Abstract

FIGUERA, Bertha et al. Growth of Listeria monocytogenes in smoked tuna vacuum packaged. Zootecnia Trop. [online]. 2005, vol.23, n.2, pp.171-181. ISSN 0798-7269.

Processed fish frequently gets contaminated with pathogenous bacteria like Listeria monocytogenes, which can grow in fresh or frozen products, with a high prevalence in smoked fish. The objective of this study is to determine growth of L. monocytogenes in a smoked tuna vacuum packed. Samples were obtained from a tuna processing plant and brought to Food Technology Laboratory INIA-Sucre/Nueva Esparta, where freshness analyses were performed on the fresh and the processed products. An inoculum was prepared with certified Mac Farland 0.4 strains. The fish were beheaded, gutted, washed and cut in pieces about 300 g. Two subsamples were prepared which were placed in 8% and 10% brine by 20 min. Then they were inoculated and smoked (40°C and 50°C) by six hours. Afterwards, they were vacuum packed and refrigerated. Growth of L. monocytogenes was monitored every 7 days, using agar PALCAM. Average values of pH (5.74), BTVN (20.85 mg/100g), coliforms (1.1 x 10³ MPN/g) and mesophils (2.7 x 10⁵ CFU/g) from the raw material showed that it was in good condition for the essay, since they were under established limits. The results of L. monocytogenes growth during refrigeration showed that smoking had an inhibitory effect of the initial population, but an increase was observed after seven days of processing

Keywords : smoking tuna; contamination.