Evaluate the effectiveness and effects of ultraviolet light‐emitting diodes for food production, preservation, and microbiological safety
Foodborne contamination causes more than 200 diseases, ranging from diarrhoea to cancers, and is expected to affect 600 million people worldwide every year. On the other hand, every year, 1.3 billion tonnes of food, approximately one-third of the food produced for consumption, is lost or wasted globally, which also represents a huge waste of resources such as land, water, and energy.
The development of effective disinfection treatment processes will be crucial to help the food industry cope with foodborne pathogens and spoilage microorganisms as well as the inevitable challenges resulting from the increase in human population and climate change. Light-emitting diodes recently emerged as a promising disinfection alternative to traditional ultraviolet mercury lamps. Besides being mercury-free, light-emitting diodes are extremely compact electronic devices with low energy demand that can be acquired with a diversity of wavelengths. Recent studies, conducted with water and food matrices, showed that if we use three small light-emitting diodes that emit at 265 nm, a wavelength closer to the peak absorption of DNA, a higher inactivation efficiency was attained compared with if we use three small light-emitting diodes that emit at 255 nm, a wavelength closer to the monochromatic light emitted by low-pressure mercury lamps, that are widely used for water disinfection and already used by some food industries. Since light-emitting diodes that emit light at different wavelengths can be acquired, with a goal of achieving the highest level of inactivation possible, this project will focus on evaluating the effectiveness of light-emitting diodes that emit at 260 nm (due to the peak absorption of DNA), light emitting diodes that emit at 280 nm (due to the peak absorption of proteins) and their combination.
The target microorganisms selected include the most common bacteria associated with food outbreaks (Listeria monocytogenes and Salmonella enterica Typhimurium) and spoilage bacteria of vegetables and fruits (Pseudomonas putida and Alicyclobacillus sp.).
The effectiveness of inactivation of the target microorganisms using the ultraviolet light emitting diodes will be tested in fresh food matrices (vegetables and fruits) that are consumed raw and thus more prone to microbial contamination. A further understanding of the mechanisms of inactivation using the different wavelengths will be also one of the goals. Changes in morphology, membrane permeability, enzymatic activity, protein profiles, and genetic damage after inactivation will be evaluated. The disinfection conditions that hinder reactivation will be defined.
A novel ultraviolet light-emitting diode tunnel will be tested and optimized using spiked and unspiked food matrices. The final food safety, quality, and shelf-life will be evaluated. This disinfection device can become a low-cost, environmentally friendly, and sustainable new advanced food disinfection technology able to cope with current and future food safety and quality challenges.
This project will deepen the knowledge of the fundamental mechanisms behind disinfection, an essential process to ensure food safety and quality in the coming decades. The knowledge gained can be of use to many other applications when effective disinfection or the sterilization of surfaces and medical devices are needed and can thus be also of interest to pharmaceutical industries as well as hospitals.
Contractor: Instituto de Biologia Experimental e Tecnológica (iBET)
This work is funded by national funds from FCT – Fundação para a Ciência e a Tecnologia, I.P., within the scope of the project 2022.01340.PTDC.