Date of Graduation

12-2013

Document Type

Thesis

Degree Name

Master of Science in Food Science (MS)

Degree Level

Graduate

Department

Food Science

Advisor/Mentor

Navam S. Hettiarachchy

Committee Member

Steven C. Ricke

Second Committee Member

Philip Crandall

Third Committee Member

Michael Slavik

Keywords

Biological sciences, Cantaloupe, Electrostatic spray, Escherichia coli, Grape seed extract, Organic seeds, Salmonella, Tomatoes

Abstract

Both consumers and suppliers have been negatively affected by an increase in foodborne pathogens contaminating fruits. Consequently, there is a need for the development of more efficient antimicrobials and application techniques to decrease contamination. Natural preservatives such as organic acids and plant extracts have demonstrated promising results in decontaminating produce. In addition, the effectiveness of such preservatives may be enhanced by the use of an electrostatic sprayer. The objective of this research was to determine the combinations and concentrations of organic acids and plant extract that were able to reduce Salmonella Typhimurium (ST) and Escherichia coli O157:H7 (EC) inoculated fruits and how the efficiency of the electrostatic spraying technique compares to conventional spraying. Quality attributes of the treated fruit were tested to determine if further deterioration occurred. Cantaloupe cubes and tomatoes were inoculated with ST and EC, and then electrostatically sprayed with different concentrations of organic acids and grape seed extract and stored at 4°C for 11 and 12 days, respectfully. Malic acid (M) (4%), alone and combined with lactic acid (L) (2%) demonstrated the greatest reduction of ST (reduced by 3.3 and 3.6 log CFU/g) and EC (4.6 log CFU/g) on cantaloupe cubes during the storage period. Lactic acid alone and in different combinations with M were able decrease EC (2.3 log CFU/g) and ST (≥ 3.7 log CFU/g) on tomatoes after 12 days of storage. Compared to conventional spraying, electrostatic spraying of organic acids was more effective in reducing more EC and ST on cantaloupe cubes. Electrostatic sprayer reduced a significant amount of EC on tomatoes, but there was no difference between the types of sprayers when reducing ST. No significant differences in color were observed when comparing non-sprayed cantaloupe cubes and tomatoes to sprayed samples. The texture of cantaloupe left untreated was no different from cantaloupe cubes treated with organic acids. Tomatoes sprayed with organic acids did not differ from untreated tomatoes until the 12th day of storage. Natural antimicrobials have the potential to be used to enhance the safety of produce without compromising the quality. Usage of multiple hurdle technology in the produce can be used along with current practices to enhance the safety of food.

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