NEWS: Sweet Potato and Thyme Make Bio Film with Nano Clay


Scientists at North Carolina A&T State University have fabricated and characterized a biodegradable nanocomposite film using sweet potato starch and thyme essential oil. They indicate that sweet potato starch may provide a viable solution to the waste disposal problem generated by plastic packaging materials.

The volume of plastics discarded annually creates a substantial waste disposal issue. Wheat starch, wheat gluten, soy and whey proteins have often been used to develop biodegradable packaging systems. But allergenic problems may occur if these compounds migrate onto edible products. However, there are no such issues with sweet potato starch, the University claims. Sweet potato is an inexpensive and readily available vegetable which is cultivated extensively for its nutritious value across many regions of the world.

As a first step in the research, montmorillonite (MMT) layered nanoclay and thyme essential oil were incorporated into sweet potato starch film to improve its physical and mechanical properties. The MMT weight percent relative to the sweet potato starch was constant at 3% and was activated by three levels of thyme essential oil: 0.5%, 1% and 1.5%. The researchers investigated the impact of the MMT nanoclay and the oil on the physical, mechanical and barrier properties of the starch films.

They found that incorporating MMT into sweet potato starch film greatly improved the firmness, water gain and water vapor permeability of the films. The combined effect of MMT and thyme essential oil improved the tensile strength, elongation and tri-stimulus colour values of the film.

This research is part of a bigger project to develop nano-composite films, investigating their mechanical characteristics and evaluating their antibacterial and biodegradability properties. The work was a funded project by USDA.