181: Novel Biodegradable Films From the Binary Mixtures of Alfalfa Cellulosic Residue and Carrageenan: A Step Toward Sustainable Packaging Material Innovation

Introduction

Plastics are widely used in packaging due to their durability and lightweight nature. However, their non-biodegradability and tendency to break down into micro- and nanoparticles and their impact on ecosystems and human health are of significant concern. Several alternatives, such as starches, proteins, and lipids, are being explored to resolve this issue. However, these staples are essential to meet the growing population's needs. More recently, cellulosic residue, a non-food structural component of plants, has emerged as a promising candidate. Its extraction from agricultural residue is sustainable and contributes to the circular bioeconomy. Herein, cellulosic residue from alfalfa field residue was used to prepare biodegradable packaging films. To further improve the film properties, mainly mechanical, water vapor permeability, and water solubility, carrageenan was complexed with the alfalfa cellulosic residue.

Methods

Alfalfa cellulosic residue (ACR) was extracted using alkaline (5% KOH, 30°C, 14h), and bleaching (3% NaClO3, 70°C, 12h, adjusting pH 5) treatments. The iota- (ι), kappa- (κ), and lambda- (λ) carrageenan solutions of 0.5, 1, and 1.5% were prepared separately. The ACR was solubilized in 68% ZnCl2, complexed with carrageenan, crosslinked with calcium ions, and plasticized, and the film was cast, framed, and dried. The nine ACR-carrageenan films were analyzed for tensile strength (TS), elongation at break (EB), water vapor permeability (WVP), color, UV-Vis-IR transmittance, water solubility, hydrophobicity, water uptake kinetics, and soil biodegradability, and compared with the control films (films without carrageenan). The R-software and Microsoft Excel were used for statistical analysis.

Results

The presence of carrageenan in ACR films improved the TS. The TS increased with the carrageenan amount, but EB decreased, and WVP was subtly affected. The water solubility and water absorption increased significantly, mainly with the presence of lambda-carrageenan. The films followed the Peleg water absorption kinetics and second-order reduction kinetics of soil biodegradation. They biodegraded within 40 days at 24% soil moisture.

Significance

Based on the premium price, even 50% of alfalfa's field residue could generate 5.44-6.12 billion USD globally, and the rest could be left in the field for soil health improvement. The outcome creates a new income pathway for alfalfa producers and addresses plastic perils.

Authors: Sandeep Paudel, Srinivas Janaswamy