Contents and Risk Assessment of Heavy Metals in Marine Invertebrates from Korean Coastal Fish Markets

MOK, JONG SOO,KWON, JI YOUNG,SON, KWANG TAE,CHOI, WOO SEOK,KANG, SUNG RIM,HA, NA YOUNG,JO, MI RA,KIM, JI HOE ational Association for Food Protection 2014 Journal of food protection Vol.77 No.6

<P>The concentrations of the heavy metals cadmium (Cd), mercury (Hg), lead (Pb), chromium, silver, nickel, copper, and zinc in the edible portions of 105 marine invertebrates representing 16 mollusk and crustacean species were accurately determined to evaluate their hazard for human consumption. The samples were collected in 2011 from major fish markets on the coast of Korea and analyzed for Hg using a direct Hg analyzer and for other metals using inductively coupled plasma mass spectrometry. Estimated dietary exposure (EDE) was determined, and a risk assessment was made of the heavy metals to provide information concerning consumer safety. The Cd concentrations, which were the highest for the three hazardous metals (Cd, Hg, and Pb), were significantly higher (P &lt; 0.05) in the bivalves and crabs than in the gastropods and cephalopods. However, the concentrations of these metals in all samples were within the regulatory limits set by Korea and other countries. The EDE was compared with the provisional tolerable daily intake (PTDI) adopted by the Joint FAO/WHO Expert Committee on Food Additives or the U.S. Environmental Protection Agency. The EDE of Cd, Hg, and Pb for each class of marine invertebrate were 0.07 to 2.64, 0.01 to 0.43, and 0.001 to 0.16% of the PTDI, respectively. The total EDE of Cd, Hg, and Pb for marine invertebrates accounted for 4.03, 0.96, and 0.21%, respectively, of the PTDI. The EDE of other metals in each class of marine invertebrate was less than 2% of the PTDI. The hazard index is a reasonable parameter for assessing the risk of heavy metal consumption associated with contaminated food. In the present study, the hazard index for all of the species was less than 1.0, which indicates that the intake of heavy metals from consumption of these marine invertebrates does not represent an appreciable hazard to humans.</P>

Reliable and Simple Detection of Ochratoxin and Fumonisin Production in Black Aspergillus

KIM, NAM YEUN,LEE, INHYUNG,JI, GEUN EOG ational Association for Food Protection 2014 Journal of food protection Vol.77 No.4

<P>To date, edible fungi such as black Aspergillus (Aspergillus niger aggregates) have been considered as safe. However, it has recently been reported that some strains have a mycotoxin biosynthetic capability, and this capability must be evaluated to determine the safety of edible fungi. In this study, we assessed the ability of mycotoxin production in A. niger aggregates isolated from various Korean foods using multiplex PCR and high-performance liquid chromatography (HPLC) analyses. Multiplex PCR and HPLC analyses of 32 A. niger aggregates showed that ochratoxin and fumonisin were produced only by strains exhibiting positive PCR patterns with ochratoxin and fumonisin biosynthesis genes. However, several strains did not produce mycotoxins, even though they contained mycotoxin biosynthesis genes. Using multiplex PCR pattern and HPLC analyses, we selected Aspergillus strains that do not produce mycotoxins, which will contribute to the development of safer fermented foods.</P>

Heat Tolerances of Salmonella, Cronobacter sakazakii, and Pediococcus acidilactici Inoculated into Galactooligosaccharide

Bang, Jihyun,Choi, Moonkak,Jeong, Haeseok,Lee, Sangseob,Kim, Yoonbin,Ryu, Jee-Hoon,Kim, Hoikyung ational Association for Food Protection 2017 Journal of food protection Vol. No.

<B>ABSTRACT</B><P>Food-grade galactooligosaccharide (GOS) with low water activity (aw of ca. 0.7) is used as an ingredient in various foods. We evaluated heat tolerances of Salmonella, Cronobacter sakazakii, and Pediococcus acidilactici at temperatures (70 to 85°C) used during the saturation process of GOS by comparing decimal reduction time (D-values) and thermal resistance constants (z-values). To determine the D- and z-values, GOS containing Salmonella (5.1 to 5.8 log CFU/g) or C. sakazakii (5.3 to 5.9 log CFU/g) was heat treated at 70, 77.5, or 85°C for up to 40, 25, or 15 s, respectively, and GOS containing P. acidilactici (6.1 to 6.5 log CFU/g) was heat treated at 70, 77.5, or 85°C for up to 150, 75, or 40 s, respectively. The D-values were calculated using a linear model for heating time versus microbial population for each bacterium. When the D-values for Salmonella, C. sakazakii, and P. acidilactici in GOS were compared, the thermal resistance of all bacteria decreased as the temperature increased. Among the three bacteria, P. acidilactici had higher D-values than did Salmonella and C. sakazakii. The z-values of Salmonella, C. sakazakii, and P. acidilactici were 30.10, 33.18, and 13.04°C, respectively. Overall order of thermal resistance was P. acidilactici &gt; Salmonella ≈ C. sakazakii. These results will be useful for selecting appropriate heat treatment conditions for the decontamination of pathogenic microorganisms during GOS manufacturing.</P>

Application of Concanavalin A-Linked Magnetic Beads for the Detection of Hepatitis A Virus

KO, SANG-MU,CHO, SE-YOUNG,OH, MYUNG-JOO,KWON, JOSEPH,VAIDYA, BIPIN,KIM, DUWOON ational Association for Food Protection 2018 Journal of food protection Vol.81 No.12

<B>ABSTRACT</B><P>Prompt and inexpensive detection of hepatitis A virus (HAV) is essential to control acute hepatitis outbreaks associated with the consumption of contaminated raw or minimally processed food. In this study, various carbohydrate-binding lectins, including concanavalin A (Con A), wheat germ agglutinin, and soybean agglutinin, were compared for their binding affinity to HAV. Con A, which showed significantly higher binding affinity than other lectins, was used to develop an alternative and affordable method to conventional antibody-linked immunomagnetic separation prior to detection of HAV using reverse transcriptase PCR. This method, Con A-linked immunomagnetic separation combined with reverse transcriptase PCR, can detect HAV at a dilution concentration of 10−4 of the virus stock (titer: 104 median tissue culture infective dose per mL), indicating that Con A could be a promising candidate for concentrating HAV.</P>

Bacteriological Quality of Vegetables from Organic and Conventional Production in Different Areas of Korea

TANGO, CHARLES NKUFI,CHOI, NA-JUNG,CHUNG, MYUNG-SUB,OH, DEOG HWAN ational Association for Food Protection 2014 Journal of food protection Vol.77 No.8

<P>Foods grown in organic production systems have been described as representing an increased risk to public health compared with foods from conventional production. Leafy vegetables (spinach, romaine lettuce, and green sesame leaves) grown in organic and conventional systems were collected from various areas in Korea and examined using standard culture methods to compare the microbiological quality of the produce grown in the two agricultural systems. The 354 samples of these leafy vegetables were analyzed for levels of indicator bacteria (aerobic bacteria, coliforms, and Escherichia coli) and the prevalence of the pathogens Staphylococcus aureus, E. coli O157:H7, Listeria monocytogenes, Bacillus cereus, and Salmonella. Aerobic bacteria and coliforms were detected in all vegetable types, but nonpathogenic E. coli was below the limit of detection in all samples. B. cereus was the most prevalent pathogen, found on 7 (11.1%) of the 63 organic spinach samples. The prevalence of S. aureus was highest in organic sesame leaves; it was found on 5 (8.0%) of the 63 samples. The prevalence of L. monocytogenes was highest on organic romaine lettuce and spinach; it was found in 4 (6.4%) of 63 samples of each type of vegetable. E. coli O157:H7 found on only 1 (1.58%) of 55 conventional spinach samples. These results suggest that farming type at most only slightly affects the hygienic quality of leafy vegetables, and no effect was found for sample collection area. Salmonella was not isolated from any of the conventional or organic leafy vegetables. These results do not support the hypothesis that organic produce poses a substantially greater risk of pathogen contamination than does conventional produce.</P>

Factors Affecting Microbiological Quality of Vegetable- and Meat-Based Meals Served at Cafeterias in the Republic of Korea

KIM, H. W.,KIM, N. H.,CHO, T. J.,PARK, S. M.,KIM, S. H.,RHEE, M. S. ational Association for Food Protection 2018 Journal of food protection Vol.81 No.11

<B>ABSTRACT</B><P>A total of 364 samples of vegetable- and meat-based meals were collected at three processing steps: step I, preparation of raw ingredients; step II, processing and cooking; and step III, finished meals. Microbiological quality was evaluated by using data for the prevalence and concentration of the aerobic plate counts, total coliforms (TC), fecal coliforms (FC), and Escherichia coli. The data were analyzed for differences between cafeterias, seasons, raw materials, and processing steps. Fourteen (15.2%) of the 92 finished meal samples were microbiologically unsatisfactory. Neither cafeteria nor season was significantly associated with microbiological quality (P &gt; 0.05). However, the type of raw ingredients and processing steps were significantly associated with differences in microbiological quality. Vegetable-based meals had higher TC concentrations than meat-based meals because salad and seasoned and fermented vegetables are not cooked, unlike heat-processed meat products. Microbial counts tended to decrease through the processing steps, and E. coli, which could only be enumerated on uncooked chicken breast (1.6 log CFU/g) and sliced pork (2.6 log CFU/g), was totally eliminated by boiling and roasting. However, the presence of FC was not completely eliminated, even by cooking, and so this group of organisms should be considered as an important indicator of hygienic meal preparation in cafeterias. Although pathogenic E. coli was not isolated in this study, continuous microbiological monitoring of composite foods served in cafeterias should be performed as the presence of TC and FC in finished meals indicates the potential for contamination by pathogenic E. coli.</P>

Prevalence, Enterotoxin Genes, and Antibiotic Resistance of Bacillus cereus Isolated from Raw Vegetables in Korea

PARK, KYUNG MIN,JEONG, MOONCHEOL,PARK, KEE JAI,KOO, MINSEON ational Association for Food Protection 2018 Journal of food protection Vol.81 No.10

<B>ABSTRACT</B><P>Bacillus cereus has long been recognized as an important pathogen in foodborne poisoning worldwide. Fresh vegetables are often contaminated with enterotoxigenic B. cereus and have been implicated as a vehicle for the transmission of this bacterium. This study reports on the occurrence, virulence gene profile, and antibiotic resistance of B. cereus in fresh vegetables. Of 102 examined samples, 48 (47%) of the samples were contaminated with B. cereus (&gt;1 log CFU/g) and 7 (6.8%) of the samples showed more than 3 log CFU/g. In total, 118 B. cereus isolates were examined for the virulence genes nheA, nheB, nheC, hblA, hblC, hblD, cytK, and entFM and for resistance to antibiotics. Of these B. cereus isolates, 70% harbored nheA, nheB, nheC, and cytK. Eighteen (80%) of 21 isolates from bell peppers possessed eight enterotoxin genes. B. cereus isolates were susceptible to imipenem, vancomycin, gentamicin, erythromycin, ciprofloxacin, and chloramphenicol, whereas 22.4% of isolates from garlic chives, 48.7% from perilla leaf, and 40.5% from romaine lettuce showed antibiotic resistance to rifampin and 6% of isolates from garlic chives exhibited resistance to tetracycline. Three isolates from garlic chives were resistant to both tetracycline and rifampin. Raw vegetables were revealed to be major sources of B. cereus containing multiple toxin genes and exhibiting antibiotic resistance. Therefore, the potential health risks of consuming these vegetables raw or undercooked should not be underestimated. This study provides basic information for monitoring the antibiotic resistance and toxigenicity of B. cereus in the food chain during vegetable distribution and for developing food safety management to reduce the contamination with and transmission of B. cereus.</P>

Rapid Detection of Listeria monocytogenes by Real-Time PCR in Processed Meat and Dairy Products

HEO, EUN JEONG,SONG, BO RA,PARK, HYUN JUNG,KIM, YOUNG JO,MOON, JIN SAN,WEE, SUNG HWAN,KIM, JIN-SEOK,YOON, YOHAN ational Association for Food Protection 2014 Journal of food protection Vol.77 No.3

<P>The objectives of this study were to evaluate the detection of Listeria monocytogenes in different ready-to-eat foods using real-time PCR (RT-PCR). Various concentrations (100 to 105 CFU/ml) of L. monocytogenes ATCC 19115 were inoculated into ham, sausage, ground meat, processed milk, cheese, and infant formula. L. monocytogenes ATCC 19115 in the samples was then enumerated on Oxford agar, and DNA was extracted from the samples before and after incubation at 36°C for 4 h. A set of primers and hybridization probe designed in this study was then used to detect the pathogen. The standard curve was then prepared by plotting cycle threshold values for each dilution versus L. monocytogenes cell counts (log CFU). The specificity of the set of primers and hybridization probe was appropriate. A 4-h incubation at 36°C before DNA extraction produced optimum standard curves in comparison to the results for a 0-h incubation. Thus, a 4-h incubation at 36°C was applied for monitoring L. monocytogenes in collected food samples. To monitor L. monocytogenes in foods, 533 samples (ham, 129; sausage, 226; ground meat, 72; processed cheese, 54; processed milk, 42; and infant formula, 10) were collected from retail markets and from the step before pasteurization in plants. Of all 533 samples, 4 samples (0.8%) showed positive signals in RT-PCR. Two samples from hams (1.6%) and two samples from sausages (0.9%) were determined to be positive for L. monocytogenes at &lt;100 CFU/g. The results indicate that the RT-PCR detection method with the set of primers and hybridization probe designed in this study should be useful in monitoring for L. monocytogenes in processed meat and milk products.</P>

Low Prevalence of Clostridium difficile in Slaughter Pigs in Korea

CHO, ARA,BYUN, JAE-WON,KIM, JONG WAN,OH, SANG-IK,LEE, MYOUNG-HEON,KIM, HA-YOUNG ational Association for Food Protection 2015 Journal of food protection Vol.78 No.5

<P>Clostridium difficile is an important cause of enteric disease in humans and animals. The prevalence of C. difficile infection is increasing, and the bacterium is frequently found in meat products, suggesting the possibility of animal-to-human transmission. Therefore, food animals must be assessed for their role as reservoirs of C. difficile. In this study, C. difficile was isolated from 2 (0.3%) of 659 slaughtered pigs in Korea. Both isolates were characterized as ribotype 078 and were multidrug resistant. The low occurrence suggests only a limited risk of C. difficile transmission from porcine food products; however, C. difficile ribotype 078 is an important pathogen in both pigs and humans, and further studies are necessary to investigate the occurrence of C. difficile in retail meats and other food animals.</P>

Natural Occurrence of Aflatoxin B1 in Marketed Foods and Risk Estimates of Dietary Exposure in Koreans

OK, HYUN EE,KIM, HYUN JUNG,SHIM, WON BO,LEE, HYOMIN,BAE, DONG-HO,CHUNG, DUCK-HWA,CHUN, HYANG SOOK ational Association for Food Protection 2007 Journal of food protection Vol.70 No.12

<P>Aflatoxin B1 (AFB1) is an unavoidable food contaminant. To evaluate the potential health risk of AFB1 to Koreans posed by food consumption, we determined the natural occurrence of AFB1 in food and estimated the excess risk for liver cancer through dietary exposure to AFB1. A total of 694 food samples collected from six different regions of South Korea were analyzed for their AFB1 content. One hundred four of the 694 samples were found to give positive enzyme-linked immunosorbent assay (ELISA) readings for AFB1 and were further investigated with high-performance liquid chromatography. Thirty-two samples, including 2 maize samples, 3 soybean products, 20 peanut samples, nut samples, and their products, and 7 spices, were found to be contaminated with AFB1 (4.6% incidence), up to 48.6 μgkg−1. The level of AFB1 contamination in 28 of the 32 food products was below 10 μgkg−1, which is the legal tolerance limit in Korea. From data on daily food consumption, the exposure dose of AFB1 was estimated to be 6.42 × 10−7 mg kg−1 body weight (bw) day−1. The major contributors to the dietary intake of AFB1 were soybean paste and soy sauce, which composed 91% of the total exposure to AFB1. The excess risk of liver cancer for those exposed to AFB1 through food intake was estimated to be 5.78 × 10−6 for hepatitis B-negative individuals and 1.48 × 10−4 for hepatitis B-positive individuals. These results suggest that special consideration is required to reduce the intake of AFB1 in hepatitis B-positive individuals.</P>