Yeast growth:: lag phase modelling in alcoholic media

A simple non-structured model is proposed here to evaluate the lag phase before yeast growth as a function of the ethanol concentration in the medium. Indeed, ethanol is the main yeast growth inhibitor acting in wine. So different cultures of Brettanomyces were run varying the initial ethanol content (0-90 g/l). Its influence on yeast growth was shown. A term representing the critical ethanol concentration was introduced in the model as an indicator of the ethanol tolerance. This model fairly represented the behaviour of Brettanomyces intermedius yeast, a wine spoilage micro-organism. The convenience of the model was also observed with literature data obtained for Saccharomyces sp. yeasts. Such a model can be applied in predictive microbiology, to determine a risk-free time lag towards the development of a given yeast. (C) 2003 Elsevier Science Ltd. All rights reserved.