Survival of Salmonella in Processed Chicken Products during Frozen Storage

Abstract

Frozen chicken products have been identified recently as a cause of salmonellosis. At least eight salmonellosis outbreaks from 1998 to 2008 have implicated undercooked frozen chicken nuggets, strips, and entrees as infection vehicles. Thus, the presence of Salmonella in frozen products may pose an infection risk if the product is improperly cooked. The objective of this study was to assess the survivability of Salmonella during frozen storage (-20 degrees ) when inoculated in processed chicken products. Four Salmonella strains originally isolated from poultry were inoculated into frozen chicken nuggets (fully cooked) and frozen chicken strips (containing raw poultry) at initial populations of 10(4) to 10(5) CFU/g. Survival was assessed during storage at -20 degrees for 16 weeks by measuring bacterial growth on minimal, selective, and nonselective agars. Results indicate that cell populations measured in nonselective agars (plate count agar and plate count agar supplemented with tetracycline) and minimal (M9) agar remained relatively constant during the entire -20 degrees storage period studied (16 weeks) for both chicken nuggets and strips. However, cell populations were significantly (P < 0.05) lower when measured in selective agar (XLT4) during the 16 weeks of frozen storage for both chicken nuggets and strips, suggesting that these cells were structurally injured. The data presented in this study indicate that Salmonella can survive frozen storage when inoculated in frozen, processed chicken products and confirm that microbial counts on selective agar are not representative of the total population of samples subject to freezing.

A 3-year hygiene and safety monitoring of a meat processing plant which uses raw materials of global origin

“…Even though the major production load of the meat plant was focused on ground meat, Salmonella was found in markedly lower percentage (P b 0.05) in these products, than in poultry. The high occurrence of the pathogen in poultry raw materials and final products (27.1%) was slightly lower compared with the 39.5% of chicken carcasses in Greece (Zdragas et al, 2012), the 34% in Turkey (Yildirim et al, 2011) or the 35.8% in Spain (Dominguez and Schaffner, 2009). However, despite the lower occurrence here compared to other studies, our findings still show markedly higher occurrence of Salmonella than the 4.1% reported at the EU level in 2012 for fresh broiler meat at processing and retail, as well as the 9.7% prevalence reported for Greece in the same year (EFSA ECDC, 2014).…”

Prevalence, Risks and Antibiotic Resistance of Salmonella in Poultry Production Chain

“…during transportation from a retail outlet to a consumer's home). Salmonella numbers are reduced under frozen storage conditions but salmonellosis outbreaks from 1998 to 2008 due to consumption of frozen products showed that bacteria can survive freezing and Salmonella may pose an infection risk if the product is improperly cooked [57]. Thus, freezing cannot be considered as an adequate control step.…”

Effect of Trisodium Phosphate or Water Dip on the Survival ofSalmonellaandListeria monocytogenesInoculated Catfish Before and After Freezing

“…In this study, we used a quickfreezing process, and little reduction of the bacteria was observed after freezing/storage. Dominguez and Schaffner (2009) reported the survival of Salmonella on chicken products after 3 months of frozen storage at −20 o C, which concurred with the results of this study for the non-dipped fillet controls also stored for 3 months at −20 o C. However, there was a significant (p < 0.05) reduction (2 log CFU/g) in Salmonella counts for the 1.5% TSP wash and frozen samples recovered after 3-months storage, but no further reduction occurred during the remainder of the frozen study. Gram-negative bacteria after a sublethal injury (TSP dip) are more prone to the lethal effects of freezing (Venugopal, 2005), which would explain the significant Salmonella reduction in the TSP dipped samples compared to the Gram-positive LM sample.…”