Heat-Assisted Pulsed Electric Field Treatment for the Inactivation of Saccharomyces cerevisiae: Effects of the Presence of Citral.

摘要: Pulsed electric field (PEF) treatment is a non-thermal technology that has shown good potential for microbial inactivation. However, in many cases, it cannot be sufficient to avoid proliferation and the combination with other stabilizing technologies needed. In framework of hurdle concept, several researches have been focused on use PEF heat and/or antimicrobials increase its efficacy. This study investigated inactivation effect strain Saccharomyces cerevisiae (isolated from spoiled beverages) model system (growth medium). The efficacy was evaluated relation different variables, such as strength (25 50 kV/cm), time (from 1 5 seconds), initial inoculum level (4 or 6 log cfu/ml), pre-heating at 50°C, medium pH 6) addition citral sub lethal concentration (i.e. half minimum inhibiting concentration). data plate counting, modelled Weibull equation, showed one main factors affecting yeast suspension 50°C. Indeed, higher cell load reductions were obtained heat-assisted PEF, especially presence citral. negligible, while affected only without pre-heating, death kinetics 6. Flow cytometry (FCM) analysis confirmed mortality under these conditions. occurrence injured cells, samples treated 4, observed. ability cells recover damages induced by treatments both pre-heating. synergic effects likely due membrane permeability (especially 6), primary target electroporation, which favoured solubilization membrane, enhancing whole process. multi-analytical approach (traditional counting FCM) allowed defining parameters against S. cerevisiae. Moreover, FCM, able discriminate physiological states population, helpful better clarify action mechanism recovery after treatment.