Use Of UV-C Radiation Research Articles

Use of UV-C radiation and packaging to maintain the quality of minimally processed kale

Kale, a imortant crop for family farms, gains added value through minimal processing, enhancing freshness and convenience. UV-C irradiation emerges as a promising method for extending kale's shelf life without chemicals, although standardization is complex due to varying food resistances to light penetration.The study in question analyzed the effects of two different irradiation times on minimally processed cabbage, packaged in bowls and Styrofoam with plastic film, observing changes in physical-chemical and sensory parameters, such as loss of mass, color, pH, and visual and olfactory signs of deterioration. Six treatments were tested, varying the exposure time and the type of packaging, as well as a treatment with chlorinated sanitizer, using the Tukey test at 5% significance to determine the most effective in preserving the product. It was found that the packaging in the cumbuca resulted in less mass loss compared to the tray, and the lowest pH values were recorded in the treatment with UV-C light in the cumbuca, which may indicate that they are an option for reducing the stress of the product after processing. None of the color parameters a* and b* or the luminosity index differed from each other, so it is valid to say that the UV-C radiation and chlorine sanitization treatments applied in the experiment were able to preserve the color of the cabbage samples for a period of 8 days. Therefore, the application of UV-C light did not negatively affect the color, pH or loss of mass of the minimally processed cabbage and combined with the correct packaging can be an alternative to conventional sanitization, in addition to maintaining the original aroma of the product.

The Impact of Time and Temperature of Operation on the Characteristics of High-Power UVC LEDs and Their Disinfection Efficiency

Disinfection and sterilization based on the use of UVC radiation are the key technologies ensuring health and safety. Their reliability depends on assuring the effectiveness of the performed process. In recent years, the rapid development of LED sources emitting high-power radiation in the UVC range has been observed, and there is a growing interest in using them in a variety of smart applications, mostly because they are easy to control, do not contain hazardous substances, and there are prospects to increase their energy efficiency. However, the literature does not provide enough knowledge on the reliability of disinfection with high-power UVC LEDs. This research aims to present a methodology of linking the performance characteristics with assessing the forecasted changes in the disinfection efficiency of exemplary UVC high-power LEDs caused by thermal and temporal changes in their characteristics. Based on the performed degradation test, the impact of the temperature and time of operation of the high-power UVC LEDs on the effectiveness of disinfection was evaluated, and the required disinfection times for exemplary pathogens were calculated. The results reveal a strong influence of the time of operation of high-power UVC LEDs on the disinfection reliability caused by the degradation of their optical power but with a low significance of wavelength shift.

Preharvest UV-C affects lettuce resistance to Xanthomonas campestris pv. vitians and quality

A series of independent trials were conducted to evaluate the use of UV-C radiation for controlling Xanthomonas campestris pv. vitians (Xcv), the causative agent of bacterial leaf spot in lettuce, and to assess the impact of this treatment on lettuce yield. The first trial involved repeated applications of a pre-established hormetic dose of UV-C (0.4 kJ/m2), for a total dose of 1.6 kJ/m2, which represented a single treatment cycle. Lettuce plants were inoculated with a virulent strain of Xcv 48 h after this treatment cycle. The second trial, which took place after Xcv inoculation, involved additional UV-C treatment cycles (0.5, 1.0 and 1.75 cycles), corresponding to total doses of 2.4, 3.2 and 4.4 kJ/m2 respectively. In the third trial, three weekly UV-C treatments were given at 48 h intervals using the standard 0.4 kJ/m2 dose, beginning the third week after seeding and continuing until the lettuce reached the commercial stage and was harvested. By the time the mature lettuce plants were harvested, they had undergone five treatment cycles, representing a total dose of 8 kJ/m2. A single UV-C treatment cycle resulted in a 90 %, 30 % or 10 % reduction in the susceptibility of the growing lettuce plants to Xcv compared with the control group, depending on when symptoms were evaluated. The application of additional treatment cycles (0.5, 1.0 and 1.75 cycles) resulted in a reduction of 30 %, 45 % and 50 % in susceptibility, respectively, in the treated lettuce plants relative to the controls. The fresh yield of lettuce treated with 2.75 cycles of UV-C (4.4 kJ/m2) was similar to that of the control lettuce; this treatment also resulted in a significant decrease (20 %) in core length, an agronomic trait associated with increased yield when lettuce is processed as fresh-cut ready-to-eat product. UV-C-treated lettuce had a significantly greater dry matter content and higher total mineral concentrations than the control lettuce. These results indicate that repeated preharvest UV-C treatments (0.4 kJ/m2) improve the tolerance of lettuce to Xcv without negative effects.

Quality of strawberries subjected to pre-harvest UV-C radiation

Abstract The objective of this work was to evaluate the influence of the use of UV-C radiation at an intensity of 0.53 KJ m-2, during strawberry (Fragaria x ananassa) cultivation, on the physicochemical and phytochemical parameters of the fruits. The used experimental design was completely randomized, in a single-factor arrangement with 11, 19, 29, and 39 UV-C applications and without UV-C application. The hue of the fruits was smaller at the end of the study period. pH varied in strawberries that received 39 applications of UV-C, and the soluble solids content differed with 19 applications. Antioxidant activity was lower in fruits with 11, 19, and 29 UV-C applications, whereas vitamin C content was lower only in fruits that received 29 applications. The use of UV-C radiation at an intensity of 0.53 KJ m-2, during strawberry cultivation, affects the physicochemical and phytochemical parameters of the fruits, but does not cause losses in their quality.

Beware of UVC sanitizers: not all are good

Disinfection is now one of the major concerns of society. Soap, or hydroalcohol are two known ways of sanitizing different objects. Now we can find in the market more sophisticated systems, which provide more confidence on their sanitizing effects, or that allows disinfection of objects that cannot be sanitized with soap or hydroalcoholic solutions. In this work we analyze a commercially available sanitizing device that claims the use of UVC radiation. We will show that this device is not suitable for complete disinfection of the objects introduced on the cabin. We provide spectral characterization of the sources, as well as irradiance measurements inside the cabin. We conclude that the cabin cannot be used for sanitizing most of the objects that are included in the documentation of the device.

On the positive effect of UVC light during the removal of benzothiazoles by photoelectro-Fenton with UVA light

Benzothiazole (BTH) and 2-hydroxybenzothiazole (2-OH-BTH) are ubiquitous pollutants in aquatic ecosystems. This article reports their photoelectro-Fenton (PEF) treatment, either alone or mixed, in sulfate medium at pH 3.0 using an IrO2-based/air diffusion cell that generates H2O2 under UVA and/or UVC irradiation. UVC-PEF was more effective than UVA-PEF to remove the target pollutants, which suggests a positive impact of OH formed via Fenton’s reaction and photo-induced homolysis of H2O2 in the former method. In addition, BTH disappeared more quickly than 2-OH BTH. Full-time UVA-/UVC-PEF outperformed UVC-PEF and UVA-PEF to mineralize the mixtures, although requiring a much higher energy consumption. The evolution of generated H2O2 and homogeneous OH confirmed the positive contribution of UVC photolysis in UVA-PEF. Part-time use of UVC radiation in UVA-PEF yielded a similar total organic carbon removal, with much lower energy consumption. BTH was oxidized to 2-OH-BTH, which was subsequently transformed into other five heteroaromatics.

Use of UV-C radiation for reducing storage losses of potato tubers

Ultraviolet radiation in the C band to limit storage losses of potato was applied. Six edible potato varieties, viz., Lord, Vineta, Owacja, Ditta, Finezja and Tajfun were used as test materials. UV-C radiation was emitted from a 15 W radiator. The wavelength of the light used to irradiate potato tubers was 253,7 nm and the power density from 80 to 100 μW/cm2. The method of reduction of storage losses of potato tubers, based on their exposure to UV-C irradiation, can complement the presently used methods of potato crop protection during long-term storage.

Use of UV-C radiation and ozonated water for the reduction of microbial load of minimally processed melon

Use of UV-C radiation and ozonated water for the reduction of microbial load of minimally processed melon

The reduction of Chlorella vulgaris concentrations through UV-C radiation treatments: A nature-based solution (NBS)

Algal blooms have become a pressing issue in inland freshwater systems on local and global scales. A plausible approach to reducing algae without the use of chemical/biological agents is through the use of UV-C radiation from lamps potentially powered by in situ solar panels to eliminate algae. Yet, the quantitative scientific base has not been established. Our objective is to conduct a controlled experiment to quantify the effectiveness of UV-C radiation on the reduction of Chlorella vulgaris, a common algal species in the Great Lakes region. A full factorial design of three intensities of UV-C radiation (0, 15, and 30W) and three sources of C. vulgaris was constructed to test the corresponding hypotheses. Empirical models were constructed to predict the reductions. UV-C radiation effectively reduced the algal concentration with clear differences by radiation level and source of algal water. Algal concentration decreased exponentially over time, with distinct decreasing trends among the radiation intensities and the samples. With 15W UV-C radiation, algal concentration of three samples were reduced to 75.3%, 51.5%, and 70.0% of the initial level within an hour, respectively. We also found a clear density-dependent reduction rate by UV radiation. Using this information, more efficient treatment systems could be constructed and implemented for cleaning algae-contaminated water.

English

Minimally processed fruits need to be treated with techniques to keep their quality, and lower the incidence of their pulp and rots becoming black. In this context, this work aims to evaluate the efficiency of the use of UV-C radiation and different additives in preventing browning and conserving ‘Fuji Suprema’ apples that are minimally processed. The experimental design was completely randomized with factorial scheme of 5x2x3 (5 additives x 2 UV-C applications x 3 storage periods). The apple slices were placed in solutions containing the following: control; ascorbic acid (1%); sodium isoascorbate (1%); ascorbic acid (0.5%) + sodium isoascorbate (0.5%); citric acid (0.5%) + sodium isoascorbate + 0.5%. It was used with and without UV-C radiation in minimally processed apples, the intensity of the radiation emitted was 2.71 kJ.m-². Then the trays were stored in a cold room at 4±1°C temperature and a relative humidity of 85-90%. They were stored for periods of 0, 6 and 12 days. The parameters assessed were: mass loss, pulp color, soluble solids, titratable acidity, rot incidence, total phenolic compounds and antioxidant activity. The use of ascorbic acid, sodium isoascorbate and associate compounds contributes to the keep of the pulp color of the minimally processed apples on 12th day of storage. UV-C reduces rot incidence, and increases the soluble solids, phenolic compounds and antioxidant activity, when compared without the use of UV-C radiation on 12th day of storage. The ascorbic acids keep the total phenolic concentration in the minimally processed apples. Key words: Malus domestica, storage duration, phytochemical content.

Color, physicochemical parameters and antioxidant potential of whole grape juices subject to different UV-C radiation doses

ABSTRACT Knowing that moderate stress such as UV radiation can activate defense mechanisms in plants, the use of UV-C radiation appears as hypothesis of a promising technique that would help to stimulate and enhance beneficial compounds for health, through a clean and healthy technology. In this study, the possible induction of secondary metabolism, the increase in the content of phytochemical compounds and physicochemical changes through the use of UV-C radiation were evaluated on whole grape juices produced with Vitis labrusca grapes, cultivar Isabel Precoce. Grapes were harvested, sanitized, exposed to UV-C radiation at doses of 0, 2, 4 and 6 KJ m-2, and then the juices were prepared and packed into amber glass bottles at room temperature. Analyses were performed at 0, 30, 60, 90 and 120 days of storage. Based on results obtained and conditions in which the experiment was performed, UV-C treatment in grapes caused abiotic stress in the fruits, affecting color, titratable acidity, soluble solids/titratable acidity ratio, vitamin C and percentage of protection against oxidation. Application of UV-C did not change levels of phenolic compounds in fruit juices or the percentage of scavenging free radicals, pH and soluble solids.

Application of UV-C Radiation in the Conservation of Minimally Processed Rocket (Eruca sativa Mill.)

The effects of UV-C pretreatments (10, 20 and 30 kJ/m2), compared with modified atmosphere packaging (MAP), on sensory change, microbial and bioactive profile of minimally processed rocket leaves throughout 12 days at 5C were investigated. Nonirradiated samples were used as controls. All UV-C treatments reduced the natural microflora growth. In relation to sensory quality, all treatments resulted in a shelf life of 8 days. Total antioxidant activity and total phenol content decreased after 8 days for all treatments. Generally, UV-C slightly reduced the initial total chlorophyll content; however, during storage, its degradation was similar to that of the control. It is concluded that UV-C pretreatment could be useful to the industry to reduce the natural microflora growth, keeping the overall quality without affecting the bioactive compound profile of fresh rocket leaves during 8 days of storage at 5C. Practical Applications The information provided in this study shows that the use of UV-C radiation could be a useful tool for the food industry for maintaining the overall quality and safety of fresh rocket leaves, while minimizing water consumption and wastewater discharge rates.

Combined effect of UV-C, ozone and electrolyzed water for keeping overall quality of date palm

The work presented here aims to contribute with a sustainable alternative to chemicals for avoiding deterioration of harvested date palm fruits by evaluating the single or combined use of UV-C radiation and ozonated or electrolyzed water (EW). In this way, the effects of UV-C light (0; 2.37; 6.22; 8.29 and 12.14 kJ m−2) alone, and the combined effect of 6.22 kJ m−2 UV-C with neutral EW (NEW, pH 6.99, 870 mV ORP, 100 mg L−1 free chlorine), alkaline EW (AEW, pH 11.28, −880 mV ORP, 1.83 mg L−1 free chlorine) and ozonated (O3, 0.55 mg/L ozone) water on overall quality of Deglet Nour dates stored for 30 days at 20 °C were studied. Microbial growth, weight loss, firmness, pH, titratable acidity, moisture, water activity, sugars and phenolics content, antioxidant activity color and sensory quality were monitored. UV-C light, mainly at 6.22 kJ m−2, alone or combined with NEW, AEW and O3, kept the overall quality of dates during storage, Moreover, those treatments reduced the most mesophilic, coliforms, yeasts and molds counts. In summary, these combined emergent sanitizers could be useful for disinfection of fresh dates while keeping quality and prolonging shelf-life.

Effect of ultraviolet-C radiation on “Kumagai” guavas infested by Ceratitis capitata (Diptera—Tephritidae) and on physical parameters of postharvest

Physical quarantine methods are being developed to replace fumigants to control arthropods and microorganisms during post-harvest management of fruit and vegetables. This study aims to evaluate the use of UV-C radiation to disinfest guava with Ceratitis capitata (Wied.) eggs and evaluate the quality of fruit irradiated at two different storage temperatures. For the in vitro test, one-day old C. capitata eggs were exposed to increasing doses of UV-C radiation and stored in a B.O.D. chamber. Applying in vivo tests, ‘Kumagai’ guavas were exposed to artificial infestation by medfly. After infestation, the fruits were subjected to an increasing intensity of UV-C radiation and stored in a B.O.D. incubator at 23.0±0.2°C for about 20 days. In vitro tests indicated that 1.383kJm−2 UV-C on C. capitata eggs was capable of preventing the eclosion of larvae. However, guavas infested by medfly eggs needed 16.0kJm−2 of UV-C to prevent pupation. The guavas subjected to treatment with UV-C radiation and stored at a temperature of 8±0.2°C, obtained much better responses in terms of quality indices than those stored at 22±0.2°C, which lends credence to the storage temperature being a key factor in maintaining fruit quality.

Effect of radiation intensity on the outcome of postharvest UV-C treatments

Studies on the use of UV-C radiation of fresh produce have focused on the selection of appropriate doses (energy per unit area) for different commodities, but little attention has been placed on the effect of radiation intensity (dose per unit time). In this study, tomatoes (Solanum lycopersicum cv. Elpida) and strawberries (Fragaria×ananassa cv. Camarosa), were harvested (breaker and 100% of surface red color respectively) and treated with 4kJm−2 of UV-C, at low (3Wm−2) or high (33Wm−2) radiation intensities. Untreated fruits were used as controls. After the treatments and at different storage times the incidence of postharvest rots and the changes in fruit physical and chemical properties were determined. UV-C treatments reduced decay, with the effects being were more marked in fruit exposed to high intensities. Mold counts were unaffected by the treatments, suggesting that improved disease control did not result from greater germicide effect. In both fruit species exposure to UV-C radiation delayed ripening, evidenced as lower color development, pigment accumulation and softening. UV-C-treated fruit maintained better quality than the control. In strawberry, high intensity treatments were more effective to prevent deterioration than in tomato where the differences between UV-C treatments were subtler. Soluble solids, titratable acidity and ethanol soluble antioxidants were not affected regardless of the UV-C intensity. Consumer tests showed higher preference of fruit treated at high UV-C intensity. Results show that in addition to the applied dose, radiation intensity is a main factor determining the effectiveness of UV-C treatments and should not be over-sighted. For a given dose, increasing radiation intensity may in some cases maximize the benefits of UV-C on fruit quality, while significantly reducing the treatments time.

Investigating Alternative Strategies for Managing Bacterial Angular Leaf Spot in Strawberry Nursery Production

This article discusses some of the approaches we have tested for managing the bacterial pathogen Xanthomonas fragariae in infected strawberry nursery stock. X. fragariae causes angular leaf spot in strawberry and is transmitted to production fields almost exclusively through infected nursery stock. Of the methods that we have investigated over the past several years, a modified heat treatment has proven to be very effective at reducing systemic infections in propagation material, but cultivar selection affected the outcome. Surface-sterilizing treatments also had an effect on angular leaf spot. We tried procedures from dipping plants in a solution of 10% chlorine bleach to the use of UV-C radiation to reduce the severity of angular leaf spots in the field. Lastly, a sanitation-type treatment, namely removing or trimming remnant leaf and petiole tissue from nursery-trimmed plants, was found to have a significant impact on angular leaf spot. No one method completely eliminated X. fragariae from the planting stock, but there is good indication that a strategic combination of control practices that includes heat treatment should help to reduce significantly the initial amount of bacteria introduced into a field.

Inactivation kinetics of peroxidase in zucchini (Cucurbita pepo L.) by heat and UV-C radiation

The effect of traditional thermal water blanching, or its combination with a UV-C radiation pre-treatment (11 J/m 2 ), on the inactivation kinetics of peroxidase in zucchini ( Cucurbita pepo L.) was carried out in the temperature range of 80 to 98 °C, and up to 3 min of processing time. Peroxidase inactivation started being noticed only at temperatures around 85 °C. For both treatments, the inactivation kinetics followed a first order reaction with the Arrhenius model describing the temperature dependence of the reaction rate. The obtained kinetic parameters ( k Heat 89.6 °C = 7.37 × 10 − 7 ± 3.47 × 10 − 7 min − 1 and E a Heat = 925 ± 69 kJ mol − 1 ; k Heat 89.6 °C + UV-C = 2.42 × 10 − 5 ± 6.58 × 10 − 6 min − 1 and E a Heat + UV-C = 596 ± 48.8 kJ mol − 1 ) showed that UV-C radiation had a significant contribution to increase the peroxidase degradation rate. These results will help to design new pre-processing conditions for the production of frozen zucchini, using less severe thermal treatments and attempt to minimize quality losses. The use of UV-C radiation in processing creates novel methodologies, which can be complementary to classical techniques, providing reduced processing times and increased efficiency. Having been proved to be particularly useful in sterilization of liquids and surfaces, inhibition of microbial population and in decrease of protein synthesis, its application in combination with the traditional blanching may be in favor of less severe heating treatments. The evaluation of the kinetics of zucchini ( Cucurbita pepo L . ) peroxidase inactivation with the traditional blanching method and combined with ultraviolet radiation suggests that short UV-C treatments may be a useful non-chemical pre-freezing method, allowing the application of shorter blanching times, leading to a product with eventual higher quality retention which is highly relevant to industry. ► Heat blanching + UV-C above 85 °C promoted a synergistic effect on enzyme inactivation. ► Peroxidase heat + UV-C radiation inactivation in zucchini follows first-order kinetics. ► Addition of UV-C radiation to heat blanching favors a less severe blanching treatment. ► A UV-C radiation chamber was conceived by University of Algarve, Portugal.

Direct UV photolysis of propranolol and metronidazole in aqueous solution

The aim of this work was to study the direct photolysis of two pharmaceuticals: propranolol (PRO) and metronidazole (MET) promoted by ultra violet radiation (UV). For this purpose, 50 and 100 mg L −1 aqueous solutions of PRO and MET were irradiated by two different UV sources: a UV-254 germicidal lamp (UV-C) and a UV-365 black light lamp (UV-A). After 8 h of irradiation, direct UV photolysis promoted substantial pharmaceuticals removal, especially with the use of UV-C radiation (near 50%). However, on average only 12% of the organic matter content was photodegraded. The photo-transformation of both compounds promoted the formation of more biodegradable byproducts. Nevertheless, PRO direct UV-C photolysis produced byproducts with less toxic character while MET irradiation promoted a slight increase of toxicity. Direct photolysis of PRO using solar radiation was proved to be as effective as those runs carried out with the UV-C device. Kinetic constants based on time and UV-C fluency were in a magnitude order of 10 −2 h −1 and 10 −5 cm 2 mJ −1, respectively.

Use of UV-C radiation as a non-thermal process for liquid egg products (LEP)

The efficacy of short wave ultraviolet light (UV-C) as a non-thermal process for liquid egg products (LEP) was investigated. Non-pathogenic Escherichia coli strain (ATCC 8739), which shows lower sensitivity to UV-C light than E. coli O157:H7 and Salmonella typhimurium, was chosen as a target microorganism. The inactivation of UV resistant strain of E. coli in LEP was examined by evaluating the effects of depth of liquid food medium (0.5, 0.3 and 0.153 cm), UV light intensity (1.314, 0.709 and 0.383 mW/cm 2) and exposure time (0, 5, 10, and 20 min) by using a collimated beam apparatus. The best reduction (>2-log) was achieved in liquid egg white (LEW) when the fluid depth and UV intensity were 0.153 cm and 1.314 mW/cm 2, respectively. Maximum inactivation was 0.675-log CFU/ml in liquid egg yolk (LEY) and 0.316-log CFU/ml in liquid whole egg (LWE) at the same conditions. The kinetics of UV inactivation of E. coli in LEP was nonlinear. Our results emphasize that UV-C radiation can be used as a pre-treatment process or combined with mild heat treatment to reduce the adverse effects of thermal pasteurization of LEP.