Pulsed light treatment reduces the growth and patulin production of Penicillium expansum and its application in apple preservation

Penicillium expansum is a major pathogen causing blue mold rot in fruits and vegetables. Given the increasing concerns over the use of chemical fungicides in postharvest treatments, this research explores the effects of pulsed light (PL) on the growth and patulin production of P. expansum . Our results exhibited that PL significantly suppressed spore germination and mycelial growth while impairing the cell membrane integrity. Mechanistic studies revealed that PL treatment caused disruption of antioxidant defense systems and the excessive accumulation of reactive oxygen species (ROS), leading to the oxidative damage and mitochondrial dysfunction. Moreover, PL treatment significantly downregulated the expression of key genes associated with P. expansum growth and patulin biosynthesis. Specifically, the expression levels of global regulators CreA and LaeA were decreased by 39 % and 62 %, and 47 % and 82 % after PL30 and PL90 treatments, respectively. Additionally, genes within the patulin biosynthesis gene cluster, including patA , patK , patN , and patL , were significantly downregulated. In apples with PL90-treated P. expansum , the rot onset was delayed by 4 d. On day 7, PL90 reduced lesion diameter by 87.9 %, decay incidence by 67 %, and patulin content by 95 %. The findings indicate that PL is an effective technology for controlling postharvest diseases in fruits, making it a promising alternative to chemical treatments.