• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.227-234
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• 2019

An analytical method was developed for the determination of oxytetracycline in agricultural products using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method by liquid chromatography-tandem mass spectrometry (LC-MS/MS). After the samples were extracted with methanol, the extracts were adjusted to pH 4 by formic acid and sodium chloride was added to remove water. Dispersive solid phase extraction (d-SPE) cleanup was carried out using $MgSO_4$ (anhydrous magnesium sulfate), PSA (primary secondary amine), $C_{18}$ (octadecyl) and GCB (graphitized carbon black). The analytes were quantified and confirmed with LC-MS/MS using ESI (electrospray ionization) in positive ion MRM (multiple reaction monitoring) mode. The matrix-matched calibration curves were constructed using six levels ($0.001{\sim}0.25{\mu}g/mL$) and coefficient of determination ($r^2$) was above 0.99. Recovery results at three concentrations (LOQ, $10{\times}LOQ$, and $50{\times}LOQ$, n=5) were from 80.0 to 108.2% with relative standard deviations (RSDs) less than of 11.4%. For inter-laboratory validation, the average recovery was in the range of 83.5~103.2% and the coefficient of variation (CV) was below 14.1%. All results satisfied the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and the Food Safety Evaluation Department guidelines (2016). The proposed analytical method was accurate, effective and sensitive for oxytetracycline determination in agricultural commodities. This study could be useful for safety management of oxytetracycline residues in agricultural products.

• Journal of Food Hygiene and Safety
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• v.34 no.2
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• pp.124-134
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• 2019

An analytical method was developed for the determination of broflanilide and its metabolites in agricultural products. Sample preparation was conducted using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method and LC-MS/MS (liquid chromatograph-tandem mass spectrometer). The analytes were extracted with acetonitrile and cleaned up using d-SPE (dispersive solid phase extraction) sorbents such as anhydrous magnesium sulfate, primary secondary amine (PSA) and octadecyl ($C_{18}$). The limit of detection (LOD) and quantification (LOQ) were 0.004 and 0.01 mg/kg, respectively. The recovery results for broflanilide, DM-8007 and S(PFP-OH)-8007 ranged between 90.7 to 113.7%, 88.2 to 109.7% and 79.8 to 97.8% at different concentration levels (LOQ, 10LOQ, 50LOQ) with relative standard deviation (RSD) less than 8.8%. The inter-laboratory study recovery results for broflanilide and DM-8007 and S (PFP-OH)-8007 ranged between 86.3 to 109.1%, 87.8 to 109.7% and 78.8 to 102.1%, and RSD values were also below 21%. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and the Food and Drug Safety Evaluation guidelines (2016). Therefore, the proposed analytical method was accurate, effective and sensitive for broflanilide determination in agricultural commodities.

• Korean Journal of Organic Agriculture
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• v.10 no.3
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• pp.41-55
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• 2002

In order to evaluate the effects of functional composts which include elvan, jade and loess, the growth and the yield of Chinese Cabbage and its content of sugar, nitrate and vitamin C were analysed. This study was conducted in lysimeter which was installed in the Experimental Farm of Dankook University. Total fresh weights of Chinese Cabbage were higher in the treatments of compost with mixture of elvan, jade and loess, while numbers of leaf was not increased in those treatments compared to control plot. Leaf length increased more than leaf width, specially in the evlan treatment. Fresh weight of leaf blade and midrib in outer leaf was highest in the plot of elvan treatment among the 6 treatments. Sugar content in the Chinese Cabbage showed lower in the treatment of compost with mixture of elvan, jade and loess compared to control plot. Vitamin content was high in leaf blade compare to those in midrib, and it showed highest value in the treatment of compost with mixture of jade. Nitrate concentration of leaf blade and midrib in the treatment of compost with mixture of loess was lowest at 2,021ppm and 2,235ppm respectively. It shows the effective function of mixture compost with jade, loess and elvan to decrease nitrate content in the Chinese Cabbage.

• Journal of Food Hygiene and Safety
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• v.28 no.1
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• pp.1-6
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• 2013

Ten commercially available red pepper powders were investigated for their hygienic quality (total aerobic count, yeasts and molds, and coliforms) and physicochemical properties (moisture content, pH, Hunter's color values, American Spice Trade Association (ASTA) color and particle size). Microbial analysis resulted in $10^3-10^6$ CFU/g of total aerobic count and same of yeasts & molds, where 2 samples were positive ($10^3$ CFU/g) for coliforms. The moisture contents (7.25% to 12.73%) were with in the range as described in the Korean Food Standards Codex. Noteworthy variations were observed in pH (4.97 to 5.15), Hunter's ${\Delta}E$ values (47.19 to 58.04) and ASTA color values (89.31 to 98.61). Although the color differences were evident among the samples, but the Hunter values were not in good correlations with ASTA color values. The average particle sizes of the all samples were comparable ranging from $605{\mu}m$ to $1251{\mu}m$ with few exceptions. There was a great variation in the key quality attributes of commercially available red pepper powders that should be considered for their various uses in food products.

• Journal of Applied Biological Chemistry
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• v.59 no.3
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• pp.189-201
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• 2016

A processing factor (PF) has been used to define the maximum residue limits of pesticide in a variety of processed fruit products. This study summarizes PF by the stage of fruit processing based on JMPR reports from 2010 to 2014. When we compared PF of 19 pesticides in apple products during the processing of washing, drying, canning, juice, sauce, puree and pomace, PF was higher than 1 only in pomace. In the comparison of 21 pesticides during the process of grape (washing, juice, wine and raisin), PF was higher than 1 in raisin. In the comparison of 19 pesticides during the process of orange (juice, oil and marmalade), PF was higher than 1 in oil. When 27 pesticides were compared during the process of tomato (juice, puree and paste), paste showed the highest PF value except pomace. During the process of plum (washing, drying and puree) with 12 pesticides, PF was higher than 1 in drying. The correlation coefficients between physical characteristics of pesticide (fat-solubility and volatility) and PF were statistically significant in the processes of apple juice, orange juice, tomato puree and paste and strawberry jam.

• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.519-525
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• 2019

The Ministry of Food and Drug Safety (MFDS) is amending its test methods for health functional foods (dietary food supplements) to establish regulatory standards and specifications in Korea. In this regard, we are continuing our research on analytical method development for the items listed in the Korean Health Functional Food Codex. In this study, we have developed a sensitive and selective test method that could simultaneously separate and determine coenzyme Q10 based on liquid chromatographic-tandem mass spectrometry (LC-MS/MS). Calibration curves showed linearity with a correlation coefficient (R²) of > 0.999 and the limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 26.0 ㎍/L and 78.9 ㎍/L, respectively. The recovery results ranged between 98.6-107.0% at 3 different concentration levels with relative standard deviations (RSDs) less than 5%. The proposed analytical method was characterized with high resolution of the coenzyme Q10 and the assay was fully validated as well.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.11
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• pp.1417-1424
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• 2007

The food components of fish (skipjack tuna, yellowfin tuna, bluefin tuna, conger eel, salmon, Spanish mackerel, armored weasel-fish) frames and their hot-water extracts were investigated to explore their possibilities as resources for fish Gomatang. According to the results of volatile basic nitrogen and heavy metal, bluefin tuna and salmon frames were below the safety limits suggested by Codex Code. Thus, bluefin tuna and salmon frames appeared to be safe as basic ingredients for fish Gomtang. The major components of all hot-water extracts from fish frames were nitrogenous component. According to the results of extractive nitrogen and sensory evaluations of hot-water extracts from fish frames, the salmon frame was a good raw material as a basic ingredient of fish Gomtang. The calcium and phosphorus contents of hot-water extracts from salmon frame were 18.0 mg/100mL and 33.1 mg/100mL, respectively.

• Analytical Science and Technology
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• v.25 no.6
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• pp.364-369
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• 2012

Isotianil is a novel fungicide which induces systemic acquired resistance in plants. It has excellent preventive effects as low dosages against rice blast which is one of the most serious diseases in rice. The Maximum Residue Limit (MRL) of Isotianil in republic of korea was set to 0.1 mg/kg in rice, so it is necessary to determine levels of Isotianil residues in agricultural commodities for controlling food safety. Therefore, The purpose of this study was to develop analytical method for the determination of isotiical residues in agricultural commodities using GC-NPD/MSD. Isotianil was extracted with acetonitrile from apple, chinese cabbage, hulled rice, mandarin, pepper, and soybean. The extract was diluted with saline water, and then dichloromethane partition was followed to recover this fungcide from the aqueous phase. A solid phase extraction with Florisil cartridge was additionally employed for final clean up. Isotianil was analyzed and quantitated by GC-NPD and confirmed by GC-MSD. Average recovery of Isotianil ranged from 70.0 to 103.9% in six representative agricultural commodities with relative standard deviations less than 10%, and limit of quantification (LOQ) was 0.05 mg/kg.

• Journal of Food Hygiene and Safety
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• v.31 no.5
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• pp.319-326
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• 2016

Colistin is a last resort antimicrobial agent against multi-drug resistant Gram-negative bacteria. This study was conducted to develop an analytical method to determine colistin in fish and shrimp. The analytes were confirmed and quantified via liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the positive ion mode using multiple reaction monitoring (MRM). The sample was extracted with acidified 5% methanol (containing 0.5% formic acid). Then, solid phase extraction (SPE) was used for cleanup. Matrix-matched calibration curves were linear over the calibration ranges (0.05-1.2 mg/kg) for all the analytes into blank sample with $r^2$ > 0.99. All the values fulfilled the criteria requested by the Codex guidelines. Average recoveries ranged from 85.9% to 107.9%. The repeatability of measurements, expressed as the coefficient of variation (CV, %), was less than 15%. The limit of detection (LOD) was 0.02 mg/kg, and the limit of quantitation (LOQ) was 0.05 mg/kg. This improved method showed higher accuracy and acceptable sensitivity to meet the CAC guideline requirements and is applicable for the analysis of residual colistin (A+B) in fish and shrimp.

• Journal of Food Hygiene and Safety
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• v.33 no.1
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• pp.65-70
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• 2018

Monitoring of Listeria monocytogenes, the causative agent of listeriosis, in food is inportant for public health. The Korean Food Standards Codex has adopted a 'zero-tolerance' policy for L. monocytogenes. The standard detection method of L. monocytogenes is based on enrichment. Thus, proper enrichment methods need to be instituted to ensure quality control of the detection procedures. In this study, the growth of L. monocytogenes and Listeria innocua as a mixed culture in Listeria enrichment broth (LEB) was monitored during artificial contamination of enrichment culture. We confirmed competitive growth or interspecies inhibitory activity of L. monocytogenes and L. innocua. Interspecies growth differences and the inhibitory activity of different inoculation and mixtures L. innocua against L. monocytogenes were examined. The concentration of L. monocytogenes must be 2.0 log CFU/mL or more than L. innocua to grow better than L. innocua. It is known that Listeria spp. and L. monocytogenes show growth difference during LEB, resulting in the risk of false-negative results. The inhibition of L. monocytogenes by L. innocua was always observed when present at lower concentrations. However, it was confirmed that L. innocua suppressed when L. monocytogenes was present at a higher concentration. Therefore if a mixture of Listeria spp. is present, detecting L. monocytogenes is difficult. Thus, a new enrichment broth to improve the detection rate of L. monocytogenes is needed.