium ions and glycerol to prepare biodegradable films. The film combination was optimized using Box Behnken Design and film properties were characterized. The optimized film is translucent and exhibits tensile strength, elongation at break, water vapor permeability, hydrophobicity, and IC50 of 6.3 ± 0.6 MPa, 30.2 ± 0.9%, 0.9 ± 0.3 × 10-10 gm-1 s-1 Pa-1, 72.6°, and 0.11 ± 0.1 g/mL, respectively. The water absorption kinetics follow the Peleg model and biodegrade within 25 days at 24% soil moisture. The film extends the shelf life of raspberries by 6 more days compared to polystyrene film. Overall, the value-added soyhull cellulosic films are advantageous in minimizing post-harvest loss and plastic-related issues, emphasizing the principles of the circular bioeconomy.

Biodegradable Food Packaging Films Using a Combination of Hemicellulose and Cellulose Derivatives

This study aims to develop biodegradable films by combining hemicellulose B (HB) with methylcellulose (MC) and carboxymethyl cellulose (CMC) at two mass ratios, HB/MC 90/10 and HB/CMC 60/40. The effect of plasticizers, glycerol (GLY) and polyethylene glycol (PEG), on these films' mechanical and physicochemical properties was also investigated. Results showed that the film thickness increased with the addition of GLY and PEG. Moisture content was lower in plasticized films, possibly contributing to better storage. Plasticizers also induced more pronounced color changes, intensifying the lightness and yellowness. Physical attributes such as peel ability, foldability, and transparency were also noticeably improved, particularly in films with higher GLY and PEG concentrations. Additionally, plasticizers enhanced the mechanical properties more significantly in the HB/CMC films, as evidenced by improved tensile stress, elongation at break, elastic modulus, and toughness. However, oxygen and water vapor permeabilities, two of the most critical factors in food packaging, were reduced in the HB/MC films with plasticizers compared to the HB/CMC counterparts. The findings of this study bear significant implications for developing sustainable packaging solutions using hemicellulose B isolated from agricultural material processing waste. These biopolymer-based films, in conjunction with biobased plasticizers, such as glycerol biopolymer, can help curtail our reliance on conventional plastics and alleviate the environmental impact of plastic waste.

Corncob-derived biodegradable packaging films: A sustainable solution for raspberry post-harvest preservation

Plastic food packaging, with its harmful migration of microplastics and nanoplastics into food, presents significant ecological imbalance and human health risks. In this regard, using food and agricultural byproducts as packaging materials reduces environmental and economic concerns and supports their sustainable management. Herein, cellulosic residue from corncob was employed as a renewable source for developing biodegradable packaging films. It was solubilized in ZnCl2 solution, crosslinked with Ca2+ ions, and plasticized with sorbitol to form films and used to improve the shelf-life of raspberries. The optimized film possesses water vapor permeability, tensile strength, and elongation at break of 1.8(4) x10-10 g-1 s-1 Pa-1, 4.7(1) MPa, and 15.4(7)%, respectively. It displays UV-blocking and antioxidant properties and biodegrades within 29 days at 24% soil moisture. It preserves raspberries for 7 and 5 more days at room temperature and refrigeration conditions, respectively, compared to polystyrene film. Overall, more value addition could be envisioned from agricultural residues to minimize post-harvest losses and food waste through biodegradable packaging, which also aids in mitigating plastic perils.

Biodegradable, Strong, and Hydrophobic Regenerated Cellulose Films Enriched with Esterified Lignin Nanoparticles

The scientific community is pursuing significant efforts worldwide to develop environmentally viable film materials from biomass, particularly transparent, high-performance regenerated cellulose (RC) films, to replace traditional plastics. However, the inferior mechanical performance and hydrophilic nature of RC films are generally not suitable for use as a substitute for plastics in practical applications. Herein, lignin homogenization is used to synthesize high-performance composite films. The esterified lignin nanoparticles (ELNPs) with dispersible and binding advantages are prepared through esterification and nanometrization. In the presence of ELNPs, RC films exhibit a higher tensile strength (110.4 MPa), hydrophobic nature (103.6° water contact angle, 36.6% water absorption at 120 min, and 1.127 × 10-12 g cm cm-2 s-1 Pa-1 water vapor permeability), and exciting optical properties (high visible and low ultraviolet transmittance). The films further display antioxidant activity, oxygen barrier ability, and thermostability. The films completely biodegrade at 12 and 30% soil moisture. Overall, this study offers new insights into lignin valorization and regenerated cellulose composite films as novel bioplastic materials.

Biodegradable, UV-blocking, and antioxidant films from alkali-digested lignocellulosic residue fibers of switchgrass

The development of bio-friendly materials to replace single-use plastics is urgently needed. In this regard, cellulosic material from plants is a promising alternative. However, due to the risk of forest depletion, agricultural biomass stands out as a favorable choice. Toward this end, switchgrass, an underutilized grass, presents itself as a viable source of lignocellulose that can be turned into a bio-friendly material. Herein, lignocellulosic residue from switchgrass has been extracted using two different concentrations of NaOH (20% and 50% w/v), solubilized in aqueous ZnCl2 solution, and crosslinked with CaCl2 (200, 300, 400, and 500 mM) to prepare biodegradable films. The color, thickness and moisture, water solubility, water absorption, water vapor permeability, tensile strength and elongation, biodegradation, UV transmittance, and antioxidant activity of films have been studied. The films possess a high tensile strength of 14.7 MPa and elongation of 4.7%. They block UVB-radiation and hold antioxidant properties. They display good water vapor permeability of 1.410-1.6 × 10-11 gm-1s-1Pa-1 and lose over 80% of their weight at 30% soil moisture within 40 days. An increase in the CaCl2 amount decreased the water vapor permeability, elongation, UV transmittance, and biodegradation but increased the transparency, tensile strength and antioxidant property. Overall, films of alkali-digested lignocellulosic residue of switchgrass showed excellent potential to be used against lightweight plastics and support the circular economy.

Manufacturing biodegradable lignocellulosic films with tunable properties from spent coffee grounds: A sustainable alternative to plastics

Manufacturing biodegradable lignocellulosic films from spent coffee grounds (SCG) as an alternative to commercial plastics is a viable solution to address plastic pollution. Here, the biodegradable lignocellulosic films from SCG were fabricated via a sequential alkaline treatment and ionic liquid-based dissolution process. The alkaline treatment process could swell the cell wall of SCG, change its carbohydrates and lignin contents, and enhance its solubility in ionic liquids. The prepared SCG films with different lignin contents exhibited outstanding UV blocking capability (42.07-99.99 % for UVB and 20.96-99.99 % for UVA) and light scattering properties, good surface hydrophobicity (water contact angle = 63.2°-88.7°), enhanced water vapor barrier property (2.28-6.79 × 10-12 g/m·s·Pa), and good thermal stability. Moreover, the SCG films exhibit excellent mechanical strength (50.10-81.56 MPa, tensile strength) and biodegradability (fully degraded within 30 days when buried in soil) compared to commercial plastic. The SCG films represent a promising alternative that can replace non-biodegradable plastics.

Biodegradable films from the lignocellulosic fibers of wheat straw biomass and the effect of calcium ions

Plastics are hazardous to human health, and plastic waste results in environmental pollution and ecological catastrophe. Biobased polymers from renewable sources have recently become promising for developing biodegradable packaging films. Among them, lignocellulosic residue from agricultural biomass is inexpensive, renewable, and biodegradable. This study aims to develop biodegradable films using lignocellulosic residue from wheat straw biomass. The methodology is a green process that solubilizes lignocellulosic chains using Zn2+ ions and crosslinks with Ca2+ ions of different concentrations (200-800 mM). The results reveal that the increase of Ca2+ ions significantly decreases moisture content, water solubility, water vapor permeability, transparency, and elongation of films. The tensile strength is recorded as 6.61 ± 0.07 MPa with the addition of 800 mM of CaCl2, which is approximately 2.5 times higher than commercial polyethylene films. Around 90 % of films biodegrade within a month in soil containing 20 % moisture content. Overall, lignocellulosic residue from wheat straw biomass could be an excellent replacement for synthetic polymer to fabricate strong, transparent, and biodegradable plastic films.