Hassan A N, Frank J F
Department of Food Science and Technology, Center for Food Safety and Quality Enhancement, The University of Georgia, Athens, GA 30602-2106, USA.
Int J Food Microbiol. 2003 Oct 15;87(1-2):145-52. doi: 10.1016/s0168-1605(03)00062-x.
The influence of surfactant hydrophobicity on detachment of Escherichia coli O157:H7 from lettuce was determined. Lettuce pieces inoculated with the pathogen were rinsed with Tween and Span surfactants of different hydrophobicity. Of the Tweens, only Tween 85, the Tween with the lowest hydrophile/lipophile balance (HLB), significantly detached the pathogen from lettuce surface. Span 85 (the surfactant with the lowest HLB studied) exhibited the greatest ability among surfactants tested to detach cells from lettuce. This surfactant removed cells attached to the leaf cuticle but not to the cut edge, and caused no detectable reduction in viability of cells remaining on the lettuce. Treatment with Span 85 did not detach cells when they were allowed to attach in the presence of calcium ions. The combination of NaCl/NaHCO3 (pH 10) and Span 85 did not detach cells possibly due to reduced hydrophobicity of the Span at this pH. This study suggests that surfactants of low HLB disrupt hydrophobic interactions between E. coli O157:H7 and the lettuce surface but cannot cause release of cells adhering to hydrophilic structures such as cut or damaged tissue.
测定了表面活性剂疏水性对大肠杆菌O157:H7从生菜上脱落的影响。用不同疏水性的吐温（Tween）和司盘（Span）表面活性剂冲洗接种了该病原体的生菜片。在吐温中，只有亲水亲油平衡（HLB）最低的吐温85能显著使病原体从生菜表面脱落。司盘85（所研究的HLB最低的表面活性剂）在测试的表面活性剂中表现出从生菜上脱落细胞的能力最强。这种表面活性剂能去除附着在叶片角质层上而非切口边缘的细胞，并且对残留在生菜上的细胞活力没有可检测到的降低作用。当细胞在钙离子存在的情况下附着时，用司盘85处理不能使其脱落。NaCl/NaHCO3（pH 10）和司盘85的组合可能由于在此pH下司盘的疏水性降低而不能使细胞脱落。本研究表明，低HLB的表面活性剂会破坏大肠杆菌O157:H7与生菜表面之间的疏水相互作用，但不能导致附着在诸如切口或受损组织等亲水结构上的细胞释放。
