Modeling and scenario-based risk estimation of Listeria monocytogenes in meatballs and Sundae, a Korean black pudding, under different packaging conditions

Abstract

Vacuum packaging is known to be an effective way to limit the growth of food spoilage and food-poisoning bacteria. However, Listeria monocytogenes (LM) can survive under low-oxygen conditions and as well as refrigeration temperatures. This study was conducted to model the fate of LM-inoculated meatballs and Sundae, a Korean black pudding, and assess the effect of packaging (aerobic packaging, AP; vacuum packaging, VP) on risk. Meatballs and Sundae were spiked with LM and stored at temperatures ranging from 5 to 37 °C. Primary models were developed using the Baranyi model, and secondary models for the maximum growth rate (μmax) of meatballs and Sundae were developed using a square root model. The developed primary and secondary models were fitted well with a high goodness-of-fit (R2 ≥ 0.98). The bias factor (Bf) was 1.002–1.015, and the root mean square error (RMSE) was 0.002–0.051 1/h. Furthermore, dynamic models were developed and validated, with corresponding RMSE values < 0.851 ln CFU/g (<0.370 log CFU/g) and acceptable simulation zone (ASZ) values > 82%. Comparing the growth of LM according to the packaging, the lag phase duration of both samples was significantly shorter in VP than in AP; however, μmax of meatball at 10 °C was significantly faster in VP than in AP (p < 0.05). The probability of infection (Pinf) from the consumption of meatballs or Sundae with different packaging types was estimated using Monte Carlo simulations and scenario analysis. Simulation results showed that Pinf from the consumption of meat-based ready-to-eat foods with VP was not always lower than that with AP. There is a need to control the contamination of LM before packaging by placing efforts on implementing control measures during processing.