Presence of Listeria Species in Ready-Made Meatballs Offered by Sale Under Freezing or Cooling Preservation

Abstract

This study was conducted to detect contamination level of Listeria species in ready-made meatballs kinds that are stored under frozen or cooled conditions. In isolations and identifications of Listeria species from the samples, method approved and suggested by USDA/FSIS (United States Department of Agriculture/Food Safety and Inspection Service) was used. The strains that were identified to be Listeria monocytogenes with biochemical tests was verified as species through Real Time PCR method by using a primary pair specific to hly A gene location. In this study, a total number of 290 different type ready-made meatball samples were analysed. As a result of examining all samples was isolated L. monocytogenes in 32 (11.04%) samples, L. ivanovii in 9 (3.10%) samples, L. innocua in 22 (7.59%) samples, L. welchimerii in 8 (2.76%) samples and also L. seeligeri in 4 (1.38%) samples. In the serotyping of the 32 L. monocytogenes strains isolated from the samples; 15 isolated are found to be Type I, where 3 strains are found to be Type 4, 11 strains to be type Poly and the rest 3 strains could not typified. The Mean pH and water activity values for the samples were found to be 6.62 +/- 0.56 and 0.985 +/- 0.007 respectively. In the result of the study, identifying Listeria species especially L. monocytogenes in cooled and frozen ready-made meatball samples studied suggest that such products whose consumption increased in the recent years pose important risk in terms of public health.