Salmonella prevalence in raw cocoa beans and a microbiological risk assessment to evaluate the impact of cocoa liquor processing on the reduction of Salmonella

Xingchen Zhao, Liesbeth Jacxsens, Vesela Tzeneva, Michiel Kokken, Anett Winkler, Cécile Vadier, Nicolau de Toledo, Tomasz Seliwiorstow, Mieke Uyttendaele*

*Corresponding author for this work

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Abstract

Salmonella in raw cocoa beans (n= 870) from main sourcing areas over nine months was analyzed. It was detected in 71 (ca. 8.2%) samples, with a contamination level of 0.3-46 MPN/g except for one sample (4.1×104 CFU/g). Using prevalence and concentration data as input, the impact of thermal treatment in cocoa processing on the risk estimate of acquiring salmonellosis by a random Belgian chocolate consumer was calculated by a quantitative microbiological risk assessment (QMRA) approach. A modular process risk model from raw cocoa beans to cocoa liquor up to a hypothetical final product (70-90% dark chocolate tablet), was set up to understand changes of Salmonella concentrations following the production process. Different thermal treatments during bean or nib steam, nib roasting or liquor sterilization (achieving a 0-6 log reduction of Salmonella) were simulated. Based on the generic FAO/WHO Salmonella dose-response model and the chocolate consumption data in Belgium, salmonellosis risk per serving and cases per year at population level were estimated. When a 5 log reduction of Salmonella was achieved, the estimated mean risk per serving was 3.35×10-8 (95% CI: 3.27×10-10-1.59×10-7), and estimated salmonellosis cases per year (11.7 million population) was 88 (95% CI: <1-418). The estimated mean risk per serving was 3.35×10-9 (95% CI: 3.27×10-11-1.59×10-8), and the estimated salmonellosis cases per year was 9 (95% CI: <1-42), for a 6 log reduction. The current QMRA model solely considered Salmonella reduction in a single-step thermal treatment in the cocoa process. Inactivation obtained during other process steps (e.g. grinding) might occur but was not considered. As the purpose was to use QMRA as a tool to evaluate the log reduction in the cocoa processing, no post-contamination from the processing environment and ingredients was included. A minimum of 5 log reduction of Salmonella in the single-step thermal treatment of cocoa process, was considered to be adequate.
Original languageEnglish
Article number100327
JournalJournal of Food Protection
Volume87
Issue number9
Number of pages14
ISSN0362-028X
DOIs
Publication statusPublished - 2024

Keywords

  • Salmonella
  • Cocoa bean
  • Chocolate
  • Residual risk
  • Thermal treatment
  • Risk reduction

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