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- Title
- EFFICACY OF PULSED LIGHT TECHNOLOGY FOR THE INACTIVATION OF SALMONELLA ENTERITIDIS PT 30 ON ALMOND KERNEL SURFACE
- Creator
- Harguindeguy, Maite
- Date
- 2016, 2016-05
- Description
-
Almond surfaces can be contaminated with pathogens such as Salmonella. Traditional thermal processing technologies used for inactivation of...
Show moreAlmond surfaces can be contaminated with pathogens such as Salmonella. Traditional thermal processing technologies used for inactivation of Salmonella on almonds can adversely impact the quality. Therefore, there is a need to investigate the efficacy of alternative technologies for inactivation of Salmonella on almonds without adversely affecting the quality. Pulsed light, a novel technology, can potentially be used to achieve this. Therefore, this study evaluated the efficacy of three pulsed light systems (operating at 1.8, 3, or 100 Hz) under various electrical input powers (1000, 1250 and 1500 W) and treatment times for inactivation of Salmonella Enteritidis PT 30 on almond surfaces. More than 4-log reduction was achieved at different treatment conditions for each of the control units. For instance, a 160 s treatment at 1500 W (100 Hz system) resulted in a 4.3 log CFU/almond reduction. Whereas, similar reductions were achieved in a shorter time with the lower frequency systems (1.8 or 3 Hz). Reductions of 4.6 and 5.9 log CFU/almond were achieved after 80 and 100 s treatment, respectively with the 1.8 Hz system (1250 W). Similarly, a 100 s treatment with the 3 Hz system (1000 W) resulted in a reduction of 4.7 log CFU/almond. Statistical analysis showed that the effect of equipment, treatment time, and electrical power input were significant (p<0.05). The D-values of 1.8, 3, and 100 Hz systems were 0.24, 0.53 and 0.73 min, respectively at 1500 W. In general, lower frequencies resulted in increased inactivation in shorter time. This can be attributed to the higher instantaneous power at lower frequencies. Similar trends were observed at other electrical input powers. The D-values found using pulsed light treatment are lower than the conventional dry heat treatment ones. Also, minimal color change was observed for treated almonds. These results indicate that pulsed light is efficacious for decontaminating almond surfaces within a relatively short time.
M.S. in Food Process Engineering, May 2016
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- Title
- INACTIVATION OF MURINE NOROVIRUS ON STRAWBERRIES USING PULSED LIGHT
- Creator
- Chen, Dongjie
- Date
- 2016, 2016-12
- Description
-
Norovirus have become the predominant viral causes of foodborne illnesses worldwide, the foodborne happened mainly in schools and childcare...
Show moreNorovirus have become the predominant viral causes of foodborne illnesses worldwide, the foodborne happened mainly in schools and childcare facilities, strawberries were identified as the most likely vehicle according to the analytical epidemiological studies. So this study evaluated the efficacy of pulsed light (PL) treatments to inactivate murine norovirus (MNV-1), a human norovirus surrogate, inoculated onto strawberries. Two different PL treatments were evaluated - 3 Hz and 100 Hz PL treatments. PL treatments inactivated 1.5-3 log PFU/g MNV-1 on strawberry in a time-dependent manner of 30-120 s at both 3 and 100 Hz. The inactivation efficacy of PL is dependent on the pulsed frequency received with both PL treatment parameters. It can achieve 1.7 log PFU/g reduction after 120 s 3 Hz PL treatment at the distance of 8.3 cm from the quartz window, on the other hand, MNV-1 was inactivated by 3.2 log PFU/g after 120 s exposure to 100 Hz PL treatment at the distance of 8.3 cm from the quartz window. These results demonstrated that higher inactivation effect of MNV-1 on strawberry was associated with higher frequency of PL treatment. Therefore, this technology could be used to improve the microbial safety of fresh strawberries.
M.S. in Food Process Engineering, December 2016
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