Ochratoxin A and Defense Mechanisms of Tomatoes against Penicillium verrucosum and Aspergillus ochraceus

Abstract

This study aimed to fill the knowledge gap about the occurrence of ochratoxin A (OTA) in tomatoes, classifying them based on their defense mechanisms by cluster analysis (CA) and assessing their susceptibility to toxigenic effects of Penicillium verrucosum and Aspergillus ochraceus. Samples of Khaki, Cherry, Italian, and Long-Life tomatoes were collected and had their phenolic acid and amino acid profiles determined by HPLC-PDA and HPLC-FL, respectively. Enzymatic activities of peroxidase (PO), polyphenoloxidase (PPO), catalase (CAT), and phenylalanine ammonia lyase (PAL) were also determined. OTA levels were below the quantification limit (2.2 ng g^–1) in every sample. Their dissimilarity was determined by the CA of the defense mechanism components. The tomato varieties were classified into three subgroups: Italian, Khaki, and Long-Life and Cherry. They had similar soluble phenolic contents whose extracts were inhibited at around 50% growth of P. verrucosum and A. ochraceus. Although they did not have any fungistatic effect, the minimal inhibitory concentration was low (0.2 ng mL^–1). Absence of OTA in samples and antifungal activity of phenolic extracts suggested that these tomato varieties had efficient strategies against damage caused by these toxigenic fungal species.