Antifungal activity of cinnamon, clove, and star anise essential oils against Aspergillus flavus and Aspergillus niger, and their potential application in chilli paste to inhibit fungal growth

Abstract

Spices are highly susceptible to fungal contamination and mycotoxin production, leading to economic losses and health risks for consumers. Plant essential oils (EOs) have gained attention as potential natural antimicrobial agents due to their ability to inhibit microbial growth. This study evaluated the antifungal activity of cinnamon, clove, and star anise EOs against Aspergillus flavus and Aspergillus niger, and assessed their efficacy in controlling fungal growth in chilli paste. The antifungal activity was screened using a disk diffusion assay, while the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were determined via broth and agar dilution methods. The most effective EO was selected for in situ study in chilli paste. Results showed that cinnamon EO exhibited the highest antifungal activity against A. niger, with complete inhibition, followed by clove EO (17 ± 3.1 mm) and star anise EO (9.3 ± 1.2 mm). Cinnamon EO recorded the lowest MIC (0.008–0.03%) and MFC (0.06–1.0 %) values for both fungi. Chilli paste supplemented with 0.5% cinnamon EO significantly reduced A. flavus and A. niger counts to <1.0 log CFU/g at ambient (30 °C) and chilled (4 °C) storage. A. flavus growth was notably suppressed at 4 °C across all treatments. Additionally, no significant differences (p > 0.05) were observed in pH, and water activity during 15 days of storage. However, cinnamon EO led to noticeable changes in the color of the chilli paste. These findings suggest that cinnamon EO is an effective natural antifungal agent and a promising preservative for chilli paste.