Calidad microbiológica de la materia prima y el producto final del ceviche de tilapia y de camarón expendidos en el Área Metropolitana de San José, Costa Rica

Microbiological quality of raw material and final product of tilapia and shrimp ceviche expended in the Metropolitan Area of San José, Costa Rica. Ceviche is a common use dish from Latin American countries, made up of raw fish or seafood marinated with lemon or lime juice, and several seasoning ingredients. It includes the normal flora coming from raw product and flora acquired from handling and additional ingredients. The product is consumed raw, representing a risk for Public Health. The aim of this work was to determine the microbiological quality of tilapia fish ceviche and shrimp ceviche sold at the Metropolitan Area of San José, Costa Rica, as well as the raw material used in its elaboration. A total of 25 samples of tilapia ceviche and 27 samples of shrimp ceviche were analyzed; the same number of raw material was analyzed. The behavior of some of the spoilage populations was analyzed in 25 samples of shrimp and same number of tilapia ceviche during its storage at 4oC. Even though the ceviche includes manipulation plus an important bacterial contamination in raw material, there is an important reduction in the bacterial charge of the final product, especially referring to total aerobic psychrofilic plate count and total coliforms; but not to fecal coliforms. Escherichia coli was isolated from 15% of the tilapia’s ceviche and 4% from shrimp’s ceviche, 3 strains of Listeria monocytogenes were isolated from tilapia, one from shrimp, 3 strains of V. parahaermolyticus were isolated from shrimp and 2 from its ceviche. Salmonella spp. was not isolated. The pH of ceviche plates stored at 4oC for one week showed a trend towards stability or a slight increase of this parameter. The concentration of spoilage microorganisms suffered slight variations, nevertheless, the low number of Pseudomonas spp. present in tilapia’s ceviche is an outstanding result considering that this population is associated to spoilage of the product.KEY WORDSCeviche, tilapia, shrimp, spoilage.