Survival of Vibrio cholerae O1 in ceviche and its reduction by heat pretreatment of raw ingredients

Abstract

The survival of Vibrio cholerae O1 serotypes Inaba and Ogawa was determined in ceviche prepared from inoculated ground fish. Ground mackerel purchased from a seafood distribution center was inoculated with V. cholerae and stored at 8 or 20 degrees C. Counts of V. cholerae decreased in 2.6 to 2.7 log10 CFU/g during 96 h of storage at 8 degrees C or 2.5 to 2.6 log10 CFU/g during 24 h at 20 degrees C. Survival studies indicated that serotype Inaba decreased its number following a linear or retarded trend, whereas serotype Ogawa followed an accelerated death trend. No effect of the initial level of inoculum was observed. Odor scores of ceviche indicated that this food became marginally acceptable within as little as 48 h of storage at 8 degrees C or 3 h at 20 degrees C and were related to total volatile nitrogen values but not to aerobic plate counts, pH, or coliform counts. A heat pretreatment that consisted of stirring 100 g of inoculated ground fish into 40 ml of boiling water produced an 8-log reduction of V. cholerae within 3 min without affecting the color, odor, or flavor of ceviche prepared with such pretreated fish. According to this study, V. cholerae present in contaminated ceviche will likely survive longer than the shelf life of this food. Preheating the ground raw fish used for preparing ceviche for 3 min should effectively eliminate V. cholerae O1, providing science-based conditions for implementing a critical control point if a hazard analysis critical control point plan were to be developed for preparation of ceviche.