Growth of Listeria monocytogenes in melon, watermelon and papaya pulps

Growth of Listeria monocytogenes in low-acid fruits (melon, watermelon and papaya) at different times of incubation and at temperatures of 10, 20 and 30 °C was studied. Fruit pulp portions with an average pH of 5.87, 5.50 and 4.87 for melon, watermelon and papaya, respectively, were obtained aseptically, homogenized, weighed and inoculated with suspensions (approximately 102 CFU/g) of L. monocytogenes. Generation times of 7.12, 13.03 and 15.05 h at 10 °C, 1.74, 2.17 and 6.42 h at 20 °C and 0.84, 1.00 and 1.16 h at 30 °C were obtained, respectively, for melon, watermelon and papaya. The results showed that L. monocytogenes grew in low-acid fruits at all tested temperatures, although growth was diminished, but not inhibited at 10 °C.