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Title: SURFACE TOPOGRAPHY AFFECTS THE ATTACHMENT AND INACTIVATION OF ESCHERICHIA COLI O157:H7 ON FRESH FRUITS

Author
item WANG, HUA - UIUC
item LIANG, WEI - UIUC
item FENG, HAO - UIUC
item Luo, Yaguang - Sunny

Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2005
Publication Date: 7/15/2005
Citation: Wang, H., Liang, W., Feng, H., Luo, Y. 2005. Surface topography affects the attachment and inactivation of escherichia coli o157:h7 on fresh fruits [abstract]. Institute of Food Technologists. Paper No. 84-6.

Interpretive Summary:

Technical Abstract: Fruit surface structure varies largely among different fruit types and maturity. However, the impact of fruit surface topography on the attachment and inactivation of human pathogens was unknown. The main objective of this study was to evaluate the effect of surface roughness of fruits on the attachment of Escherichia coli O157:H7 and its inactivation by sanitizers. Golden delicious apples, Navel oranges and cantaloupes were washed with 75% ethanol and then treated with UV light for 20 min to inactivate naturally occurring microorganisms on the fruit surfaces. Cultures of E.coli O157:H7 were spot inoculated onto the surface skin of disks of fruit and air dried at room temperature. The inoculated samples were then treated with POAA (80mg/L) or sterilized water. The surface topography and hydrophobicity of the fruit surface and adhesion strength of E. coli O157:H7 to the surface were examined, and the viable counts of E. coli O157:H7 were taken. The fruit surface roughness was assessed by reconstructing a series of 2-D layered images taken by confocal laser scanning microscopy (CLSM) into 3-D images. Test results indicated that there was a positive correlation among roughness, adhesion strength of E. coli O157:H7, and the efficacy of inactivation by the sanitizer. The water wash achieved a 0.21-log, 2.6-log and 2.78-log reduction for cantaloupes, oranges and apples, respectively, when compared to the unwashed control. POAA resulted in 1.04-log, 2.71-log and 8.59-log reduction on cantaloupe, orange and apple surfaces, respectively, when compared to the unwashed control. These results suggest that surface topography and the physical conditions have a major impact on the adhesion of E.coli O157:H7 and therefore the inactivation by the sanitizing agent.