3.2.2. Vegetable damage parameters
In Figs. 3 and 4, lag phase period, S , andalteration percentage, A , are plotted as a function of temperature. Incubation of bacterial cultures to anabusive temperature such as 108C had dramaticconsequences on vegetable damage. In fact, lagperiod fell from 25 days at 48C to 3 days at 108C.Moreover, alteration percentage increased with temperature: 70–87% with temperature of 4 and 108C,respectively. To predict the effect of temperature ondegradation of pectic compounds, Ratkowsky’sequation was adapted and written as ÏSp 5b ? (T-T ) with T value estimated to 1.38C. To fidegradation percentage, the linear equation Ap=b(T-Cte) seemed sufficient. As suggested by Ratkowsky (1993) or by Baranyi et al. (1996), in apredictive microbiology approach, a model should beas parsimonious as possible. The square root modelwas employed in this study to determine the temperature effects on the two different parameters, mand S . Moreover, in each case, T values weresimilar and in agreement with experimental data (nogrowth at 08C). This homogeneity and also the ratheraccurate fitting results led us to use this model asreference in predictive model validation.