The efficacy of ultrasonic fumigation for disinfestation of storage facilities against postharvest pathogens

Inoculum of postharvest pathogens can accumulate inside storage rooms and contaminate new batches of fruit and vegetables, but this chain can be broken by disinfecting storage facilities between storage periods. Quaternary ammonium (QA) has been known for over 50 years as an efficient disinfectant against microorganisms, with wide applications in the food industry. The aim of this study was to determine the efficacy of didecyldimethylammonium chloride (Sporekill, designated here as QAsk), against development of Botrytis cinerea after direct exposure or by ultrasonic fogging. Following direct exposure to a concentration of QAsk below 5 mg L−1, a population of 104 conidia of B. cinerea was inactivated after 2 min; ultrasonic fogging with QAsk at 500 mg L−1 took 30 min to achieve consistent inactivation. Fumigation at 20 °C was considerably more effective than fumigation at 5 °C, and similar results were obtained for three other postharvest pathogens, Penicillium expansum, Colletotrichum gloeosporioides and Alternaria alternata. These results show that conidia of B. cinerea are highly sensitive to direct exposure to QAsk, but that effective sanitation of a storage facility by ultrasonic fumigation requires a QAsk concentration two orders of magnitude greater.

► Conidia of Botrytis cinerea are very sensitive to a commercial formulation of quaternary ammonium by direct exposure.
► Ultrasonic fogging requires about 100-fold higher concentrations for efficient disinfection of Botrytis, Penicillium expansum and Colletotrichum gleosporides.
► The efficacy of the treatment by ultrasonic fogging depends on temperature and is much higher at 20 °C compared to 5 °C.
► Ultrasonic fogging of such compounds can be used to disinfect storage facilities prior to storage and to reduce the inoculums of postharvest pathogens.