Pulsed Light Treatment Research Articles

Effective pulsed light treatments for inactivating Salmonella enterica serotypes

Pulsed light (PL) is a nonthermal treatment that kills microorganisms by exposing them to short-duration pulses of high-intensity broad-spectrum light. This study evaluated the PL inactivation of different serotypes of Salmonella enterica subsp. enterica (Typhimurium, Enteritidis, Heidelberg, and Minnesota) to specifically assess how pulse width and voltage can affect treatment effectiveness. Bacterial suspensions were spread onto solid agar plates, used as a model food surface, and then treated with PL at different treatment parameters (voltage, pulse width, and fluence). Surviving cells were recovered, enumerated, and the proportion of surviving cells were determined. The log-linear model was used to characterize inactivation kinetics. Three independent replicates were performed for all treatments, and data were analyzed statistically. The results obtained with S. Typhimurium highlighted that the inactivation effectiveness of PL treatment could be enhanced by selecting the right combination of parameters within the practical limitations of the equipment. Higher voltages delivered more energy with pulse width, (i.e., a higher irradiance) resulting in a more lethal process. PL was very effective for the inactivation of Salmonella, and a 6 to 7 log reduction was achieved for all four serotypes and their cocktail, after a single light pulse with a fluence of 338 mJ/cm2 and 280 mJ/cm2, at 2500 V (200 μs) and 3000 V (100 μs), respectively. The results demonstrated similar log reductions for individual serotypes and the cocktail.

Effect of Pulsed Light on Quality of Shelled Walnuts.

Shelled walnuts are considered a microbiologically low-risk food but have been linked to some outbreaks, and a treatment aiming to decrease this risk is desirable. Pulsed light (PL) may be an alternative, providing it does not seriously impair their quality. This work assessed the impact of PL on some quality attributes of walnuts. To do this, measurements of rancidity, volatiles, total phenols, antioxidant activity, and descriptive sensory analysis were carried out on untreated and PL (43 J/cm2)-treated kernels. PL had no statistically significant (p > 0.05) effects on TBARS, peroxide value, total phenols, and antioxidant activity but significantly increased the concentration of volatiles related to green/herbaceous odors and decreased compounds related to fruity and citrus odors. The descriptors nut overall, walnut odor and flavor, and aftertaste were given statistically significantly (p < 0.05) higher scores, while descriptors woody odor and sweet received lower scores; 16 other traits such as all those related to color, texture, and rancidity were unaffected. No significant (p > 0.05) effects on total phenols and antioxidant activity in general were observed during the course of PL treatment. It can be concluded that PL technology may be used in shelled walnuts with only mild effects on their quality; a storage study must be carried out in order to determine the effect of PL treatment on its shelf-life.

Effect of pulsed light treatment on the physicochemical properties of wheat flour and quality of fresh wet noodles

AbstractBackground and ObjectivesPulsed light (PL) was first applied to the production of low bacterial wheat flour—treating wheat kernels with PL. The effect of PL on the physicochemical properties of wheat flour and the quality of fresh wet noodles (FWN) were investigated.FindingsAfter treatment, the total plate count (TPC), yeast and mold count (YMC) in wheat flour decreased significantly. Wet gluten content and the stability time reached their maximums when the pulsed flash frequency was 10 c. Starch viscosity increased slightly, mainly due to an increase in damaged starch content. Secondary structures altered remarkably, which were consistent with changes in gluten protein microstructures. Moreover, the textural properties of FWN were improved greatly. Browning of FWN was significantly inhibited because of low polyphenol oxidase (PPO) activity in wheat flour.ConclusionPL was effective in decreasing the initial microorganisms in wheat flour as well as improving the quality of dough and FWN, and the optimum treatment was pulsed energy of 500 J, pulsed flash distance of 9 cm, and pulsed frequency of 10 c.Significance and NoveltyThese results showed that PL treatment could decrease TPC and YMC in wheat flour significantly, improve farinograph and pasting properties, change gluten protein microstructures and secondary structures, as well as improve textural properties of FWN and inhibit its darkening greatly, which provided a new method for low bacterial wheat flour production and promoted PL's industrialization.

An introduction to treating rosacea

Rosacea is a fairly common condition, especially in fair-haired, blue-eyed people, that mainly affects the centre of the face, causing erythema and papules and pustules. It is a chronic condition and requires correct diagnosis and careful management to achieve optimal results. Gentle skincare is vital. Topical agents, such as azelaic acid, metronidazole, ivermectin and brimodinine tartrate are useful. Oral antibiotics, such as doxcycline and clarithromycin, as well as isotretinion, also play a role. Aesthetic clinics may see patients presenting for laser or intense pulsed light treatments for the telangectasia that is often present. This forms only part of the overall package of treatments.

Application of pulsed light technology for fruits and vegetables disinfection: A review.

Non-thermal technologies can maintain fruit and vegetable products quality better than traditional thermal processing. Pulsed light (PL) is a non-thermal method for microbial inactivation (vegetative cells and spores) in fruits and vegetables. The PL treatment involves the application of intense and short-duration pulses of broad spectrum wavelengths ranging from UV to near-infrared (100-1100nm). This review summarized application of PL technology to control microbial contamination and increasing shelf-life of some fruits and vegetables including apple, blueberries, grape, orange, strawberries, carrot, lettuce, spinach, and tomato. The microbial inactivation in very short treatment times, low energy used by this system, flexibility for solid or liquid samples, few residual compounds and no synthetic chemicals that cause environmental pollution or harm humans, is benefits of PL technique. The efficiency of PL disinfection is closely associated with the input voltage, fluence (energy dose), composition of the emitted light spectrum, number of lamps, the distance between samples and light source, and frequency and number of applied pulses. The PL treatments control pathogenic and spoilage microorganisms, so it facilitates the growth and development of the starter microorganisms affecting product quality.

Impact of voltage and pulse delivery mode on the efficacy of pulsed light for the inactivation of Listeria

Listeria innocua inactivation by pulsed light (PL) was evaluated at different settings and voltages, to establish the best treatment conditions and post-treatment handling for further implementation of PL in the food industry. Fluences up to 0.2 J/cm2 were applied to superficially inoculated TSA agar plates (4.5–5 log cfu/cm2). Inactivation was calculated, and log-linear and Weibull models were applied. A fluence of 0.2 J/cm2 applied in a single pulse inactivated 3.8 log cfu/cm2, while sequential application of this fluence yielded an inactivation between 1.5 and 2.5 log cfu/cm2 depending on the delivery mode (consecutive flashing or with 5 min-holding times under ambient light or in the dark). Data from consecutive PL treatment were fitted with the Weibull model. No photoreactivation following PL was observed after 120-min exposure to ambient light in any of the conditions assayed. This study showed that flashing with a single pulse at higher voltage would offer the highest inactivation of Listeria. Industrial relevanceThis study offered information of practical interest to establish pulsed light processing and post-processing conditions for the control of Listeria spp. in the food industry, for instance in ready-to-eat (RTE) products. The use of higher voltages provided higher inactivation and allowed to minimise the number of flashes. If sequential treatments are to be applied, the treatment is more effective if short holding times are kept between pulses. The post-processing illumination conditions do not influence the efficacy of PL treatment.

Comparison Between Heated Eye Mask and Intense Pulsed Light Treatment for Contact Lens-Related Dry Eye.

Background: Contact lens-related dry eye (CLDE) is common in contact lens (CL) wearers and can lead to ocular pain, decreased visual quality, and reduced quality of life. Objective: The purpose of this prospective, randomized, examiner masked study was to compare the effectiveness of intense pulsed light (IPL) and heated eye mask (HEM) for relieving CLDE. Methods: The final analysis included 60 patients (30 in the IPL group and 30 in the HEM group) who were using CL and had been suffering contact lens discomfort for more than a year. The IPL treatment group had two IPL treatments spaced 3 weeks apart, whereas the HEM group received HEM daily for 6 weeks (42 days). Non-invasive tear break-up time (NITBUT), tear-film lipid layer (TFLL), conjunctival fluorescein staining, meibum gland quality and expression, conjunctival redness score, ocular surface disease index (OSDI), best-corrected visual acuity, endothelial cell count, and intraocular pressure were assessed at baseline: first visit (V1), second visit (V2), and third visit (V3). Results: The mean age of the IPL group was 28.6 ± 4.3 years (16 females, 53%) and that of the HEM group was 28.6 ± 4.2 years (16 females, 53%). Mean NITBUT for the IPL group at V2 was 5.53 ± 0.77 sec (p < 0.001) and at V3 was 7.72 ± 0.88 sec (p < 0.001); the IPL group demonstrated a clinically and statistically significant improvement in mean NITBUT. In addition, the HEM group showed a clinically and statistically significant improvement in mean NITBUT at V3 (5.86 ± 0.76 sec, p < 0.001). At V3, the C-OSDI, TFLL score, and meibum gland quality and expressibility all increased considerably (p < 0.05) in both groups. Conclusions: Our results imply that IPL or HEM treatment of CLDE can be safely used to relieve symptoms of CLDE. In addition, IPL treatment is more effective in improving the general stability of the tear-film and decreasing the need for artificial tears in CLDE.

Effects of pulsed light on germination and gamma-aminobutyric acid synthesis in brown rice.

This study observed the effects of pulsed light (PL) on the germination and gamma-aminobutyric acid (GABA) production of brown rice and analyzed the correlations among glutamic acid (Glu) content, glutamate decarboxylase (GAD) activity, and GABA content in germinating brown rice. Both germination and GABA content were increased by exposure to PL, and this effect was evident when brown rice was exposed to PL immediately after being soaked. The PL group had significantly higher Glu and GABA content than the control check (CK) group which was unexposed to PL during the germination of brown rice. Glu content peaked at 18 h and GABA peaked at 24h in the PL group, which were 12 h and 6 h earlier than the CK group, respectively. GAD activity of the PL group peaked 12 h after germination, 6 h earlier than the CK group. PL exposure also increased the free amino acid content in the earliest stage of brown-rice germination. During brown-rice germination, the production of GABA is regulated by GAD activity and is significantly positively correlated with Glu content. PL treatment had a significant effect on GAD activity and Glu content during the germination process of brown rice and helped to increase its GABA content. PRACTICAL APPLICATION: This study has shown that pulsed light exposure is an efficient and stable processing method for producing brown rice with high GABA. This will provide a new direction for developing novel germination grain foods.

Potential of pulsed light treatment to pasteurize pomegranate juice: Microbial safety, enzyme inactivation, and phytochemical retention

The study explores the pasteurization condition of pomegranate juice using pulsed light (PL) treatment within a fluence domain of 312–2988 J cm−2. A 5-log reduction (microbial safety) in Escherichia coli ATCC 43888, aerobic mesophiles, yeasts & molds count in the juice was obtained at 761.4 J cm−2 (2.7 kV for 90 s). The thermal treatment attaining the equivalent lethality was 95 °C for 2 min. A complete inactivation in enzyme activity (polyphenol oxidase and peroxidase) along with microbial safety was attained for the treatments at 2988 J cm−2 (PL) and 95 °C/3 min (thermal treatment). The thermally pasteurized sample (95 °C/3 min) showed 30 and 37% depletion in phenolic compounds and antioxidant capacity, respectively, with only 34% vitamin C in the juice. The equivalent PL pasteurized (2988 J cm−2) juice retained 97%, 94%, and 83% phenolics, antioxidants, and ascorbic acid, respectively. The PL-pasteurized sample's quality attributes and sensory profile were on par with high-pressure and pulsed electric field pasteurized juices from the literature. In turn, PL treatment of the pomegranate juice at 2988 J cm−2 satisfies the criteria for all the stakeholders such as microbial safety (manufacturers demand), enzymatic stability (retailer's demand), and phytochemical retention (consumers demand).

Inactivation of hepatitis A virus and norovirus on berries by broad-spectrum pulsed light

Foodborne diseases are still a major global health and economic burden, and are mainly caused by viral pathogens, such as human norovirus and hepatitis A virus, which may remain infective for long times on food contact surfaces and on produce. The strategies of viral inactivation applied in the industry are not generally suitable for delicate foods such as berries. Brief exposure to high-intensity white light (UV to IR) has been shown to inactivate many bacteria. The effectiveness of this treatment against foodborne viruses on fresh produce is largely unknown. We show that pulsed light treatment causes a moderate drop in the luminosity (L*, which ranges from bright (high) to dark (low)) of blueberries (to 36.31 ± 0.99 from 42.47 ± 1.17) and affects the luminosity of lettuce slightly but does not affect the appearance of strawberries, blackberries or raspberries. Hepatitis A virus and murine norovirus 1 are thus reduced by 2 log cycles. Viral inactivation on blackberries was less effective. These results will help food industries evaluate the suitability of pulsed light disinfecting technology for specific fruits and vegetables.

Intense pulsed UV light treatment to design functional optical films from perhydropolysilazane: an alternative to conventional heat treatment processes

Intense pulsed UV light treatment to design functional optical films from perhydropolysilazane: an alternative to conventional heat treatment processes

Pulsed light treatment reduces microorganisms and mycotoxins naturally present in red pepper (Capsicum annuum L.) powder

AbstractThe impact of pulsed light (PL) treatment on naturally occurring microorganisms, mycotoxins, and on physicochemical properties in red pepper powder was investigated. Powder samples were exposed to different PL treatments up to 61 pulses, with fluence ranging from 1.0 to 9.1 J/cm2. The highest fluence applied (9.1 J/cm2, 61 pulses, 20 s) resulted in 2.7, 3.1, and 4.1 log CFU/g reduction of yeasts, molds, and total plate counts (TPC), where initial microbial loads were 4.6, 5.5, and 6.5 log CFU/g, respectively. At the same fluence intensity, a maximum reduction of 67.2, 50.9, and 36.9% of aflatoxin B1 (AFB1), total aflatoxins (AF), and ochratoxin A (OTA) were detected, respectively. Proportional increase in temperature of the samples was observed from the absorbed PL energy, reaching maximum of 59.8°C. The inactivation of investigated microorganisms and mycotoxins followed first‐order kinetics (R2 &gt; 0.95). The fluence intensity at 6.9 and 9.1 J/cm2 did not cause degradation, but rather a significant (p &lt; .05) and apparent increase of total phenols. Total color difference (ΔE*) revealed only “slight differences,” compared to the untreated sample. In conclusion, higher reduction of microbial load and mycotoxins in red pepper powder could be achieved, when higher treatment intensity was applied. This suggests the PL as a potential technology for decontamination of red pepper powder and other spice powders.Practical ApplicationsPulsed light could be used for the decontamination of foods and reduce variety of spoilage and pathogenic microorganisms. Exposure of red pepper powder to different levels of doses proposed in this study demonstrates alternative approaches for microbial inactivation and mycotoxins degradation of the product. Moreover, pulsed light treatment is a young technology using short treatment times with potential feasibility. The technique can be of great interest for the scientific and industrial R&amp;D community dealing with pulsed light technology, microbial, and mycotoxins inactivation kinetics, food safety, and quality control.

Decontamination and quality assessment of freshly squeezed grape juice under spiral continuous flow‐through pulsed light (SCFPL) treatment

Decontamination and quality assessment of freshly squeezed grape juice under spiral continuous flow‐through pulsed light (SCFPL) treatment

Efficacy of Intense Pulsed Light Treatment in Patients with Sjögren’s Syndrome Associated with Meibomian Gland Dysfunction

Purpose: To investigate the efficacy of intense pulsed light (IPL) treatment in patients with meibomian gland dysfunction (MGD) associated with Sjögren’s syndrome.Methods: This study included 43 patients with MGD and Sjögren’s syndrome. Patients received either IPL with meibomian gland expression (IPL/MGX) (n = 22) or MGX only (n = 21). Treatments were administered three times at a 3-week interval. Patients were followed up 6 weeks after the end of the treatment. Ocular Surface Disease Index (OSDI), tear film breakup time with fluorescein dye (FBUT), non-invasive tear breakup time, tear meniscus height (TMH), Schirmer test, SICCA ocular surface staining score, meibum quality score (MQS), and meibum expression score (MES) were evaluated at each visit. Meibomian gland dropouts (meiboscore) and tear film lipid layer grade were measured using keratography.Results: OSDI, FBUT, corneal surface staining score, MQS, meiboscore, and tear film lipid layer grade improved after IPL/MGX treatment (p &lt; 0.05). In both treatment groups, MES significantly improved (p &lt; 0.01 and p &lt; 0.05 for IPL/MGX and MGX groups, respectively). The Schirmer test score, conjunctival surface staining score, and TMH after treatment were not significantly different between the groups. After treatment, the IPL/MGX group had significantly lower OSDI, FBUT, corneal staining score, MQS, and MES, but higher FBUT, compared with the MGX group (p &lt; 0.05).Conclusions: IPL treatment effectively improved tear film, ocular surface parameters, meibomian gland function, and lipid layer grade in patients with Sjögren’s syndrome and MGD.

Development of a mixed fruit beverage and pulsed light treatment thereof to obtain a microbially safe and enzymatically stable product

A mixed fruit beverage was formulated according to D-optimal mixture design using apple ber juice (X1, 45–59% v/v) - an underexplored fruit, carambola juice (X2, 1–20% v/v), and black table grape juice (X3, 35–40% v/v). The crisp overall acceptability (COA) from 16 semi-trained panelists and overall hedonic score (OSH) from consumers were estimated. The best formulation was apple ber: carambola: black table grape juices = 59.0: 3.5: 37.5 v/v with COA and OSH values of 3.23 (on a scale of 5) and 7.55 (on a scale of 9), respectively. Further, the efficacy of pulsed light (PL) (18–30 W cm−2 for 33–167 s; total fluence 600–5000 J cm−2) and thermal treatments (90 °C for 1–5 min) were studied on various attributes of the mixed beverage. The beverages processed at 90 °C for 5 min (thermal treatment) and 5000 J cm−2 (PL treatment at 30 W cm−2 for 167 s) showed no microbial count with a complete enzyme inactivation. The thermally pasteurized sample (90 °C/5 min) was more brown (browning index = 70.15) than the PL pasteurized beverage (browning index = 65.98). Interestingly, the PL pasteurized (5000 J cm−2) beverage showed 25%, 27%, and 19% more vitamin C, antioxidants, and phenolic compounds, respectively, than the thermally pasteurized (90 °C/5 min) beverage. The PL-treated beverage had a greater sensory appeal than the thermally treated beverage. PL-treatment can be an efficient non-thermal pasteurization treatment for ensuring complete microbial and enzymatic inactivation with maximal retention of nutritional and sensory attributes of the blended beverage.

Rapid photodegradation of organic micro-pollutants in water using high-intensity pulsed light

The rising concentration of organic micro-pollutants (OMPs) in water resources has become a major concern for aquatic ecosystems and human health. Advanced oxidation processes (AOPs), based on ultraviolet (UV) photolysis and photochemical reactions, have been suggested for the degradation of various micropollutants present in water and wastewater. However, the application of these methods on large scale is limited due to the long treatment times. Here we evaluate the efficiency of high-intensity pulsed light treatment (HIPL) for the degradation of organic compounds in aqueous conditions. A solution containing 11 OMPs was treated with short (<2 ms) and high-intensity light pulses produced by a Xenon flash lamp. It was observed that the HIPL parameters, such as the number of pulses and optical energy dose, have a significant impact on the efficiency of the treatment. The main advantage of HIPL is the fast kinetics that allows efficient photodegradation of OMPs from the aqueous solution rapidly and within milliseconds. The present work showcases the potential of HIPL technique for the post-treatment of contaminated water containing pharmaceuticals and endocrine disruptor compounds.

Pasteurization of fruit juices by pulsed light treatment: A review on the microbial safety, enzymatic stability, and kinetic approach to process design.

Pulsed light (PL) is a polychromatic radiation-based technology, among many other non-thermal processing techniques. The microbiological lethality of the PL technique has been explored in different food matrices along with their associated mechanisms. Pasteurization of fruit juice requires a 5-log cycle reduction in the resistant pathogen in the product. The manufacturers look toward achieving the microbial safety and stability of the juice, while consumers demand high-quality juice. Enzymatic spoilage in fruit juice is also a crucial factor that needs attention. The retailers want the processed juice to be stable, which can be achieved by inactivating the spoilage enzymes and native microflora inside it. The present review argued about the potential of PL technology to produce a microbiologically safe and enzymatically stable fruit juice with a minimal loss in bioactive compounds in the product. Concise information of factors affecting the PL treatment (PLT), primary inactivation mechanism associated with microorganisms, enzymes, the effect of PLT on various quality attributes (microorganisms, spoilage enzymes, bioactive components, sensory properties, color), and shelf life of fruit juices has been put forward. The potential of PL integrated with other non-thermal and mild thermal technologies on the microbial safety and stability of fruit juices has been corroborated. The review also provides suggestions to the readers for designing, modeling, and optimizing the PLT and discusses the use of various primary, secondary kinetic models in detail that have been utilized for different quality parameters in juices. Finally, the challenges and future need associated with PL technology has been summarized.

Treatment for telangiectasias and reticular veins.

Treatment for telangiectasias and reticular veins.

Impact of factors affecting the efficacy of intense pulsed light for reducing Bacillus subtilis spores.

This study investigated how the following four intense pulsed light (IPL) treatment factors affect the inactivation of Bacillus subtilis (KCCM 11,315) spores: distance between the sample and IPL lamp (8, 13, and 18cm), pulse width (0.5, 1.3, and 2.1ms), charging voltage (1000, 1200, and 1400V), and processing time (10, 20, and 30s). The results showed that all four factors considerably influenced the spore inactivation rate in different ways. Excluding processing time, which does not affect the pulse itself, the effect was largest for pulse width, followed by distance, and charging voltage. The optimal treatment condition that maximized the inactivation rate was a distance of 8cm, a pulse width of 2.1ms, a charging voltage of 1000V, and a processing time of 30s, which together produced a 6 log reduction. It revealed that individual factors need to be investigated together for achieving the optimal condition of IPL.

Electrospun Polystyrene and Acid-Treated Cellulose Nanocrystals with Intense Pulsed Light Treatment for N95-Equivalent Filters

The coronavirus (SARS-CoV-2) has prompted a global need and shortage of face masks and respirators. Electrospinning of polystyrene and cellulose nanocrystals (CNCs) is used to fabricate filter materials exceeding N95 standards set by the National Institute for Occupational Health and Safety. The desired filtration efficiency and pressure drop are achieved from filters with varying amounts of input material. The water contact angle, fiber morphology, and surface potential are reported to explain the enhancements in filtration performance after the addition of CNCs or application of intense pulsed light (IPL). The improved durability in the form of increased mechanical properties and lower pressure drop after testing are also examined. The samples exhibited filtration efficiencies greater than 99% and an initial pressure drop as low as 231 Pa. The combination of CNCs and IPL shows the potential to use thinner membranes with less material to achieve comparable filtration performance, which may result in lower manufacturing costs. © 2021 American Chemical Society.