Banana trees become a renewable source of bioplastics

Biodegradable 'plastic' bags made from a banana plant may sound a bit . bananas, but some Australian researchers have found a way to do that and make it a public solution. To solve the current problems of plastic pollution.

Endless source of cellulose from banana stem

Two researchers at the University of New South Wales (UNSW) Sydney, Australia have discovered a new way to turn banana-grown waste into packaging material that is not only biodegradable but also recyclable.

Only bananas are used, while bananas are discarded wasted.

Associate Professor Jayashree Arcot and Professor Martina Stenzel are seeking to convert agricultural waste into something that can add value to the industry. And they chose bananas because this is a plant that is producing large amounts of organic waste. Currently, only bananas are used, accounting for only 12% of the tree, while the rest is removed after harvesting.

"What makes the banana business so special compared to other fruit trees is that they die after each harvest," Arcot said .

"We are especially interested in banana stems, because this is a multi-layered stem, which is often cut after each harvest and thrown away in the field. Some are used for textiles, some are compost, but In addition, it is a huge waste , " Associate Professor Arcot said.

And Professor Stenzel wondered if bananas were a valuable source of cellulose. Cellulose, which is an important structural component of plant cell walls, can be used in packaging, paper, textiles and even medical applications such as wound healing and drug transportation.

Using a supply of banana stem material grown at the Royal Botanic garden in Sydney, the duo worked to extract cellulose from bananas to replace the plastic that produces the packaging.

"Banana stems contain 90% water, so the solid material eventually drops to about 10%," said Associate Professor Arcot. "We bring the banana stem into the lab and cut it into pieces, dry it at a very low temperature in the kiln, then grind it into a very fine powder."

The final product film is similar to paper.(Photo: University of New South Wales).

Professor Stenzel continued : "Then we took this powder and softened it with chemical treatment. The new material is called nano-cellulose, a high-value material in all applications. One of our applications of particular interest is using it to make single-use food packaging that replaces the type of plastic packaging being thrown away in many landfills. "

The bioplastics from bananas can decompose in six months

When processed, this material looks similar to paper. Arcot said that, depending on the intended thickness, the material could be used in a number of different formats in food packaging."There are a number of options available at this time, and we can sew into shopping bags , " she said.

Arcot Associate Professor said she and Professor Stenzel have confirmed in tests that the material decomposes after being placed in the ground for six months. The results showed that the cellulose sheets were disintegrating into soil samples.

According to Professor Arcot: "This material is also recyclable. One of our PhD students has demonstrated that they can be recycled up to three times without any change in properties." .

Trials with food have also proven that it does not pose a risk of contamination. Professor Stenzel said: "We tested this material with food samples to see if there was any leakage into the cells and the results didn't see anything. I also tested it. it is on mammalian cells, cancer cells, T cells, a leukocyte layer which is very sensitive and the result is all non-toxic, so it is very benign ".

Banana stalks are dried, pulverized, then placed in an alkaline solution to extract cellulose and processed into membranes of different thicknesses.(Photo: University of New South Wales).

Potential cellulose extract from bananas and many other plants

The two scientists also studied other agricultural wastes such as cotton industry and rice growing industry, and they extracted cellulose from both waste cotton collected from cotton swabs and husks.

"In theory, you can get nano-cellulose from all plants, just some plants are better than others in that they have higher levels of cellulose , " Professor Stenzel said.

"What makes bananas so attractive is that they are an annual crop," says Associate Professor Arcot.

Researchers say that bananas are a practical alternative to plastic bags and food packaging, which makes sense for the banana industry to start processing them into flour and sell to bag suppliers. packaging.

And at the other end of the supply chain, if packaging manufacturers update their machines so they can make nano-cellulose films into bags and other food packaging materials, then the banana stem has a real chance. becoming a much more sustainable food packaging material.

"What we want at this stage is a partner in the plastics industry, who can consider how this can be enhanced and how cheap we can make it , " Church said. said Stenzel.

Associate Professor Arcot agrees."I think packaging companies will be more willing to use this material, if they know that this material is available."