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RESEARCH PRODUCT

Use of the Weibull model to describe inactivation of dry harvested conidia of different Penicillium species by ethanol vapours

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Aims:  This study aimed at modelling the effect of ethanol vapours, in the range 0·7–7·5 kPa, on the inactivation of dry-harvested conidia of Penicillium chrysogenum, Penicillium digitatum and Penicillium italicum. Methods and Results:  Survival curves were modelled by a Weibull model: log (N/N0) = −1/2·303 (t/α)β. The shape parameter β was different from one in all cases, indicating that the classical first-order kinetics approach is the exception rather than the rule. Survival curves exhibited upward concavity (β < 1) with the notable exception of P. chrysogenum at ethanol vapour pressures 0·7 and 1·5 kPa. The scale parameter α (h) varied greatly depending on the ethanol vapour pressure and on the species. Conclusions:  For safety reasons, it is recommended not to exceed an ethanol vapour pressure of 3·3 kPa. At 2·8 kPa, more than 4 log10 reductions in viable conidia were achieved for all the species after 24-h exposure. Significance and Impact of the Study:  Ethanol has GRAS status in the USA and represents an interesting alternative to fungicides. The effectiveness of ethanol vapours to inactivate dry-harvested conidia of some Penicillium was demonstrated in this study.