Thermal inactivation of Botrytis cinerea conidia in synthetic medium and strawberry puree

Botrytis cinerea is one of the most important post-harvest molds that cause quality deterioration of strawberries and other fruits even during refrigeration storage. This research studied the effects of thermal inactivation of B. cinerea in synthetic medium and strawberry puree using hot water baths at different temperatures. These media were studied in order to determine if results obtained in a solution with the major components of the fruit (synthetic media), are comparable to the ones obtained in fruit purees. The results demonstrated that B. cinerea spores can be inactivated by heat treatments using relatively low temperatures (42-46 °C). Inactivation curves were well described by first order kinetics (R² 0.91-0.99). B. cinerea conidia inoculated in synthetic medium required less time to achieve one log reduction in population than those inoculated in the fruit puree. D values were 22, 8.5, 4 and 1.4 min at 42, 44, 46 and 48 °C, respectively, in synthetic medium; while D values in strawberry puree were 44.9, 13.8, 4.7 and 1.4 min at 42, 44, 46 and 48 °C, respectively. The z values obtained were 4.15 and 5.08 °C for the strawberry puree and synthetic medium respectively, showing higher sensitivity of B. cinerea in fruit purees than in the synthetic medium. Thus, a change in the medium composition had a marked difference in the heat inactivation of B. cinerea conidia, and the results obtained in synthetic medium are not accurate to describe the behavior of the microorganism in the fruit.