Decontamination of Berries Using Ozone and Pulsed UV-Light
Open Access
- Author:
- Bialka, Katherine L
- Graduate Program:
- Agricultural and Biological Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- December 21, 2006
- Committee Members:
- Ali Demirci, Committee Chair/Co-Chair
Virendra Puri, Committee Member
Paul Walker, Committee Member
Robert Bruce Beelman, Committee Member - Keywords:
- strawberries
raspberries
blueberries
novel technologies
food safety
food engineering - Abstract:
- Fresh produce is the second most common vehicle for foodborne illnesses and small fruits have been implicated in several notable outbreaks. Prior to marketing, small fruits are not washed or otherwise treated to extend their shelf life. Previous research has shown that conventional sanitizers are not effective in killing food borne pathogens on small fruits. Therefore, there is a need to evaluate novel technologies as a method of inactivating pathogens on the surfaces of berries. Two such technologies are ozone and pulsed ultraviolet-light. Ozone has been used as a disinfectant in the water industry for over a century, and was approved in 1997 by the USDA for use as a disinfecting agent. Pulsed UV-light is a much more efficient method of applying UV-light, in that is supplies greater instantaneous energy and thus reduces treatment times. The goal of this research was to evaluate ozone, gaseous and aqueous, and pulsed UV-light for the purpose of inactivating E. coli O157:H7 and Salmonella enterica on the surfaces of berries. The efficacy of gaseous ozone to decontaminate pathogens on strawberries and raspberries was evaluated. Fruits were treated with four ozone treatments; i) continuous ozone flow (5% wt/wt) for 2, 4, 8, 16, 32, and 64 min, ii) pressurized ozone (83 kPa) for 2, 4, 8, 16, 32, and 64 min, iii) continuous ozone (64 min) followed by pressurized ozone (64 min), and iv) vacuum followed by 64-min pressurized ozone. To determine the efficacy of ozone used as an additive to wash water, pathogen inoculated fruit were treated with aqueous ozone at 20oC and 4oC, and with water as a control. Pulsed UV-light was evaluated as a method for decontamination. There was no observable damage to the fruits at UV doses deemed optimal. All technologies were modeled using the Weibull distribution to calculate microbial inactivation. Finally, a separate study was conducted to model the penetration of pulsed UV-light through model food systems. The results obtained in this study indicated that both ozone and pulsed UV-light have potential to be used as methods of decontamination.