Effect of thyme oil, temperature, and storage period on the reduction of Ochratoxin A produced by Aspergillus niger in almond fruits

Abstract

An experiment was conducted in one of the laboratories of the College of Agriculture - University of Kufa, to evaluate the effect of  thyme oil and temperatures (10°C, 20°C, and 30°C) on the concentration of Ochratoxin A (OTA) produced by Aspergillus niger in Almonds stored for one and two months. The results showed significant differences in toxin concentrations according to the type of treatment, the treatment with fungus only, recorded the highest concentration (74.68 µg kg^-1) compared to the control treatment, which recorded a concentration of (5.39 µg kg^-1), confirming the strong toxigenic potential of the fungus to produce the toxin. In contrast, the treatment combining of thyme oil with the fungus significantly reduced the toxin concentration (32.40 µg kg^-1), indicating the effectiveness of the oil as an antifungal and toxin reducer. It was also found that increasing the storage temperature significantly increased OTA concentrations, with values of (12.9, 29.4, and 35.1 µg kg^-1) at 10, 20, and 30°C, respectively. Extending the storage period from one to two months also resulted in a significant increase in the toxin level (from 20.3 to 31.4 µg kg^-1). The highest value was recorded in the treatment with fungus only at 30°C for two months (124.8 µg kg^-1). Therefore, these results confirm that thyme oil can serve as an effective natural strategy for reducing the risk on contamination of Almonds with Ochratoxin A, especially under suboptimal storage conditions.