Valorization of grapevine agricultural waste into transparent and high-strength biodegradable films for sustainable packaging†

Abstract

The impact of single-use and short-lived plastic food packaging is significant, contributing substantially to environmental waste that harms ecosystems. Microplastic pollution and chemical leaching from plastic packaging pose risks to humans, animals, and plants. Consequently, our environment is increasingly contaminated by plastic waste, microplastics, and nanoplastics, resulting in a pervasive pollutant. In this context, alternative biodegradable and sustainable packaging can help mitigate the harmful effects of plastic waste. Agricultural byproducts, which might otherwise be discarded, hold considerable potential for this purpose. This study demonstrates the use of grapevines as a source of cellulose to develop novel, transparent, and biodegradable films. Grapevine canes are major woody berry crops that generate substantial winter pruning waste. This waste contains a high level of cellulose, approximately 35%. Herein, the cellulose fraction was extracted using alkaline (10% KOH) and bleaching (10% NaClO₂) treatments. It was then solubilized in a ZnCl₂ solution, crosslinked with calcium ions, and plasticized with glycerol to develop films. These films exhibit a transparency of 83.70–84.30% mm⁻¹ and a tensile strength of 15.42–18.20 MPa. They biodegrade within 17 days in soil at 24% moisture content. These films demonstrate outstanding potential for food packaging applications. Our research approach of repurposing agricultural byproducts to create high-value products helps reduce plastic waste, conserve the environment, and provide economic benefits to farmers.