• Journal of Dairy Science and Biotechnology
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• v.33 no.1
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• pp.27-34
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• 2015

The aim of this study was to optimize a simple, fast, and economic analytical method for the simultaneous determination of various pesticides (aldrin, p,p'-DDT, o,p'-DDT, p,p'-DDE, ${\alpha}$-endosulfan, ${\beta}$-endosulfan, dieldrin, heptachlor, permethrin, chlordane, deltamethrin, diazinon, bifenthrin, methoprene, propargite, fenpropathrin, cypermethrin, fenvalerate, and fenpropathrin) in milk by using dispersive solid phase extraction (SPE). In this study, two different extraction methods (low temperature cleanup and liquid-liquid partitioning), which were followed by a cleanup process based on dispersive-SPE, were evaluated and compared for the 19 pesticides. The results for all the pesticides were determined by gas chromatography mass spectrometry (GC/MS) with selected-ion monitoring mode, and the matrix effect of the method was evaluated. Comparison of these approaches yielded higher and more consistent recoveries of most pesticides at fortification levels of $1{\mu}g/mL$ using low-temperature fat precipitation, followed by cleanup process based on dispersive-SPE with PSA and C18 as sorbents, than other preparation process. The relative standard deviation was <20 % and the combination of this method were very effective for the cleanup.

• Korean Journal of Environmental Agriculture
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• v.37 no.1
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• pp.57-65
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• 2018

BACKGROUND: An analytical method was developed using HPLC-UVD/MS to precisely determine the residue of flusulfamide, a benzenesulfonamide fungicide used to inhibit spore germination. METHODS AND RESULTS: Flusulfamide residue was extracted with acetone from representative samples of five raw products which comprised apple, green pepper, Kimchi cabbage, hulled rice, and soybean. The extract was diluted with large volume of saline water and directly partitioned into dichloromethane to remove polar co-extractives in the aqueous phase. For the hulled rice and soybean samples, n-hexane/acetonitrile partition was additionally employed to remove non-polar lipids. The extract was finally purified by optimized Florisil column chromatography. On an octadecylsilyl column in HPLC, flusulfamide was successfully separated from co-extractives of sample, and sensitively quantitated by ultraviolet absorption at 280 nm with no interference. Accuracy and precision of the proposed method was validated by the recovery experiment on every crop sample fortified with flusulfamide at 3 concentration levels per crop in each triplication. CONCLUSION: Mean recoveries ranged from 82.3 to 98.2% in five representative agricultural commodities. The coefficients of variation were all less than 10%, irrespective of sample types and fortification levels. Limit of quantitation (LOQ) of flusulfamide was 0.02 mg/kg as verified by the recovery experiment. A confirmatory method using LC/MS with selected-ion monitoring technique was also provided to clearly identify the suspected residue.

• Journal of Animal Science and Technology
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• v.51 no.5
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• pp.387-394
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• 2009

This study was carried out to screen and identify the chitinase and chitosanase producing microorganisms from the feces of calves medicated DFM sincluding chitin in order to do the immune fortification of Korean Native calves. Ten isolates were grown in the medium containing chitin and chitosan that had more than $10^5$ cfu/g in feces. Among these 10 strains, 2 strains (HANDI 110 and HANDI 309) had the chitinase activities and 2 strains (HANWOO and HANYOO) had the chitosanase activities in calves' feces. They showed no reaction in hemolysis tests by utilizing chitin and chitosan. The results from morphological, physicochemical and genetical identification indicated the HANDI 110 as a strain of Escherichia fergusonii, HANDI 309 was identified as a strain of Acinetobacter parvus, HANWOO was identified as a strain of Comamonas koreensis, and HANYOO as a strain of Chryseobacterium indologenes.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1197-1202
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• 1998

Organic acids-eggshell calcium salts were prepared to recycle calcium component from discarded egg shells, and the effects of addition of the salts on dough characteristics of raw noodle and physical properties of cooked noodle were also investigated. Based on Farinograms, calcium malate (CM) affected absorption, stability time, and development time more considerably than calcium citrate (CC). Maximum concentrations of both CM and CC with little influence on dough characteristics were found to be 0.1% and 0.4%, respectively. Addition of calcium salts led to reduce the volume expansion rate of cooked noodle and this was more clearly shown in a sample fortified with CM than CC. As for CC, addition of more than 0.6% resulted in rapid increase in springiness which was in a good agreement with sensory evaluation results. Calcium ion concentration of cooked noodle fortified with 0.4% CC was 48 ppm, equivalent to 86 mg of calcium obtained from 200 g of cooked noodle.

• Journal of Applied Biological Chemistry
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• v.63 no.2
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• pp.153-159
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• 2020

The analytical method was established for simultaneous determination of fungicide prochloraz and its metabolites in several animal commodities using gas chromatography (GC) coupled with electron capture detector (ECD). Samples including beef meat, pork meat, chicken meat, milk, and egg were hydrolyzed with pyridine hydrochloride which converts prochloraz and its metabolites to 2,4,6-trichlorophenol (2,4,6-TCP) because residue definition for prochloraz was 'sum of prochloraz and its metabolites containing the 2,4,6-trichlorophenol moiety, expressed as prochloraz', for compliance with MRLs from animal commodities. Therefore, residual prochloraz was extracted with acetone, decomposed to 2,4,6-TCP, partitioned with dichloromethane, purified with aminopropyl SPE and quantified as 2,4,6-TCP with GC-ECD. The instrumental limit of quantitation and method LOQ (MLOQ) was 0.01 ㎍/mL and 0.02 mg/kg for prochloraz and 0.005 ㎍/mL and 0.01 mg/kg for 2,4,6-TCP, respectively. The linearity of the calibration curve was good with R² >0.995 in the range of 0.005-0.2 ㎍/mL. Fortification levels of prochloraz were 0.02 mg/kg (MLOQ) and 0.2 mg/kg (10MLOQ) for recovery tests. Overall recoveries of prochloraz were >90% with <10% of coefficient variation (C.V.). This established analytical method was fully validated and could be useful for quantification of prochloraz and its metabolites in animal commodities as official analytical method.

• Korean Journal of Food Science and Technology
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• v.43 no.3
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• pp.277-281
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• 2011

A rapid and very sensitive high-performance liquid chromatography/atmospheric-pressure chemical-ionization mass spectrometry method to detect ethylenethiourea (ETU) fungicide residues in fruits was developed. Methylene chloride was used as the surface extraction solvent for the target component. Recovery rates improved when cysteine hydrochloride and sodium carbonate were added to product prior to fortification. The limits of detection and quantification were approximately 0.006 and 0.02 mg/kg, respectively, from mandarin oranges. Recoveries from mandarin oranges, oranges, bananas, and pears, spiked in the range of 0.05-0.5 mg/kg, averaged 80-100%. The proposed method was used to monitor the presence of ETU in commercial fruits purchased from different markets in Seoul, Korea. ETU was found in four orange peels and in three mandarin orange peel samples. The highest ETU residue levels were $73.6{\mu}g/kg$ and $29.8{\mu}g/kg$.

• Korean Journal of Food Science and Technology
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• v.44 no.2
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• pp.216-223
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• 2012

Dextran was produced by $Leuconostoc$ $mesenteroides$ SM with various contents of yeast extract and its rheological properties were modulated, via an addition of hydroxypropyl methylcellulose (HPMC) of different viscosities. The conversion yield reached 90% after adding 3% yeast extract, which remained constant, thereafter. The acidity of the cultures was approximately 1.4 and 0.9% after fermentation for 24 h at 25 and $30^{\circ}C$, respectively. The total dextran content (107.3 g/kg) was the highest in the presence of the 3% yeast extract. Under the same conditions, the consistency, viscous modulus (G"), and elastic modulus (G') of the cultures were $37.6\;Pa{\cdot}s^n$, 38 Pa, and 50 Pa, respectively. The rheological properties of the culture were changed drastically by the fortification with HPMC of higher concentration and viscosity. The addition of 10% HPMC (4,000 cp) resulted in a significant increase in G" to 1,950 Pa. Furthermore, adding HPMC to a viscous culture resulted in a remarkable increase in both hardness and firmness.

• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.434-440
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• 2013

Functional properties of Cheonnyuncho fruit paste (CFP) were enhanced by fermentation, using Leuconostoc mesenteroides SM. The stability of CFP pigment was maintained and microorganisms in crude CFP were sterilized by heating at $80^{\circ}C$ for 30 min. The production of dextran in CFP was increased by increasing the fermentation time and sugar content, resulting in an increase of consistency. The CFP fermented with 20% sucrose contained 4.8% mucilage after fermentation for 2 days. In particular, the production of mucilage was greatly enhanced by fortification with 3% sodium citrate in CFP, resulting in mucilage production of 7%. In addition, the viscous modulus of fermented CFP showed a greater increase than that of the elastic modulus. Thus, it was concluded that CFP fermented by L. mesenteroides SM can be fortified with functional ingredients, such as mucilage and probiotics, with enhanced rheological properties. Therefore fermented CFP can be utilized as the functional ingredients for functional foods.

• Korean Journal of Environmental Agriculture
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• v.31 no.1
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• pp.45-51
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• 2012

BACKGROUND: This study was carried out to establish pre-harvest residue limit of fungicides pyrimethanil and trifloxystrobin in persimmon, based on dissipation and biological half-lives of two fungicides residue. METHODS AND RESULTS: Both pyrimethanil and trifloxystrobin were extracted with acetonitrile, clean-up with $NH_2$ SPE cartridge and residue were analyzed by HPLC/DAD. Limit of Detection was 0.01 mg/kg. Average recovery were $81{\pm}1.62%$, $98{\pm}1.58%$ of pyrimethanil, and $91{\pm}2.94%$, $98{\pm}1.25%$ of trifloxystrobin at fortification levels at 0.1 and 0.5 mg/kg, respectively. CONCLUSION: The biological half-lives of pyrimethanil were 15.6 and 11.6 days at sprayed with recommended and double dosage, respectively. The biological half-lives of trifloxystrobin were 10.4 and 10.3 days at sprayed with recommended and double dosage, respectively. The pre-harvest residue limit of pyrimethanil and trifloxystrobin were recommended as 2.69 and 0.83 mg/kg for 10 days before harvest, respectively.

• Korean Journal of Environmental Agriculture
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• v.39 no.2
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• pp.130-137
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• 2020

BACKGROUND: Mefentrifluconazole and triticonazole are the triazole fungicides. The maximum residue levels for agricultural products need to be set up. Therefore, development of the official analytical method for determination of mefentrifluconazole and triticonazole residues from agricultural crops was necessary due to safety management, and then a simultaneous analytical method was developed for the determination of mefentrifluconazole and triticonazole in agricultural crops. METHODS AND RESULTS: Samples were extracted using acetonitrile and purified using dispersive solid phase extraction, and then detected with liquid chromatograph-tandem mass spectrometry (LC-MS/MS). Matrix-matched calibration curves (0.0025-0.25 ㎍/mL) were linear into a sample extract with r²>0.99. For validation, the recovery test was carried out at three fortification levels (LOQ, 10 LOQ and 50 LOQ) from agricultural samples. The results for mefentrifluconazole and triticonazole ranged between 92.3 to 115.3% and 91.4 to 108.5%, respectively and RSD (relative standard deviation) values were also below 6.0%. Furthermore, inter-laboratory was conducted to validate the method. CONCLUSION: All values were corresponded with the criteria ranges requested by both the CODEX (CAC/GL 40-1993, 2003) and MFDS guidelines (2016). Therefore, the proposed method can be used as an official analytical method for determination of mefentrifluconazole and triticonazole (triazole fungicides) in the Republic of Korea.