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# Physiology of escherichia coli in orange juice: applications of flow cytometry

Anvarian, Amir Hossein Pour-Taghi (2015)
Ph.D. thesis, University of Birmingham.

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## Abstract

Flow cytometry (FCM) was utilized for monitoring the physiology of $$E.$$ $$coli$$ cells in orange juice (OJ) as well as a model orange juice (MOJ). Compared to FCM, plate counts highly underestimated the true number of viable cells in OJ. As a part of this study, the effects of the change in major components of OJ on viability of the cells in OJ and MOJ was investigated using FCM. Increase in ascorbic acid and amino acid concentrations of MOJ improved both the culturability and FCM viability of the cells. FCM was also employed for studying the effects of OJ clarification on viability of $$E.$$ $$coli$$ in OJ. Although, reduction in cloud content of OJ increased the number of healthy cells, however, the removal of cloud particles of larger than 0.7 μm appeared to increase the antimicrobial efficacy of particles of smaller than 0.7 μm. The effects of washing E. coli cells with available chlorine, H$$_2$$O$$_2$$ and organic acids on their subsequent viability in OJ was also investigated. While increase in concentration of sanitizers resulted in a significant reduction in healthy populations, the total number of viable cells either remained constant or increased particularly in case of H$$_2$$O$$_2$$-washed cells.

Type of Work: Ph.D. thesis. Overton, Tim and Smith, Madeleine Colleges (2008 onwards) > College of Engineering & Physical Sciences School of Chemical Engineering QH426 GeneticsQR MicrobiologyRA0421 Public health. Hygiene. Preventive Medicine University of Birmingham 5653
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