• Korean Journal of Food Science and Technology
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• v.50 no.3
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• pp.274-279
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• 2018

To evaluate the antioxidant activities of Korean and Chinese Torreya seeds, their total phenolic compound content, total flavonoid content, DPPH radical and ONOO-scavenging activities were compared using their water and methanol extracts. The effective compounds were identified and quantitatively analyzed by GC-MS. The DPPH and ONOO-scavenging activities were the highest in the Korean Torreya seeds. After using GC-MS to identify the active compounds, a total of eight compounds were identified in Korean Torreya seeds, and five compounds were found in Chinese Torreya seeds. In conclusion, we could confirm the antioxidant activity and the difference between active compounds of the Korean and Chinese Torreya seeds; we also confirmed the superiority of Korean Torreya seeds. Futhermore, this basic data about the Korean and Chinese Torreya seeds can be provided to consumers, so that they can select proper and suitable functional foods.

• Korean Journal of Food Science and Technology
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• v.50 no.3
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• pp.331-338
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• 2018

The purpose of this study was to determine the optimum sterilization conditions for the production of retorted steamed egg using response surface methodology. Sterilization processes for eighteen conditions using varying sterilization temperature ($X_1$), time ($X_2$), and method ($X_3$) as the independent variables were carried out through a $3^2{\times}2$ experimental factorial design. Quality evaluations after sterilization included measurements of $F_0$ value ($Y_1$), peak stress ($Y_2$), pH ($Y_3$), color value ($Y_{4-6}$), and organoleptic test [preference for appearance ($Y_7$), overall acceptability ($Y_8$), and preference for texture ($Y_9$) and egg taste ($Y_{10}$)]. Dependent variables ($Y_{1-10}$) of eighteen conditions were more affected by temperature and time than by the sterilization method. Eight factors were selected among the dependent variables as significant factors related to the quality of the steamed egg. Finally, by establishing an optimum range of each dependent variable and contour analysis, the optimum sterilization conditions for the production of steamed egg were determined to be $120^{\circ}C$ for 25 min using a 2-step sterilization process.

• Horticultural Science & Technology
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• v.33 no.1
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• pp.47-54
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• 2015

This research was conducted to investigate the changes in moisture retention capacities of expanded rice-hull (ERH)-based root media and their influences on the growth of mother and daughter plants in vegetative propagation of 'Seolhyang' strawberry. The proportion of water at the container capacity of ERH medium was in the range of 20 to 23%. This range was lower than the 60 to 66% of strawberry-specialized medium, the 30 to 34% of soil mother material (SMM) and the 30 to 35% of loamy sand. The moisture content of ERH was reduced to 10 to 12% at 8 hours after irrigation, and there were large variations among replications of ERH medium. Among four kinds of root media formulated to contain ERH, the medium of ERH + coir dust (CD) (55 + 45%, v/v) had 26.5 and 32.5% water contents at 20 and 40 days after irrigation to daughter plants, respectively. The m edia o f ERH + sandy loam (S L) and E RH + S MM showed similar trends i n moisture r etention. The pH and EC i n the all root media tested were in the range of 6.7 to 7.1 and 0.03 to $0.08dS{\cdot}m^{-1}$, respectively. The pHs and ECs measured at 20 and 40 days after irrigation were not significantly different in each root medium. Among the root media formulated to contain ERH, the growth of daughter plants was the highest in the treatment of ERH + SL (55 + 45%, v/v). As the blending rate of coir dust was elevated in the ERH + CD media, moisture retention capacity increased gradually, but the growth of daughter plants became worse even though the medium showed higher moisture retention capacity than other root media tested. The growth of roots and aboveground tissues of daughter plants deteriorated in the root media formulated by blending ERH + perlite (PE) at various ratios. The results of this research suggest the optimum formulations of root media and management of moisture content in raising of strawberry daughter plants when ERH is a component of root media.

• Horticultural Science & Technology
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• v.34 no.1
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• pp.195-205
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• 2016

Sugar beet cyst nematode, Heterodera schachtii, causes serious economic losses worldwide in Brassicaceae crops. In 2011, this nematode was first found in highland vegetable cultivation areas in Korea, and thereafter spread to the surrounding healthy Chinese cabbage fields. However, little has been documented on the biological and ecological characteristics of the sugar beet nematode in highland vegetable cultivation areas. In this study the dispersal of the sugar beet cyst nematode was examined, focusing on spreading through soil and/or water infested with the nematode. When farmers with work boots trampled on Chinese cabbage fields for 10 minutes, the number of cysts recovered from the soil attached to the working differed depending on the research sites. Under irrigation conditions of 2, 4, and 8 liters of water per $m^2$, the amounts of soils attached on the bottom of the work boots and the number of healthy cysts in the soils increased significantly with the increase in soil moisture, although the total number of cysts, eggs, and juveniles did not increase significantly. After driving on the farm road adjacent to cabbage fields infested with the sugar beet cyst nematode, cysts were also recovered from the soil attached to the vehicle's tires, suggesting that the sugar beet cyst nematode can spread to new fields through soil carried by vehicles and by farmers. An excavator and a motor truck could deliver 41 kg and 224 g, respectively, of soil on the shovel shoes and the wheels to other locations during the Chinese cabbage harvest, suggesting that farming equipment and transportation vehicles may be vital means by which the cyst nematode spreads to non-infested fields in the highland area of Korea. Runoff water also contained cysts, whose amounts increased after water irrigation onto the ridges to simulate rainy conditions, with no significant difference in the number of cysts with increasing amounts of irrigation water. All of these results confirmed that the sugar beet cyst nematode spreads through soil attached to work boots, harvesting tools, and transportation vehicles, especially during the harvest time, and through runoff water on rainy days. These observations suggest that personal sanitization and cleaning of working tools and vehicles are one of the most important means to prevent the dispersal of the sugar beet cyst nematode in fields.

• Journal of Food Hygiene and Safety
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• v.29 no.1
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• pp.1-5
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• 2014

Many community gardens in large cities worldwide grow vegetables; however, no information regarding the levels of sanitary indicator bacteria and prevalence of foodborne pathogens in vegetables grown in urban community gardens is available. To evaluate the microbiological quality of vegetables from urban community gardens in Korea, 530 samples (nine types of vegetable, including Chinese cabbage, lettuce, radish leaves, spinach, mustard leaves, crown daisy, leek, Korean cabbage, and chicory) were collected at 11 urban community gardens in Seoul, Korea from September through October 2012. The levels of total aerobic bacteria, Escherichia coli, total coliforms, Salmonella spp. Listeria monocytogenes, and E. coli O157:H7 were evaluated quantitatively and/or qualitatively. The mean numbers of total aerobic bacteria and coliforms were 6.3 log CFU/g (range 3.8-8.1 log CFU/g) and 4.3 log CFU/g (range 2.1-6.4 log CFU/g), respectively. Total coliforms were detected on 67% of whole vegetables. Chicory showed the highest number of total aerobic bacteria and coliforms, whereas the lowest number of coliforms was detected on leeks. E. coli was detected on 2.3% of whole vegetables, including lettuce, radish leaves, mustard leaves, and chicory; however, foodborne pathogenic bacteria were not detected on any of the vegetable samples using this highly sensitive and validated procedure. Based on these findings, the presence of coliforms and E. coli demonstrates that opportunity for improvement of microbiological safety exists throughout the produce production chain, although no major foodborne pathogens were present in vegetables grown in urban community gardens.

• Journal of Food Hygiene and Safety
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• v.30 no.3
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• pp.272-280
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• 2015

A simultaneous official method was developed for the determination of phorate and its metabolites (phorate sulfoxide, phorate sulfone, phorate oxon, phorate oxon sulfoxide, phorate oxon sulfone) in livestock samples. The analytes were quantified and confirmed via liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). Phorate and its metabolites were extracted from beef and milk samples with acidified acetonitrile (containing 1% acetic acid) and partitioned with anhydrous magnesium sulfate. Then, the extract was purified through primary secondary amine (PSA) and C18 dispersive sorbent. Matrix matched calibration curves were linear over the calibration ranges (0.005-0.5 mg/L) for all the analytes into blank extract with $r^2$ > 0.996. For validation purposes, recovery studies were carried out at three different concentration levels (beef 0.004, 0.04 and 0.2 mg/kg; milk 0.008, 0.04 and 0.2 mg/kg, n = 5). The recoveries were within 79.2-113.9% with relative standard deviations (RSDs) less than 19.2% for all analytes. All values were consistent with the criteria ranges requested in the Codex guidelines. The limit of quantification was quite lower than the maximum residue limit (MRL) set by the Ministry of Food and Drug Safety (0.05 mg/kg). The proposed analytical method was accurate, effective and sensitive for phorate and its metabolites determination and it will be used to as an official analytical method in Korea.

• Journal of Food Hygiene and Safety
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• v.27 no.4
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• pp.432-441
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• 2012

In this study, the transfer rate of wild type Listeria mon, ytogenes (LM) was investigated to establish the standard of safety management during pork meat pr, essing for meat to meat and meat to food contact surfaces contamination at 5 and $10^{\circ}C$. The transfer rate of LM from meat to meat during the pr, essing increased from 0.02% after 30 min to 0.42% after 120 min at $5^{\circ}C$, while for conveyor belt and stainless steel, it decreased from 0.015% and 0.013% after 30 min to 0.002% and 0.0003% after 120 min at $5^{\circ}C$, respectively (p < 0.05). When temperature increased to $10^{\circ}C$, the transfer rates of LM from meat to meat, conveyor belt and stainless steel were the highest at 60 min exposure, and all decreased after 120 min. In reverse, the transfer rate from food contact surface to pork meat was significantly higher than that from pork meat to food contact surface (p < 0.01). Also, the transfer rate to conveyor belt was significantly higher than stainless steel (p < 0.05) and it was highest at 30 min exposure time in both 5 and $10^{\circ}C$. This study indicates that the transfer and adherence rates of LM are influenced by the contact time and temperature. Consequently, these results were utilized to develop a predictive model with a high level of confidence which can lead to prevent cross-contamination during pork meat processing.

• Journal of Food Hygiene and Safety
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• v.29 no.2
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• pp.131-140
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• 2014

The objective of this study was to develop a simultaneous method of 8 penicillin antibiotics including amoxicillin, ampicillin, cloxacillin, dicloxacillin, nafcillin, oxacillin, penicillin G and penicillin V in meat using LC-MS/MS. The procedure involves solid phase extraction with HLB cartridge and subsequent analysis by LC-MS/MS. To optimize MS analytical condition of 8 compounds, each parameter was established by multiple reaction monitoring in positive ion mode. The chromatographic separation was achieved on a $C_{18}$ column with a mobile phase of 0.05% formic acid and 0.05% formic acid in acetonitrile at a flow rate of 0.2 mL/min for 20 min with a gradient elution. The developed method was validated for specificity, linearity, accuracy and precision in beef, pork and chicken. The recoveries were 71.0~106%, and relative standard deviations (RSD) were 4.0~11.2%. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.003~0.008 mg/kg and 0.01~0.03 mg/kg, respectively, that are below maximum residue limit (MRL) of the penicillins. This study also performed survey of residual penicillin antibiotics for 193 samples of beef, pork and chicken collected from 9 cities in Korea. Penicillins were not found in all the samples except a sample of pork which contained cloxacillin (concentration of 0.08 mg/kg) below the MRL (0.3 mg/kg).

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.260-267
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• 2014

To evaluate microbiological and aflatoxin safety on traditional dried persimmon, a total of 315 samples were collected from 105 farms. The collected samples were assessed on aflatoxin and microorganisms (Aerobic plate count, coliform count, Escherichia coli, Escherichia coli O157:H7, Salmonella spp., Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus). The the APC of sliced dried persimmon, dried persimmon, and semi dried persimmon were $3.93{\pm}0.96$, $2.12{\pm}0.93$, and $1.50{\pm}1.08{\log}\;CFU/g$, respectively. S. aureus was detected in 40.0% of sliced dried persimmon, 29.5% of dried persimmon, and 23.5% of semi dried persimmon. E. coli recovered from dried persimmon and semi dried persimmon was 6.6%, and 2.9%, respectively. However, E. coli O157:H7, Salmonella spp., and L. monocytogenes were not detected. According to the result of aflatoxin by ELISA and UPLC, aflatoxin was not detected in any sample. These data suggested that safety management system should be introduce to the farms producing traditional dried persimmon to enhance the safety of traditional dried persimmon.

• Korean journal of food and cookery science
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• v.25 no.4
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• pp.435-444
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• 2009

In this study, Paeonia japonica powder was extracted with ethanol, and its antimicrobial activity was investigated. The ethanol extract of the P. japonica had antimicrobial activity against Bacillus subtilis, Escherichia coli and Staphylococcus aureus. The inhibition zones of the P. japonica ethanol extract (3 mg/disc) against B. subtilis, E. coli and S. aureus were 10, 11, 8.5 mm, respectively. To test the food preservation effect of P. japonica and determine the optimal ratio of the P. japonica extract in the formulation, Sulgidduk samples were prepared with substitutions of 0, 0.25, 0.5, 0.75 and 1% P. japonica extract, and the quality characteristics of the samples were then investigated over 4 days of storage. In these experiments, total cell counts tended to decrease as the amount of added P. japonica extract increased. Moisture contents were not significantly different among the Sulgidduk samples. As the content of the P. japonica extract increased, the L-values of the samples decreased and the a- and b- values increased. In regards to the textural characteristics, the hardness, gumminess, and chewiness of the Sulgidduk samples decreased as the amount of P. japonica extract increased; however, they increased with the progression of storage time. Adhesiveness, springiness and cohesiveness were not significantly different at the different P. japonica extract concentrations and decreased with storage time. In the sensory evaluation, the control group had significantly higher scores for color, flavor and after taste as compared to the P. japonica extract added groups. When the P. japonica extract content was increased, the flavor and overall acceptability decreased, while Bakjakyak flavor, bitterness and off-flavor increased. Softness was not significantly different among the samples. In conclusion, the results indicate that substituting $0.25{\sim}1%$ P. japonica extract in Sulgidduk is optimal for quality and provides a product with reasonably high overall acceptability.