The effect of combined stress factors on resistant Bacillus cereus spores in sauerkraut production
Sauerkraut is traditionally prepared by shredding cabbage, salting it, and allowing facultative fermentation to occur at room temperature. However, improper hygiene practices during handling can still introduce Bacillus cereus spores, a potential foodborne pathogen, into the sauerkraut. This study investigated the effectiveness of a combination of stress factors (lactic acid, NaCl, and temperature) on B. cereus spores. The findings indicated that all three factors significantly affected spore germination rate, membrane permeability, fluidity, and the release of dipicolinic acid (DPA) and DNA. A mathematical model was established to predict stress responses based on the combined effects of these factors. The optimal conditions for controlling B. cereus spore outgrowth were identified as 2% NaCl, 1.2% lactic acid, and heat treatment at 82°C for 20 min. This combination effectively disrupted B. cereus spores and could be used as a control point during sauerkraut fermentation. Verification through a sauerkraut production model with a B. cereus spores challenge test demonstrated the efficacy of this approach, with significant reductions in B. cereus spores to approximately 1 log cycle during fermentation. This study highlights the potential of combining multiple stress factors to control B. cereus spores in pickled and fermented fruit and vegetable products.