Effect of UV-C Light Against Listeria monocytogenes on Hydroponically Grown Lettuce and its Effect on Quality
Semester of Graduation
Master of Science (MS)
School of Nutrition and Food Sciences
Controlled agriculture environments like hydroponic systems are a growing industry. However, studies have shown potential of microbial growth in hydroponic systems, highlighting the need for decontamination techniques to prevent the risk of foodborne diseases. This study evaluated the effect of UV-C light against Listeria monocytogenes on hydroponically grown lettuce and seeds. Lettuce leaves were spot inoculated (100μL) with Listeria monocytogenes cocktail and exposed to UV-C light (0.28mW/cm2) for 10 to 50 seconds in 10-second increments and 1 to 5 minutes in 1- minute increments. UV treated leaves were stored at 4C° and visually inspected for 5 days. Additionally, the smooth and rough surfaces of lettuce leaves were inoculated and exposed to UV-C light. Lettuce plants growing in a hydroponic system were spot inoculated with Listeria 15 days after germination and treated with UV-C light for 50s every day between days 16-25. Lettuce seeds (n=40) were inoculated with Listeria and expose to UV-C light (0.28mW/cm2) prior to germination for 0-40 min and the rate of germination (%) was measured. Seeds treated with UV-C did not present significant impact on germination percentage (P Listeria levels in seeds were observed after 20- and 40-min treatment (0.94±0.32 log CFU/g). UV-C light significantly reduced Listeria levels on lettuce leaves within 40 and 50s 0.92 ± 0.22 and 1.14 ± 0.22 log CFU/g respectively and remained similar up to four min treatment. Five min significantly reduced Listeria by 2.14±0.33log CFU/g. Listeria reduction was significantly different (P0.05) effect was found on the color, and the weight, irrespective of the UV time exposure. UV-C treatment decreased Listeria levels in the hydroponic system after two days of treatment (3.85±1.09 log CFU/g). UV- C light could be a potential intervention strategy to minimize the food safety risk of fresh produce in a hydroponic system.
Lituma, Ivannova, "Effect of UV-C Light Against Listeria monocytogenes on Hydroponically Grown Lettuce and its Effect on Quality" (2023). LSU Master's Theses. 5721.
Available for download on Monday, March 30, 2026