School of Food Science, Washington State University, Pullman, WA 99163, USA.
J Food Sci. 2012 Jan;77(1):M86-93. doi: 10.1111/j.1750-3841.2011.02503.x. Epub 2011 Dec 19.
Cronobacter sakazakii is an opportunistic pathogen associated with dry infant formula presenting a high risk to low birth weight neonates. The inactivation of C. sakazakii in dry infant formula by ultraviolet (UV) radiation alone and combined with hot water treatment at temperatures of 55, 60, and 65 °C were applied in this study. UV radiation with doses in a range from 12.1 ± 0.30 kJ/m² to 72.8 ± 1.83 kJ/m² at room temperature demonstrated significant inactivation of C. sakazakii in dry infant formula (P < 0.05). UV radiation combining 60 °C hot water treatment increased inactivation of C. sakazakii cells significantly (P < 0.05) in reconstituted infant formula. Significant effects of UV radiation on C. sakazakii inactivation kinetics (D value) were not observed in infant formula reconstituted in 55 and 65 °C water (P > 0.05). The inactivation mechanism was investigated using vibrational spectroscopy. Infrared spectroscopy detected significant stretching mode changes of macromolecules on the basis of spectral features, such as DNA, proteins, and lipids. Minor changes on cell membrane composition of C. sakazakii under UV radiation could be accurately and correctly monitored by infrared spectroscopy coupled with 2nd derivative transformation and principal component analysis.
阪崎克罗诺杆菌是一种与干婴儿配方奶粉有关的机会致病菌，对低出生体重儿构成高风险。本研究应用紫外线（UV）单独辐射和结合 55、60 和 65°C 热水处理对干婴儿配方奶粉中的阪崎克罗诺杆菌进行失活处理。在室温下，剂量范围为 12.1±0.30 kJ/m²至 72.8±1.83 kJ/m²的紫外线辐射对干婴儿配方奶粉中的阪崎克罗诺杆菌具有显著的失活作用（P<0.05）。UV 辐射与 60°C 热水处理相结合，显著增加了婴儿配方奶粉中阪崎克罗诺杆菌细胞的失活（P<0.05）。在 55 和 65°C 水中重新配制的婴儿配方中，未观察到紫外线辐射对阪崎克罗诺杆菌失活动力学（D 值）的显著影响（P>0.05）。利用振动光谱研究了失活机制。基于光谱特征，如 DNA、蛋白质和脂质，红外光谱检测到了大分子的显著伸缩模式变化。红外光谱结合二阶导数变换和主成分分析，可以准确、正确地监测到阪崎克罗诺杆菌细胞膜组成在紫外线辐射下的微小变化。
