• Korean Journal of Food Science and Technology
• /
• v.47 no.1
• /
• pp.81-86
• /
• 2015

Intense pulsed light (IPL), a nonthermal technology, has attracted increasing interest as a food processing technology. However, its efficacy in inactivating microorganisms has not been evaluated thoroughly. In this study, we investigated the influence of IPL treatment on the inactivation of Escherichia coli O157:H7 depending on light intensity, treatment time, and pulse number. Increased light intensity from 500 V to 1,000 V, raised the inactivation rate at room temperature. At 1000 V, the cell numbers were reduced by 7.1 log cycles within 120 s. In addition, increased pulse number or decreased distance between the light source and sample surface also led to an increase in the inactivation rate. IPL exposure caused a significant increase in the absorption at 260 nm of the suspending agent used in our experiments. This indicates that IPL-treated cells were damaged, consequently releasing intracellular materials. The growth of IPL-irradiated cells were delayed by about 5 h. The degree of damage to the cells after IPL treatment was confimed by transmission electron microscopy.

• Journal of Korean Society of Water and Wastewater
• /
• v.34 no.3
• /
• pp.183-190
• /
• 2020

Although membrane bio-reactor (MBR) has been widely applied for wastewater treatment plants, the membrane fouling problems are still considered as an obstacle to overcome. Thus, many studies and commercial developments on mitigating membrane fouling in MBR have been carried out. Recently, high voltage impulse (HVI) has gained attention for a possible alternative technique for desalting, non-thermal sterilization, bromate-free disinfection and mitigation of membrane fouling. In this study, it was verified if the HVI could be used for mitigation of membrane fouling, particularly the internal pore fouling in MBR. The HVI was applied to the fouled membrane under different conditions of electric fields (E) and contact time (t) of HVI in order to investigate how much of internal pore fouling was reduced. The internal pore fouling resistance (R_f) after HVI induction was reduced as both E and t increased. For example, R_f decreased by 19% when the applied E was 5 kV/cm and t was 80 min. However, the R_f decreased by 71% as the E increased to 15 kV/cm under the same contact time. The correlation between E and t that needed for 20% of R_f reduction was modeled based on kinetics. The model equation, E^1.54t = 1.2 × 10³ was obtained by the membrane filtration data that were obtained with and without HVI induction. The equation states the products of En and t is always constant, which means that the required contact time can be reduced in accordance with the increase of E.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.24 no.2
• /
• pp.130-136
• /
• 1991

In present paper, we investigated the changes in lipid components of skipjack and Alaska pollack meat by thermal processing at high temperature. TBA values and peroxide values of both fish meats decreased markedly by heat treatment; decreasing range of TBA and peroxide values in skipjack meat was larger than those of Alaska pollack meat. Also carbonyl value of skipjack meat was decreased by thermal processing, contrary, that of Alaska pollack meat was increased. Total lipid(TL) of skipjack and Alaska pollack meat consisted of $61.9\%,\;49.6\%$ non-polar lipid(NL), $38.1\%,\;50.4\%$ polar lipid(PL), respectively. When the samples were heated at the Fo values of 5 or higher, contents of NL were increased, while that of PL were decreased. In fatty acid composition of NL and PL in both fishes, NL revealed higher contents in saturates and monoenes such as 16:0, 18:1, while PL showed higher contents in polyenes such as 20:5, 22:6; percentages of polyenes such as 22:6 especially in both fishes decreased with increasing of Fo values. The remaining ratio of PUFA(20:5+22:6/16:0) of Fo 20 samples in skipjack and Alaska pollack meat were $73\%$ and $65\%$, respectively. However, when the samples were heated at $98^{\circ}C$ for 30 minutes, no appreciable changes occured in fatty acid composition of TL, NL and PL in both fish meats examined.

• Korean journal of food and cookery science
• /
• v.29 no.4
• /
• pp.387-398
• /
• 2013

Seasoned soy sauce is one of the popular seasoning sauces added to the Korean traditional foods such as Bulgogi, Galbi. However, industrially processed sauces have poor sensory quality because of heating treatment for sterilization. The purpose of this study was to develop seasoned soy sauce having fresh taste and good quality by applying superheated steam (SHS) and high hydrostatic pressure (HHP) technologies. To maintenance the sauce qualities, food materials such as apple, onion, and garlic were pretreated with SHS (heater $100^{\circ}C$, steam $280^{\circ}C$, 30 s~1 min 30 s) before mixing with other ingredients. During storage of 7 days, color, pH, and browning potential of SHS treated samples (apple, onion and garlic) did not change and also polyphenol oxidase was inactivated (p<0.05). The seasoned soy sauce including SHS treated materials was sterilized by thermal process ($85^{\circ}C$, 30min) or non-thermal process, HHP (550 MPa, $5{\sim}10^{\circ}C$, 3 min). In SHS+HHP treated sauce, salinity, sugar contents, lightness, viscosity did not change (p<0.05), and total viable cell counts were detected below 4 log cycle at $5^{\circ}C$ for 30 days. E.coli and B.cereus are not determined in all samples. In sensory evaluation, Bulgogi prepared with SHS+HHP treated sauce was more acceptable than others.