Penicillium expansum adhesion to materials used in food industry

Penicillium expansum causes rotting of fruits and vegetables and form secondary metabolites that present a food safety risk. The main purpose was to determine P. expansum adhesion to materials used in the food industry. Adhesion was evaluated with crystal violet method and observed with scanning electron microscopy (SEM). Adhesion was stronger when an inoculum was prepared from a 10-day-old colony than from a 7-day-old colony. Further, adhesion was evaluated on different materials and physical properties of investigated materials were determined. P. expansum adhered to all investigated materials inmira declining order polystyrene (PST), polypropylene (PP), high-density polyethylene (HDPE), polyethylene terephthalate (PET), glass (G), stainless steel (SS). SEM observation confirmed adhered conidia and mycelium of P. expansum on all investigated materials, except SS where only conidia were observed. SEM also revealed that conidia were surrounded with extracellular polymorphic substances especially in case of HDPE, G and PET. The physical properties of the materials (contact angle, roughness, zeta potential) showed a minor role in P. expansum adhesion to investigated materials. Since adhesion leads to biofilm formation, preventing the adhesion of P. expansum would reduce the likelihood of food contamination by molds, indicating the need for further studies.