• Food Science and Preservation
• /
• v.20 no.1
• /
• pp.45-51
• /
• 2013

This study was conducted to evaluate the changes in the quality of rice wine (Makgeolli) treated with UV-C and electron beam (EB) irradiation during its storage at $4^{\circ}C$ for 15 days. The EB irradiation was found to be more effective than the UV-C irradiation for microbiological control. The pH tended to be increased by UV-C, EB irradiation, and storage period. Acidity was significantly higher in rice wine treated with EB irradiation than those of control and UV-C irradiation during storage period. The $L^*$-value of the samples treated with UV-C and EB irradiation tended to be proportionately higher than that of the control, but this was not consistent during storage period. The $a^*$-value of the sample treated with EB was higher than that of the others, but this was not consistent during the storage period. The reducing sugar content was higher in the control at day 0, but it rapidly decreased compared with the control during the storage. The results indicate that EB irradiation was more effective than UV-C irradiation in controlling microorganisms of rice wine. However, a further study is needed to minimize the rice wine quality deterioration caused by UV-C or EB irradiation during storage.

• Journal of Conservation Science
• /
• v.27 no.2
• /
• pp.191-199
• /
• 2011

A study was done to compare the properties of artificially deteriorated silk with ultraviolets for reinforcing of loss area of paintings on silk. Deteriorated surface of raw silk irradiated by long-wavelength ultraviolet(UV-A) than short-wavelength ultraviolet(UV-C) was similar to naturally aged raw silk. UV-A irradiation raw silk was slowly decreased in tensile tenacity and elongation and lowered in yellowness index than that of UV-C. Water content of UV-A irradiation raw silk than that of UV-C was higher. UV-A irradiation raw silk had no problem in dyeing and inpainting for conservation because of low yellowness index. UV-C irradiation raw silk was brittle, but UV-A irradiation raw silk was seemed to tough and similar to naturally aged raw silk. Korean painting conservator estimated that UV-A irradiation raw silk was more proper for reinforcing of loss area of paintings on silk than that of UV-C.

• Food Science and Preservation
• /
• v.17 no.3
• /
• pp.425-429
• /
• 2010

Inactivation by UV-C irradiation of Listeria monocytogenes cocktail inoculated on hamburger patties was examined. Hamburger patty samples were inoculated with 6-7 log CFU/mL of L. monocytogenes cocktail, and then exposed to doses of 0, 1, 5, or $10kJ/m^2$ of UV-C light, followed by storage at $4{\pm}1^{\circ}C$ for 7 d. Microbiological evaluation indicated that the populations of L. monocytogenes decreased significantly (p<0.05) as irradiation dose increased. In particular, L. monocytogenes populations decreased by 2.03 log CFU/g after exposure to 10 $kJ/m^2$, compared with control samples. The thiobarbituric acid-reactive substance levels of hamburger patty samples increased during storage, regardless of UV-C irradiation status. These results indicate that UV-C irradiation may be useful in improving the microbial safety of hamburger patties during storage.

• Journal of Mushroom
• /
• v.13 no.3
• /
• pp.256-261
• /
• 2015

This study was conducted to reduce contamination ratio of oyster mushroom bottle cultivation. The optimal conditions of substrate sterilization for reducing of contamination ratio were at $121^{\circ}C$ for 90 min. In addition, UV-C irradiation is good for lower contamination ratio to continue over 6 hours at cooling and inoculation room after sterilization. The contamination ratio and density of microorganisms of substrate were showed 0% after sterilization at $121^{\circ}C$ for 90 min. Trichoderma sp., main pathogen of mushrooms, was detected from substrate after sterilized during 2 or 4 hours at $101^{\circ}C$ and $105^{\circ}C$, respectively. The amount of electricity used was the lowest at $121^{\circ}C$ for 90 min than that of other sterilization conditions. The UV-C irradiation treatment was used UV-C lamp(40 watts) in the inoculation room($56m^3$). The density of bacteria did not detected after UV-C irradiation for 6 hours. And the death ratio of bacteria and Trichoderma sp. was 99.9% after UV-C irradiation for 6 hours. However, in the same UV-C irradiation time, the death ration of Cladosporium sp. was 90.9%. Therefore, the death ratio of fungi was lower than that of bacteria at the same UV-C irradiation treatment.

• Journal of Microbiology and Biotechnology
• /
• v.33 no.4
• /
• pp.419-429
• /
• 2023

Ultraviolet C (UV-C, 200-280 nm) light has germicidal properties that inactivate a wide range of pathogenic and spoilage microorganisms. UV-C has been extensively studied as an alternative to thermal decontamination of fruit juices. Recent studies suggest that the efficacy of UV-C irradiation in reducing microorganisms in fruit juices is greatly dependent on the characteristics of the target microorganisms, juice matrices, and parameters of the UV-C treatment procedure, such as equipment and processing. Based on evidence from recent studies, this review describes how the characteristics of target microorganisms (e.g., type of microorganism/strain, acid adaptation, physiological states, single/composite inoculum, spore, etc.) and fruit juice matrices (e.g., UV absorbance, UV transmittance, turbidity, soluble solid content, pH, color, etc.) affect the efficacy of UV-C. We also discuss the influences on UV-C treatment efficacy of parameters, including UV-C light source, reactor conditions (e.g., continuous/batch, size, thickness, volume, diameter, outer case, configuration/arrangement), pumping/flow system conditions (e.g., sample flow rate and pattern, sample residence time, number of cycles), homogenization conditions (e.g., continuous flow/recirculation, stirring, mixing), and cleaning capability of the reactor. The collective facts indicate the immense potential of UV-C irradiation in the fruit juice industry. Existing drawbacks need to be addressed in future studies before the technique is applicable at the industrial scale.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.41 no.12
• /
• pp.1798-1804
• /
• 2012

To prolong the shelf-life of domestic peaches, samples were treated with UV-C (0~10.0 $kJ/m^2$) and the spoiling rate and changes in physico-chemical and sensory properties were investigated. No spoiled peaches were observed within the first four days of storage in the control and 2.5 $kJ/m^2$ UV-C treatment groups. However, spoilage was observed in these groups on day six, and 29.17% and 25.0% of the samples showed spoilage on 10 day, respectively. Moreover, samples treated with greater than 5.0 $kJ/m^2$ of UV-C showed a higher percentage (41.67% or higher) of spoilage than those of the control or 2.5 $kJ/m^2$ UV-C treatment groups on 10 day. Additionally, weight changes in the peaches were the lower in the control group and 2.5 $kJ/m^2$ UV-C treatment group than in those treated with 5.0 $kJ/m^2$ of UV-C treatment or higher during 10 days of storage. There was no difference in pH among treatments, regardless of storage time. The hardness of the samples was not changed immediately after UV-C treatment, but that of samples treated with 5.0~10.0 $kJ/m^2$ of UV-C decreased rapidly after four days, when compared to the control and 2.5 $kJ/m^2$ UV-C treatment groups. No significant changes in the lightness and redness of the samples were observed in response to UV-C treatment, however, UV-C treatment led to a slight decrease in the yellowness of the samples. The initial taste, flavor, color, texture, and overall acceptance did not differ among control and UV-C treatments. The sensory score of the samples was the highest after 2 and 4 days of storage, while it decreased thereafter. In general, samples in the control and the 2.5 $kJ/m^2$ UV-C treatment groups showed higher sensory quality than those treated with UV-C at 5.0 $kJ/m^2$ or higher.

• Food Science and Preservation
• /
• v.16 no.3
• /
• pp.454-458
• /
• 2009

The effect of UV-C irradiation on microbial growth and quality of red pepper powder during storage was examined. Red pepper powder was irradiated with doses of 27, 54, or $108\;kJ/m^2$ and stored at $20^{\circ}C$ for 4 weeks. UV-C treatment of red pepper powder decreased the populations of total aerobic bacteria and Bacillus cereus in proportion to radiation dose. In particular, total aerobic bacteria and B. cereus populations decreased by 1.03 and 0.90 log CFU/g after irradiation at $108\;kJ/m^2$, respectively, compared with control values. UV-C irradiation caused negligible changes in the Hunter color L, a, or b values. Sensory quality results on red pepper powder were not significantly different between treatments. Therefore, UV-C irradiation can be used to inhibit microbial growth in red pepper powder, without impairing quality during storage.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.5
• /
• pp.517-523
• /
• 2008

The degradation mechanism of Triclosan(TCS), which is a potent broad-spectrum antimicrobial agent and has been considered as an emerging pollutant, was investigated in the Fenton and the hybrid reaction with Fe$^{2+}$ and UV-C. The results show that the Fe$^{2+}$ is oxidized to 30% by $H_2O_2$, 28% by UV-C, and 15% by UV-A for 10 min. The degradation rate of TCS for beginning time(10 min) was higher in UV-C only reaction than that in hybrid reaction, which of the order was inverted according to the lapse of reaction time. The effect of methanol was the greatest in Fenton reaction, in which the degradation rate of TCS decreased from 90% to 5% by the addition of methanol. Chloride, ionic intermediate, was produced to 77% for 150 min of hybrid reaction(Fe$^{2+}$ + UV-C), which was the greatest. In case with methanol, the generation rate of chloride for 15 min was ignorable in all reactions($\leq$2%) but the hybrid reaction with Fe$^{2+}$ and UV-C(12%). Additionally, the removal rate of TOC in each reaction was estimated as the followed orders; Fe$^{2+}$ + UV-C > Fe$^{2+}$ + $H_2O_2$ > Fe$^{2+}$ + UV-A > UV-C > UV-A. However, the Fenton reaction was almost stopped after 90 min because the reaction between Fe$^{2+}$ and $H_2O_2$ cannot be kept on without adding the oxidant. The phenomena was not observed in the hybrid reaction. In view of generating chloride, the reductive degradation of TCS may be in the hybrid reaction with Fe$^{2+}$ and UV-C, which is favorable to mineralize halogenated organic compounds such as TCS. Consequently, the hybrid process with Fe$^{2+}$ and UV-C may be considered as the alternative treatment method for TCS.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.12
• /
• pp.1937-1943
• /
• 2020

Although classical metabolic engineering strategies have succeeded in developing microbial strains capable of producing desired bioproducts, metabolic imbalance resulting from extensive genetic manipulation often leads to decreased productivity. Thus, abiotic strategies for improving microbial production performance can be an alternative to overcome drawbacks arising from intensive metabolic engineering. Herein, we report a promising abiotic method for enhancing lycopene production by UV-C irradiation using a radiation-resistant ΔcrtLm/crtB+dxs+ Deinococcus radiodurans R1 strain. First, the onset of UV irradiation was determined through analysis of the expression of 11 genes mainly involved in the carotenoid biosynthetic pathway in the ΔcrtLm/crtB+dxs+ D. radiodurans R1 strain. Second, the effects of different UV wavelengths (UV-A, UV-B, and UV-C) on lycopene production were investigated. UV-C irradiation induced the highest production, resulting in a 69.9% increase in lycopene content [64.2 ± 3.2 mg/g dry cell weight (DCW)]. Extended UV-C irradiation further enhanced lycopene content up to 73.9 ± 2.3 mg/g DCW, a 95.5% increase compared to production without UV-C irradiation (37.8 ± 0.7 mg/g DCW).

• Journal of Food Hygiene and Safety
• /
• v.33 no.6
• /
• pp.495-499
• /
• 2018

The reduction effect of UV-C irradiation and mild heat treatment was examined against Escherichia coli O157:H7 and Salmonella Typhimurium on black pepper powder. E. coli O157:H7 (ATCC 35150) and S. Typhimurium (ATCC 19585) were inoculated onto black pepper powder at approximately $10^7$ and $10^6CFU/g$, respectively. E. coli O157:H7 and S. Typhimurium were treated with UV-C and mild heat at $60^{\circ}C$. A UV-C intensity ($2.32W/cm^2$ ) was used for 10 min to 70 min at $60^{\circ}C$. After UV-C and heat treatment at $60^{\circ}C$, microbial analysis and color change of black pepper powder was conducted. E. coli O157:H7 and S. Typhimurium were reduced by a level of 1.89 and 2.24 log CFU/g, respectively, when treated with UV-C alone for 70 min. And E. coli O157:H7 and S. Typhimurium were reduced by 2.22 and 5.10 log CFU/g, respectively, when treated with mild heat treatment at $60^{\circ}C$ alone for 70 min. But when combined with UV-C and mild heat, it showed higher levels of reduction by 2.46 and 5.70 log CFU/g. S. Typhimurium was more easily reduced than E. coli O157:H7. Color values were not significantly (p > 0.05) different in all treated samples. Therefore, these results suggest that the combined treatment with UV-C and mild heat was effective to inactivate the food pathogens in black pepper powder and can be used as a food industrial microbial intervention method.