Quantitative assessment of the risk of microbial spoilage in foods. Prediction of non-stability at 55°C caused by Geobacillus stearothermophilus in canned green beans

Abstract

Microbial spoilage of canned foods by thermophilic and highly heat-resistant spore-forming bacteria, such as Geobacillus stearothermophilus, is a persistent problem in the food industry. An incubation test at 55°C for 7 days, then validation of biological stability, is used as an indicator of compliance with good manufacturing practices. We propose a microbial risk assessment model predicting the percentage of non-stability due to G. stearothermophilus in canned green beans manufactured by a French company. The model accounts for initial microbial contaminations of fresh unprocessed green beans with G. stearothermophilus, cross-contaminations in the processing chain, inactivation processes and probability of survival and growth. The sterilization process is modeled by an equivalent heating time depending on sterilization value F 0 and on G. stearothermophilus resistance parameter z T . Following the recommendations of international organizations, second order MonteCarlo simulations are used, separately propagating uncertainty and variability on parameters. As a result of the model, the mean predicted non-stability rate is of 0.5%, with a 95% uncertainty interval of [0.1%; 1.2%], which is highly similar to data communicated by the French industry. A sensitivity analysis based on Sobol indices and some scenario tests underline the importance of cross-contamination at the blanching step, in addition to inactivation due to the sterilization process.

Probabilistic exposure assessment model to estimate aseptic-UHT product failure rate

“…μ opt Cb was set based on mean of data found in the database Combase at optimal condition in culture medium (no data with milk-based product). μ opt Gs was set with values from Rigaux et al (2014). Lag min k were set as a large distribution to include possible damage from previous treatment.T min Bc , T opt Bc , T max Bc , pH min Bc and pH opt Bc were set with values from European Food Safety Authority (2005) and Daelman (2013).…”

Added value of experts' knowledge to improve a quantitative microbial exposure assessment model — Application to aseptic-UHT food products

“…On the other hand, if the model is driven by uncertainty, it might be valuable to reduce the uncertainty before suggesting any risk management options. For all these reasons, separating uncertainty and variability in exposure or risk assessment model is a technique that is increasingly being applied (Bier and Lin, 2013;Cummins et al, 2008;Gallagher et al, 2013;Pouillot et al, 2004;Rigaux et al, 2013aRigaux et al, , 2014.…”

Multiplex PCR for rapid detection of thermophilic Moorella thermoaceticaand Geobacillus stearothermophilus from canned foods and beverages

“…Bacteria belonging to these genera can survive heat treatment at 100°C for 10 min and have previously been associated with canned food spoilage (Feig & Stersky, 1981;Raso et al, 1995;Andr e & Remize, 2013). To guarantee microbiological stability, an additional heat treatment step has been added to commercial food sterilization processes by many manufacturers; however, this is a costly operation in terms of energy and impact on the organoleptic quality and nutritional value of the product (Rigaux et al, 2014).…”