title: Effect of surface roughness on inactivation of Escherichia coli O157:H7 87-23 by new organic acid-surfactant combinations on alfalfa, broccoli, and radish seeds.
abstract: Surface roughness has been reported as one of the factors affecting microbial attachment and removal. Seed surfaces are complex, and different seed varieties have different surface topographies. As a result, a sanitizer effective in eliminating pathogenic bacteria on one seed may not  be as effective when applied to another seed. The objectives of this research were (i) to investigate the efficacy of malic acid and thiamine dilaurylsulfate (TDS) combined treatments for inactivation of E. coli O157:H7 strain 87-23 on alfalfa, broccoli, and radish seeds, (ii) to quantify  surface roughness of the seeds, and (iii) to determine the correlation between microbial removal and surface roughness. The surface roughness of each seed type was measured by confocal laser scanning microscopy (CLSM) and surface profilometry. Surface roughness (Ra) values of the seeds were  then calculated from CLSM data. Seeds inoculated with E. coli O157:H7 87-23 were washed for 20 min in malic acid and TDS solutions and rinsed for 10 min in tap water. Radish seeds had the highest Ra values, followed by broccoli and alfalfa seeds. A combination of 10% malic acid and  1% TDS was more effective than 20,000 ppm of Ca(OCl)(2) for inactivation of E. coli O157:H7 87-23 on broccoli seeds, while the inactivation on radish and alfalfa seeds was not significantly different compared with the 20,000-ppm Ca(OCl)(2) wash. Overall, a negative  correlation existed between the seeds' Ra values and microbial removal. Different seeds had different surface roughness, contributing to discrepancies in the ability of the sanitizers to eliminate E. coli O157:H7 87-23 on the seeds. Therefore, the effectiveness of one sanitizer on one  seed type should not be translated to all seed varieties.
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Lilia
authors.initials: L
authors.lastname: Fransisca
authors.forename: Hao
authors.initials: H
authors.lastname: Feng
mesh_terms: D001422:Bacterial Adhesion / Q000187:drug effects*; D001937:Brassica / Q000382:microbiology; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004202:Disinfectants / Q000494:pharmacology*; D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D006801:Humans; D008293:Malates / Q000494:pharmacology; D000455:Medicago sativa / Q000382:microbiology; D031224:Raphanus / Q000382:microbiology; D012639:Seeds / Q000382:microbiology*
chemical_list: D004202:Disinfectants; D008293:Malates; C030298:malic acid