Inactivation of foodborne pathogenic and spoilage micro-organisms using ultraviolet-A light in combination with ferulic acid

Abstract

Microbial contamination is one of the most serious problems for foods, fruit and sugar thick juices. UV light is suitable for the nonthermal decontamination of food products by inactivating the contaminating micro-organisms. However, UV-A exposure is insufficient for disinfection. This study demonstrates that the combination of UV-A LED light (350-385 nm), which is not hazardous to human eyes and skin, and ferulic acid (FA), a known phytochemical and food additive, provides synergistic antimicrobial activity against foodborne pathogenic and spoilage micro-organisms. Therefore, FA addition to UV-A light treatment may be useful for improvement of UV-A disinfection technology to prevent food deterioration.

Antifungal action of the combination of ferulic acid and ultraviolet-A irradiation against Saccharomyces cerevisiae

“…The photofungicidal effect of the FA and UV-A combination against Saccharomyces sp. was similar to the bactericidal efficacy against E. coli dependent on UV-A light fluence (Shirai et al, 2017). Previous studies examining photobactericidal activity against E. coli and Staphylococcus aureus found that adsorption of phenolic acids onto the cell surface and their subsequent incorporation into the bacterial membrane plays an important role in mediating the bactericidal effect (Nakamura et al, 2015;Shirai & Yasutomo, 2019).…”

“…was similar to the bactericidal efficacy against E . coli dependent on UV‐A light fluence (Shirai et al, 2017). Previous studies examining photobactericidal activity against E .…”

“…All antifungal activity experiments were performed using a device equipped with a UV-A LED (NCSU033B; Nichia Corp.), which emits in the range 360-370 nm, with a 365-nm peak wavelength, as described previously (Shirai et al, 2014). The irradiance was adjusted to 4.77 mW cm −2 by changing the distance of the sample from the LED and measured according to a previous method (Shirai et al, 2017). All assays were performed at 30°C in an incubator box using a suspension of yeast cells in plastic Petri dishes (90 mm × 15 mm, Ecopetri ELS; Sansyo Co. Ltd).…”

“…Studies have shown that the antimicrobial activity of FA increases markedly when used in combination with ultraviolet-A (UV-A) light (315-400 nm) irradiation. Many reports have described similar bactericidal synergism of naturally occurring phenolic acids such as coumaric acid, caffeic acid (CaA) and gallic acid when combined with UV-A light irradiation at wavelengths from 365 to 400 nm (Cossu et al, 2016;Nakamura et al, 2012Nakamura et al, , 2015Nakamura et al, , 2017de Oliveira et al, 2021;Shirai et al, 2017). Such photodynamic antimicrobial chemotherapy (PACT) approaches combine non-toxic photosensitizers with irradiation in the light-emitting wavelength range appropriate for photoexcitation reactions.…”

“…FA also exhibits potential therapeutic antioxidant, hepatoprotective, cholesterol‐lowering and anti‐inflammatory activities (Paiva et al, 2013). In addition, FA has antimicrobial activity, although it is relatively weak, with reported minimum inhibitory concentrations of ≥1 mg ml −1 for bacteria and fungi (yeasts and filamentous fungi) (Shirai et al, 2017; Zabka & Pavela, 2013).…”