Extended cardinal parameter growth and growth boundary model for non-proteolytic Clostridium botulibum – effect of ten environmental factors

Ioulia Koukou, Tina Dahl Devitt, Juoazas Janionis, Ole Mejholm, Paw Dalgaard

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Introduction: Growth and toxin formation by non-proteolytic Clostridium botulinum in chilled seafood can be managed with ≥ 3.5% water phase salt (WPS). However, recent dietary recommendations suggest reduced salt intake due to negative health effects of sodium and therefore, other environmental factors should be used to prevent growth of C. botulinum. The aim of this study was to expand an available growth and growth boundary model for nonproteolytic C. botulinum with terms for CO2 and smoke components (phenol) to predict growth responses and facilitate product development as well as documentation of food safety for MAP smoked seafood. Methodology: Four nontoxigenic C. botulinum group II isolates were studied and cardinal parameter values for CO2 (CO2max in equilibrium = 280.75%) and phenol (Pmax = 27.52 ppm) were determined in seafood challenge studies and used to expand an available model. The new model included the effect of ten environmental factors (temperature, pH, aw, acetic, benzoic, citric, lactic and sorbic acids, CO2 and phenol). Results: Evaluation of the new model by comparison of observed and predicted μmax-values for 56 growth curves in seafood resulted in bias factor of 1.12 and accuracy factor of 1.40. Interestingly, smoke components (phenol) in hot-smoked fish, opposed to cold-smoked fish, had no inhibitory effect on growth of non-proteolytic C. botulinum. Conclusions and relevance: The new and expanded model can be used to facilitate product development for a wide range of chilled seafood. As an example for chilled (7°C) cold-smoked halibut with pH 6.3, 15 ppm phenol and 3500 ppm acetic and 7000 ppm lactic acids: Reducing WPS from 3.5% to 1.5% resulted in predicted growth (ψ-value = 0.69). However, with 5500 ppm acetic and 9000 lactic acids at pH 6.0 growth of non-proteolytic C. botulinum was prevented (ψvalue = 1.56). For vacuum-packed cold-smoked salmon at 5°C, with pH 6.2, 7000 ppm lactic acid and 10 ppm phenol: When WPS was reduced from 3.5% to 1.5%, growth was predicted (ψvalue = 0.63). When using MAP with 50% CO2 in equilibrium, 3000 ppm acetic acid and pH 5.8 growth was prevented (ψ-value > 2) as for 3.5 %WPS.
Original languageEnglish
Publication date2019
Number of pages1
Publication statusPublished - 2019
Event11th International Conference on Predictive Modelling in Food - Braganza, Portugal
Duration: 17 Sep 201920 Sep 2019
Conference number: 11


Conference11th International Conference on Predictive Modelling in Food
Internet address


  • Phenol
  • Low salt
  • Carbon dioxide
  • MAP
  • Chilled seafood


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