Abstract

MORALES, Graciela; BLANCO, Laura; ARIAS, María Laura  and  CHAVES, Carolina. Evaluación de la calidad bacteriológica de tilapia fresca (Oreochromis niloticus) proveniente de la Zona Norte de Costa Rica. ALAN [online]. 2004, vol.54, n.4, pp.433-437. ISSN 0004-0622.

SUMMARY Bacteriological evaluation of fresh tilapia (Oreochromis niloticus) coming from the northern region of Costa Rica. The following work presents an evaluation of the normal and pathogenic flora associated to tilapia (Oreochromis niloticus), since there are no previous national studies referred to the microbiological quality of this product. The total aerobic plate count, lactic bacteria, Enterococcus sp and Aeromonas sp and fecal and total coliform count, and the presence of Listeria sp and Salmonella spp from the external surface of tilapias were evaluated. A total of 50 samples, coming from San Carlos and Cañas zones were transported in ice to the Food and Water Microbiology Laboratory, Universidad de Costa Rica, where the laboratory analysis were performed, according to the methodology presented by de American Public Health Association, 1998. The results obtained confirm the microbiological freshness of the product when the analysis was performed, although coliform levels were unacceptable. Listeria sp was not found, but the isolation of Salmonella spp. confirms the fecal contamination of water where the tilapia is grown, aside of the Public Health concern. Also, it was found a high number of Aeromonas sp, as part of its normal flora, so we recommend including this genus in the quality standards for fresh fish. According to the data obtained, there was no significant difference (95% confidence) between the total plate count, fecal and total coliforms, Enterococcus sp. and Aeromonas sp. from the samples coming from the zones of San Carlos and Cañas.

Keywords : Tilapia; microbiological evaluation; Enterococcus sp; Aeromonas sp; Listeria sp; Salmonella spp..