Inactivation of Bacillus cereus spores in infant formula by combination of high pressure and trans-cinnamaldehyde

This study investigated the combined effects of trans-cinnamaldehyde (TC) and high pressure (HP) to inactivate B. cereus spores in reconstituted infant formula. High pressure (600 MPa for 5 min), with or without TC (0.1%), was applied to reconstituted infant formula with B. cereus spores. Samples were stored at 23 and 7 °C for 4 and 6 weeks, respectively. Microbiological and sensory analyses, pH and emulsion stability of each sample were determined. At 7 °C, B. cereus spores in HP and TC treated formula were reduced by 2.4 and 3.1 log, respectively. At 23 °C, the highest inactivation was observed with TC alone and TC combined with HP, by 2.1 log. Overall, HP showed the highest inactivation rate when combined with TC, confirming the synergistic antimicrobial effect of TC and HP. Remarkable deformation and damage in both B. cereus vegetative cells and spores were observed by transmission electron microscopy after the application of HP and TC. Although TC exhibited a cinnamon-like taste, overall sensory attributes were not significantly different than the control samples. These results suggest that TC and HP could be incorporated in infant formula as a natural intervention to replace the synthetic preservatives and/or enhance the microbiological safety and shelf-life.