Food Science and Technology Department


First Advisor

Andreia Bianchini

Date of this Version

Fall 10-2018


A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Food Science and Technology, Under the Supervision of Professor Andreia Bianchini. Lincoln, Nebraska: October, 2018.

Copyright (c) 2018 Luis E. Sabillon


Pathogens are emerging on previously unrecognized food vehicles, such as wheat flour, which is a widely consumed commodity. Despite its low water activity, wheat-based ingredients and products have been implicated in several foodborne outbreaks over the last few years, resulting not only in the recall of food products but also in consumer illnesses. As a raw agricultural commodity, wheat is exposed to naturally occurring microbiological contamination that may compromise the overall safety of flour and other derived products. To address the increased concern regarding the safety of wheat-based foods, the objectives of the present research study were designed to develop and implement intervention strategies (i.e., acidic saline tempering solutions and high-pressure processing) aimed at reducing foodborne contaminants at different points along the mill-to-table continuum. Additionally, the effectiveness of such interventions at reducing public health risks was assessed using a stochastic, risk assessment model.

Tempering with acidic saline solutions significantly improved the safety of wheat prior to milling, without substantially affecting the functional properties of straight-grade flour. For instance, the combination of lactic acid (5.0% v/v) and NaCl (~26% w/v) reduced the aerobic mesophilic bacteria and E. coli O157:H7 counts in soft wheat by 3.1 and 1.8 log CFU/g, respectively. A microbiological survey conducted in a commercial milling facility revealed that, as wheat is milled into flour, there is a substantial risk of cross-contamination by microorganisms potentially inhabiting the milling equipment. Appropriate cleaning and sanitization regimens should, therefore, be implemented in the mill to reduce such risk. The application of high-pressure processing (600 MPa, 6 min), as a post-packaging intervention, significantly reduced E. coli counts in cookie dough by as much as 2.0 log CFU/g, without causing significant changes on product quality parameters. The risk assessment modeling revealed that the application of these interventions along the mill-to-table continuum can significantly reduce the public health risks associated with the consumption of cookie dough contaminated with E. coli O157:H7. The findings of this study will lead to better decision-making regarding strategies that could be applied throughout the grain processing chain to safeguard consumers.

Advisor: Andréia Bianchini