Efficacy of blue LED in microbial inactivation: Effect of photosensitization and process parameters.

Bhavya, M. L. and Umesh Hebbar, H. (2019) Efficacy of blue LED in microbial inactivation: Effect of photosensitization and process parameters. International Journal of Food Microbiology, 290. pp. 296-304. ISSN 0168-1605

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Abstract

Efficacy of blue (462 ± 3 nm) Light emitting diode (LED) illumination to inactivate the foodborne pathogens like Escherichia coli and Staphylococcus aureus in the presence of exogenous photosensitizer (curcumin) was studied in vitro. The effect of temperature, concentration of photosensitizer and incubation time with photosensitizer for microbial inactivation was investigated and sublethal injury of cells was determined. Mechanism of inactivation by the combination of photosensitizer and blue light was also examined. A maximum reduction of 5.94 ± 0.22 and 5.91 ± 0.20 log CFU/ml was obtained for E. coli and S. aureus, respectively, when treated with photosensitizer (20 μM) at 13 J/cm2 of blue light. There was no significant change in the inactivation of these pathogens both at 9 °C and 27 °C in the presence of photosensitizer. Even, the incubation with the photosensitizer didn't show any significant difference on the inactivation of these food-borne pathogens. Sublethal injury (> 90% injury) was also observed for the cells treated with photosensitizer and blue light simultaneously. Confocal laser scanning microscopy analysis revealed that membrane integrity was disturbed due to photodynamic activity of curcumin in both the bacteria. Further, both cells produced intracellular reactive oxygen species by the action of photosensitizer and blue light. Scanning electron microscopy of E. coli and S. aureus cells treated with photosensitizer and blue light showed morphological changes in the cell wall compared to untreated group. The study indicated that photodynamic inactivation of foodborne pathogens using LED-based photosensitization can be explored as a potential technique for food safety.

Item Type:	Article
Uncontrolled Keywords:	Blue light Food safety Photosensitizer Curcumin Photodynamic inactivation Non-thermal processing
Subjects:	600 Technology > 08 Food technology > 10 Food Microorganisms 600 Technology > 08 Food technology > 06 Preservation and Storage > 04 Irradiation
Divisions:	Food Engineering
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	10 Jan 2019 08:42
Last Modified:	10 Jan 2019 08:42
URI:	http://ir.cftri.res.in/id/eprint/13898

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