Ultraviolet Light-Assisted Photocatalytic Disinfection of Escherichia coli and Its Effects on the Quality Attributes of White Grape Juice

Ultraviolet (UV) light-assisted titanium dioxide (TiO 2 ) photocatalysis is an emerging technology in food safety that utilizes TiO 2 photocatalysts to accelerate the generation of reactive oxygen species during UV illumination. In this work, we studied the use of immobilized TiO 2 -SiO 2 photocatalysts illuminated with UVA radiation (350 nm; 14.8 mW/cm 2 ) for the inactivation of Escherichia coli ATCC 25922 in white grape juice, and compared the effectiveness of the photocatalytic disinfection with respect to the quality attributes of white grape juice against those of thermal and UVC (254 nm; 19.7 mW/cm 2 ) treated samples. To obtain a 5-log reduction of the target microorganism, treatment durations of UVA in the absence and presence of the photocatalyst were 60 and 40 min, respectively. A 5-log reduction with UVC radiation led to the loss of health-related compounds such as vitamin C, total phenolic content, and total antioxidant capacity at 92.0 ± 1.1%, 19.4 ± 5.6%, and 54.3 ± 10.0%, respectively. However, the same level of reduction with UVA led to a loss of 74.2 ± 2.3%, 7.1 ± 3.6%, and 39.7 ± 2.5%, and with UVA-assisted photocatalytic method resulted in a loss of 75.8 ± 6.1%, 13.6 ± 5.8%, and 45.6 ± 4.4% of vitamin C, total phenolic content, and total anti-oxidant capacity, respectively. Given its efficacy in deactivating E. coli while retaining a relatively higher level of health-related constituents in the fruit juice compared to other common pasteurization techniques, the photocatalyst developed in this study provides a promising technology for food disinfection.