Using UVC Light-Emitting Diodes at Wavelengths of 266 to 279 Nanometers To Inactivate Foodborne Pathogens and Pasteurize Sliced Cheese

ABSTRACTUVC light is a widely used sterilization technology. However, UV lamps have several limitations, including low activity at refrigeration temperatures, a long warm-up time, and risk of mercury exposure. UV-type lamps only emit light at 254 nm, so as an alternative, UV light-emitting diodes (UV-LEDs) which can produce the desired wavelengths have been developed. In this study, we validated the inactivation efficacy of UV-LEDs by wavelength and compared the results to those of conventional UV lamps. Selective media inoculated withEscherichia coliO157:H7,Salmonella entericaserovar Typhimurium, andListeria monocytogeneswere irradiated using UV-LEDs at 266, 270, 275, and 279 nm in the UVC spectrum at 0.1, 0.2, 0.5, and 0.7 mJ/cm2, respectively. The radiation intensity of the UV-LEDs was about 4 μW/cm2, and UV lamps were covered with polypropylene films to adjust the light intensity similar to those of UV-LEDs. In addition, we applied UV-LED to sliced cheese at doses of 1, 2, and 3 mJ/cm2. Our results showed that inactivation rates after UV-LED treatment were significantly different (P< 0.05) from those of UV lamps at a similar intensity. On microbiological media, UV-LED treatments at 266 and 270 nm showed significantly different (P< 0.05) inactivation effects than other wavelength modules. For sliced cheeses, 4- to 5-log reductions occurred after treatment at 3 mJ/cm2for all three pathogens, with negligible generation of injured cells.

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Fundamental Characteristics of Deep-UV Light-Emitting Diodes and Their Application To Control Foodborne Pathogens

Applied and Environmental Microbiology ◽

10.1128/aem.01186-15 ◽

2015 ◽

Vol 82 (1) ◽

pp. 2-10 ◽

Cited By ~ 38

Author(s):

Joo-Yeon Shin ◽

Soo-Ji Kim ◽

Do-Kyun Kim ◽

Dong-Hyun Kang

Keyword(s):

Foodborne Pathogens ◽

Light Emitting Diodes ◽

Uv Light ◽

Bacterial Inactivation ◽

Content Type ◽

Light Emitting ◽

E Coli ◽

Deep Uv ◽

Uv Lamps ◽

Uv C

ABSTRACTLow-pressure mercury UV (LP-UV) lamps have long been used for bacterial inactivation, but due to certain disadvantages, such as the possibility of mercury leakage, deep-UV-C light-emitting diodes (DUV-LEDs) for disinfection have recently been of great interest as an alternative. Therefore, in this study, we examined the basic spectral properties of DUV-LEDs and the effects of UV-C irradiation for inactivating foodborne pathogens, includingEscherichia coliO157:H7,Salmonella entericaserovar Typhimurium, andListeria monocytogenes, on solid media, as well as in water. As the temperature increased, DUV-LED light intensity decreased slightly, whereas LP-UV lamps showed increasing intensity until they reached a peak at around 30°C. As the irradiation dosage and temperature increased,E. coliO157:H7 andS. Typhimurium experienced 5- to 6-log-unit reductions.L. monocytogeneswas reduced by over 5 log units at a dose of 1.67 mJ/cm2. At 90% relative humidity (RH), onlyE. coliO157:H7 experienced inactivation significantly greater than at 30 and 60% RH. In a water treatment study involving a continuous system, 6.38-, 5.81-, and 3.47-log-unit reductions were achieved inE. coliO157:H7,S. Typhimurium, andL. monocytogenes, respectively, at 0.5 liter per minute (LPM) and 200 mW output power. The results of this study suggest that the use of DUV-LEDs may compensate for the drawbacks of using LP-UV lamps to inactivate foodborne pathogens.

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Inactivation of health-related microorganisms in water using UV light-emitting diodes

Water Science & Technology Water Supply ◽

10.2166/ws.2019.022 ◽

2019 ◽

Vol 19 (5) ◽

pp. 1507-1514 ◽

Cited By ~ 5

Author(s):

Kumiko Oguma ◽

Surapong Rattanakul ◽

Mie Masaike

Keyword(s):

Spectral Sensitivity ◽

Legionella Pneumophila ◽

Light Emitting Diodes ◽

Uv Light ◽

Feline Calicivirus ◽

Response Curves ◽

K Value ◽

Light Emitting ◽

Uv Led ◽

Uv Leds

Abstract UV light-emitting diodes (UV-LEDs) offer various wavelength options, while microorganisms have spectral sensitivity, or so-called action spectra, which can be different among species. Accordingly, matching properly the emission spectra of UV-LEDs and the spectral sensitivity of microorganisms is a reasonable strategy to enhance inactivation. In this study, UV-LEDs with nominal peak emissions at 265, 280 and 300 nm were applied to pathogens including Legionella pneumophila, Pseudomonas aeruginosa, Vibrio parahaemolyticus and feline calicivirus, in comparison with indicator species including Escherichia coli, Bacillus subtilis spores, bacteriophage Qβ and MS2. The results indicated that, for all species tested, 265 nm UV-LED was highest in the fluence-based inactivation rate constant k, followed by 280 nm and 300 nm was much lower. The k value at 280 nm was close to that at 265 nm for feline calicivirus and MS2, suggesting that 280 nm UV-LED can be as good an option as 265 nm UV-LED to inactivate these viruses. Bacteria tended to show fluence-response curves with shoulder and tailing, while viruses followed log-linear profiles at all wavelengths tested. This study indicates the fluence-response profiles and the fluence required for a target inactivation of microorganisms, which would serve as reference data for future study and applications of UV-LEDs.

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ACCURATE MEASUREMENT OF ULTRAVIOLET LIGHT-EMITTING DIODES

10.25039/x48.2021.op43 ◽

2021 ◽

Author(s):

C. Yuqin Zong ◽

Cameron Miller

Keyword(s):

Ultraviolet Light ◽

Light Emitting Diodes ◽

Luminous Flux ◽

Junction Temperature ◽

Integrating Sphere ◽

Light Emitting ◽

Type D ◽

Uv Led ◽

Uv Leds ◽

Ultraviolet Light Emitting Diodes

We have developed a new calibration capability for 200 nm to 400 nm ultraviolet light-emitting diodes (UV LEDs) using a Type D gonio-spectroradiometer. The recently-introduced mean differential continuous pulse (M-DCP) method is used to overcome the measurement difficulty associated with the initial forward voltage, VF, anomaly of a UV LED, which makes it impossible to use VF to infer junction temperature, TJ, during pulsed operation. The new measurement facility was validated indirectly by comparing the measured total luminous flux of a white LED with that measured using the NIST’s 2.5 m absolute integrating sphere. The expanded calibration uncertainty for the total radiant flux is approximately 2 % to 3 % (k = 2) depending the wavelength of the UV LED.

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Transcriptome and metabolome analyses revealed that narrowband 280 and 310 nm UV-B induce distinctive responses in Arabidopsis

10.1101/2021.02.12.430709 ◽

2021 ◽

Author(s):

Tomohiro Tsurumoto ◽

Yasuo Fujikawa ◽

Daisaku Ohta ◽

Atsushi Okazawa

Keyword(s):

Anthocyanin Biosynthesis ◽

Uv Light ◽

Current Model ◽

Phenylpropanoid Pathway ◽

Metabolic Responses ◽

Uv Resistance ◽

Light Emitting ◽

Uv Led ◽

Uv Leds ◽

Led Irradiation

SUMMARYIn plants, the UV-B photoreceptor UV RESISTANCE LOCUS8 (UVR8) perceives UV-B and induces UV-B responses including synthesis of UV-B absorbing phenolic compounds such as anthocyanins. UVR8 absorbs a range of UV-B (260–335 nm). However, the responsiveness of plants to each UV-B wavelength has not been intensively studied so far. Here, we performed transcriptome and metabolome analyses of Arabidopsis using UV light emitting diodes (LEDs) with peak wavelengths of 280 and 310 nm to investigate the differences in the wavelength-specific UV-B responses. Irradiation with both UV-LEDs induced gene expression of the transcription factor ELONGATED HYPOCOTYL 5 (HY5), which has a central role in the UVR8 signaling pathway. However, the overall transcriptomic and metabolic responses to 280 and 310 nm UV-LED irradiation were different. Most of the known UV-B-responsive genes, such as salicylic acid, jasmonic acid, and defense-related genes, responded only to 280 nm UV-LED irradiation. Lipids, polyamines and organic acids were the metabolites most affected by 280 nm UV-LED irradiation, whereas the effect of 310 nm UV-LED irradiation on the metabolome was considerably less. Enzymatic genes involved in the phenylpropanoid pathway upstream in anthocyanin biosynthesis were up-regulated only by 280 nm UV-LED irradiation. On the other hand, no enzymatic genes downstream in anthocyanin biosynthesis were induced by the UV-LEDs, but rather, they were down-regulated by 310 nm UV-LED irradiation. These results revealed that the responsivenesses of Arabidopsis to 280 and 310 nm UV-B were significantly different, suggesting that UV-B signaling is mediated by more complex pathways than the current model.

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Elevated Inactivation Efficacy of a Pulsed UVC Light-Emitting Diode System for Foodborne Pathogens on Selective Media and Food Surfaces

Applied and Environmental Microbiology ◽

10.1128/aem.01340-18 ◽

2018 ◽

Vol 84 (20) ◽

Cited By ~ 14

Author(s):

Do-Kyun Kim ◽

Dong-Hyun Kang

Keyword(s):

Light Source ◽

Foodborne Pathogens ◽

Uv Light ◽

Light Emitting Diode ◽

Bactericidal Effect ◽

Duty Ratio ◽

Content Type ◽

Light Emitting ◽

Minamata Convention On Mercury ◽

Led Irradiation

ABSTRACTUVC light, a strong surface disinfection technology, is used worldwide to ensure not only environmental safety but also food safety. Several drawbacks associated with the use of mercury-containing UV lamps, especially human and environmental health risks, led to the Minamata Convention on Mercury, which prohibits the manufacture and import/export of products containing mercury. Therefore, light-emitting diode (LED)-based UVC irradiation, a new technology that is ecofriendly and represents an effective UV light source, has been researched recently. To date, however, there has been no report describing pulsed UVC-LED irradiation for improvement of inactivation of foodborne pathogens, although much research regarding conventional pulsed xenon lamps has been published. In this investigation, we evaluated the enhanced bactericidal effect of a pulsed UVC-LED system, compared to continuous irradiation, and optimum conditions for maximizing the effect were determined. Also, the differences in inactivation between pulsed and continuous UVC-LED irradiation were determined by inactivation mechanism analyses. The combination of 20-Hz frequency and 50% duty ratio for pulsed UVC-LED irradiation achieved 4- to 5-log-unit reductions ofEscherichia coliO157:H7,Salmonella entericaserovar Typhimurium, andListeria monocytogenes; this combination showed the greatest bactericidal effect among various treatment conditions using 2 or 5 mJ/cm2. In mechanism assessments, membrane integrity (propidium iodide uptake) was not affected by UVC-LED treatment but membrane potential [bis-(1,3-dibutylbarbituric acid)trimethine oxonol [DiBAC4(3)] accumulation] showed significantly different values when pulsed and continuous treatments were compared. Changes in membrane lipid peroxidation and respiratory enzyme activity were attributed to generation of more reactive oxygen species by pulsed UVC-LED irradiation.IMPORTANCEIn 2013, the United Nations Environment Programme convened the Minamata Convention on Mercury, which prohibits trade in mercury-containing products in order to ensure human health. It will be effectuated in 2020; use of low-pressure mercury lamps will be discontinued and a new UV light source selected to replace the conventional technology. In this regard, UVC-LEDs have been developed and the fundamental inactivating effect has been researched. However, a pulsed UVC-LED system has not been studied, because of the difficulty of generating a UVC-LED pulse wave. An optical chopper system that physically divides the light with an adjustable blade, with personalized frequency and duty ratio settings, was introduced for generation of pulsed UVC-LED irradiation. This study elucidated the efficacy of a pulsed UVC-LED system and investigated its enhanced bactericidal effect in mechanism analyses.

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Double-Sided Freeform Lens for Light Collimation of Light Emitting Diodes

Applied Sciences ◽

10.3390/app9245452 ◽

2019 ◽

Vol 9 (24) ◽

pp. 5452

Author(s):

Yong-Sin Syu ◽

Chun-Ying Wu ◽

Yung-Chun Lee

Keyword(s):

Light Emitting Diodes ◽

Uv Light ◽

Design Parameters ◽

Injection Molding Process ◽

Light Sources ◽

Molding Process ◽

Light Emitting ◽

Uv Led ◽

Simulation Results ◽

Freeform Lens

A double-sided freeform lens is proposed for collimating light emitted from light emitting diodes (LEDs). The surface profiles of the lens are mathematically characterized and precisely determined based on a point-source assumption and differential geometry theory. The proposed lens design method is straightforward, flexible, and effective. Moreover, the optical performance of the lens can be intuitively adjusted by tuning just a small number of design parameters. The simulation results showed that the proposed lens achieved an excellent collimating effect for a commercial ultraviolet (UV) LED. A prototype lens is fabricated in UV-grade poly(methyl methacrylate) material using a standard injection molding process. The light collimating effect of the lens/UV-LED assembly was measured experimentally and was shown to be in good agreement with the simulation results. The collimating angle at the half-energy level was equal to 1.88°. The performance of the UV-LED is thus comparable to that of conventional lithography UV light sources based on mercury arc lamps. Consequently, the proposed double freeform lens showed significant potential for photolithography applications within the industry.

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Current Injection UV-Emission from InAlGaN Multi-Quantum-Well Light-Emitting Diodes

MRS Proceedings ◽

10.1557/proc-639-g12.6 ◽

2000 ◽

Vol 639 ◽

Author(s):

A. Kinoshita ◽

H. Hirayama ◽

M. Ainoya ◽

J. S. Kim ◽

A. Hirata ◽

...

Keyword(s):

Quantum Well ◽

Light Emitting Diodes ◽

Uv Light ◽

Current Injection ◽

Light Emitting ◽

Organic Vapor ◽

Uv Emission ◽

Metal Organic ◽

Uv Leds ◽

Multi Quantum Well

ABSTRACTInAlGaN quaternary material is very attractive for realizing ultraviolet (UV) emitting devices working at 300 – 350 nm wavelength range. We demonstrate current injection into 340 nm-band InAlGaN based UV light emitting diodes (LEDs), for the first time, fabricated by metal organic vapor phase epitaxy (MOVPE). We performed current injection into AlGaN/AlGaN multi quantum well (MQW), bulk InAlGaN quaternary and InAlGaN/InAlGaN MQW LEDs through Mg-doped AlGaN/GaN superlattice hole conductive layers. The injected current density was ranging 0 – 0.5 kA/cm2 under pulsed or CW operation. The intensity of both photoluminescence (PL) and electroluminescence for InAlGaN quaternary-based LED was much higher than that for AlGaN based LEDs at room temperature. From these results InAlGaN quaternary-based QWs are expected to realize high intensity UV LEDs and LDs.

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Demonstration and evaluation of germicidal UV-LEDs for point-of-use water disinfection

Journal of Water and Health ◽

10.2166/wh.2010.124 ◽

2010 ◽

Vol 8 (3) ◽

pp. 479-486 ◽

Cited By ~ 74

Author(s):

Christie Chatterley ◽

Karl Linden

Keyword(s):

Uv Irradiation ◽

Uv Light ◽

Low Pressure ◽

Water Disinfection ◽

Light Emitting ◽

E Coli ◽

Point Of Use ◽

One Year ◽

Uv Lamps ◽

Uv Leds

Ultraviolet (UV) irradiation is a common disinfection option for water treatment in the developed world. There are a few systems installed in developing countries for point-of-use treatment, but the low-pressure mercury lamps currently used as the UV irradiation source have a number of sustainability issues including a fragile envelope, a lifetime of approximately one year, and they contain mercury. UV light emitting diodes (LEDs) may offer solutions to many of the sustainability issues presented by current UV systems. LEDs are small, efficient, have long lifetimes, and do not contain mercury. Germicidal UV LEDs emitting at 265 nm were evaluated for inactivation of E. coli in water and compared to conventional low-pressure UV lamps. Both systems provided an equivalent level of treatment. A UV-LED prototype was developed and evaluated as a proof-of-concept of this technology for a point-of-use disinfection option, and the economics of UV-LEDs were evaluated.

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UV Light Application as a Mean for Disinfection Applied in the Dairy Industry

Applied Sciences ◽

10.3390/app11167285 ◽

2021 ◽

Vol 11 (16) ◽

pp. 7285

Author(s):

Arpit Chawla ◽

Adriana Lobacz ◽

Justyna Tarapata ◽

Justyna Zulewska

Keyword(s):

Uv Light ◽

Dairy Industry ◽

Microbial Inactivation ◽

Microbial Pathogens ◽

Great Promise ◽

Market Demand ◽

Light Emitting ◽

Long Time ◽

Uv Lamps ◽

Uv Leds

Thermal treatment is the most popular decontamination technique used in the dairy industry to ensure food protection and prolong shelf life. But it also causes nutrient and aroma degradation, non-enzymatic browning, and organoleptic changes of dairy products. Non-thermal solutions, on the other hand, have been extensively explored in a response to rising market demand for more sustainable and safe goods. For a long time, the use of ultraviolet (UV) light in the food industry has held great promise. Irradiation with shortwave UV light has excellent germicidal properties, which can destroy a variety of microbial pathogens (for example bacteria, fungi, molds, yeasts, and viruses), at low maintenance and installation costs with minimal use of energy to preserve food without undesirable effects of heat treatment. The purpose of this review is to update the studies made on the possibilities of UV-C radiation while also addressing the essential processing factors involved in the disinfection. It also sheds light on the promise of UV light-emitting diodes (UV-LEDs) as a microbial inactivation alternative to conventional UV lamps.

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