Cornstarch conversion demonstrates potential to kickstart mosquito-repellent food-safe packaging

06 Mar 2020 --- Converting cornstarch into a new class of material called amylose inclusion complex (AIC) has given life to food-safe and mosquito-repellent packaging. This research conducted at the US Department of Agriculture (USDA)’s Agricultural Research Service (ARS) may bear the potential to improve essential packaging properties, such as reduced oxygen and water permeability, increased elongation as well as hydrophobicity by blending AIC polymers with polyvinyl alcohol or hydroxypropyl cellulose. Although food products containing cornstarch are already ubiquitous, this research presents a new avenue for cornstarch-based packaging materials through its pest control potential.

Products created from the AIC include emulsions using essential oils from garlic, the spice asafoetida and other plants to control mosquito larvae in aquatic habitats. The emulsions envelope droplets of the oils, stabilizing them and protecting them from extreme heat or oxidation that can reduce their potency when applied to mosquito larvae habitats.

The emulsions also allow the oil droplets to disperse in water, contrary to their natural tendency. This, in turn, increases the likelihood of their contacting and killing the larvae. Notably, the AIC emulsions are toxic to mosquito larvae but not the environment, which makes them promising botanical alternatives to synthetic insecticides.

Besides packaging, the ARS researchers have developed numerous potential end-uses for the new AICs, including emulsifiers, surfactants, surface modifiers and pesticides, Gordon Selling, Research Chemist at the ARS, tells PackagingInsights. “While any new product would need to be assessed for appropriate use, we have made AICs that use materials appropriate for food contact and consumption. After proper screening by the US government or private agencies, they may be found suitable for food contact or for use in food,” he says.

Theory meets practice
Water solution, or colloidal suspension specifically, remains a constant challenge. “While this is not an issue for many applications, it would be better if a solid product was provided for some end-uses. We have shown that this can be done via industry-standard techniques, but this would entail added expenses as the water would have to be removed,” Selling details. The mosquito Aedes aegypti can spread several diseases as it travels from person to person.

Exposure to the essential oil emulsions killed the larvae of yellow fever mosquitoes (Aedes aegypti) within 24 hours in laboratory trials. The number that died upon exposure was dependent on the type of oil and formulation used.

Selling underscores that the AIC material would be most effective in regions that have ready access to corn processing, considering 95 percent of the material is made from cornstarch and the remaining 5 percent is a vegetable oil derivative. Moreover, the AIC may be able to incorporate compounds that may have insecticidal activity in film. “We have developed AIC articles which inherently can control fungi and bacteria,” Selling notes.

Future applications
Ultimately, the research team envisions using the essential oil emulsions as part of an integrated approach to controlling mosquitoes and preventing the diseases they can spread, such as West Nile virus, yellow fever, dengue and Zika.

In terms of market commercialization, the AIC material samples are currently being sent to companies across the globe. At the same time, the ARS provides articles and presentations to companies and other institutions to promote this technology. “Our goal is for companies to see the benefits of this technology and utilize this high-value, low-cost technology to provide improved products that are biobased and biodegradable,” Selling explains. 

To ensure AIC material comes to market, Selling also highlights he and his team continue to “aggressively seek industrial partnerships.” From a research perspective, there are still many avenues to investigate regarding the carbohydrate, the ligand and the process.

By Anni Schleicher