Combined Effects of Clove and Cinnamon Oils against Aspergillus flavus and Aflatoxin B1 Production in Georgia-Grown Organic Peanuts

Abstract

Aspergillus flavus is a common saprotrophic and pathogenic fungal contaminant of peanuts and a major producer of aflatoxin B1 (AFB1), a potent Group 1 carcinogen. Current control strategies rely heavily on synthetic fungicides, which pose environmental and human health concerns. This study evaluated the antifungal and antiaflatoxigenic efficacy of clove and cinnamon essential oils (EOs), applied individually and in combination, against A. flavus in culture-based assays and artificially inoculated Georgia-grown organic peanuts. Peanuts were treated with cinnamon, clove, or a combined EO formulation at concentrations ranging from 250 to 2000 ppm, followed by quantitative analysis of AFB1 using selected ion monitoring-based liquid chromatography−mass spectrometry (LC−MS) method. Individual EO treatments produced moderate, concentration-dependent reductions in AFB1 production, with clove and cinnamon EOs reducing AFB1 levels to approximately 49−58% of untreated controls at 2000 ppm. In contrast, the combined EO formulation produced consistently enhanced inhibitory performance across both cultures and peanut systems, reducing AFB1 accumulation by up to 81.6% in peanut samples and 69−71% in culture assays, with efficacy comparable to or exceeding that of synthetic fungicide control. The combined treatment exhibited a consistent, but limited concentration-dependent inhibitory trend across the tested range (R² = 0.9992), suggesting early saturation of inhibitory activity. Nonlinear regression analysis yielded an IC₅₀ value of 46.83 ppm; however, this estimate is based on the concentration range evaluated and should be interpreted as an approximate indicator of inhibitory potency rather than a fully resolved kinetic parameter. These findings indicate that the combined application of clove and cinnamon EOs is associated with enhanced antifungal and antiaflatoxigenic activity against A. flavus in a food-relevant system. This study extends prior work by demonstrating the effectiveness of EO combinations within a peanut matrix using LC−MS-based quantification of AFB1. Collectively, these results identify EO blends as a promising, generally recognized as safe (GRAS), plant-based alternative to synthetic fungicides for mitigating AFB1 contamination in peanuts.