The effect of preparation of cebiche on the survival of enterotoxigenic Escherichia coli, Aeromonas hydrophila, and Vibrio parahaemolyticus.

BACKGROUND

Cebiche is a common dish in Latin America, prepared using raw fish mixed with vegetables and marinated with lime juice. The acidity of the lime juice is commonly believed to destroy bacteria and render cebiche as safe to eat. Little data exist concerning rates of cebiche-associated gastroenteritis outbreaks, although these may be high given the popularity of the dish.

METHODS

We inoculated raw fish with Aeromonas hydrophila, Vibrio parahaemolyticus, and enterotoxigenic Escherichia coli to determine the effect of the cebiche preparation process on bacterial viability. Raw fish were exposed to a suspension of 1.0 × 10(8) colony-forming units (CFUs) of each organism in a 50-mL solution, prior to the addition of cebiche ingredients. A typical Peruvian cebiche recipe was used combining limes, onions, sweet potatoes, cilantro, and hot peppers marinated together for 30 minutes. A homogenized mixture of the dish was then evaluated for pH and bacterial counts at 0, 10, and 30 minutes. As much as 100 µL of inocula were streaked onto tryptic soy agar (TSA) agar plates and incubated for 24 hours.

RESULTS

The initial average pH of the fish was 6.4 prior to adding cebiche ingredients and 5.0 immediately afterwards. The pH at 10- and 30-minute periods was 5.4 and 5.2, respectively. Little reduction in bacterial counts was observed at either the 10- or 30-minute time periods, with counts increasing at 30 minutes.

CONCLUSIONS

The putative bactericidal role of lime juice in the preparation process is not sufficient to reduce the microbial population present in cebiche. Pathogens may remain viable after exposure to acidic conditions. The increasing popularity of Peruvian cuisine may also lead to cebiche-associated illness outside of Latin America.