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CHLORINE DECAY AND PATHOGEN CROSS CONTAMINATION DYNAMICS IN FRESH PRODUCE WASHING PROCESS

Dehghan Abnavi, Mohammadreza Dehghan
http://orcid.org/0000-0002-8407-2129
http://rave.ohiolink.edu/etdc/view?acc_num=csu1624196282479244

Abstract Details

2021, Doctor of Philosophy in Engineering, Cleveland State University, Washkewicz College of Engineering.
In this study, we developed a comprehensive mathematical model to predict the free chlorine (FC) concentration and bacterial cross-contamination during produce wash processes. A second-order chemical reaction model for FC decay which utilizes a proportion of chemical oxygen demand (COD) as an indicator of organic content in the wash water was employed, yielding an apparent reaction rate of 9.45 ± 0.22 × 10-4 µM-1.min-1. Using a proportion of successive changes in COD in the wash water due to produce washing, typically ranging from 6 to 11% across produce types, the model was able to consistently predict experimental FC levels, however, we note that while the FC level drops, the COD level stays constant. Therefore, we established the total amino acids concentration as an alternative indicator of organic load, and modified our model based on modeling the reaction kinetics of chlorine and amino acids. Apparent reaction rate between FC and amino acids was in the range of 15.3 – 16.6 M-1.s-1 and an amplification factor in the range of 11.52 - 11.94. This study also presents a modified disinfection kinetics model to evaluate the potential effect of organic content on the chlorine inactivation coefficient of Escherichia coli O157:H7 in produce wash process. While the chlorine inactivation coefficient of E. coli was 70.39 ± 3.19 L.mg-1.min-1 in the absence of organic content, it dropped by 73% for a COD level of 600 - 800 mg.L-1. Finally, the mechanisms by which FC inactivates E. coli was studied. Results showed that at low levels of FC and shorter exposure times, cell surface became rough and plicate; however, holes and wrinkles formed on the cell surface at higher FC concentrations or at longer exposure times, causing significant damage to the cell membrane. The cellular permeability changed due to chlorination, resulting in a significant decrease in the number of viable cells. Besides, around 3.45% ± 0.62 of cells lost their culturability and transform to viable but not culturable (VBCN) state during the disinfection process in low CT values (> 0.2 mg.min.L-1). Our studies have implications in the design of disinfection protocols relevant for produce wash industry.
Chandrasekhar Kothapalli (Committee Chair)
Jorge Gatica (Committee Member)
Joanne Belovich (Committee Member)
Daniel Munther (Committee Member)
Srinivasan Parthasarathy (Committee Member)
Chemical Engineering; Microbiology
Fresh produce wash process; Free chlorine decay; Pathogen cross contamination; Escherichia coli inactivation model; bacterial disinfection mechanisms

Recommended Citations

Citations

  • Dehghan Abnavi, M. D. (2021). CHLORINE DECAY AND PATHOGEN CROSS CONTAMINATION DYNAMICS IN FRESH PRODUCE WASHING PROCESS [Doctoral dissertation, Cleveland State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=csu1624196282479244

    APA Style (7th edition)

  • Dehghan Abnavi, Mohammadreza. CHLORINE DECAY AND PATHOGEN CROSS CONTAMINATION DYNAMICS IN FRESH PRODUCE WASHING PROCESS. 2021. Cleveland State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=csu1624196282479244.

    MLA Style (8th edition)

  • Dehghan Abnavi, Mohammadreza. "CHLORINE DECAY AND PATHOGEN CROSS CONTAMINATION DYNAMICS IN FRESH PRODUCE WASHING PROCESS." Doctoral dissertation, Cleveland State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=csu1624196282479244

    Chicago Manual of Style (17th edition)

csu1624196282479244
692
© , some rights reserved.Creative Commons License CHLORINE DECAY AND PATHOGEN CROSS CONTAMINATION DYNAMICS IN FRESH PRODUCE WASHING PROCESS by Mohammadreza Dehghan Dehghan Abnavi is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Cleveland State University and OhioLINK.