Fate of Salmonella spp. in fresh-cut papaya (Carica papaya L.) at different storage temperature and relative humidity

Salmonella has been a recurring issue in the papaya industry. The purpose of this study was to determine the effect of post-harvest storage conditions on the growth kinetics of Salmonella in fresh-cut papaya. Papaya samples were spot inoculated with nalidixic acid adopted Salmonella spp (4-strain) at 4-5 log CFU/g and then stored in an environmental chamber at six different temperature (4, 12 and 21 degrees C) and relative humidity (55 and 90%) combinations for up to 14 days. The levels of Salmonella and the changes in pH, TSS, color, and water activity of papaya were determined. Increasing the storage temperature from 4 to 21 degrees C and RH from 55 to 90% increased the log survival. However, no significant effect (P > 0.05) of RH was observed when the samples were stored either at 12 or 4 degrees C for 14 days. Both Baryani-Roberts (R20.794-0.975) and Biphasic models (0.793-0.975) best fitted the experimental data at the tested storage conditions. Salmonella showed a maximum growth rate ranging from -0.0207 to 0.0632 (1/h) and the highest growth rate was observed at 21 degrees C and 90% RH. These findings demonstrate that better control over storage temperature and RH is critical to mitigate the risk of Salmonella in papaya.