UV-C Irradiated Research Articles

Persistence luminescence and thermoluminescence of 260 nm UVC irradiated mixed-phase (BaAl2O4 - BaAl12O19) barium aluminate

Persistence luminescence (PerL) and thermoluminescence (TL) of BaAl2O4 - BaAl12O19 mixed phase compound under 260 nm UVC irradiation are studied. The sample shows PerL for more than 1 hour post irradiation. TL glow curves of the sample recorded at 1 oC/s following irradiation to UVC radiation shows a composite glow peak between 30 and 230 oC. The TL intensity is found to be affected by thermal quenching. The activation energy for thermal quenching is estimated to be W=0.85±0.12 eV. A Tm-Tstop analysis reveals that the TL glow peak is composed of multiple first order components. The activation energy associated with the electron traps are found to vary from 0.66 to 1.70 eV. The density of traps is high between 0.60 and 1.20 eV. Due to presence of continuous distribution of electron traps, there is an excellent scope of developing colour tuneable persistence luminescence phosphor using mixed phase barium aluminate.

Improvement of Drought Resistance of Osteospermum ecklonis Plants as a Physiological and Biochemical Response to Low Doses of UV-C Irradiation

Osteospermum ecklonis DC. NORL. is native to South Africa and is fully adapted to the Mediterranean climate. The aim of the study was to elucidate morphological and developmental changes in O. ecklonis plants associated with drought resistance in response to low doses of UV-C. Growth responses under three levels of drought stress (NW: normal watering, MD: moderate drought stress and SD: severe drought) were recorded. The results showed that 1 kJ m−2 UV-C significantly (p < 0.05) increased resistance to water stress without affecting growth and development or damaging photosystem II. Fresh weights of the upper parts and the root system of the irradiated plants were maintained at similar levels to those of the non-irradiated control plants. Fv/Fm values in the irradiated plants ranged from 0.73 to 0.82 depending on the stress level, while in the non-irradiated plants, the values ranged from 0.69 to 0.83. Differences between UV-C irradiated and non-irradiated plants were recorded in electrolyte leakage (EL), in malondialdehyde (MDA) and in relative water content (RWC) at all drought levels. The EL percentage of the non-irradiated plants at SD was 19.7%, while in the irradiated plants, it was 17.8%. RWC rates in the irradiated plants ranged between 60.6 and 76.4%, while in the non-irradiated plants, they ranged from 54.2 to 63.6%. Superoxide dismutase (SOD) and catalase (CAT) activities increased with UV-C irradiation, suggesting that antioxidant responses were induced and protected cell membranes from lipid peroxidation and damage. The results of the present study showed that UV-C irradiation at 1 kJ m−2 alleviated the drought symptoms of O. ecklonis by reducing oxidative stress and membrane lipid peroxidation.

Coagulation studies on photodegraded and photocatalytically degraded polystyrene microplastics using polyaluminium chloride

Microplastics are ubiquitous persistent emerging contaminants, and its presence has been detected even in the most pristine and fragile ecosystems. Advanced oxidation processes are one of the novel degradation technologies used for the elimination of microplastics from the environment. In this study, the effect of ultraviolet C (UV-C, 253.7 nm) and ultraviolet A (UV-A, 365 nm) irradiations on polystyrene (PS) microplastic properties in the presence and absence of titanium dioxide were studied along with their coagulation performances using polyaluminium chloride (PAC). The effects of solar irradiation on the chemical properties of microplastics in aqueous and dry conditions were also investigated. PS microplastics (1.5 g) in three size ranges, 300–150 μm, 150–75 μm, and <75 μm were used during this experiment. After 45 days of irradiation, samples showed discolouration, brittleness, and loss of hydrophobicity. Images obtained from scanning electron microscope revealed smoothening and melting of PS surfaces upon UV exposure. Attenuated total reflectance- Fourier transform infrared spectroscopy and X-ray photon spectroscopy of photoaged samples revealed chemical alterations, bond cleavage and formation of oxygenated functional groups on microplastic surfaces. PAC coagulation of samples before and after UV irradiation showed drastic differences in removal efficiencies, with UV-C irradiated microplastics exhibiting maximum efficiency. Large sized and photocatalytically degraded microplastics showed better removal efficiencies than small sized particles. The 300–150 μm sized PS microplastic, degraded photo catalytically under UV-C irradiation showed approximately 99 % removal efficiency, while PS < 75 μm photodegraded under UV-A irradiation showed only 74.2 % removal efficiency.

Study of the thermoluminescence properties of γ and UV-C irradiated Li3PO4: Dy synthesized by solid state diffusion method

This paper reports the thermoluminescence (TL) properties of Li3PO4 doped with rare earth Dy3+ ions. The solid state diffusion method is used to synthesize phosphors with varying concentrations of the dopant (0.1, 0.2, 0.3, 0.4 and 0.5 mol%). Characterization of the samples is performed using X-ray diffraction (XRD), Fourier Transform Infrared-Attenuated Total Reflection spectroscopy (FTIR-ATR) and Scanning Electron Microscopy (SEM). Samples are irradiated with γ rays in the dose range of 10 Gy to 6 kGy and by UV-C rays (254 nm) for exposure duration ranging from 0.5 to 5 h. Maximum TL intensity in both cases is observed for the phosphor doped with 0.2 mol% Dy3+. While a linear TL response is found for the entire duration of UV-C irradiation, the dose response for γ irradiation stays linear upto 3 kGy for the high temperature peak at 335∘C. Appreciable repeatability values are found (for both γ and UV-C irradiated samples) and significantly low fading (for the UV-C irradiated phosphor) is reported. The computerized glow curve deconvolution has been done using an R-package, “tgcd: Thermoluminescence Glow Curve Deconvolution” by assuming the Kitis general order kinetics model. Chen’s peak shape method is utilized to extract trapping parameters such as the order of kinetics (b), shape factor (μg), frequency factor (s), activation energy (E) and trap density (n0). Various promising properties of this material are found suggesting that it could be used as a TL dosimeter.

UV-C irradiation accelerated the deposition of suberin and lignin at wounds by activating phenylpropanoid metabolism in potato tubers

UV-C could directly inactivate pathogens, and reduce postharvest diseases of fruits and vegetables by inducing resistance. To date, no studies have been carried out to verify whether UV-C may accelerate the wound healing of potato tubers. The present results demonstrated that UV-C irradiation up-regulated StPAL, St4CL, and StCAD expression and activated phenylalanine ammonia-lyase (PAL), 4-coumarate: coenzyme A ligase (4CL), and cinnamyl alcohol dehydrogenase (CAD). Meanwhile, UV-C irradiation elevated the levels of four phenolic acids (p-coumaric acid, caffeic acid, sinapic acid, and ferulic acid) and three lignin monomers (coniferyl alcohol, sinapyl alcohol, and p-coumaryl alcohol), and accelerated the suberin polyphenolic (SPP) and lignin accumulation at wounds, thereby decreasing weight loss and disease index. The weight loss and disease index in the UV-C irradiated tubers were 36.48% and 56.25% lower than that of the control on the 14 d of healing, respectively. Taken together, UV-C irradiation promoted the process of wound healing in potato tubers by stimulating phenylpropanoid metabolism as well as accelerating the SPP and lignin accumulation at wounds. Therefore, UV-C irradiation could be employed as a simple, safe, and low-cost handling technology for accelerating wound healing of potato tubers.

Photosynthetic Pigments Content in Emmer Wheat Plants as Criteria of Productivity in Traditional and Organic Farming Technology

Background. Estimation of chlorophyll and carotenoid content is an informative way to obtain ideas about the plants photosynthetic process and is an indirect method for assessing the productivity of plant crops, including cereals. As the worldwide interest at now for traditional and natural foods is growing, in the work we used one of the oldest grain crops – emmer wheat (Triticum dicoccum (Schrank.) Schuebl.) which was cultivated in traditional and organic farming system. Objective. The study aim was to determine the role of chlorophyll and carotenoids in the emmer wheat productivity formation by traditional and organic farming technology under different pre-sowing seed treatment systems. Methods. Field experiment was establishment during 2019–2021 on low-humus, hard-loam chernozems, the condition of which meets the “virgin land” criterion. The emmer wheat cultivation in organic technology was carried out in crop rotation: winter rye (green manure crop) – mustard (to improve the field phytosanitary condition and soil organic matter indicators) – emmer wheat. Two variants of pre-sowing seed treatment were studied: irradiation with ultraviolet light of the C range (100–280 nm) and seed treatment with 1r Seed Treatment humic preparation. The pre-sowing seed treatment in the traditional technology of the emmer wheat cultivation was carried out by the UV-C irradiation. In organic technology both UV-C irradiation and treatment with 1r Seed Treatment humic preparation of natural origin were used. Statistical data processing was performed by methods of descriptive statistics, regression and analysis of variance by the program Statistica 10.0. The experimental data significance was evaluated by using multifactor analysis of variance (ANOVA) to calculate the least significant difference (LSD05). Results. It was found the use of UV-C seeds irradiation in organic and traditional cultivation technologies leads to increase in the chlorophyll a (Chl a) content by 9.2 % and chlorophyll b (Chl b) content by 14.5 % in plants grown by organic technology, however to decrease in carotenoid content (Ct) by 14.9 %. The increase in the photosynthetic pigments content by UV-C seeds irradiation lead to yield increase from 4.26 t/ha by the traditional technology to 5.17 t/ha by the organic technology, ie by 21.4 %. In organic technology based on the comparison of the photosynthetic apparatus main indicators of the emmer wheat and yield, the most effective method for seed treatment was determined. It was established that at result of 1r Seed Treatment humic preparation application in pre-sowing seed treatment, the Chl a concentration decreased by 2.4 %, the Chl b and Ct concentration increased by 5 and 25.5 %, respectively, compared with plants grown from UV-C irradiated seeds. When 1r Seed Treatment was used for pre-sowing treatment yield was 5.58 t/ha, while at UV-C seed treatment – 5.17 t/ha, ie, the yield increase was 8 %. An inverse correlation between the ratio of the photosynthetic pigments Chl a/Chl b content and the emmer wheat yield was determined. Conclusions. According to the study results, it can be assumed that the introduction of organic farming technology with pre-sowing seed treatment by the 1r Seed Treatment humic preparation can increase the emmer wheat yield by 31% compared to the traditional technology. Thus, the photosynthetic pigments content and their ratio can be the effectiveness indicators of the implemented agricultural technologies.

A COMBINED METHOD OF POST-HARVEST HANDLING OF SWEET CHERRY FRUIT VERSUS FRUIT STORABILITY

The objective of the research was to determine an optimum method of postharvest handling of sweet cherry fruits which may contribute to prolonged shelf-life. The following physical factors were examined – storage temperature: 2–4°C, 6–8°C, 18–20°C; postharvest fruit packaging and treatment: Xtend® CH-49 bags + no exposure to UV-C, Xtend® + exposure to UV-C for 120 s or 600 s, no bagging + no exposure to UV-C, no bagging + UV-C for 120 s or 600 s. UV-C irradiation, regardless of the duration and storage conditions, prolonged the storage life of sweet cherry fruit. During the 14-day period of storage, the smallest weight loss as well as the highest number of fruits suitable for consumption were found after exposure to UV-C for 600 s in both Xtend® bags and flat, exposed polyethylene containers. After 28 days, higher amount of fruits suitable for consumption were found after storage at 2–4°C than at 6–8ºC. The most advantageous postharvest treatment method was placing fruits in containers and irradiating them with UV-C for 600 s. However, statistically similar results were obtained also after packing the fruits in Xtend® bags and irradiating them with UV-C for 600 s as well as placing them in containers and irradiation with UV-C for 120 s. In addition, UV-C irradiated fruits for 120 s and 600 s contained significantly more reducing sugars than non-irradiated fruits after 14 days of storage. UV-C irradiated fruits for 600 s also contained the greatest amount of flavonoids. After 28 days of storage, the highest content of flavonoids and phenols was determined in UV-C exposed fruits stored in containers. In addition, it emerged that storing sweet cherry fruit at 2–4°C without bagging contributed to increased total phenolic content compared with fruit stored in Xtend® bags. Packaging cherry fruit in Xtend® bags is the most reasonable when it stored at 6–8°C and at room temperature.

Effect of UV-C Irradiation, Storage and Subsequent Cooking on Chemical Constituents of Fresh-Cut Potatoes.

UV-C irradiation successfully reduces the growth of microorganisms, but it can also affect the content of phenolics and sugars of fresh-cut potatoes (FCP). This could consequently alter antioxidant capacity of FCP or its potential for acrylamide formation. Therefore, this paper investigates the influence of UV-C irradiation on the content of phenolics [chlorogenic acid (CA)] and individual sugars during storage of FCP as well as after cooking. Acrylamide was also monitored in FCP after frying. Potato slices pre-treated with sodium ascorbate solution and vacuum-packaged were UV-C irradiated for 0, 3, 5, and 10 min in order to obtain irradiation doses of 0, 1.62, 2.70, and 5.40 kJ m−2, respectively, stored for 23 days (+6 °C), and subsequently boiled and fried. As the applied dose and storage duration increased, the CA content in raw FCP decreased (it retained for 75.53–88.34%), while the content of sugars as well as acrylamide in fried FCP increased. Although the increase was the most noticeable at the applied dose of 2.70 kJ m−2, the acrylamide content was always below proposed limit. Boiling and frying reduced the content of CA and sugars. In spite of certain alterations, applied doses of irradiation can ensure acceptable product in regard to phenolics and sugars, and acrylamide content particularly.

Application of UV-C Irradiation to Rosa x hybrida Plants as a Tool to Minimise Macrosiphum rosae Populations

UV-C irradiation is known to enhance plant resistance against insect pests. In the present study, we evaluated the effects of low doses of UV-C on Macrosiphum rosae infesting greenhouse rose (Rosa x hybrida) plants. The application of 2.5-kJ/m2 UV-C irradiation on rose leaves before infestation induced anti-herbivore resistance and negatively affected the aphid fecundity. No eggs and first instar nymphs were recorded on irradiated leaves, whereas an average of 4.3 and 2.7 eggs and 6.7 and 14 first instars were recorded on vars. “Etoile Brilante” and “Arlen Francis” untreated leaves, respectively. UV-C irradiation reduced the aphid population from naturally infested rose plants by up to 58%. In a greenhouse pot trial (GPT) in 2019, UV-C irradiation minimised the initial aphid population six hours after treatment. UV-C elicited host resistance and, also, helped in aphid repulsion without killing the adult individuals. UV-C did not affect the physiological responses of rose plants. The net CO2 assimilation of the UV-C irradiated plants ranged between 10.55 and 15.21 μmol/m2. sec for “Arlen Francis” and between 10.51 and 13.75 μmol/m2. sec for “Etoile Brilante” plants. These values, with only a few exceptions, were similar to those recorded to the untreated plants.

Efficacy of Orange Essential Oil and Citral after Exposure to UV-C Irradiation to Inhibit Penicillium digitatum in Navel Oranges

The effect of UV-C irradiation on antifungal properties of orange essential oil (EO) against Penicillium digitatum in inoculated Navel oranges was examined. The UV-C irradiation of orange EO resulted in a 20% loss of the major constituent, limonene, and the generation of three hydroperoxide oxidation products, (2S,4R)-p-mentha-6,8-diene-2-hydroperoxide,(1S,4R)-p-mentha-2,8-diene-1-hydroperoxide, and (1R,4R)-p-mentha-2,8-diene-1-hydroperoxide. The P. digitatum growth in oranges dipped in non-irradiated orange EO at 1000–4000 µL L−1 was not significantly different to control the fruit. Dipping in UV-C treated orange EO inhibited the growth of P. digitatum with 4000 µL L−1 having the greatest effect. No phytotoxic injury to the rind was observed at any concentration. Citral, as a known antifungal chemical, was included for comparison. The non-irradiated citral (1000 µL L−1) was more effective than irradiated orange EO, but elicited rind phytotoxicity. The irradiated citral was less effective in inhibiting P. digitatum growth with the loss of citral, but not hydroperoxide formation. These results suggest UV-C irradiated orange EO as a potential alternative to synthetic fungicides to inhibit P. digitatum decay. The source of orange EO could be waste flavedo generated by the orange juice processing industry.

In vitro gastrointestinal digestion and colonic fermentation of phenolic compounds in UV-C irradiated pineapple (Ananas comosus) snack-bars

Pineapple (Ananas comosus) is a widely consumed tropical fruit. UV-C irradiation reduces the microbial load of fruits and contributes to the increase their content of phenolic compounds (PCs). Snack-bars were prepared batch using UV-C irradiated pineapple slices (irradiated pineapple bar, IPB) or with non-irradiated pineapple slices (non-irradiated pineapple bar, NIPB). Both snacks-bar samples were submitted to simulated gastrointestinal digestion and in vitro colonic fermentation, to evaluate the in vitro bioaccesiblility of PCs present in these fruit-based products. The bioaccesibility of PCs in both samples at the end of the digestion process was 45%. PCs in the intestinal phase increased about 52.7% (NIPB) and 62.8% (IPB) compared to the gastric phase, a change that indicates how many of the PCs cross the intestinal barrier. Twenty-six different compounds, including flavonoids, hydroxycinnamic and phenolic acids were identified in the digested samples. The non-digestible fraction submitted to colonic fermentation, was rich in flavonoids, mostly gallocatechin. This compound was degraded and biotransformed by the gut microbiota producing different compounds, including 3-hydroxybenzoic and 4-hydroxyphenylacetic acids. The study of the bioconversion of PCs present in different food matrices stress the relevance of the metabolites produced during the colonic fermentation.

Impact of ozone and UV irradiation sanitation treatments on the survival of Salmonella and the physical–chemical characteristics of hen eggs

Summary Salmonella is the second main cause of foodborne illness in poultry production. It is one of the most problematic zoonoses in terms of public health worldwide because of the difficulty in controlling it and its significant morbidity and mortality rates. Recent surveys have shown that small flocks of laying hens have the same or higher prevalence of salmonellosis than larger flocks, mainly due to a lack of control actions, that is, the control of mice and wild animals, employees, and poor management practices. In this regard, different physical and chemical procedures have proven efficacious for reducing external and/or internal Salmonella contamination. This research evaluated the effect of ozone and UV-C rays on Salmonella growth and hen egg quality. Microbiological evaluation was performed on 120 eggs: negative control (C−), eggs not contaminated with Salmonella; positive control (C+), eggs contaminated; contaminated ozonate-treated (O, 600 mg/h for 2 h); and contaminated UV-C–irradiated (ʎ, 254 nm for 15 s) eggs. Moreover, 30 eggs were used (10/group) for the quality assessments of the C, O, and UV-C groups. A 2 log10 CFU/g reduction in Salmonella on contaminated eggs was found in the UV-C group compared with the C+ and O groups. Compared with UV-C treatment, ozonization reduced the amount of yolk tocols and carotenoids (by 2 times). The lipid oxidative status decreased (−1.5 times), similar to the cholesterol level (−28.5%), whereas the amount of cholesterol and its oxidized products increased (+82.1%) in the O group compared with the C group. UV-C irradiation is an effective strategy to reduce Salmonella contamination in eggs without negatively affecting the quality. Therefore, UV treatments remain among the more promising procedures.

Prolonged UV-C Irradiation is a Double-Edged Sword on the Zirconia Surface.

Zirconia has become an excellent choice of dental implants because of its excellent mechanical strength, aesthetic, and biocompatibility. Although some studies have shown ultraviolet (UV) irradiation is effective to photofunctionalize dental zirconia that can improve osteoblastic function, the scattered information has not identified the most effective exposure time and wavelength of UV. Herein, this study has investigated the effects of UV irradiation on zirconia after UV-A (365 nm) or UV-C (243 nm) photofunctionalization for different times (15 min, 3 and 24 h). After irradiation, the zirconia surface was analyzed by color spectrophotometry, scanned electron microscopy (SEM), energy-dispersive X-ray spectrometry, water contact angle (WCA) with goniometer, and X-ray diffraction. Osteoblastic (MC3T3-E1) cells were cultured on zirconia discs and evaluated with a CCK-8 test kit for cell proliferation (3 h and 1 day) and with alkaline phosphatase (ALP) activity (14 days). Significant color change (ΔE) was observed by irradiating with UV-C for 15 min (1.99), 3 h (1.92), and 24 h (3.35), whereas only minute changes were observed with UV-A (respectively, ΔE: 0.18, 0.14, 0.57). No surface textural changes were observed nor a monoclinic phase was detected on both the UV-A and UV-C irradiated samples. UV-C significantly decreased the C/Zr ratios and WCA, with irradiating for 24 h presenting the lowest values, and it was the only condition to give significantly higher ALP activity at 14 days (p < 0.05) and CCK-8 values for 1 day culture (p < 0.05). It is concluded that UV-C (but not UV-A) irradiation can significantly change the aesthetic in color, and only prolonged 24 h UV-C irradiation can enhance MC3T3-E1 cell adhesion on zirconia by photofunctionalization.

Astaxanthin Has a Potential Role in Antioxidation and Oxidative Damage Repair in UVC Irradiated Mice

The anti-oxidative activity and oxidative damage repair potential of dietary AS in UVC irradiated mice was studied in present study. The activities of superdismutase (SOD) and glutathione peroxidase (GPx) in the liver and serum of mice increased dramatically at treatment with a dose of 100 mg/kg bodyweight AS during 10 days UVC light irradiation in comparison with the control group. Concurrently, the gene expression levels of sod1, sod2, gpx1 and gpx2, as determined by real-time quantitative PCR, were also up-regulated in the liver in the AS treated group during the UVC irradiation. For further understanding the oxidative damage repair potential of dietary AS in UVC irradiated mice, after 7 days AS and VE treatment, the SOD and GPx activities also increased significantly in liver and serum in mice fed with AS compared to the UVC light treated group. The results obtained here strongly suggested that AS reduces the UVC irradiation oxidative stress dramatically in short time.

Ultraviolet (UV-C) inactivation of Enterococcus faecium, Salmonella choleraesuis and Salmonella typhimurium in porcine plasma.

The objective of this study was to assess the effectiveness of an ultraviolet (UV-C, 254 nm) irradiation system on reducing the load of Salmonella typhimurium (S. typhimurium), Salmonella choleraesuis (S. choleraesuis) resistant to streptomycin and Enterococcus faecium (E. faecium) inoculated in sterile porcine plasma and then subjected to different UV-C irradiation doses (750, 1500, 3000, 6000 and 9000 J/L) using a pilot plant UV-C device working under turbulent flow. Results indicated that UV-C treatment induced a viability reduction of 0.38, 1.18, 3.59, 4.72 and 5.06 log10 S. typhimurium when irradiated at 750, 1500, 3000, 6000 and 9000 J/L, respectively. The observed log10 reduction of S. choleraesuis was 1.44, 2.68, 5.55, 7.07 and 7.97 at 750, 1500, 3000, 6000 and 9000 J/L, respectively. The best-fit inactivation for S. choleraesuis was the Weibull distribution curve, while the best-fit curve for S. typhimurium was the Weibull plus tail model, indicating that around 102 cfu/mL resistant S. typhimurium was detected when the liquid plasma was UV-C irradiated at doses up to 9000 J/L. Viability reduction for E. faecium was 0.44, 1.01, 3.70, 5.61 and 6.22 log10 when irradiated at 750, 1500, 3000, 6000 and 9000 J/L, respectively, with no bacterial resistance observed with UV-C doses of 6000 J/L or higher. The biphasic model was the best fit model for the inactivation curve for E. faecium. For the three microorganisms tested, about a 4 log-unit reduction was achieved when the liquid plasma was irradiated at 3000J/L. Overall results demonstrate the usefulness of the UV-C system to inactivate bacteria in liquid plasma before spray-drying. We conclude that the UV-C system can provide an additional biosafety feature that can be incorporated into the manufacturing process for spray-dried animal plasma.

Determination of 2-alkylcyclobutanones in ultraviolet light-irradiated fatty acids, triglycerides, corn oil, and pork samples: Identifying a new source of 2-alkylcyclobutanones

Previous studies have established that 2-alkylcyclobutanones (2-ACBs) are unique radiolytic products in lipid-containing foods that could only be formed through exposure to ionizing radiation, but not by any other means of physical/heat treatment methods. Therefore, 2-ACBs are currently the marker molecules required by the European Committee for Standardization to be used to identify foods irradiated with ionizing irradiation. Using a spectrum of state-of-the-art analytical instruments, we present in this study for the first time that the generation of 2-ACBs was also possible when fatty acids and triglycerides are exposed to a non-ionizing, short-wavelength ultraviolet (UV-C) light source. An irradiation dosage-dependent formation of 2-ACBs was also observed in UV-C irradiated fatty acids, triglycerides, corn oil, and pork samples. With UV-C irradiation becoming an increasingly common food treatment procedure, it is anticipated that the results from this study will alert food scientists and regulatory officials to a potential new source for 2-ACBs.

UV-C irradiation as an alternative disinfection technique: Study of its effect on polyphenols and antioxidant activity of apple juice

Abstract Ultraviolet (UV-C) irradiation is a non-thermal disinfection method, effective against a range of bacteria and viruses, which is being considered as an alternative to pasteurization of fruit juices. The objective of this study was to investigate the effect of UV-C irradiation on the polyphenolic content and in-vitro total antioxidant activity of apple juice. UV irradiation doses ranging from 0 to 240 mJ·cm− 2 were delivered to apple juice and polyphenols, sugars, in-vitro total antioxidant activity and total phenols were profiled. The results demonstrated that UV-C irradiation in apple juices at relevant commercial disinfection doses induced significant reduction in the concentrations of chlorogenic acid, phloridzin, and epicatechin (p 0.05). In contrast, a slight increase in sugar concentrations as increase in UV-C exposure after 40 mJ·cm− 2 was observed. These changes were not significantly different from control. Total phenolic content was well retained regardless of the UV-C exposure for apple juice. In-vitro total antioxidant activity changed when UV-C exposure exceeded 40 mJ·cm− 2, but remained unchanged at the maximum UV-C dose of 240 mJ·cm− 2. These results suggested that UV-C irradiation could be an effective alternative to conventional thermal processing for production of high quality apple juice. Industrial Relevance This research paper provides scientific evidence of the potential for UV-C irradiation to achieve meaningful levels of disinfection while retaining important bioactive compounds (polyphenols) in apple juice. In-vitro antioxidant activity and individual polyphenols were well retained at commercially relevant doses of 40 mJ·cm− 2. From a nutritional perspective, UV-C irradiation is an attractive food preservation technology and offers opportunities for horticultural and food processing industries to meet the growing demand from consumers for healthier food products. Therefore, UV-C irradiated foods could be sold at a premium price to their thermally-processed counterparts, as they have retained their fresh-like properties. This study would provide technical information relevant for commercialization of UV-C treatment of juices.

Investigation of the stabilization and preservation of sweet sorghum juices

Sweet sorghum juice is extremely vulnerable to microbial spoilage during storage because of its high water activity and rich sugar medium, and this represents a major technical challenge. The effects of clarification (80°C; limed to pH 6.5; 5ppm polyanionic flocculant) and UV-C irradiation were investigated as stabilization and preservation treatments for juices stored at ambient temperature (∼25°C). Juices were extracted by roller press from various sweet sorghum cultivars grown in humid and dry environments in Louisiana and Tennessee, respectively. Raw juices contained up to 109 total bacteria cfu/mL. Initial results indicated that pilot plant clarified juice was considerably more stable than raw or UV-C irradiated (15W lamp aquaculture system at ∼25°C) juice, irrespective of cultivar. Further experiments were undertaken to elucidate if heating (80°C; 30min) or impurity precipitation or both of these components of the clarification process were responsible for improved juice stability. Clarification or heating both achieved 3- to 4-log reductions of lactic acid bacteria in juices to negligible levels (<150cfu/mL), and also significantly (P<0.05) reduced total bacterial counts. Juice heating gave similar results as the whole clarification process up to ∼24h storage, but became slightly worse between 24–28h. Overall, clarified or heated (80°C; 30min) juice stored at 25°C can be stored for at least 48h before unacceptable spoilage occurs. Fingerprint ion chromatography with integrated pulsed amperometric detection (IC-IPAD) oligosaccharide profiles can be used to monitor sweet sorghum juice spoilage >100cfu/mL lactic acid bacteria.

Resveratrol synthesis under natural conditions and after UV-C irradiation in berry skin is associated with berry development stages in ‘Beihong’ (V. vinifera × V. amurensis)

Though UV-C irradiation may induce the synthesis of resveratrol in grape berry skins, it is unclear which developmental stage is most sensitive to UV-C induction. In this study, we investigated resveratrol content and gene expression of ‘Beihong’ (Vitisvinifera×Vitisamurensis) berries by UV-C irradiation compared with under natural conditions during different developmental stages. Under natural condition, resveratrol synthesis was related to veraison. Before veraison, resveratrol content was very low; however, total resveratrol increased about 500% from veraison to maturity in the main forms of piceids. UV-C irradiation significantly stimulated resveratrol synthesis, mainly in the form of trans-resveratrol. Young berries at 55days after anthesis were most sensitive to UV-C irradiation, the total resveratrol in the skin of UV-C irradiated berry is about 90 times higher than that of the control; however, resveratrol synthesis subsequently declined, which may be attributed to STS regulation by Myb14.

The Effect of UV-C Pasteurization on Bacteriostatic Properties and Immunological Proteins of Donor Human Milk

BackgroundHuman milk possesses bacteriostatic properties, largely due to the presence of immunological proteins. Heat treatments such as Holder pasteurization reduce the concentration of immunological proteins in human milk and consequently increase the bacterial growth rate. This study investigated the bacterial growth rate and the immunological protein concentration of ultraviolet (UV-C) irradiated, Holder pasteurized and untreated human milk.MethodsSamples (n=10) of untreated, Holder pasteurized and UV-C irradiated human milk were inoculated with E. coli and S. aureus and the growth rate over 2 hours incubation time at 37°C was observed. Additionally, the concentration of sIgA, lactoferrin and lysozyme of untreated and treated human milk was analyzed.ResultsThe bacterial growth rate of untreated and UV-C irradiated human milk was not significantly different. The bacterial growth rate of Holder pasteurized human milk was double compared to untreated human milk (p<0.001). The retention of sIgA, lactoferrin and lysozyme after UV-C irradiation was 89%, 87%, and 75% respectively, which were higher than Holder treated with 49%, 9%, and 41% respectively.ConclusionUV-C irradiation of human milk preserves significantly higher levels of immunological proteins than Holder pasteurization, resulting in bacteriostatic properties similar to those of untreated human milk.