Abstract:In order to find a safe and effective control method for Cronobacter sakazakii (C. sakazakii), the antimicrobial activity of trans-cinnamaldehyde (TC) against C. sakazakii and its possible mechanism of action were investigated in this study. The minimum inhibitory concentrations (MICs) of TC against C. sakazakii and its effect on growth curve of C. sakazakii were determined. The effects of TC on cell membrane integrity and cell morphology of C. sakazakii were assessed by using LIVE/DEAD BacLight bacterial activity assay kit, laser scanning confocal microscope and field emission scanning electron microscope. The inhibitory effect of TC on C. sakazakii at 4 ℃, 25 ℃ and 37 ℃ was studied by constructing a reconstituted infant formula model (containing 0%, 0.1%, 0.2% or 0.4% TC), and the practical effect of TC was fully considered. The results showed that the MICs of TC against C. sakazakii ranged from 0.4 to 1.0 mg/mL and TC could effectively prolong the growth lag phase of C. sakazakii. Compared with control group, the membrane integrity of the C. sakazakii strain treated with TC at MIC and 2 MIC wasdramatically declined to 60% and 46%, respectively. The field emission scanning electron microscope confirmed that the samples treated with TC had more wrinkled surface compared with the smooth surface of the untreated cells TC at 0.4% (V/V) reduced the number of C. sakazakii in the reconstituted infant formula below the detection limit at 25 ℃ for 90 min or at 37 ℃ for 60 min. In conclusion, TC had the potential to be used as a natural antimicrobial substance in foods such as milk powder and could be further used in the food to effectively prevent and reduce related foodborne diseases caused by C. sakazakii.
