Factors that affect liquid chemical intervention methods of controlling pathogens
on fresh-cut produce were investigated. The relationship between produce tissue
structure (intercellular space, cell size, and cell distribution) and the sanitizing
effectiveness of liquid chemical treatment was studied. Experiments determined if
sanitizer contact with bacteria could be improved through the use of surfactants and
different application methods (drop application method, negative pressure differential,
and sonication). To test these factors, a model sanitizer, H2O2, and a model
microorganism: Salmonella Typhimurium, along with various fresh-cut produce (apple,
pear, carrot, and potato) were tested. Microscopic analysis revealed a very complicated
pore structure consisting of irregular capillaries. S. Typhimurium was found to survive in
all produce tested, and washing did not significantly reduced inoculated bacteria
regardless of the bacterial incubation time or produce type. The results showed that a 3%
H2O2 solution reduced S. Typhimurium in produce and the solutionÂs efficiency varied in
the following descending order: potato>apple>carrot>pear. In seven min treatments,
bacteria were reduced by 2.5 CFU/ml in potato, 2.3 CFU/ml in apple, 1.5 CFU/ml in
carrot, and 0.7 CFU/ml in pear. There was no direct evidence on how intercellular space,
its percentage or cellular distribution and shape affected efficiency, but some possibilites
were discussed. The rate and extent of liquid penetration, and how varying pore
diameter in each cell or air space prevent complete chemical treatment penetration were
also analyzed.
It was determined that bacterial density has a slight effect in bacterial reduction
but this depends on type of produce inoculated. The use of surfactants did not improve
bacterial reduction in either washing or chemical treatments, and neither did the use of drop application method or temperature differential. On the other hand, applying the
chemical treatment with a surfactant while using a sonicator did improve the treatmentÂs
efficiency. This thesis provides a number of factors to be considered when designing a
chemical treatment and a guideline for further research in areas such as rate and extent of
liquid chemical treatment penetration into fresh-cut produce.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/3929 |
| Date | 16 August 2006 |
| Creators | Troya, Maria Rosa |
| Contributors | Cisneros-Zevallos, Luis |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 1683266 bytes, electronic, application/pdf, born digital |
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