• Food Science of Animal Resources
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• v.38 no.3
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• pp.636-652
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• 2018

The study aims to determine the optimum sterilization rate and water activity of Chinese traditional smoke-cured bacon product (Larou) in the preservation with natural coating solution. With the response surface methodology (RSM), we analyzed 3 factors of processing conditions (the concentration of lysozyme, concentration of sodium alginate, and concentration of chitosan) and 2 response factors (sterilization rate and water activity). Sterilization rate and water activity of Larou were largely affected by the concentration of lysozyme, concentration of sodium alginate, and concentration of chitosan. The final optimum concentrations of lysozyme, sodium alginate, and chitosan were 0.09, 1.40, and 1.60% and realized the high sterilization rate. Water activity of sliced Larou was significantly correlated with the sterilization rate. Low-field nuclear magnetic resonance analysis verified the optimum processing conditions. The coating resulted in 99.69% rate of reducing bacteria after 30-day storage. The data of the total number of colony, peroxidation value, moisture content, pH, and sensory evaluation provided the theoretical basis for extending the shelf life of Chinese traditional smoke-cured bacon product (Larou) with natural coating solution.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.2
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• pp.100-104
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• 2013

Zoysiagrass (Zoysia japonica Steud.) is an important forage and turfgrass that spreads by stolons and rhizomes. Zoysiagrass stolon can be used directly for Agrobacterium-mediated genetic transformation by exploiting the potential of direct shoot formation. However, surface sterilization of field-grown stolons is difficult and remains to be explored. We developed an effective surface sterilization and culture method using the stolon explant for infection with Agrobacterium tumefaciens. Among various treatments, sequential disinfection in 30% bleach for 15 min followed by 0.1% mercuric chloride for 25 min resulted in the highest number of clean stolons. The efficacy of mercuric chloride was increased under vacuum conditions by incubating at 800 mbar for 5 min. The inclusion of 2.5 mg/l amphotericin B further prevents fungal growth in in vitro cultures. This protocol would speed up the development of transgenic plants by utilizing field-grown stolon nodes.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1069-1075
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• 1999

The sterilization was attempted to improve the quality deterioration of soybean paste during its storage. For this experiment, soybean paste was sterilized at 80oC for 30 minutes and stored during 6 months at 15oC and 30oC, respectively. The total approximate composition contents were moisture 52.5%, crude protein 11.94%, crude fat 2.0%, amino nitrogen 413.3mg%, sodium chloride 11.61% and ash 15.5%. According to the increase of storage period, pH was decreased gradually because of the increase of organic acids by the metabolism of microorganisms and the acid accumulation by acid forming bacteria, but titratable acidity was increased during storage. Amino nitrogen was rapidly increased for the first one or two month storage period and maintained as the same level for the rest of them. Each amino acid contents of soybean paste, which were glutamic acid, tryptophan, proline, arginine, and aspartic acid, had much higher level than others. In color changes sterilized soybean paste(SSP) was much lower than that of raw ones(RSP). Hunter L and b values on the surface of soybean paste were decreased during storage, and the decreasing levels were higher at 30oC than at 15oC. Hunter a value, however, was increased a little in the initial storage, and thereafter it was decreased. Lactic acid bacteria, yeasts, and molds were disappeared completely by the sterilization. However, the bacteria of aerobes and anaerobes were not disappeared by this processing.

• The Korean Journal of Food And Nutrition
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• v.25 no.1
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• pp.69-76
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• 2012

Intense pulsed light(IPL) has been highlighted as an innovative nonthermal sterilization technology that can kill spoilage or pathogenic microorganisms by using short-duration pulses of intense broad-spectrum electromagnetic radiation. This paper examines the inactivation effects of IPL on Listeria monocytogenes, Escherichia coli O157:H7, and Pseudomonas aeruginosa inoculated on seafood products such as salmon, flatfish, and shrimps and evaluates the possibility of extending the shelf-life of seafood products. The results indicate that the inactivation of microorganisms increased with an increase in IPL energy density($J/cm^2$) and a decrease in the distance between the sample surface and the lamp. In addition, temperature increases on the fish fillets during the treatments were well controlled within the range of 5.7~$9.8^{\circ}C$. The IPL treatment had a significant positive effect on the storage stability of seafood products at the storage temperature of $4^{\circ}C$ for 12 days. These results suggest that the storage period for fish fillets can be extended from 4 days to 6~8 days through the IPL treatment.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1045-1051
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• 1996

The influence of electrolyzed acid-water (oxidation-reduction potential (ORP): above 1,150 mV, pH : 2.5) on the survival of some microorganisms was investigated. It was observed that the ORP of electrolyzed acid-water was kept at the level of above 1,000 mV for 15 days at room temperature. Escherichia coli. Salmonella typhi, Staphylococcus aureus and Saccharomyces cerevisiae were not detected after 10 to 40 min in electrolyzed acid-water. However, Bacillus cereus showed higher tolerance to electrolyzed acid-water than other test microorganisms. After 60 min of inoculation, only 0.4% of initial population remained. The investigation of surface sterilization effect on some vegetables was carried out too. Total count of cabbage, Chinese cabbage and kale were reduced to below 3% of initial count, and no coliform was detected after 20 to 60 min of immersion in 5 volumes of electrolyzed acid-water. In the lettuce, total and coliform counts were reduced to 90% and 2% of initial population. This study shows that the electrolyzed acid-water has a potential for the sterilization of food products such as vegetables and fruits which cannot be thermally sterilized.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.570-575
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• 2005

In this study, we have manufactured electrodeless ultraviolet lamp which has a long life and a high degree of efficiency than the existing electrode UV lamp used in sewage effluent sterilization disinfection. First, we investigated change of UV intensity and temperature of lamp by activation materials. The best results for the dose response experiments were 250 minutes stabilizing to UV intensity of $300{\mu}W/cm^2$ and surface temperature $200{\sim}250^{\circ}C$ in Hg/Ind's weight ratio 95/5. When electrodeless UV lamp emits light for prolonged hours, surface temperature of lamp increases. therefore, temperature change is studied using a duplex lamp for cooling in actual sewerage process. Also, manufactured electrodeless UV lamp showed sterilization efficiency of more than 99.9% as result that experiment manufactured electrodeless UV lamp by E-coli. for sterilization disinfection of sewage effluent.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.172-172
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• 2016

The International Maritime Organization(IMO) adopted the International Convention for the Control and Management of Ships' Ballast Water and Sediments in 2004 to prevent the transfer of aquatic organisms via ballast water. Forty ballast water treatment systems were granted final approval. A variety of techniques have been developed for ballast water treatment including UV treatment, indirect or direct electrolysis, ozone treatment, chemical compounds and plasma-arc method. In particular, using plasma and ozone nano-bubble treatments have been attracted in the fields. However, these treatment systems have a problem such as remained toxic substance, demand for high power source, low efficiency, ets. In this paper, we present our strilization results obtained from membrane type electrolytic-reduction treatment system The core of an electrolysis unit is an electrochemical cell, which is filled with pure water and has two electrodes connected with an external power supply. At a certain voltage, which is called critical voltage, between both electrodes, the electrodes start to produce hydrogen gas at the negatively biased electrode and oxygen gas at the positively biased electrode. The amount of gases produced per unit time is directly related to the current that passes through the electrochemical cell. From the results, we could confirm the sterilization effect of bacteria such as S. aureus, E. Coli and demonstrate the mechanism of sterilization phenomena by electrolytic-reduction treatment system.

• Journal of Biosystems Engineering
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• v.43 no.4
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• pp.401-409
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• 2018

Decay of fruit is one of the greatest issues in fruit storage. Purpose: In this study, citrus sterilization was performed to evaluate a dry sterilization method using an atmospheric-pressure nonthermal plasma treatment based on a dielectric-barrier discharge technique. Methods: Citrus samples were stored under four different environmental conditions as follows: group A had cold storage with plasma treatment with a temperature of $6.2{\pm}1.0^{\circ}C$ and relative humidity (RH) of $93.4{\pm}8.2%$, group B had ambient-temperature storage with $22.9{\pm}2.3^{\circ}C$ and $82.1{\pm}4.5%$ RH, group C ambient-temperature storage with plasma treatment with $25.3{\pm}2.2^{\circ}C$ and $90.0{\pm}2.8%$ RH, and group D had cold storage with $5.7{\pm}1.0^{\circ}C$ and $93.4{\pm}6.5%$ RH. Results: As a result of citrus surface sterilization by plasma treatment, treatment groups A and C together showed an average of 16.1 CFU/mL of mold colonies, while control groups B and D showed an average of $2.2{\times}10^2CFU/mL$ or approximately 13 times greater than the treatment groups. Regarding the mean concentration of aerobic bacteria colonies, the treatment groups (A and C) and control groups (B and D) showed an average of 7.1 CFU/mL and $1.9{\times}10^3CFU/mL$, respectively. This is approximately a 270-fold difference in the concentration of pathogen colonies between treatment and control groups. Conclusions: The results showed the potential of nonthermal plasma treatment for citrus storage in enhancing storage duration and quality preservation.

• Current Optics and Photonics
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• v.6 no.2
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• pp.202-211
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• 2022

In the pasteurization of escalator handrails using ultraviolet (UV) sterilizers, a combination of light distribution and escalator speed has priority over other important factors. Furthermore, since part of the escalator handrail has a curved structure, proper design is needed to improve the sterilization rate on the surfaces touched by users. In this paper, two types of sterilizers satisfying these conditions are manufactured with 275-nm UV-C LEDs, after modeling the three-dimensional (3D) structure of an escalator handrail and simulating optical distributions of UV-C irradiation on the handrail's surface according to light-emitting diode (LED) positions and reflector variations in the sterilizers. Pasteurization experiments with the UV-C LED sterilizers are conducted on six types of gram-positive and gram-negative bacteria, with exposure times of 0.2, 5, and 15 s at an actual installation distance of 20 mm. The sterilization rates for the gram-positive bacteria are 10.63% to 27.94% at 0.2 s, 89.44% to 96.30% at 5 s, and 99.64% to 99.88% at 15 s. Those for the gram-negative bacteria are 57.70% to 77.63% at 0.2 s, 98.90% to 99.49% at 5 s, and 99.88% to 99.99% at 15 s. The power consumption of the UV-C LED sterilizer is about 8 W, which can be supplied by a self-generation module instead of an external power supply.

• Journal of the Korean institute of surface engineering
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• v.41 no.2
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• pp.76-82
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• 2008

We investigated sterilization characteristics of UV lights by counting the number of bacteria units with varying sterilization time and distance from the light source. We focused on an idea that UV light of 184.9 nm could generate ozone and developed a new sterilizer. The UV-ozone duplex system sterilized bacteria faster than UV-only sterilizers. To reduce shadowing effects by target objects, we used UV transparent quartz plate as a support and put a reflecting plate. Distribution of UV irradiation intensity and ozone supply were analyzed by a 3D model and measured by a semiconductor UV sensor. But even with an Al reflector, multi-layered pens could not be treated properly from UV irradiation only. Ozone generating lamp could treat more uniformly multi-layered pens with a stirring fan by supplying ozone to shadowed surfaces.