• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.7
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• pp.1062-1067
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• 2014

In the present study, a new analytical method was devised for the simultaneous determination of soluble carbohydrates in soybean seeds using high performance liquid chromatography/evaporative light scattering detection (HPLC/ELSD). The limit of quantification (LOQ) for soybean soluble carbohydrates ranged from 5.6~7.6 mg/kg using the HPLC/ELSD method and from 16.2~33.9 mg/kg using the high performance liquid chromatography/refractive index detection (HPLC/RID) method. Therefore, the HPLC/ELSD method was more sensitive than HPLC/RID. The precision values for retention time and peak area of the HPLC/ELSD method were evaluated by inter-day (n=5) and intra-day (n=10) assays using a standard solution. All precision values (CV<2.5%) for soybean soluble carbohydrates were acceptable and fulfilled international acceptance criteria. All linear calibration curves were obtained with a correlation coefficient of $R^2$ >0.999. The contents of soluble carbohydrates for the "Shingikong" (yellow soybean) and "Cheongjakong 3" (black soybean) samples were analyzed using the HPLC/RID and HPLC/ELSD methods. The difference in carbohydrate contents between the two detection methods was significant. Carbohydrate contents in the HPLC/ELSD method were higher than those in the HPLC/RID method. Overall, the HPLC/ELSD method showed satisfactory resolution with a favorable LOQ and reproducibility. Therefore, these results indicate that the HPLC/ELSD method may be applied to determine the contents of soluble carbohydrates in soybean seeds and related food stuffs.

• Journal of Dairy Science and Biotechnology
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• v.33 no.4
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• pp.263-269
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• 2015

Various carbohydrates (lactose, glucose, and fructose), lactic acid, uric acid, and acetoin were separated on a ZORBAX Carbohydrate Analysis column using the Agilent 1200 HPLC ChemStation$^{TM}$, and were identified according to retention times with 325 Dual Wavelength UV-Vis Detector and Refractive Index Detector with 0.013 N $H_2SO_4$ at a flow rate of 0.8 mL/min. In addition, the lactase activity of four commercial probiotic lactic acid bacteria during 6-hour incubation was determined using a high-performance liquid chromatography (HPLC) method. Among the tested samples, Bifidobacterium animalis subsp. lactis showed the greatest lactase activity, followed by Lactobacillus rhamnosus and Lactobacillus casei, with Streptococcus salivarius subsp. thermophilus showing the lowest activity. Therefore, this HPLC technique shows potential for evaluating the fermentation processes of probiotic lactic acid bacteria and could simultaneously confirm the degree of ripening in various fermented dairy foods within only a half hour.

• Korean Journal of Food Science and Technology
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• v.43 no.1
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• pp.58-64
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• 2011

The purpose of this study was to analyze the content and consumption of total sugar from school lunches at Incheon and Chuncheon. The samples were collected from eight elementary schools and eight middle schools in Incheon and Chuncheon for 15 days. The analysis of total sugar content was performed for 1334 main dishes, side dishes, and desserts, which were supplied by elementary and middle school foodservices. Total sugar content was extracted from various types of food with 50% ethanol after defatting. We simultaneously analyzed sugars such as fructose, glucose, sucrose, maltose, and lactose by a high performance liquid chromatography with refractive index detector. The average lunch intake for elementary school and middle school students was $372.6{\pm}72.2g$ and $449.2{\pm}81.1g$, respectively. The total sugar content in desserts was $7.21{\pm}6.32g/100g$, $1.69{\pm}2.44g/100g$ in side dishes, and $0.32{\pm}0.77g/100g$ in main dishes. Among side dishes, fried foods, stir-fried foods, and sauces contained the highest amounts of total sugar. The total sugar intake was $4.63{\pm}5.11g$ in desserts, $0.64{\pm}1.01g$ in side dishes, and $0.55{\pm}1.48g$ in main dishes. Main and side dishes with a high total sugar intake included cooked rice with seasoning, fried foods, stir-fried foods, and preserved foods. The average total sugar intake per meal for elementary school, middle school, and all students was $4.03{\pm}3.67g$, $6.97{\pm}6.59g$, and $5.50{\pm}5.53g$, respectively. We have provided useful information to decrease the intake of total sugar in school lunches. It is recommended that total sugar intake be continuously monitored.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.14-18
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• 2004

Analysis methods of artificial sweeteners, aspartame, acesulfame potassium, sodium saccharin, and sucralose isolated from foods were developed using high performance liquid chromatography, HPLC conditions for aspartame, acesulfame potassium, and sodium saccharin were: column, Symmetry $C_{18}(3.9mm\;i.d{\times}150mm,\;5{\mu}m)$; mobile phase, 0.05M sodium phosphate monobasic : acetonitrile (9 : 1, pH 3.5, containing 0.01M tetrapropylammonium hydroxide); detector, UV detector at 210 nm. HPLC condition for sucralose were : column, Symmetry $C_{18}(3.9mm\;i.d{\times}150mm,\;5{\mu}m)$; mobile phase, water:methanol (7 : 3); detector, refractive index detection (sensitivity = 16). Recoveries of artificial sweeteners in foods including soft drinks, fruit and vegetable beverages, alcoholic beverages, fermented milk beverages, soybean milk, ice cream, snacks, chewing gums, jam, honey, kimchi salted food, special dietary products, processed fish products, candies, food additive mixtures, chocolate and cocoa were 76.1-101.3%, 82.3-103.2%, 83.1-103.7%, and 80,6-99.5% for aspartame, acesulfame potassium, sodium saccharin, and sucralose, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.11
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• pp.1666-1671
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• 2015

The purpose of this study was to provide trustworthy nutritional information by analyzing sugar contents of commercial retort foods. A total of 70 retort food samples were collected, which included curry (n=21), blackbean- sauce (n=16), sauce (n=17), and meat (n=16) from markets in Seoul and Gyeonggi-do. Contents of sugars such as glucose, fructose, sucrose, maltose, and lactose were analyzed in retort foods by using a high performance liquid chromatography-refractive index detector and compared to their assigned values on nutritional information labels. Analyzed sugar contents of curries, black-bean-sauces, sauces, and meats ranged from 1.05~4.63 g/100 g, 1.76~5.16 g/100 g, 0.35~25.44 g/100 g, and 1.98~11.07 g/100 g, respectively. Sauces were found to contain the highest amounts of total sugar. These analysis values were equivalent to the reference values indicated on nutrition labels, which were 40~119.5% for curries, 29~118% for black-bean-sauces, 18~118% for sauces, and 70~119.8% for meats. Therefore, this study provides reliable analytical values for sugar contents in retort foods.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.196-202
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• 2011

In this paper, a series of alkyl succinic acid esters for base oil were synthesized by condensation reaction of succinic anhydride and fatty alcohol. The structures of the synthesized esters were confirmed by $^1H-NMR$, FT-IR spectrum and GC analysis. Basic properties of esters such as kinematic viscosity (KV), refractive index (RI), total acid number (TAN) and pour points were measured and lubricating properties such as SRV wear scar diameter (SRV WSD), fraction coefficient (COF) and 4-ball wear (4-ball WSD) were also evaluated. As the results of basic properties, KV, RI and pour point of synthetic esters increased as the carbon chain of the esters increased. Measurement value of total acid number (TAN) was indicated between 0.2~4 mgKOH/g, and that metal working fluids and pressure working oils are acceptable to use as base oil. Also, lubricating properties of the esters showed as follows: 0.391~0.689 mm of SRV WSD, 0.110~0.138 of SRV COF and 0.49~0.55 mm of 4-ball WSD depended on the structure of the esters. In a comparison on the lubrication capacity of the SRV test based on polyester TMPTO, SRV WSD result showed that a better performance caused by the alkyl group. On the other hand, SRV COF test was not influenced of the alkyl group which the capacity of the lubricant was sightly diminished than the comparison material, regardless of the alkyl group.