| dc.description.abstract | The main aim of this study was to enhance the safety if fresh produce in general, and grape tomatoes in particular, by the combined treatments of electron beam (e-beam) irradiation and hydrogen peroxide (Hv2Ov2) aqueous solution. For the achieving this aim, this study was divided into three steps. At first and second steps, the effect of culture media used for the preparation of inoculum and water quality parameters, respectively, on the effectiveness of e-beam irradiation to inactivate Salmonella Typhimurium were evaluated. At final step, the decontamination ability of the combined treatment of ebeam and Hv2Ov2 for the inactivation of Salmonella spp. in whole grape tomatoes was evaluated. In the first step, the radiation sensitivity (Dv10 value) of the pathogen in deionized (DI) water decreased (P < 0.05) by 19.73% and 26.53% with the addition of PW and PBS, respectively, into DI water. Accordingly, the addition of 10 mM and 50 mM phosphate buffer into DI water decreased (P < 0.05) the radiation sensitivity of S. Typhimurium in DI water by 6.12% and 32.65%, respectively. Similarly, the calculated Dv10 value for this bacterium in 10 mM PB increased (P < 0.05) by 19.23% when 150 mM NaCI was added into 10 mM PB. However, the addition of 1.0 mM PB into water did not affect (P > 0.05) the Dv10 value calculated for S. Typhimurium in DI water. In addition, the presence of hydroxyl radical scavengers, ethanol and polyethylene glycol (PEG), provided a protection to S. Typhimurium cells. The radiation sensitivity of the pathogen in buffer solution decreased (P < 0.05) by 65.51%, 162.07%, and 250.34% when the concentration of membrane-permeable ethanol in the solution was modified as 78.9 mM, 394.5mM, and 1578 mM, respectively. Likewise, although the addition of 0.125 mM and 1.875 mM PEG into buffer solution decreased (P < 0.05) the radiation sensitivity of S. Typhimurium in buffer solution by 29.66% and 43.45%, respectively, 0.0125 mM PEG did not influence (P > 0.05) the Dv10 value calculate for the bacterium in buffer solution. In the second step, the pH ranged from 5.5 to 8.5 and alkalinity (≤ 500mg/l) did not affect (P > 0.05) the radiation sensitivity of S. Typhimurium in buffer solution. Nevertheless, the radiation sensitivity of S. Typhimurium in buffer solution increased (P < 0.05) when fulvic acid (100 mg/l ≤) and nitrate (≥ 100 mg/l) was added into buffer solution as organic and inorganic substances, respectively. In addition, the radiation sensitivity of S. Typhimurium in buffer solution increased (P < 0.05) regardless of Hv2Ov2 concentration. In the third step, it is found that this integrated treatment was effective to inactivate Salmonella spp. in grape tomatoes. The calculated Dv10 value for Salmonella spp. on grape tomatoes was 0.25 kGy. In addition, this system improved uniform dose distribution throughout tomatoes. Furthermore, the e-beam dose up to 1.25 kGy did not affect the quality of tomatoes. Ultimately, the present study demonstrated that the combined treatments of ebeam and Hv2Ov2 aqueous solution could be a promising alternative to conventional processes and should enhance the safety of fresh produce. | en |
