Department of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713, Republic of Korea.
Int J Food Microbiol. 2013 Sep 16;166(3):499-507. doi: 10.1016/j.ijfoodmicro.2013.08.016. Epub 2013 Aug 29.
The antimicrobial effects of natural compounds (caprylic acid, CA; citric acid, CTA; and vanillin, VNL) on the inactivation of Cronobacter sakazakii and Salmonella enterica serovar Typhimurium were examined in reconstituted infant formula. The samples were treated with: 1) CA, CTA, or VNL alone (0, 10, 20, 30, 40, 60, and 80 mM); 2) a combination of CA (10 and 20 mM) and CTA (15 and 30 mM); and 3) a combination of CA (10 and 20 mM) and VNL (15 and 30 mM), at mild feeding temperatures (40 °C and 45 °C), and the bacterial populations were assayed periodically (0, 5, 10, and 30 min). For both bacteria, the combined treatments had marked synergistic antimicrobial effects compared with the sum of the effects of each individual treatment. For example, there was no noticeable reduction (P > 0.05) in the population of C. sakazakii following an individual treatment with 20 mM CA or 30 mM CTA for 5 min at 40 °C, whereas the population was reduced to undetectable levels (reduction > 7.3 log CFU/ml) following treatment with a combination of CA and CTA (20 CA+30 CTA for 5 min at 40 °C). As the temperature increased, the bactericidal effect was stronger at all time points with a synergistic effect. In a validation assay using a low level inoculum (approximately 10³ CFU/ml) of desiccation-stressed bacteria in certain conditions, the combined treatments (e.g., CA 10 mM+CTA 30 mM for 5 min at 45 °C for C. sakazakii, and CA 10mM+VNL 15 mM for 10 min at 45 °C for S. Typhimurium) completely destroyed the bacteria with no recovery of cell viability. Disintegration of the membrane and changes in the cell structure or morphology, such as plasmolysis and membrane disruption, were detected by flow cytometry and electron microscopy, respectively. These methods use antimicrobials that could be applied as food additives in infant formula, which may help to eliminate bacteria.
研究了天然化合物（辛酸、CA；柠檬酸、CTA；和香草醛、VNL）在配制婴儿配方奶粉中对阪崎克罗诺杆菌和肠炎沙门氏菌 Typhimurium 失活的抗菌作用。样品分别用：1）CA、CTA 或 VNL 单独处理（0、10、20、30、40、60 和 80 mM）；2）CA（10 和 20 mM）和 CTA（15 和 30 mM）的组合；3）CA（10 和 20 mM）和 VNL（15 和 30 mM）的组合，在温和的喂养温度（40°C 和 45°C）下处理，并且定期检测细菌群体（0、5、10 和 30 分钟）。对于两种细菌，与每种单独处理的效果总和相比，联合处理具有明显的协同抗菌作用。例如，在 40°C 下，单独用 20 mM CA 或 30 mM CTA 处理 5 分钟，不会导致阪崎克罗诺杆菌种群数量明显减少（P>0.05），而用 CA 和 CTA 的组合处理（20 CA+30 CTA 在 40°C 下处理 5 分钟），则会减少到无法检测到的水平（减少>7.3 log CFU/ml）。随着温度升高，在所有时间点均具有协同作用，杀菌效果更强。在某些条件下，使用低水平接种物（约 10³ CFU/ml）的干燥胁迫细菌进行验证试验时，联合处理（例如，CA 10 mM+CTA 30 mM 在 45°C 下处理 5 分钟，用于阪崎克罗诺杆菌，以及 CA 10 mM+VNL 15 mM 在 45°C 下处理 10 分钟，用于肠炎沙门氏菌）可完全破坏细菌，细胞活力无恢复。通过流式细胞术和电子显微镜分别检测到细胞膜的崩解以及细胞结构或形态的变化，如质壁分离和膜破裂。这些方法使用的抗菌剂可以作为婴儿配方奶粉中的食品添加剂，有助于消除细菌。
