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United States Department of Agriculture

Agricultural Research Service

Research Project: MICROBIAL FOOD SAFETY OF FRESH AND FRESH-CUT PRODUCE Title: Effect of surface characteristics on retention and removal of Escherichia coli O157:H7 on surfaces of spinach

item Zhou, Bin -
item Feng, Hao -
item Luo, Yaguang

Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2011
Publication Date: June 11, 2011
Citation: Zhou, B., Feng, H., Luo, Y. 2011. Effect of surface characteristics on retention and removal of Escherichia coli O157:H7 on surfaces of spinach/ [abstract].. Annual Meeting of the Institute of Food Technologists.

Technical Abstract: The topography and the spatial heterogeneity of produce surfaces may impact the attachment of microbial cells onto produce surfaces and affect disinfection efficacy. In this study, the effects of produce surface characteristics on the removal of bacteria were studied. Fresh spinach leaves were spot-inoculated on abaxial and adaxial surfaces of each leaf, and treated with 200 mg/L acidified sodium chlorite (ASC) and 21.2 kHz ultrasonication. The recovery of E. coli O157:H7 cells from treated spinach leaves was analyzed. In addition, the surface microstructure of fresh spinach leaf disks (11 mm in diameter) was imaged by an environmental scanning electron microscopy (ESEM) and a 3D optical surface profiler. The surface roughness of spinach was determined based on an area of 100 x 100 micro meter. The surface hydrophobicity of spinach leaf was measured using the sessile drop technique with a Goniometer-KSV CAM200 The results showed that E. coli O157:H7 inoculated on the abaxial surface of spinach leaves (rough side) were more resistant to the combined treatment of ASC and ultrasonication. The SEM images and optical profiler of the spinach leaf revealed that the undulations were fewer in numbers but deeper on the adaxial side than on the abaxial side. E. coli O157:H7 cells mainly attached on the outer surfaces of the folds, around or in stomata. In addition, there were no significant differences in surface roughness and surface hydrophobicity between the abaxial and adaxial surfaces of spinach leaf under this magnification.

Last Modified: 8/27/2015
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