UV LEDs as a novel contemporary Solution against common pathogens and spoilage organisms in foods and Beverages

By Tatiana Koutchma, PhD

Agriculture and Agri-Food Canada /Government of Canada

Thursday September 10th, 2020 at 10:00 am (Mexico City, MX; 15:00 UTC)

Ultraviolet light emitting diodes (UV-LEDs) have exponentially surged in popularity for air, water and surface disinfection because they are small, robust, non-toxic, energy efficient, offer design and operation flexibility. LEDs can be tuned to emit light at wavelengths in UV-C, -B, -A and visible range although commercially used mercury lamps emit light at a single wavelength of 253.7 nm. Wavelengths in the far UV-C and lower UV-B range (280 nm) are attractive due to their increased penetration depth as opposed to 253.7 nm. Moreover, some food-borne pathogens such as Escherichia coli O157:H7 and Listeria monocytogenes were shown to peak in UV-sensitivity at 260 nm and 270 nm respectively while other organisms showed sensitivity to light beyond 280 nm. Because of these essential advantages, feasibility of UV-C LEDs was evaluated for applications in fresh produce and juices industry. This paper discusses results of studying the efficacy of UV-C LEDs for microbial inactivation of pathogens such as E. coli and L. monocytogenes on fresh lettuce and apples. Also, UV-C LEDs were investigated for reduction of Penicillium expansum mold spores and shelf life extension of fresh apples. A microbial reduction of 1.5-2 log similar to commonly used chlorine washing was observed. The effect of UV-C light emitted by UV-C LEDs and mercury lamp on quality characteristics of lettuce and apples after optimized light treatments and during storage will be presented.

Furthermore, the UVC-LEDs were tested to reduce pathogens in commercially produced cold-pressed juices with low UV transmittance. The tests in commercial UV-C LEDs flow through unit at multiple wavelengths demonstrated feasibility to achieve 5log reduction of E.coli indicator organism and to establish UV dose, wavelength and flow conditions. The research demonstrated potential of UV-C LEDs as a promising contemporary solution for sanitation and preservation of fresh produce and juices, disinfection and point-of use applications.