M. ABELLANA, J. BENEDÍ, V . S AN C HI S A N D A .J . RA MO S . 1999. This study investigated the effect of temperature (5-30°C), water activity (0·775-0·90 a w ) and their interactions on the temporal rates of germination and mycelial growth of three species of Eurotium on flour wheat sucrose medium. Germination was quite rapid at a w × 0·85, with an almost linear increase with time for all isolates. However, under more extreme water stress, germination was slower. The a w minima for germination were usually lower than those for growth and varied with temperature. The effect of a w × temperature interactions on the lag phases (h) prior to germination and on the germination rates (h −1 ) were predicted using the Gompertz model modified by Zwietering. Eurotium spp. had shown short lag times at 0·90 a w over a wide range of temperatures. At marginal temperatures, lag phases were significantly longer, especially at ×15°C. The temperature × a w profiles for mycelial growth varied between species in terms of rates (mm d −1 ). Predictions of the effect of important environmental factors, such as temperature, a w and their interactions on lag times to germination, germination rates and mycelial growth, are important in the development of hurdle technology approaches to predict fungal spoilage in food products.

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