Researchers collected rotted walnuts from storage in Shanxi, China and identified five types of Aspergillus fungi contaminating them, with Aspergillus flavus being the most common. They tested cinnamon essential oil as a natural antifungal treatment and found it effectively stopped fungal growth by damaging the fungi’s cell membranes and causing oxidative stress. This research suggests cinnamon essential oil could be used as a safe, natural alternative to chemical fungicides for preserving walnuts and other foods from fungal spoilage.