Kyeong-Hun Park

Biological Hazard Analysis of Angelica gigas Nakai on Production and Marketing Steps

This study is aimed to investigate microbiological contamination of Angelica gigas Nakai. A total of 111 samples including root, soil, and irrigation water were collected from farms and market to detect aerobic bacteria, Bacillus cereus, coliform, Escherichia coli, Listeria monocytogenes,. Salmonella spp., and Staphylococcus aureus. The contaminations of aerobic bacteria, coliform, and Bacillus cereus in the root during cultivation were found 6.71 log CFU , 4.13 log CFU , and 3.54 log CFU , respectively. The contamination of coliform and B. cereus were detected in all steps from harvesting to processing, with the highest count recorded from the cutting step. In marketing, the contaminations of aerobic bacterial, coliform, and B. cereus were 5.5~6.0 log CFU , 2.4~2.6 log CFU , and 3.5~4.0 log CFU , respectively. Listeria monocytogenes, Salmonella spp, and Staphylococcus aureus were not detected in any of samples. This result indicated that hygienic soil management and post harvest management should be performed to reduce the contamination of hazard microorganisms and to produce safe agro-products.

Investigation of Microbial Contamination Levels of Leafy Greens and Its Distributing Conditions at Different Time - Focused on Perilla leaf and Lettuce -

The objective of this study was to investigate and evaluate microbial contamination levels of leafy greens (perilla leaf and lettuce) and its distributing conditions at different seasons (Feb, May, Aug, and Nov of the year 2011) in order to provide insight into any potential health hazards associated with consumption of these commodities. Leafy greens were collected from a farm located in Geumsan, Chungnam and wholesale markets (WM) and traditional markets (TM) located in Suwon. At the same time, temperature and relative humidity fluctuations experienced by the leafy greens during distribution from the farm to the distribution center were measured by a data logger. The contam- ination levels of perilla leaf and lettuce were determined by analyzing total plate count. Coliform groups, Bacillus cereus, Escherichia coli, Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes and Staphylococcus aureus were determined. The contamination levels of total aerobic bacteria, coliform groups and B. cereus in both vegetables sampled during May and August found to be higher than those sampled during February and November. E. coli O157:H7, Salmonella spp., L. monocytogenes were not detected in the vegetables analyzed in this study. There were no significant trends between samples at WM and TM in the contamination levels. Relative humidity of vegeta- bles distributed from the farm to the distribution center showed over 90% during distribution regardless of measured seasons. In the case of background microflora on leafy greens, the density was significantly increased at 20, 30 and 37 o C during storage of 24h. E. coli O157:H7 and B. cereus inoculated on the leaves also showed similar increases in the storage tests. The microbial contamination levels determined in this study may be used as the fundamental data for microbial risk assessment.

Survey of Microbial Contamination of Tomatoes at Farms in Korea

This study investigated and evaluated contamination levels of bacteria on tomatoes at farms stage to evaluate potential hazards associated with fresh tomatoes. A total of 170 samples, 90 samples from 5 sampling sites from 18 farms and 80 samples from 1 sampling site from 4 farms every month for four months, were analyzed to enu- merate aerobic bacterial counts, coliforms, E. coli, Bacillus cereus, Staphylococcus aureus, Escherichia coli, E. coli O157:H7, Salmonella spp., and Listeria monocytogenes. Aerobic bacterial counts ranged from 0.48 to 6.15 Log CFU/ g, with the lowest and the highest bacterial cell counts recorded for A site and E site, respectively. Thirty five percent of the samples from the E site contained more than 2 Log CFU/g. Six samples (6.6%) of 90 samples contained B. cereus less than 1 Log CFU/g. In addition, the contamination level of indicator bacteria and B. cereus in tomatoes were higher on March than on April, May and June (P < 0.05). S. aureus, E. coli, E. coli O157:H7, Salmonella spp. and L. monocytogenes were not detected in the tomato samples. The microbial contamination levels of tomatoes deter- mined in this study may be used as the data for microbiological risk assessment.

Analyses of Microbiological Contamination in Cultivation and Distrubution Stage of Tomato and Evaluation of Microbial Growth in Tomato Extract

This study investigated the microbiological contamination of tomato in cultivation and distribution stage. Growth of Escherichia coli O157:H7 and Listeria monocytogens examined in tomato extracts (0.1, 1.0, and 10.0%) and incubation temperatures (5, 15, 25, and 35 o C). In cultivation stage of tomato, total aerobic bacteria were 7.77 log CFU/g in gloves of APC (Agricultural Products Processing Center) worker and Bacillus cereus were 0.33 log CFU/g at nutrient tank, respectively. And Staphylococcus aureus, Salmonella spp., were not detected. After APC stage, total aerobic bacteria were significantly higher compared with before-APC stage. Among of general, pes- ticide-free and organic produce in tomato were no significant difference in microbial contamination. Coliforms of tomato in small vinyl package were significantly higher when compared to tomato in whole boxes package. There was no significant difference in bacteria count between unwashed tomato and washed tomato using tap water for one minute. The growth of E. coli O157:H7 and L. monocytogens in tomato extracts were decreased significantly as the concentration increased, and the microbial population was reached the lowest point during storage in 10% tomato extracts concentration for 72h at 5 o C. However, the population of E. coli O157:H7 and L. monocytogens were gradu- ally increased at 7.33~8.51 and 7.73~8.60 log CFU/ml during storage at 15~35 o C for 72h, respectively.

Monitoring of Pathogenic Bacteria in Organic Vegetables from Korean Market

This study was undertaken to assess the microbiological quality and prevalence of pathogens in organic vegetables produced in Korea. A total of 189 organically grown vegetable samples (perilla leaf 50, lettuce 50, tomato 39, cucumber 50) were analyzed for the presence of aerobic plate count, Escherichia coli O157:H7, Salmonella spp., Staphylococcus aureus, Listeria monocytogenes, and Yersinia enterocolitica. The total aerobic plate counts were in the range of 4.2 to for perilla leaf, 5.0 to for lettuce, 4.0 to for tomato, and 6.6 to for cucumber. The highest counts were found in cucumber. E. coli O157:H7, Salmonella spp., S. aureus, L. monocytogenes, and Y. enterocolitica were not detected from any organically grown vegetable samples. This research suggests that continuous monitoring in organic vegetables is required to improve fresh produce safety.

Effects of LED Treatment on Microbial Reduction and Quality Characteristics of Red Pepper Powder

This study investigated reduction of microbial population, water soluble pigment, capsanthin con- tent, surface color (Hunter L, a, b, ∆E), and sensory properties of pepper powder by LED (red, yellow, blue, green) treatments. LED (red, yellow, blue, green) treatment were conducted in 1,000 lux storage at 25 o C for 10 days. The total aerobic bacteria was no significant difference among the control and treated with LED during 10 days. In yellow LED treatment, yeast and molds were decreased about 1.76 log. Surface color such as lightness (L), redness (a), yel- lowness (b) were showed a decreasing tendency as the storage period. In the overall color difference (∆E) of yellow LED treatment was lower less than 3.0. Water soluble pigment was no difference in control and LED treated samples during storage period. Capsanthin content was significantly decreased as storage period was increased, but no signif- icant differences were observed among red and yellow LED treatments. Sensory properties of control was signifi- cantly reduced by storage period but yellow and green LED treatments were no significantly differences.

Evaluation of Selective Media for Isolation of Staphylococcus aureus from Agricultural Products

Five kinds of selective media, such as mannitol salt agar (MSA), Baird-Parker agar (BPA), Baird- Parker supplemented with rabbit plasma fibrinogen (BPA+RPF), CHROMagar Staphylococcus aureus (CSA), and Petrifilm Staph Express count system (Petrifilm), were compared to recommend the optimum selective media for iso- lation of Staphylococcus aureus from agricultural products. Seventy four target and non target bacteria were inocu- lated on five selective media to analyze sensitivity and specificity. In the recovery test of injured S. aureus cells, S. aureus was exposed to acid (1% lactic acid for 10 min), heat (60 o C for 90s), and cold (�20 o C for 1h) conditions. And artificially contaminated agricultural products (iceberg lettuce, green pepper, and cherry tomato) was enumerated on five selective media. The sensitivity of BPA+RPF, CSA, Petrifilm, MSA, and BPA were 100%, 100%, 100%, 90.5%, 90.5%, respectively. In addition, the specificity of BPA+RPF, CSA, MSA, BPA and Petrifilm were 100%, 100%, 84.6%, 75.0%, 67.3%, respectively. However, no difference among five selective media was observed in recovery on injured S. aureus cell and enumeration from agricultural products. This results suggest that BPA+RPF and CSA are the optimum media for detection of S. aureus from agricultural products.

The Monitoring of Agricultural Environment in Daegwallyeong Area

In order to provide the basic information on the agricultural environment in Daegwallyeong Highland, the characters of weather, water, and soil quality were investigated. The meteorological characteristics was monitored by automatic weather system (AWS) at 17 sites. The quality of water for samples were collected monthly at 24 sites depending on landuse style. Soil samples were collected from a forest, grassland, and the major vegetable cultivation areas such as potato, carrot, Chinese cabbage, onion, head lettuce, and welsh onion field. The weather showed the mountain climate, and the average yearly temperature is 6.4℃, the average temperature in January is -7.6℃ and the average temperature in July is 19.1℃, and the change of temperature on the districts of Daegwallyeong is severe. The yearly record of precipitation shows 1717.2 mm. The water quality of crop field was worse than forest or grassland in Daewallyeong highland. In 2005, annual T-N, T-P, SS distribution of Chinese cabbage field showed 7.4~11.3, 0.061~0.1, and 3.0~53.0 mg L -1 . The potato field showed 3.1~7.2 , 0.019~0.056 and 0.5~3.0 mg L -1 , respectively. Being compared of water quality between potato field and chinese cabbage field, it showed that the water quality of Chinese cabbage field was worse than potato field. On farming, the soil of crop cultivation showed pH 5.6 to 6.8, 18.0~42.4 g kg -1 of OM, 316~658 mg kg -1 of Avail. P2O5. The content of cations showed 0.41~0.88 cmolc kg -1 of Exch. K, 3.73~7.07 cmolc kg -1 of Exch. Ca and 1.17~1.90 cmolc kg -1 of Exch. Mg.

Characteristics of Water Quality at Main Streams and Lake Doam in Daegwallyeong Area

This study was surveyed that water physiochemical characteristics and phytoplankton incidence of main stream and Lake Doam near to Daegwallyeong agricultural area. Based on above results, it was conducted to get information overall water characteristics in south Han upstream river. COD value of Lake Doam was and T-P (Total phosphorous) from there was which was higher than the value of grade VI based on lake water living environment standard. Suspended solid was an average of 9.77 NTU which was higher than value of lake living standard. Concentration of phytoplankton was over from July to September. It was considered that cyanobacteria were occurred due to massive influx of nutrient material by high temperature and rainfall during this season. Compare to Ontarios sediment quality guidelines, T-N and T-P was middle value between LEL and SEL in Lake Doam. This value means that contamination in water is serious. Therefore, it is considered that systematic management was needed to reduce and block contamination source.

Gray Mold on Carrot Caused by Botrytis cinerea in Korea

Gray mold caused by Botrytis cinerea was found on a carrot seedling in a greenhouse and a field at Daegwallryeong, Gangwon Province in 2007-2009. Symptoms included irregular, brown, blight, or chlorotic halo on leaves and petioles of the carrots. Fungal conidia were globose to subglobose or ellipsoid, hyaline or pale brown, nonseptate, one celled, () in size, and were formed on botryose heads. B. cinerea colonies were hyaline on PDA, and then turned gray and later changed dark gray or brown when spores appeared. The fungal growth stopped at , temperature range for proper growth was on MEA and PDA. Carrots inoculated with ml conidial suspension were incubated in a moist chamber at for pathogenicity testing. Symptoms included irregular, brown, water-soaked rot on carrot roots and irregular, pale brown or dark brown, water-soaked rot on leaves. Symptoms were similar to the original symptoms under natural conditions. The pathogen was reisolated from diseased leaves, sliced roots, and whole roots after inoculation. As a result, this is the first report of carrot gray mold caused by B. cinerea in Korea.