Table 1 shows the results of pH, Brix, Titratable Acidity, and total and reducing sugars of the different fruit pulp. The physical and chemical results show that, with respect to carbohydrate content, fruit pulp is an adequate substrate for L. monocytogenes to grow in. The average pH cannot be considered inhibitory,especially in melon and watermelon. Papaya pulp, being even more acidic, is typically a low acid fruit (pH>4.6). Thus, the fruit pulp composition alone of the fruits does not appear to be a barrier to Listeria growth. endogenous microflora in the interior tissues of thefruits. Samish et al. (1963) stated that in healthy fruits,the bacterial flora is assumed to be limited to thesurface, while the inner tissue remains sterile. The results shown in Figs. 1–3 confirm the adequacy of the fruit pulp as a substrate for L. monocytogenes growth at different temperatures and incubation times. Our results are supported by those of Nguyen and Carlin (1994), who mentioned that minimally processed fresh fruits and vegetables are good media for growth of microorganisms. For papaya, Listeria presented a lag time longer when compared with the others pulps, this was probably due to the fact that the pH of papaya is 4.87, lower than the ones noticed for melon and watermelon. The maximum populations of about 5, 4 and 7 log units were reached in temperatures of 10, 20 and 30 jC at the end of the incubation periods.