SMART ULTRAVIOLET (UV) LIGHT-EMITTING DIODE SYSTEM FOR CONTROLLING CHEMICAL AND BIOLOGICAL CONTAMINANTS IN FOODS AND FOOD CONTACT SURFACES

Food safety is an important component of public health world-wide. Every year, more than 16% of the U.S. population acquire a foodborne illness, and 3,000 people are killed by consuming contaminated foods (http://www.cdc.gov/foodborneburden/index.html). Also, the United States is burdened by more than $50 billion in economic costs related to foodborne illnesses each year (Erickson et al., 2010). The contamination and persistence of pathogenic bacteria and viruses in foods have become an emerging concern. Ready-to-eat fruits and vegetables including juices/beverages may contain human pathogens among their microflora owing to contamination at some point in the process from cultivation to consumption (Montgomery and Banerjee, 2015). Human enteric pathogens including E. coli O157:H7, hepatitis A virus (HAV), and human norovirus (NoV) and other pathogens have each been implicated in outbreaks of food-borne illness associated with consumption of fresh produce items including juices (Ponka et al., 1999; Anderson et al., 2001; Centers for Disease Control and Prevention (CDC), 2003; Schmid et al., 2007; Grant et al., 2008).Cross-contamination in the food industry is defined as direct or indirect microbial transference from a contaminated to a non-contaminated matrix, which can be food, work surfaces, or workers, among others. In contrast, recontamination refers to the contamination of food after it has undergone a sanitizing treatment (Carrasco, Morales-Rueda, & Gar?ia-Gimeno, 2012). Cross-contamination plays a critical role in transmitting pathogens to food (Kusumaningrum, Riboldi, Hazeleger, & Beumer, 2003). Microorganisms colonize by adhering to living or inert surfaces, growing, and forming a self-produced polymeric matrix in which multiple microbial species may converge, known as biofilm (Carpentier & Cerf, 1993; Satpathy, Sen, Pattanaik, & Raut, 2016). These masses of cells further become large enough to entrap organic and inorganic debris, nutrients, and other microorganisms, leading to the formation of a microbial biofilm (Kumar & Anand, 1998). Mixed biofilms are reported to have higher resistance to disinfectants such as quaternary ammonium compounds (QAC) and other biocides. Since complex microbial communities in biofilms develop resistance to current physical and chemical disinfection methods2, there is a critical and urgent need to develop effective approaches to disinfect biofilms on food contact surfacesIn comparison to biological contamination; chemical contamination is another public heath risk. Among chemical contaminants, Aflatoxins are the most prominent one, produced by Aspergillus species (A. flavus, A. parasiticus, A. nomius, A. bombycis, A. ochraceoroseus, and A. pseudotamari). Majorly, aflatoxins are subdivided into B1, B2, G1 and G2 (Dhanasekaran et al., 2011). Climatic factors of tropical region favor the production of aflatoxins in commodities like nuts, spices, cereals, maize, soybean, peanuts, pistachios, cotton and rice (Ukwuru et al., 2017). Agricultural commodities, especially peanuts and peanut-based foods, are highly prone to aflatoxin contamination (Liu et al. 2010). Significant quantities of aflatoxins were observed in soybean, rice, corn, pasta, condiments, milk, dairy products and edible oil products (Richard, 2007; Dhanasekaran et al., 2011, FAO/WHO (2009, Binder et al, 2007). The ability of mycotoxins to remain stable throughout food processing is a concern (Bullerman and Bianchini, 2007). Among all the foods implicated in mycotoxin contamination, AFB1 is the most commonly mycotoxin primarily found in meat, milk and nuts. Aflatoxins are mutagenic, carcinogenic, teratogenic, hepatotoxic, and have immunosuppressive properties. Sufficient evidence on the carcinogenic potential of AFB1 led the International Agency for Research on Cancer (IARC) to categorize AFB1 under Group 1 carcinogens. AFM1 is considered to be possibly carcinogenic to humans and hence, IARC placed it under Group 2B carcinogens (IARC. (2012).Smart approaches and control strategies that prevent growth of pathogenic organisms and degrades mycotoxins, remain crucial for providing safer foods. Tennessee State University [TSU] propose a novel approach to decontaminate food contact surfaces [stainless steel, rubber, glass, plastic] and opaque beverages using High Intensity Ultraviolet Light Emitting Diodes [LED] technology. We propose an integrated project to investigate the effect of high intensity UV-C photons on bacterial biofilm-forming communities on surfaces. A secondary goal is to develop UV dose response curves of pathogens in opaque beverages using targeting wave-lengths. This study utilizes sophisticated computing algorithms in quantifying the optical properties [absorption coefficient, reduced scattering and scattering anisotropy] of the biofilm or opaque beverages; this will enable delivery of accurate and quantifiable UV dose on surfaces. The novelty of the current proposed work is improved penetration capability of UV light technology via [A] selection of appropriate germicidal wavelength (where light absorption of biofilm is low) and [B] development of UV dose response curves for biofilms and viruses on various food contact surfaces and in opaque beverages; account for spectra characteristics. In addition, this study will determine the frequency of UV light exposure with respect to age and thickness of complex biofilms for efficient decontamination of surfaces.Within this project the team will focus on the application of highly energetic photons at wave-length from 254- 300 nm (high selective/tunable) on the inactivation of viruses and bacterial spores including biofilms. An important aspect of the study is the creation of science-based knowledge and bridge existing knowledge gaps by assessing the sensitivity of target foodborne bacteria, viruses and bacterial biofilms using appropriate wave-lengths of exposure.Project HypothesesWe hypothesize that effective inactivation of target microbes in opaque beverages and biofilm-forming pathogens on surfaces can be achieved through complete understanding of their spectral characteristics together with effective UV dose delivery. This project is intended to address the challenges of UV technologies by developing a novel high-power UV Light emitting diode (LED) system and by assessing the sensitivity of foodborne bacteria and foodborne biofilm-forming bacterial pathogens using the generated-germicidal UV regime.Goals and ObjectivesThe project members will work closely to achieve 4 key objectives that are structured into 4 work packages (WP). The major goal is to demonstrate and validate UV LED technology's potential to disinfect pathogenic bacterial biofilms and viruses (surrogates) on food contact surfaces including opaque beverages.Perform effective management of all project work and resources;Evaluate UV light spectra of target microbial biofilms and opaque beverages, assess optical properties & quantify UV dose using artificial neural networks;Design and develop a novel high-power UV LED system and develop UV dose response curves for simple and complex biofilms (L. monocytogenes, E. coli O157:H7) with respect to biofilm thickness;Develop UV dose response curves of L. monocytogenes, S. enterica, E. coli O157:H7, Bacillus cereus in opaque beverages using selected germicidal wave-lengths (including action spectra);