• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.327-333
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• 2014

A method for analysis of five artificial sweetners (sodium saccharin, aspartame, acesulfame-K, sucralose, cyclamate) in beverage samples was developed using high-performance liquid chromatography/triple quadrupole mass spectrometry (HPLC/MS/MS). The method uses a single-step dilution for sample preperation. Seperation was achieved on a $C_{18}$ column ($2.1{\times}150mm$, $3.5{\mu}m$) with A- 2% methanol (1 mM ammonium acetate), B-95% methanol (1 mM ammonium acetate) as mobile phase with gradient mode. The quantitation of target compounds was performed by external calibration in selected reaction monitorning (SRM) mode. The coefficient of determination of calibration curve for sodium saccharin, aspartame, acesulfame-K, sucralose and cyclamate were 0.9957, 0.9991, 0.9943, 0.9982 and 0.9948, respectively. The limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 0.001~0.022 mg/L and 0.004~0.073 mg/L, repectively. Recoveries for beverage samples were in the range of 92.76~113.50% with RSD < 10.91%. The method has applied to the determination of the five sweetners in 102 beverage samples. Three artificial sweetners-aspartame, acesulfame-K, sucralose were detected from 42 samples. Sodium saccharin and cyclamate were not detected in all samples.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.322-326
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• 2014

According to Centers for Disease Control and Prevention (CDC, USA) recently it was reported that the children (< 5 year-old children) were more susceptible to Foodborne-illness. Confectionery products should be strictly controlled because they are children-preferred foods. Ministry of Food and Drug Safety (MFDS, South of Korea) tried to monitor contamination of organisms in confectionery products (such as biscuits, candies, chewing gums and ice candies) distributed in South Korea. MFDS evaluated the levels of indicator organisms: total aerobic bacteria, coliforms, Escherichia coli as well as the levels of food-borne illness organisms: Staphylococcus aureus, Bacillus cereus, Clostridium perfringens. Experimental plans for microbiological test were in accordance with the International Commission on Microbiological Specifications for Food (ICMSF). For this study, 1,005 samples were collected and from Seoul and Gyeongin region, South Korea. The average level of total aerobic bacteria in 1,005 samples was 1.7 log Colony Forming Unit(CFU)/g and the detection rate was 26.8%. The average level of Bacillus cereus was detected in 1.7 log CFU/g and the rate was 0.9%. There was no detection of coliforms, Escherichia coli, Staphylococcus aureus and Clostridium perfringens. The results of this study will be provided as the basic data to set the reasonable microbiological criteria of Korea Food Code.

• Journal of Food Hygiene and Safety
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• v.32 no.6
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• pp.477-484
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• 2017

This study was conducted to investigate the content of sulfur dioxide, carotenoids and the degree of contamination of Bacillus cereus in 33 kinds of dried sweet potato from domestic mainly dried agricultural products in Korea. According to the characteristics of dried sweet potato samples, it was classified into four clusters and as a result of analyzing the contents of sulfur dioxide, carotenoids and the degree of contamination B. cereus was no significant difference among the clusters. The detection ranges of residual sulfur dioxide from 33 dried sweet potatoes ranged from 0.38 to 28.16 mg/kg, three cases (9.09%) were detected at the reference level of 10 mg/kg or more. But no samples exceeding 30 mg/kg, the tolerance level of sulfur dioxide in dried sweet potatoes were detected. Since dried sweet potato does not have a standard for carotenoids, when comparing the national and international standards of carotenoids, the range of detection of carotenoids in dried sweet potato was $46{\sim}2,663{\mu}g$/100 g, which was within the reference range of $0{\sim}9,826{\mu}g$/100 g. In principle colonies suspected to be B. cereus in dried sweet potato were not detected. In 7 cases (21.21%), there were detected in the range of 0.05~1.59 log CFU/g but not more than 3 log CFU/g as the reference value. The results of this study are expected to be used as basic data to establish quality standard for dried sweet potatoes. In order to control the quality of dried sweet potatoes in domestic market, raw materials, drying method and packaging after distribution, it is necessary to maintain and maintain the process steadily.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.1
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• pp.85-95
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• 1998

The broadband ultrasonic transducers have been designed to use in obtaining the broadband echo signals from fish schools in relation to the identification of fish species. The broadening of bandwidth was achieved by attaching double acoustic matching layers on the front face of a Tonpilz transducer consisted of an aluminum head, a piezoelectric ring, a brass tail and to evaluate the performance characteristics, such as the transmitting voltage response(TVR) of transducers. The constructed transducers were tested experimentally and numerically by changing the parameters such as impedances and thicknesses of the head, tail and matching layers, in the water tank. Also, the developed transducer was excited by a chirp signal and the received chirp waveforms were analyzed. According to the measured TVR results, the available 3 dB bandwidth of the transducer with double matching layers of an $Al_O_3/epoxy$ composite of 7 mm thick and a polyurethane window of 18 mm thick was 7.3 kHz with a center frequency of 38.8 kHz, and the maximum and the minimum values of the TVR in this frequency region were 135.7 dB and 132.7 dB re $1\;{\mu}Pa/V$ at 1 m, respectively. Also, the available 3 dB bandwidth of the transducer with double matching layers of an $Al_O_3/epoxy$ composite of 11 mm thick and a polyurethane window of 15 mm thick was 6.2 kHz with a center frequency of 38.6 kHz, and the maximum TVR value in the frequency region was 136.3 dB re $1\;{\mu}Pa/V$ at 1 m. Reasonable agreement between the experimental results and the numerical results for the TVR of the developed transducers was achieved. The frequency dependant characteristics of experimentally observed chirp signals closely matched to the measured TVR results. These results suggest that there is potential for increasing the bandwidth by varying other parameters in the transducer design and the material of the acoustic matching layers.

• The Journal of the Korean Society for Microbiology
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• v.8 no.1
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• pp.7-11
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• 1973

The authors identified eighty-eight Shigella cultures among about four thousands specimens collected from all over the country in 1972. Of eighty-eight cultures, seventy-seven cultures belonged to Shigella flexneri and eleven cultures to Shigella sonnei. None of cultures belonging to either subgroup A or C was detected in 1972. Of seventy-seven cultures of Shigella flexneri one was $B_{1b}$, fifty-six were $B_{2a}$, nine were $B_{3a}$, six were $B_{4a}$, three were By and one was each of $B_{3b}$ and $B_{3c}$. Of eleven cultures of Shigella sonnei seven cultures appeared to be phase I and the others phase II. Although there was quite a difference found in the incidence of isolating Shigella organisms between different areas as shown in Table 1, it would not be possible to understand that there might not have been the cases or carriers of Shigella in the areas where the organisms were not isolated in 1972. Concerning the biochemical properties it was not possible to compare the results obtained from the decarboxylase and dihydrolase tests with them obtained in previous years except that of lysine decarboxylase tests since they were not reported individually by the different serotypes in the previous reports. These results obtained in 1972 would be the data for the future comparison. In regards to the antibiotics-sensitivity of Shigella cultures the most of them showed sensitive results to nitrofurantoin, ampicillin, cephalosporin, gentamycin and geopen, and the majority of them appeared to be resistant to cloxacillin, tetracycline and streptomycin by means of the In Vitro tests.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.17 no.2
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• pp.93-103
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• 1981

It is well-known that nowadays heat resisting and anti-corrosive materials have been widely used as the components materials of gas turbines, nuclear power plants and engines etc. In the fields of machine production industry. And materials for engine components, like as the exhaust valve of internal combustion engine, have been required to operate under the high temperature range of $700^{\circ}C$-$800^{\circ}C$ and high pressured gas with repeated mechanical load for the high performance of engines. For these components, friction welding for bonding of dissimilar steels can be applied for in order to obtain process shortening, production cost reduction and excellent bonding quality. And age hardening recently has been noticed to the heat resisting materials for further strengthening of high temperature strength, especially high temperature fatigue strength. However, it is difficult to find out any report concerning the effects of age hardening for strengthening high temperature fatigue strength to the Friction welded heat resisting and anti-corrosive materials. In this study the experiment was carried out as the high temperature rotary bending fatigue testing under the condition of $700^{\circ}C$ high temperature to the friction welded domestic heat resisting steels, SUH3-SUS303, which were 10hr., 100hr. aging heat treated at $700^{\circ}C$ after solution treatment 1hr. at $1, 060^{\circ}C$ for the purpose of observing the effects of the high temperature fatigue strength and fatigue fracture behaviors as well as with various mechanical properties of welded joints. The results obtained are summarized as follows: 1) Through mechanical tests and micro-structural examinations, the determined optimum welding conditions, rotating speed 2420 rpm, heating pressure 8kg/mm super(2), upsetting pressure 22kg/mm super(2), the amount of total upset 7mm (heating time 3 sec and upsetting time 2 sec) were satisfied. 2) The solution treated material SUH 3, SUS 303, have the highest inclination gradient on S-N curve due to the high temperature fatigue testing for long time at $700^{\circ}C$. 3) The optimum aging time of friction welded SUH3-SUS 303, has been recognized near the 10hr. at $700^{\circ}C$ after the solution treatment of 1hr. at $1, 060^{\circ}C$. 4) The high temperature fatigue limits of aging treated materials were compared with those of raw material according to the extender of aging time, on 10hr. aging, fatigue limits were increased by SUH 3 75.4%, SUS 303 28.5%, friction welded joints SUH 3-SUS 303 44.2% and 100hr. aging the rates were 64.9%, 30.4% and 36.6% respectively. 5) The fatigue fractures occurred at the side of the base matal SUS303 of the friction welded joints SUH 3-SUS 303 and it is difficult to find out fractures at the friction welding interfaces. 6) The cracking mode of SUS 303, SUH 3-303 is intergranular in any case, but SUH 3 is fractured by transgranular cracking.

• The Korean Journal of Food And Nutrition
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• v.18 no.4
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• pp.341-348
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• 2005

The quality characteristics of bread added with the levels of $0\%,\;1.0\%,\;2.0\%\;3.0\%\;and\;4.0\%$ prickly pear powder were investigated. Mixing water absorption capacity was increased by increasing amounts of prickly pear powder. Mixing time of dough was increased compared to that of wheat flour by added prickly pear powder, while it decreased as prickly pear powder content increased. Dough stability of wheat flour added with $1.0\%$ prickly pear powder was similar to wheat flour dough, while decreased by increasing amount of prickly pear powder at the range of $2.0\~4.0\%$. Pasting temperature($66.1\~66.9^{\circ}C$) of wheat flour added with $1.0\%,\;2.0\%\;3.0\%\;and\;4.0\%$ prickly pear powder was lower($67.8^{\circ}C$) than that of wheat flour. Peak viscosity($2,226\~2,375$ cp) of wheat flour added with $1.0\%,\;2.0\%\;3.0\%\;and\;4.0\%$ prickly pear powder were higher(2,288 cp) than control, and increased with increasing amount of prickly pear powder Setback($797\~750$ cp) of wheat flour added with $1.0\%,\;2.0\%\;3.0\%\;and\;4.0\%$ prickly pear powder were lower(803 cp) than that of wheat flour, and decreased with increasing amount of prickly pear powder. The volume of dough added with prickly pear powder decreased compared to that of the wheat dough. The specific loaf volume of bread added with prickly pear powder decreased($8.0\~18.5\%$) compared to that of the wheat bread. Color of crumb was deep red gradually with the increasing amount of substituted prickly pear powder. Hardness, adhesiveness, gumminess and chewiness of bread were increased gradually with the increasing amount of substituted prickly pear powder but the springiness was decreased. The sensory evaluation showed that bread of wheat flour added with $2.0\%$ prickly pew powder was superiority than the wheat flour bread.

• The Korean Journal of Food And Nutrition
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• v.18 no.4
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• pp.349-356
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• 2005

For the purpose of making a new type of functional drinkable yoghurt, skim milk containing $0.5\~2.0\%$(w/v) green tea powder was fermented by the mixed stains of Streptococcus thermophilus and Lactobacillus acidophilus. Quality characteristics of the drinkable yoghurts were evaluated in terms of quality-keeping properties(number of viable cells, pH, titratable acidity) and sensory properties. When the drinkable yoghurts added with $0.5\~2.0\%$ green tea powder were kept at $4^{\circ}C\;and\;20^{\circ}C$ for 20 days, the number of viable cell counts of the lactic acid bacteria($2.1\times10^8\~6.2\times10^8$ CFU/mL). pH($4.16\~4.22$) and titratable acidity($0.792\~0.881\%$) were not significantly changed for all drinkable yoghurts during the storage at $4^{\circ}C\;and\;20^{\circ}C$ days, but the number of viable cell counts($4.2\times10^3\~1.8\times10^5$ CFU/mL), pH($3.82\~3.92$) and titratable acidity($1.057\~1.174\%$) were markedly changed f3r the storage at $20^{\circ}C$ for 20 days. Therefore the keeping quality of the drinkable yoghurts with addition of green tea powder was relatively good at $4^{\circ}C$ for 20 days. The results of sensory evaluation of the drinkable yoghurts containing peen tea powder indicated that flavor, sweet taste, mouthfeel and aftertaste of the drinkable yoghurt with $0.5\%$ green tea powder showed higher preference than others. And the drinkable yoghurt containing $0.5\% green tea powder added $20\%$(v/v) oligosaccharide had the higher sensory scores in sweet taste, aftertaste and overall acceptability among the treatments.

• Korean journal of food and cookery science
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• v.19 no.2
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• pp.223-230
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• 2003

This study was conducted to estimate the contents of 6 trace metals in potatoes and root vegetables purchased in wholesale market in the Seoul region, specifically, Cu. As, Zn, Pb, Cd and Hg. The minimum and maximum results obtained for each metal are summarized as follows for potatoes; Cu : 0.094∼0.344, As : N.D∼0.070, Zn : 0.247∼1.547, Pb : N.D∼0.268, Cd : N.D∼0.005, Hg : 0.001∼0.027, and for root vegetables; Cu : 0.021∼0.510, As : 0.004∼0.045, Zn : 0.143∼3.137, Pb : N.D∼0.372, Cd : N.D∼0.009, Hg : 0.001∼0.195. The daily intakes of trace metals from potatoes and root vegetables were estimated on the basis of the daily intake of these foods by Koreans, which were 0.073∼22.253 and 0.567∼156.219$\mu\textrm{g}$ from potatoes and root vegetables, respectively. The weekly intakes of trace metals were 0.009∼2.596 and 0.066∼18.224$\mu\textrm{g}$ for potatoes and root vegetables, respectively. The weekly intakes of trace metals for potatoes and root vegetables were very much lower than the PTWI(provisional tolerable weekly intake), enough to be within a safe range.

• The Korean Journal of Food And Nutrition
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• v.24 no.1
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• pp.138-143
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• 2011

This study analyzed the maltol quality, composition ratio of fatty acids, and contents of phenolic compounds in white ginseng extracts(four types), red ginseng extracts(five types), black ginseng extracts(two types), and Chinese ginseng extracts(nine types). By examining patterns in these measurements, we determined the characteristic factors of the extracts and measured the possibility of qualitative analysis. In the analysis of maltol using TLC, white ginseng extracts were not detected while red and black ginseng extracts were detected, so the possibility of detection was considered as a characteristic factor for qualitative analysis. Regarding the composition of fatty acids, palmitic and linoleic acids were the main fatty acids in the ginseng extracts palmitic acid was high in white ginseng extracts while linoleic was low in red ginseng extracts. Regarding the ratio(Pal/Lin) of the two fatty acids, there was a large difference between white ginseng extracts(56.7~64.3%) and red ginseng extracts(32.0~38.5%), and these figures seemed to be characteristic factors for the analysis. For the phenolic compounds, extracts contained maltol, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, and cinnamic acid. White ginseng extracts contained similar percentages of phenolic compounds while red ginseng extracts had high maltol content. According to the measurement results of the percentages of maltol and cinnamic acid, white ginseng extracts showed values below five, whereas red and black ginseng extracts showed 53~289, which was also a characteristic factor for qualitative analysis. Consequently, we found that we can differentiate between ginseng extracts using characteristic factors that we analyzed in an experiment on white ginseng extracts from China.