Chinese scientists create edible food packaging to replace plastic

The world is drowning in plastic, and one can hardly buy anything in the supermarket without encountering wrapping and other packaging made of this oil-based polluter that accounts for a major proportion of waste in landfills. 

Now, scientists at the Chinese University of Hong Kong have developed an edible, transparent and biodegradable material with considerable potential for use as food packaging.

The heavy reliance on petrochemicals and inherent non-biodegradability of plastic packaging means it has long been a significant contributor to environmental contamination. The team members have turned their attention to bacterial cellulose (BC) – an organic compound derived from certain types of bacteria that has gained attention as a sustainable, easily available and non-toxic solution to the pervasive use of plastics.

What is the key to bacterial cellulose's potential?

Prof. To Ngai from the chemistry department explained that the impressive tensile strength and high versatility of BC are the keys to its potential.

“Extensive research has been conducted on BC, including its use in intelligent packaging, smart films and functionalized materials created through blending, coating and other techniques. These studies demonstrate the potential of BC as a replacement for single-use plastic packaging materials, making it a logical starting point for our research.”

Unlike the cellulose found in the cell walls of plants, BC can be produced through microbial fermentation that eliminates the need for harvesting trees or crops. Ngai noted that as a result, “this production method does not contribute to deforestation or habitat loss, making BC a more sustainable and environmentally friendly material alternative to plant cellulose.”

Up until now, the widespread adoption of BC has been limited by its unfavorable sensitivity to moisture in the air (hygroscopicity) that detrimentally impacts its physical properties. 

In the recent paper, published in the Journal of the Science of Food and Agriculture and titled “Edible, strong, and low-hygroscopic bacterial cellulose derived from biosynthesis and physical modification for food packaging,” the researchers presented a novel approach to address the limitations of BC-based materials.

By incorporating certain soy proteins into the structure and coating it with an oil-resistant composite, the scientists successfully created an edible, transparent and robust BC-based composite packaging.

Ngai noted that this approach has high feasibility for scale-up. “It doesn’t need specific conditions like chemical reactions, but rather a simple and practical method with mixing and coating,” he added. “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 showed that the plastic alternative could be degraded completely within one or two months. Unlike other bio-derived plastics such as polylactic acid, the BC-based composite does not require specific industrial composting conditions to degrade. “The material developed in this research is completely edible, making it safe for turtles and other sea animals to consume without causing aquatic toxicity in the ocean,” Ngai continued.

The researchers are now exploring the directions for future research, hoping to increase the versatility of modified BC films, making them suitable for a wider range of applications. Specifically, they are focused 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 use in certain applications. By dealing with this problem, we hope to make bacterial cellulose films more competitive with traditional plastics while maintaining their eco-friendliness, the Chinese chemist said. He hopes that their study will help reduce the excessive use of single-use plastics that can persist for hundreds of years after only a few days of being displayed on supermarket shelves. “This research serves as a reminder that natural raw materials may already possess the necessary characteristics to perform beyond the functions of plastic packaging.”