Wang H, Feng H, Liang W, Luo Y, Malyarchuk V
Grocery Manufacturers Assn., Washington, D.C. 20005, USA.
J Food Sci. 2009 Jan-Feb;74(1):E8-E15. doi: 10.1111/j.1750-3841.2008.00998.x.
This study was undertaken to evaluate the effect of surface roughness on the attachment and removal of Escherichia coli O157:H7 on selected fruit and metal surfaces. A new method to determine surface roughness was developed using confocal laser scanning microscopy (CLSM). A series of 2-D layered images were taken by CLSM optical slicing of the surfaces of Golden Delicious apples, navel oranges, avocadoes, and cantaloupes. The average roughness (R(a)) of the fruit surfaces was assessed by reconstructing a series of 2-D images into 3-D images. A cocktail of 5 E. coli O157:H7 strains were spot inoculated onto fruit skin surfaces with different R(a). The fruits were then treated with acidic electrolyzed water (AEW), peroxyacetic acid (POAA), and sterilized deionized water. Aluminum stubs with different R(a) values as a model system were also spot inoculated with E. coli O157:H7 and subjected to a sonication treatment. Test results indicated that there was a positive linear correlation between R(a) and adhesion rate of E. coli O157:H7, and a negative correlation between R(a) and the efficacy of inactivation by AEW and POAA, respectively, on fruit surfaces. A linear increase of residual bacteria population with increased surface roughness of aluminum stubs was also observed. The relationship between surface roughness and surface hydrophobicity was negative linear for the aluminum stubs, but was quadratic for the 4 fruits. The environmental scanning electron microscopy images showed that bacteria tended to attach to or be entrapped in the grooves or cavities of fruits, which provided protection to the cells against washing treatments.
本研究旨在评估表面粗糙度对大肠杆菌O157:H7在选定水果和金属表面的附着及去除效果。利用共聚焦激光扫描显微镜（CLSM）开发了一种测定表面粗糙度的新方法。通过CLSM对金冠苹果、脐橙、鳄梨和哈密瓜表面进行光学切片，获取了一系列二维分层图像。通过将一系列二维图像重建为三维图像来评估水果表面的平均粗糙度（R(a)）。将5株大肠杆菌O157:H7菌株的混合菌液点接种到具有不同R(a)值的水果表皮表面。然后用酸性电解水（AEW）、过氧乙酸（POAA）和无菌去离子水对水果进行处理。还将具有不同R(a)值的铝短柱作为模型系统，点接种大肠杆菌O157:H7并进行超声处理。测试结果表明，R(a)与大肠杆菌O157:H7的粘附率之间呈正线性相关，而R(a)与AEW和POAA在水果表面的灭活效果之间分别呈负相关。还观察到随着铝短柱表面粗糙度的增加，残留细菌数量呈线性增加。对于铝短柱，表面粗糙度与表面疏水性之间呈负线性关系，但对于这4种水果则呈二次关系。环境扫描电子显微镜图像显示，细菌倾向于附着在水果的凹槽或空洞中或被困在其中，这为细胞提供了抵御清洗处理的保护。
