creator Liu, Shi advisor Zhang, Wei According to CDC's Foodborne Disease Outbreak Surveillance System database, from the years 2007-2011, there were eight outbreaks associated with low-moisture food including nuts, cheese, cookie dough, and wheat snack food involving Shiga toxinproducing Escherichia coli O157:H7 (STEC), which led to over 318 cases of foodborne illnesses. Yet, insufficient data on STEC thermal inactivation has been obtained in lowmoisture food. In this study, a novel methodology using a Differential Scanning Calorimeter was used to measure STEC thermal inactivation kinetics in low moisture environments. The objective of this study was to use a Differential Scanning Calorimeter to measure D- and z-values, and therefore to determine the microbial thermal resistance, of select STEC strains. Five strains of outbreak related E. coli O157:H7 and one strain of E. coli K12 were individually grown on tryptic soy agar with 0.6% yeast extract (TSAYE). The cells were harvested and inoculated into sample matrices. Matrices included a moist buffered peptone water solution, a simple model low-moisture food matrix (corn syrup), and lowmoisture food (oat flour and peanut butter). Samples were individually heated using a Differential Scanning Calorimeter (DSC). The DSC was able to achieve a reproducible and accurate thermal environment. Following heat treatment, microbial survivors were enumerated via a traditional plate counting method. The six strains showed greater thermal resistance in corn syrup than in a buffered solution and in peanut butter and oat flour compared with both the corn syrup or buffer solution (p < 0.05). At the same processing condition linearly rising temperature at 5oC/min, in low moisture food matrices, approximately 90oC and 95oC was needed to reduce the outbreak strains of STEC in peanut butter and oat flour by 5-log CFU/g; whereas 85oC and 75oC were needed for corn syrup and buffer solution, respectively. D65 o C ranged from 0.26-0.92 min for all strains tested in buffer. Those same strains exhibited a 10-100 times increase in resistance in corn syrup (D65 o C = 2.6-108.6 min). The measurement that quantifies the increased heat resistance of STEC in low moisture food will improve science-based risk reduction by ensuring process lethality in these types of food. Submitted by Erma Thomas (thomase@iit.edu) on 2015-07-13T17:30:34Z No. of bitstreams: 2 Shi Liu--Thesis.pdf: 8479457 bytes, checksum: 6a2ec837f93a4679ee1e75910c216360 (MD5) thesis cover.pdf: 879973 bytes, checksum: 2592d7a724552d3cad7545e0ccd3a267 (MD5) Made available in DSpace on 2015-07-13T17:30:34Z (GMT). No. of bitstreams: 2 Shi Liu--Thesis.pdf: 8479457 bytes, checksum: 6a2ec837f93a4679ee1e75910c216360 (MD5) thesis cover.pdf: 879973 bytes, checksum: 2592d7a724552d3cad7545e0ccd3a267 (MD5) Previous issue date: 2014-12 M.S. in Food Safety and Technology, December 2014 2014 2014-12 http://hdl.handle.net/10560/3441 en Thesis born digital application/pdf In Copyright http://rightsstatements.org/page/InC/1.0/ Restricted Access NCFST / National Center for Food Safety and Technology Illinois Institute of Technology Affiliated department