Theses and Dissertations

Date of Award


Document Type


Degree Name

Master of Science (MS)


Agricultural, Environmental, and Sustainability Sciences

First Advisor

Dr. Veerachandra K. Yemmireddy

Second Advisor

Dr. Alexis Racelis

Third Advisor

Dr. Robin Choudhury


Fresh produce safety is major concern in United States. Fresh produce has been associated with numerous food-borne outbreaks each year. Salmonella has been a recurring issue in the papaya industry. Since 2010, imported papayas have been implicated in 8 multistate outbreaks associated with Salmonella spp. causing 480 illnesses, 113 hospitalization and 3 deaths. The main reason behind this problem is as fresh papaya is grown on fields where they are constantly exposed to preharvest microbial contamination through contaminated irrigation water, agricultural soil, raw manure and/or feces deposited by intruding domestic or wild animals. Moreover, majority fresh papaya is also consumed raw which intensifies the risk to public health. Once contaminated, survival of foodborne pathogen is dependent on storage conditions and physico-chemical properties of fresh produce. The main objective of this study is to understand the survival kinetics of Salmonella spp. in fresh and fresh-cut papaya of different ripeness levels. In this study effect of storage relative humidity (RH): 55, and 90% on the survival kinetics was determined over a period of 7-14 days at 4, 12, and 21ºC. In addition, effect of fruit ripeness on the survival kinetics of Salmonella spp. were also examined. Results showed that papaya ripeness level in combination with storage temperature and RH have shown to affect Salmonella survival on both fresh-cut papaya and papaya peel. Increasing the fruit ripeness level from 0 to 100 %, storage temperature from 4 to 21 °C and RH from 55 to 90 % increased the log survival. Samples at low ripeness levels showed slower growth of yeast and molds compared to samples at higher ripeness levels. Ripeness levels also showed an effect on the total soluble solids content of fresh-cut papaya during the storage. Baranyi and Roberts model better described the growth behavior of Salmonella spp. on the fresh and fresh-cut papaya of different ripeness levels at the tested conditions.


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