Hyejin Park

Winter Wheat Quality Responses to Water, Environment, and Nitrogen Fertilization

Decreasing carbon (C) footprints by reducing nitrogen (N) and water inputs has been speculated to have negative impacts on wheat grain yield and flour processing quality. The objective of this study was to determine the impact of N and water stress on winter wheat grain yield, protein composition, and dough quality. Wheat fertilized at two N rates (unfertilized and recommended) was grown under water-stressed and well-watered environments. Nitrogen and water stress were measured using the 13C isotopic approach. Research showed that (1) N fertilizer and the water-management environment produced similar impacts on wheat quality and yield loss due to N stress and yield loss due to water stress (YLWS); (2) N fertilizer increased flour protein, dough stability, and relative concentration of glutenin (%Glu), unextractable polymeric protein (UPP), and relative amount of high-molecular-weight glutenin subunits (HMW-GS/LMW-GS); (3) the well-watered environment reduced protein contents when N mineralization was low, whereas it did not influence protein content when mineralization was high; and (4) the %Glu was negatively correlated with yield loss due to N stress (YLNS) and positively correlated with stability. This study showed that a clear understanding of the complex relationship between soil variability and climatic conditions should make it possible to develop adaptive management practices, increase profitability, and improve quality.

Development and Validation of an Analytical Method for the Insecticide Sulfoxaflor in Agricultural Commodities using HPLC-UVD

Sulfoxaflor is a new active ingredient within the sulfoximine insecticide class that acts via a unique interaction with the nicotinic receptor. The MRLs (maximun residue limit) of sulfoxaflor in apple and pear are set at 0.4 mg/kg and that in pepper is set at 0.5 mg/kg. The purpose of this study was to develop an analytical method for the determination of sulfoxaflor residues in agricultural commodities using HPLC-UVD and LC-MS. The analysis of sulfoxaflor was performed by reverse phase-HPLC using an UV detector. Acetone and methanol were used for the extraction and aminopropyl (NH2) cartridge was used for the clean-up in the samples. Recovery experiments were conducted on 7 representative agricultural products to validate the analytical method. The recoveries of the proposed method ranged from 82.8% to 108.2% and relative standard deviations were less than 10%. Finally, LC-MS with selected ion monitoring was also applied to confirm the suspected residues of sulfoxaflor in agricultural commodities.

Development and Validation of an Analytical Method for Flutianil Residue Identification Using Gas Chromatography-Electron Capture Detection

Ji-Eun Kwon, Jung-Ah Do, Hyejin Park, Ji-Young Lee, Yoon-Jae Cho,Jae-Ho Oh, Gyu-Seek Rhee, Sang-Jae Lee, and Moon-Ik Chang*Food Safety Evaluation Department, National Institute of Food and Drug Safety Evaluation, MFDSAbstract A sensitive and simple analytical method to identify flutianil residues in agricultural commodities wasdeveloped and validated using gas chromatography-electron capture detection (GC-ECD) and mass spectrometry (GC-MS).The flutianil residues were extracted with acetonitrile, partitioned with dichloromethane, and then purified using a silicasolid-phase extraction (SPE) cartridge. The method was validated using pepper, sweet pepper, mandarin, hulled rice,soybean, and potato spiked with 0.02 or 0.2 mg/kg flutianil. The average recovery of flutianil was 76.5-108.0% with arelative standard deviation of less than 10%. The limit of detection and limit of quantification were 0.004 and 0.02 mg/kg, respectively. The result of recoveries and relative standard deviation were in line with Codex Alimentarius CommissionGuidelines (CAC/GL 40). These results show that the method developed in this study is appropriate for flutianilidentification and can be used to maintain the safety of agricultural products containing flutianil residues.Keywords: flutianil, fungicide, GC-ECD, GC-MS, agricultural commodities

Effects of High Hydrostatic Pressure Treatment on the Chemical Composition of Germinated Rough Rice (Oryza sativar L.)

This study was performed to evaluate changes in the chemical composition of germinated rough rice with high hydrostatic pressure treatment (HPT). Rough rice was germinated at 37oC over 6 days (control), and then subjected to HPT at 30 MPa for 24 h. The highest crude protein content was 9.54% in the control sample after 6 days of germination. Crude lipid content increased from 2.04-2.74% (control) to 2.27-3.10% (HPT). HPT samples showed higher values of total free sugar and glucose content than those of the control. The total amino acid value was not significant, but the essential amino acid content increased from 0.45-5.09 mg/g in the control to 1.57-5.30 mg/g in the HPT sample. The major fatty acids were found to be palmitic, oleic, and linoleic acid. The content of oleic acid decreases with HPT, whereas that of linoleic and linolenic acid increased slightly during the initial stages of germination. These results suggest that HPT after germination efficiently depolymerizes chemical components and enhances the content of essential nutrients.This study was performed to evaluate changes in the chemical composition of germinated rough rice with high hydrostatic pressure treatment (HPT). Rough rice was germinated at 37 o C over 6 days (control), and then subjected to HPT at 30 MPa for 24 h. The highest crude protein content was 9.54% in the control sample after 6 days of germination. Crude lipid content increased from 2.04-2.74% (control) to 2.27-3.10% (HPT). HPT samples showed higher values of total free sugar and glucose content than those of the control. The total amino acid value was not significant, but the essential amino acid content increased from 0.45-5.09 mg/g in the control to 1.57-5.30 mg/g in the HPT sample. The major fatty acids were found to be palmitic, oleic, and linoleic acid. The content of oleic acid decreases with HPT, whereas that of linoleic and linolenic acid increased slightly during the initial stages of germination. These results suggest that HPT after germination efficiently depolymerizes chemical components and enhances the content of essential nutrients.

The Enzyme Inhibitory Activity of Ethanol Extracts Derived from Germinated Rough Rice (Oryza sativar L.) Treated by High Pressure

Department of Food and Nutrition, Daejeon Health Sciences CollegeAbstract We evaluated the enzyme inhibitory activity of germinated rough rice (Oryza sativar L.) treated by highpressure (30 MPa) for 24 h (HP24) and 48 h (HP48). In rice germinated for 1 day, the α-glucosidase inhibitory activityreached its highest level, 68.32%, at HP48. The α-amylase inhibitory activity increased from 32.66-57.00% at HP0, to43.67-74.82% at HP48. On the other hand, the inhibitory activity of angiotensin-converting enzyme increased from 27.98%to 49.42% over the course of the second day of HP48. The inhibitory activity of xanthine oxidase peaked of 67.51% atHP48 and subsequently decreased. Lipase inhibitory activity increased from 24.04-47.91% at HP0, to 29.62-64.63% atHP48. These results provide useful information for the use of germinated rough rice as a functional food material anddemonstrate that high-pressure treatment during the germination process efficiently increase enzyme inhibitory activity.Keywords: rough rice, germination, high-pressure treatment, enzyme inhibitory activity

Development and Interlaboratory Validation of an Analytical Method for the Determination of Saflufenacil in Agricultural Products by HPLC-UVD and LC-MS

Saflufenacil is a low-volatile and uracil-based herbicide. This herbicide is used for pre-and post- emergence control of major broadleaf weeds. The objective of present study was to develop and validate an analytical method for saflufenacil determination in agricultural products for ensuring the food safety. The saflufenacil residues in samples were extracted with acetone, dichloromethane, and then purified with silica and graphitized carbon car- tridge. The purified samples were analyzed by HPLC-UVD and confirmed with LC-MS. The linear range of saflufenacil was 0.1~5.0 µ gm L �1 with the correlation coefficient (r) = 0.999. Average recoveries of saflufenacil ranged from 80.5% to 110.2% at the spiked level of 0.02~0.5 mg kg �1 , while the relative standard deviation was 0.3~7.3%. In addition, the limit of detection and limit of quantification were 0.005 and 0.02 mg L �1 , respectively. Furthermore, an interlaboratory study among three labs was conducted to validate the method, and the results were satisfactory.

Development and validation of an analytical method for fungicide fenpyrazamine determination in agricultural products by HPLC-UVD

Fenpyrazamine which is a pyrazole fungicide class for controlling gray mold, sclerotinia rot, and Monilinia in grapevines, stone fruit trees, and vegetables has been registered in republic of Korea in 2013 and the maximum residue limits of fenpyrazamine is set to grape, peach, and mandarin as 5.0, 2.0, and 2.0 mg/ kg, respectively. Very reliable and sensitive analytical method for determination of fenpyrazamine residues is required for ensuring the food safety in agricultural products. Fenpyrazamine residues in samples were extracted with acetonitrile, partitioned with dichloromethane, and then purified with silica-SPE cartridge and eluted with hexane and acetone mixture. The purified samples were determined by HPLC-UVD and confirmed with LC- MS and quantified using external standard method. Linear range of fenpyrazamine was between 0.1~5.0 µg/mL with the correlation coefficient (r) 0.999. The average recovery ranged from 71.8 to 102.7% at the spiked level of 0.05, 0.5, and 5.0 mg/kg, while the relative standard deviation was between 0.1 and 7.3%. In addition, limit of detection and limit of quantitation were 0.01 and 0.05 mg/L, respectively. The results revealed that the developed and validated analytical method is possible for fenpyrazamine determination in agricultural product samples and will be used as an official analytical method.

Development of an Analytical Method for Chloropicrin Determination in Hulled Rice by GC-ECD and GC-MS

ABSTRACT - A simple and sensitive analytical method was developed using gas chromatograph with electroncapture detector (GC-ECD) and gas chromatograph-mass spectrometer (GC-MS) for determination and identificationof chloropicrin. Because of small molecular weight and high volatile properties of chloropicrin, analytical method wasdeveloped utilizing headspace extraction and direct injection to the GC. The developed method was validated usinghulled rice sample spiked with chloropicrin at different concentration levels, 0.1 and 0.5 mg/kg. Average recoveriesof chloropicrin (using each concentration three replicates) ranged 77.7~79.3% with relative standard deviations lessthan 10% and calibration solutions concentration in the range 0.005~0.5 µ g/mL, and limit of detection (LOD) andlimit of quantification (LOQ) were 0.004 and 0.01 mg/kg, respectively. The result showed that developed analyticalmethods was successfully applied to detect a small amount of chloropicrin in hulled rice.Key words: chloropicrin, headspace extraction, hulled rice, GC-ECD, GC-MS

Development and Validation of an Analytical Method for Tridemorph Determination in Tea Samples by Liquid Chromatograph-Electrospray Ionization-Tandem Mass Spectrometry

Tridemorph is a systemic morpholine fungicide for crops. The objective of this study was to develop reliable and sensitive analytical method for determination of tridemorph residues in tea samples for ensuring the food safety. Tridemorph residues in samples were extracted with acetonitrile after hydration, partitioned with saline water, and then purified using an aminopropyl (NH2) SPE cartridge. The purified samples were detected and quantified using LC-ESI-MS/MS. The linear detection limits for tridemorph ranged from 0.02 to 1.0 mg L �1 with a correlation coefficient of 0.9999. The method was validated using tea samples spiked with tridemorph at different con- centration levels (0.02 and 0.05 µ gm L �1 ). The average recovery ranged between 75.0 and 84.7% with relative standard deviations less than 10%. The LOD and LOQ were 0.01 and 0.02 mg L �1 , respectively. The developed method was applied successfully to the identification of tridemorph in real tea samples obtained from different sources, and tride- morph was not detected in any of the samples. The results show that the developed analytical method is accurate and suitable for tridemorph determination in tea samples.

Development of an Analytical Method for Fluxapyroxad Determination in Agricultural Commodities by HPLC-UVD

Fluxapyroxad is classified as carboxamide fungicide that inhibits succinate dehydrogenase in com- plex II of mitochondrial respiratory chain, which results in inhibition of mycelial growth within the fungus target spe- cies. This study was carried out to assure the safety of fluxapyroxad residues in agricultural products by developing an official analytical method. A new, reliable analytical method was developed and validated using High Performance liquid Chromatograph- UV/visible detector (HPLC-UVD) for the determination of fluxapyroxad residues. The flux- apyroxad residues in samples were extracted with acetonitrile, partitioned with dichloromethane, and then purified with silica solid phase extraction (SPE) cartridge. Correlation coefficient(R 2 ) of fluxapyroxad standard solution was 0.9999. The method was validated using apple, pear, peanut, pepper, hulled rice, potato, and soybean spiked with flux- apyroxad at 0.05 and 0.5 mg/kg. Average recoveries were 80.6~114.0% with relative standard deviation less than 10%, and limit of detection (LOD) and limit of quantification (LOQ) were 0.01 and 0.05 mg/kg, respectively. All val- idation parameters were followed with Codex guideline (CAC/GL 40). LC-MS (Liquid Chromatograph-Mass Spec- trometer) was also applied to confirm the analytical method. Base on these results, this method was found to be appropriate fluxapyroxad residue determination and can be used as the official method of analysis.