Percorrer por autor "Dong, Qingli"
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- A Quantitative Risk Assessment Model for Listeria monocytogenes in Non-Ready-to-Eat Frozen VegetablesPublication . Gonzales-Barron, Ursula; Pouillot, Régis; Mota, Juliana de Oliveira; Hasegawa, Akio; Allende, Ana; Dong, Qingli; Stasiewicz, Matthew J.; Kovacevic, Jovana; Cadavez, Vasco; Guillier, Laurent; Sanaa, MoezA quantitative risk assessment (QRA) model was developed to evaluate the risk of invasive listeriosis from the consumption of non-ready-to-eat (non-RTE) frozen vegetables. On a lot basis, the QRA model simulates Listeria monocytogenes concentration and prevalence in a “Processing module” that comprises blanching, potential recontamination and packaging, any post-packaging inactivation treatment, and within-lot end-product testing and in a subsequent “Consumer’s handling module” that encompasses portioning of frozen vegetables, defrosting, and cooking. Based on available published data, the model was coded in nine sequential R functions designed to assess the effectiveness of blanching, the improvement in processing environment hygiene, the implementation of sampling schemes at the end of processing, and improved consumer instructions on the product’s package. In a reference scenario, the model estimated that 9.4% of 500 g packages of frozen vegetables would be contaminated, although at mean levels lower than 10 CFU/g, and assuming that 20% of the portions of frozen vegetables would be left to thaw at room temperature for 2 h, the lot-level mean risk of listeriosis in the susceptible population would be 2.935 × 10−14 (median 5.446 × 10−15) for uncooked 50 g servings and 2.765 × 10−17 (median 5.184 × 10−18) for cooked 50 g servings. Analysis of selected scenarios suggested that not cooking the non-RTE product contributes to the risk to a greater extent than the level of contamination in the incoming raw vegetables, the latter in turn being more influential than the level of contamination in the processing environment. The QRA model is freely available as an R package with full documentation and can be used as a tool to inform the consideration of strengthened risk management measures in view of the current changes in consumer behavior and new diet trends.
- A Quantitative Risk Assessment Model for Listeria monocytogenes in Ready-to-Eat CantaloupePublication . Guillier, Laurent; Gonzales-Barron, Ursula; Pouillot, Régis; Mota, Juliana De Oliveira; Allende, Ana; Kovacevic, Jovana; Guldimann, Claudia; Fazil, Aamir; Al-Qadiri, Hamzah; Dong, Qingli; Hasegawa, Akio; Cadavez, Vasco; Sanaa, MoezThis study introduces a farm-to-fork quantitative risk assessment (QRA) model for invasive listeriosis from ready-to-eat diced cantaloupe. The modular model comprises seven stages-preharvest (soil and irrigation contamination), harvest (cross-contamination and survival), pre-processing (brushing), processing (flume tank washing, dicing and equipment cross-contamination), lot testing, cold-chain transport and retail growth, and consumer storage/handling. Each stage employs stochastic functions to simulate microbial prevalence and concentration changes (growth, inactivation, removal, partitioning, cross-contamination) using published data. In a reference scenario-good agricultural practices (soil barriers, no preharvest irrigation), hygienic processing and proper cold storage-the model predicts low lot- and pack-level contamination, with few packs >10 CFU/g and most servings below detection; the mean risk per serving is very low. "What-if" analyses highlight critical control points: the absence of soil barriers with preharvest irrigation can increase the risk by 10,000-fold; flume tank water contamination has a greater impact than harvest-stage cross-contamination; and poor consumer storage can raise the risk by up to 500-fold. This flexible QRA framework enables regulators and industry to evaluate and optimize interventions-from improved agricultural measures to targeted sampling plans and consumer guidance-to mitigate listeriosis risk from RTE diced cantaloupe.