Patulin in apple products: elucidation of its biosynthetic pathway and development of preventive measures (PATPOM)

Patulin is the most important mycotoxin in apple cultivation and the apple processing industry. The main source of patulin is the production by the mold Penicillium expansum. The aim of the research project "PATPOM" is to map the external factors that influence the growth of P. expansum. In parallel, we study the biosynthesis and the stability of patulin.

The first part of this project (performed at INRA-TOULOUSE) focused on the influence of external conditions on (1) the growth and morphology of P. expansum, (2) the correlated in vitro production of secondary metabolites (including patulin) and (3) the virulence of the mold after inoculation of apples. Special attention was paid to the role of the Velvet gene complex in the whole picture. The second part of the project (performed at ILVO) focused on the behaviour of patulin during processing of apples into cloudy apple juice. The influence of oxygen, as well as the addition of ascorbic acid and the storage/packaging on the content and stability of patulin were explored.

The in vitro growth of P. expansum and the production of secondary metabolites (e.g. patulin) appears to be negatively affected when the veA gene is switched off. Addition of ascorbic acid reduces patulin concentration in contaminated cloudy apple juice with formation of less toxic degradation products. Presence of oxygen and storage at room temperature appear to promote this process. The results obtained during this research project provide both fundamental and practice-relevant scientific information on the possible influences of external factors on the growth / morphology of Penicillium expansum and the stability of the mycotoxin patulin in cloudy apple juice. In addition to the publication of the data in peer-reviewed journals, the results have also been presented at international conferences. Finally, these results led to publication of a doctoral thesis.