MODELING GROWTH FOR PREDICTING THE CONTAMINATION LEVEL OF GUAVA NECTAR BY CANDIDA-PELLICULOSA UNDER DIFFERENT CONDITIONS OF PH AND STORAGE-TEMPERATURE

The combined effects of temperature (2-46 degrees C) and pH (1.55-6.25 ) on the growth of Candida pelliculosa isolated from guava nectar prod uced in Cameroon were studied using a turbidity method, ie measurement of optical density at 630 nm, A quadratic polynomial model was constr ucted to predict the effects and interactions of these two environment al conditions on the maximal optical density obtained (r(2) = 0.97), T he relation between optical density and population density of C, pelli culosa (CFU ml(-1)) was also established using an exponential regressi on (r(2) = 0.99), According to the model, maximal growth conditions we re 37 degrees C and pH 6.25 for obtaining the maximal optical density of 1.25 corresponding to about 60 x 10(6) CFU ml(-1), A good agreement of the model was found between the predicted values and the observed values of maximal optical density, The model was validated by the expe rimental values of maximal optical density obtained in the growth of C . pelliculosa in commercial guava nectar (pH 3.15).