• Korean journal of food and cookery science
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• v.32 no.1
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• pp.9-15
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• 2016

The changes of resistant starch (RS) contents of cooked rice with soybean and coconut oils under different storage conditions were investigated and RS contents were compared between the rice and cooker types. The japonica (Hopyeong) and the indica (Thailand) type rice were cooked (washed rice: water = 100: 130) using an electric cooker and a saucepan. The coconut oil and soybean oil (3%, based on rice, w/w) were added into cooking water before heating. The RS contents of freeze-dried cooked rice powders (newly-cooked rice, stored for 12 h in the refrigerator, microwave heating after storage for 12 h in the refrigerator) were measured by the AOAC method. The RS contents of cooked rice using a saucepan were higher than those using an electric cooker. The indica type cooked rice had a higher RS content than the japonica type cooked rice, regardless of storage conditions. However, addition of oil before cooking rice resulted in increased RS content on storage in the refrigerator. The highest RS content of the cooked indica type rice with soybean oil ($5.89{\pm}0.22%$) that was stored for 12 h in the refrigerator was analyzed. The results suggested that the cooked rice formed retrograded (RS3) and amylose-lipid complex (RS5) type RS; furthermore, the RS content is affected by storage conditions, rice, cooker and oil types.

• Korean Journal of Materials Research
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• v.30 no.9
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• pp.489-494
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• 2020

SiC is a material with excellent strength, heat resistance, and corrosion resistance. It is generally used as a material for SiC invertors, semiconductor susceptors, edge rings, MOCVD susceptors, and mechanical bearings. Recently, SiC single crystals for LED are expected to be a new market application. In addition, SiC is also used as a heating element applied directly to electrical energy. Research in this study has focused on the manufacture of heating elements that can raise the temperature in a short time by irradiating SiC-I₂ with microwaves with polarization difference, instead of applying electric energy directly to increase the convenience and efficiency. In this experiment, Polydimethylsilane (PDMS) with 1,2 wt% of iodine is synthesized under high temperature and pressure using an autoclave. The synthesized Polycarbosilane (PCS) is heat treated in an argon gas atmosphere after curing process. The experimental results obtain resonance peaks using FT-IR and UV-Visible, and the crystal structure is measured by XRD. Also, the heat-generating characteristics are determined in the frequency band of 2.45 GHz after heat treatment in an air atmosphere furnace.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.873-881
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• 2005

This study was conducted to improve the properties of frozen dough foods (buns and noodles etc.) on the quality deterioration with microwave oven cooking. Microwave is a useful cooking method, but it quickly takes moisture from food surface and makes lowering food quality abruptly. For improvement of these problems, mixing doughs with addition of various additives of 34 types manufactured respectively; starches, modified starches, gums and emulsifiers etc. Each mixing dough produced in sheet type $(30{\times}30{\times}1mm)$ and steamed them, was quickly froze at $-70^{\circ}C$ and packed with polyethylene. Packed samples kept at $-20^{\circ}C$ for 48 hours. After they were steam or microwave treatment packed or non-packed with polyethylene, studied for improvement effects of quality as sensory evaluation and selected 6 type additives; modified starches (TA, ST), gums (AR, GA) and emulsifiers (E, S1) as improvement agent. Because moisture loss from microwave oven cooking leads to quality deterioration of frozen dough foods, additive, such as including starches, modified starch, gums, and emusifiers were added to improve dough properties. Amylogram, scanning electron microscopy, textural analysis, and differential scanning calorimetry revealed addition of additives improved textural properties including surface-hardening of frozen dough foods compared to the control.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.4
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• pp.186-193
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• 2017

Microwave (MW) is an effective method for solubilizing organic solids because it has thermal, non-thermal and ionic conduction effects by dielectric heating and high energy efficiency. In this study, we evaluated the application of MW to the solubilization of cattle manure and investigated the solubilization ratio of cattle manure by solid concentration, MW power and target temperature. And $H_2SO_4$ and NaCl were added to investigated the effects on the MW-assisted solubilization. Also, we evaluated the solubilization efficiency by biochemical methane potential(BMP) test according to the solubilization conditions. Maximum SCOD increment per energy supply was 70.5 mg $SCOD_{increased}/kJ$ at 12% of the solid concentration, MW power of 800 W and the target temperature of $40^{\circ}C$. And SCOD concentration went up 153.2% compared to the initial concentration. In the MW-assisted solubilization with $H_2SO_4$ and NaCl as chemical catalysts, SCOD concentration was increased by 36% and 22.7%, respectively, compared to the result of MW. The methane production was increased by 13.3% and 11.3% with the addition of $H_2SO_4$ and NaCl. Therefore, MW is an effective method for solubilization of cattle manure, and it is necessary to use chemical catalysts to increase the solubilzation efficiency.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.4
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• pp.263-270
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• 1982

In an attempt to evaluate the nutritional quality of seaweed protein, the effects of heat treatment on the in vitro digestibility and trypsin inhibitor content in seaweed were determined. In this study, the nitrogen-to-protein conversion factors were also calculated on the basis of quantitative amino acid data. The results are as follows : 1. The in vitro protein digestbilty of red seaweeds (P. teoera anc P. suborbiculata) were ranged from 78.5 to 82.2, and green seawerd (E. linza) and brown seaweeds showed value under 80 in vitro digestibility. In general, trypsin inhibitor contents in brown seaweed were higher (0.33-0.54 mg/g) than those of red seaweeds (0.26-0.39 mg/g). And it is noted that the lowest trypsin inhibitor content was shown in green seaweed (E. linza) in spite of lowest in spite digestibility (78.5). 2. The in vitro protein digestibility of sun dried laver (P. tenera) was increased with cooling time (microwave heating), but it was not significant. Hot plate cooking raised the in vitro digestibility from 81. 1 to 84.5. The influence pot cooking time on trypsin inhibitor content was inversely proportional to in vitro digestibility. 3. Computed nitrogen factor, based on amino acid content (Factor method) and Kjeldahl nitrogen content (Kjeldahl mettled), were 5.83 (H. fusiforme)- 6.52 (P. tencra) as Factor method and 5.40 (U. pinnatifida)-6.29 (P. tenera) as Kjeldahl method. Individual value for each nitrogen conversion factor differed by species, especially in brown seaweeds. The best estimate of the protein content of seaweed can be calculated, from multiplying the summed amino acid content by conversion factor (Factor method).

• Analytical Science and Technology
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• v.16 no.5
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• pp.399-406
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• 2003

This study was conducted to find out the analysis condition of selenium(Se) in oil refinery wastewater with a high concentration of Se using the atomic absorption spectrometry with hydride generation system (HG-AAS). From various experiments that reduced Se(VI) to Se(IV), the optimum pretreatment condition was determined to be a sample volume of 10 mL, HCl 10 mL, with a 30 min heating time in a water bath. In oil refinery wastewater, as the concentration of organics and constitution became higher, the recovery rates of Se decreased. Therefore, three acid digestion methods ($HNO_3/HClO_4$ digestion, $KMnO_4$ digestion, and microwave acid digestion) were tested on the recovery rates of Se in reference to the digestion of organics, petroleum and oxidation from organic Se(org.), Se(IV) to Se(VI). The experiment results showed that the average recovery rate of Se was the highest in microwave acid digestion, although all of the digestions were more than 90%. In consequence, the pretreatment procedure of microwave digestion followed by HCl addition was the most suitable for selenium analysis in oil refinery wastewater by using HG-AAS.

• Food Science and Preservation
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• v.12 no.1
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• pp.62-67
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• 2005

Microwave-assisted extraction (50 W, 2,450 MHz, MAE) with properties of selective heating and subsequent extraction for certain phytochemicals from natural materials was applied to pre-establish the extraction conditions for total yield total phenolics, and electron donating ability (EDA) from Brossica oleacea. The experiments with $50\%$ EtOH solvent showed that 20 mesh in particle size of cabbage flake $(moisture\;4.5\%)$ and 1:10 (g/mL) in the sample to solvent ratio for both raw $(moisture\;90.2\%)$ and flake cabbages were optimal for MAE efficiency. Under these conditions, total yield increased with extraction tim, which was highest for raw cabbage extract in $50\%\;EtOH$ solvent followed by $100\%\;EtOH$ and water. While that of flake cabbage extracts was highest in $50\%\;EtOH$ followed by water and $100\%\;EtOH$. The contents of total phenolics and EDA in extracts gradually increased after 3 min of MAE, which were highest when using $100\%\;EtOH$ solvent followed by $50\%\;EtOH$ and water in raw cabbage and $50\%\;EtOH$ followed by water and $100\%\;EtOH$ in flake cabbage, respectively.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1778-1780
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• 2004

Microwave heating system of KSTAR consists of ECH and LHCD. ECH and LHCD offer the reliability of operation in the beginning of plasma formation and non-inductive current drive for long time steady state operation with maintaining MHD stability, respectively. LHCD demands 5 GHz of frequency and consists of c-band waveguide, 4-port circuitor, dry dummy load, dual directional coupler, E-bend, arc detector. Our system is a lineup type pulse modulator that has 45 kV of output pulse voltage, 90 A of pulse current, 4 us of pulse width. 1:4 step-up pulse transformer, 7 stages of PFN and thyratron tube (E2V, CX1191D) are used in this modulator. The purpose of this paper is to show the modulator design and experimental result.

• Journal of Food Hygiene and Safety
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• v.12 no.2
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• pp.125-131
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• 1997

Gulbi, salted and dried yellow corvenia, is a favorite diet food in Korea from the ancient times. A Few studies have dealt with sanitary concerns related to its products, while a number of investigators studied its taste compounds. This study attemps to establish the basic data for ensuring the safety of Gulbi. The contents of nitrate and nitrite were detected 1.2 and <0.1 mg/kg in raw sample, but their contents were detected 3.6~3.9 and 1.2~2.0 mg/kg during its processing and storage of Gulbi, respectively. TMAO contents decreased while betaine, TMA, DMA and formaldehyde increased in yellow corvenia during its processing and storage. Recovery from raw, salted, salt-dried and stored sample spiked with 10$\mu\textrm{g}$/kg for NDBA was 83.2~102.7% average 92.7%). N-nitrosamine such as NDMA, NDEA and NDPA was not detected in raw sample and drastically increased during Gulbi processing and storage. The levels of NDMA, NDEA and NDPA in Gulbi stored for 30 days were about 2.7,4.5 and 5.3 times higher than those in salted sample, respectively. Regardless of cooking methods, NDMA, NDEA and NDPA during cooking when sample were cooked using direct heating methods such as a gas and a briquet fire than when sample were cooked using indirect methods such as an microwave oven and a fried pan. Indirect cooking methods was effective to minimize the N-nitrosamine formation such as NDMA, NDEA and NDPA during cooking of Gulbi.

• Food Science of Animal Resources
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• v.38 no.5
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• pp.970-980
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• 2018

We evaluated the effects of pre-cooking methods on the quality of reheated marinated pork loin. Frozen marinated pork loins cooked using various methods (boiling, grilling, pan frying, infrared cooking, and superheated steam cooking) were reheated in a microwave, and their pH, color, cooking loss, re-heating loss, total loss, thiobarbituric acid reactive substance (TBARS) value, sensory properties, and shear force were determined. Although all parameters varied with different cooking methods, lightness values and TBARS values showed the tendency to decrease and increase, respectively, after reheating. Superheated steam-cooked samples showed the lowest values of cooking loss, total loss, TBARS value, and shear force (p<0.05) and the highest lightness, redness, and yellowssness values and juiciness, chewiness, and overall acceptability scores (p<0.05). These results show that pre-cooking with superheated steam maintains the quality characteristics of marinated pork loin upon reheating. Therefore, pre-cooking with superheated steam may be beneficial for the commercial distribution of frozen cooked marinated pork loin.