Plastic food packaging is a major contributor to the growing plastic waste problem in landfills. With increasing environmental concerns, researchers have been seeking bio-derived alternatives. Scientists at The Chinese University of Hong Kong (CUHK) have made significant progress in this area by developing an edible, transparent, and biodegradable material that shows great promise for food packaging applications. The findings of their study were published in the Journal of the Science of Food and Agriculture.
Plastic packaging has long been a significant cause of environmental contamination due to its heavy reliance on petrochemicals and its non-biodegradable nature. To combat this issue, the CUHK team turned their attention to bacterial cellulose (BC), an organic compound derived from certain types of bacteria. BC has gained attention as a sustainable, readily available, and non-toxic solution to the widespread use of plastics.
According to Professor To Ngai, the corresponding author of the study from the Department of Chemistry at CUHK, the impressive tensile strength and versatility of BC are key factors in its potential as a plastic packaging alternative. Extensive research has already been conducted on BC, including its use in intelligent packaging, smart films, and functionalized materials. These studies have demonstrated the potential of BC as a replacement for single-use plastic packaging materials, making it a logical starting point for further research.
Unlike cellulose found in plant cell walls, BC can be produced through microbial fermentation, eliminating the need for tree or crop harvesting. Ngai highlighted that this production method is more sustainable and environmentally friendly compared to plant cellulose, as it does not contribute to deforestation or habitat loss.
However, the widespread adoption of BC has been limited due to its sensitivity to moisture in the air, which negatively affects its physical properties. In their paper, the researchers presented a novel approach to address this limitation. By incorporating specific soy proteins into the structure and coating it with an oil-resistant composite, they successfully created an edible, transparent, and robust BC-based composite packaging.
Ngai emphasized the high feasibility of this approach for large-scale production, as it does not require specific reaction conditions like chemical reactions. Instead, it involves a simple and practical method of mixing and coating. This approach offers a promising solution to the challenge of developing sustainable and environmentally friendly packaging materials that can replace single-use plastics on a large scale.
The study demonstrated that the BC-based composite could be completely degraded within 1-2 months. Unlike other bio-derived plastics, such as polylactic acid, the BC-based composite does not require specific industrial composting conditions for degradation. This makes it safe for turtles and other sea animals to consume without causing aquatic toxicity in the ocean.
Future Directions and Challenges
The researchers at CUHK are now exploring future research directions to enhance the versatility of modified BC films, making them suitable for a wider range of applications. Their focus is on developing a thermosetting glue that can create strong bonds between bacterial cellulose, allowing it to be easily molded into various shapes when heated.
One of the main challenges with bacterial cellulose films is that they are not thermoplastic, which limits their potential for certain applications. By addressing this issue, the researchers hope to make bacterial cellulose films more competitive with traditional plastics while maintaining their eco-friendliness.
Professor Ngai hopes that this study will contribute to the reduction of excessive single-use plastics, which can persist for hundreds of years after only a few days on supermarket shelves. He concludes by stating that this research serves as a reminder that natural raw materials may already possess the necessary characteristics to outperform plastic packaging in terms of functionality and sustainability.
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