Evaluation of ultraviolet (UV-C) light treatment for microbial inactivation in agricultural waters with different levels of turbidity

Authors: ADHIKARI, ACHYUT - Louisiana State University; PARRAGA ESTRADA, KATHERYN - Louisiana State University; CHHETRI, VIJAY SINGH - Louisiana State University; JANES, MARLENE - Louisiana State University; FONTENOT, KATHYRYN - Louisiana State University; Beaulieu, John

Submitted to: Journal of Food Science and Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2019
Publication Date: 1/14/2019
Citation: Adhikari, A., Parraga Estrada, K.J., Chhetri, V., Janes, M., Fontenot, K., Beaulieu, J.C. 2019. Evaluation of ultraviolet (UV-C) light treatment for microbial inactivation in agricultural waters with different levels of turbidity. Journal of Food Science and Nutrition. 8:1237-1243. https://doi.org/10.1002/fsn3.1412.
DOI: https://doi.org/10.1002/fsn3.1412

Interpretive Summary: In this study, we evaluated the effectiveness of ultraviolet (UV-C) light treatment on reducing the generic Escherichia coli levels in surface water used for irrigation of cantaloupes. Mixtures of pond and well water were collected in a tank and inoculated with a cocktail of generic Escherichia coli. The inoculated water was then treated with the UV-C light at varying doses. We also examined the effect of irrigation system (drip or sprinkle) on generic Escherichia coli levels on cantaloupe surfaces. Our results indicated that the UV-C light treatment is effective on reducing microbial levels from high turbidity surface water sources used on small farms.

Technical Abstract: Contaminated surface water used for irrigation is a potential source of microbial contamination in fruit and vegetable crops. Fruit and vegetable producers using surface water to irrigate crops are required to have appropriate water treatments in place that do not leave any chemical residue. This study evaluated the efficacy of ultraviolet (UV-C) light on reducing generic E. coli levels in surface water in an agriculture setting. Different mixtures of pond and well water were collected in a tank (1000 L) and inoculated with a 1 L of cocktail of generic E. coli (ATCC 23716, 25922, and 11775). The inoculated water (7.4 log MPN 100 mL–1) was then treated with UV-C light at varying doses (20-30, 30-40, 40-50, 50-60 mJ cm–2) using a continuous UV-C light emitting equipment. A significant reduction (P< 0.05) of generic E. coli (>3 log MPN 100 mL–1) was achieved using low doses of UV-C light (20-30 mJ cm–2). Reductions below the detectable limit of the test used for the quantifications of generic E. coli were achieved using UV-C doses above 50-60 mJ cm–2. Our results indicated that the UV-C light is an effective antimicrobial treatment for the microbial risk reduction of surface irrigation water.