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Dr. Hyun Lee
University of Idaho

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0 Toxicity
0 mycotoxin
0 functional food
0 diabete

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mycotoxin

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Short Biography

My current research focuses on the toxicity mechanism of xenobiotics and their interactions with functional food components or with other toxicants using in vitro and in vivo models. Previously I have also worked on the identification and characterization of functional properties of food components such as phenolic compounds. In addition, my past research involved bioconversion of natural materials using microorganism or enzymes to improve the bioavailability and/or the amount of active compounds in foods.

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Journal article
Published: 22 July 2021 in Foods
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Spent coffee grounds (SCG) are inexpensive materials that have been used as a source of antioxidants and polysaccharides with immunostimulatory activity. In this study, we performed a microbial fermentation of SCG using Cordyceps sinensis and investigated the radical scavenging and immunostimulatory activity of fermented SCG. SCG fermentation using C. sinensis was performed at 25 °C for 8 d. The polyphenol content of the fermented SCG increased from 1022.4 to 1562.0 μg/mL. The glucosamine content of the mycelia also continuously increased during fermentation. The main polyphenol compounds of fermented SCG were chlorogenic acid and p-coumaric acid, which were increased by fermentation. Fermented SCG also showed significantly higher content of chlorogenic acid isomers than unfermented SCG. The fermented SCG exhibited significantly higher 2,2-diphenyl-2-picrylhydrazyl hydrate (half maximal inhibitory concentration: IC50, 0.37 mg/mL) and 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (IC50, 0.93 mg/mL) radical scavenging activities than those of the control (0.54 mg/mL and 1.20 mg/mL, respectively; p< 0.05). The fermented SCG stimulated macrophages and promoted the production of various immunostimulatory cytokines (IL-12, IL-6, and TNF-α) compared to control; therefore, microbial fermentation of SCG using C. sinensis is an effective means of generating antioxidant and immunostimulatory materials.

ACS Style

Sung Han; Yejin Ahn; Hyun Lee; Hyung Suh; Kyungae Jo. Antioxidant and Immunostimulatory Activities of a Submerged Culture of Cordyceps sinensis Using Spent Coffee. Foods 2021, 10, 1697 .

AMA Style

Sung Han, Yejin Ahn, Hyun Lee, Hyung Suh, Kyungae Jo. Antioxidant and Immunostimulatory Activities of a Submerged Culture of Cordyceps sinensis Using Spent Coffee. Foods. 2021; 10 (8):1697.

Chicago/Turabian Style

Sung Han; Yejin Ahn; Hyun Lee; Hyung Suh; Kyungae Jo. 2021. "Antioxidant and Immunostimulatory Activities of a Submerged Culture of Cordyceps sinensis Using Spent Coffee." Foods 10, no. 8: 1697.

Journal article
Published: 09 April 2021 in Toxins
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Ochratoxin A (OTA) is a mycotoxin frequently found in raw and processed foods. While it is considered a possible human carcinogen, the mechanism of action remains unclear. OTA has been shown to be hepatotoxic in both in vitro and in vivo models and oxidative stress may be one of the factors contributing to its toxicity. Hence, the effect of OTA on human hepatocellular carcinoma, HepG2 cells, was investigated on oxidative stress parameters. The cytotoxicity of OTA on HepG2 was time- and dose-dependent within a range between 0.1 and 10 µM; while 100 μM of OTA increased the intracellular reactive oxygen species (ROS) in a time-dependent manner. Additionally, the levels of glutathione (GSH) were increased by 9.7% and 11.3% at 10 and 100 nM of OTA, respectively; while OTA at 100 μM depleted GSH by 40.5% after 24 h exposure compared with the control. Finally, the mRNA level of catalase (CAT) was downregulated by 2.33-, 1.92-, and 1.82-fold after cells were treated with 1, 10, and 10 μM OTA for 24 h, respectively; which was linked to a decrease in CAT enzymatic activity. These results suggest that oxidative stress is involved in OTA-mediated toxicity in HepG2 cells.

ACS Style

Enrique García-Pérez; Dojin Ryu; Chan Lee; Hyun Lee. Ochratoxin A Induces Oxidative Stress in HepG2 Cells by Impairing the Gene Expression of Antioxidant Enzymes. Toxins 2021, 13, 271 .

AMA Style

Enrique García-Pérez, Dojin Ryu, Chan Lee, Hyun Lee. Ochratoxin A Induces Oxidative Stress in HepG2 Cells by Impairing the Gene Expression of Antioxidant Enzymes. Toxins. 2021; 13 (4):271.

Chicago/Turabian Style

Enrique García-Pérez; Dojin Ryu; Chan Lee; Hyun Lee. 2021. "Ochratoxin A Induces Oxidative Stress in HepG2 Cells by Impairing the Gene Expression of Antioxidant Enzymes." Toxins 13, no. 4: 271.

Journal article
Published: 19 March 2021 in Toxins
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Ochratoxin A (OTA) is a potential human carcinogen that poses a significant concern in food safety and public health. OTA has been found in a wide variety of agricultural commodities, including cereal grains. This study investigated the reduction of OTA during the preparation of rice- and oat-based porridge by a simulated indirect steam process. The effects of sodium bicarbonate (NaHCO3) and fructose on the reduction of OTA were also investigated. During the processing, OTA in rice- and oat-porridge was decreased by 59% and 14%, respectively, from initial OTA artificially added at 20 μg/kg (dry weight basis). When 0.5% and 1% of sodium bicarbonate were added to rice porridge, increased reduction of OTA was observed as 78% and 68%, respectively. The same amounts of added sodium bicarbonate also further reduced OTA in oat porridge to 58% and 72%, respectively. In addition, increased reduction of OTA in the presence of fructose was observed. A combination of the two, i.e., 0.5% sodium bicarbonate and 0.5% fructose, resulted in a 79% and 67% reduction in rice porridge and oat porridge, respectively. These results indicate that indirect steaming may effectively reduce OTA in preparation of porridge-type products, particularly when sodium bicarbonate and/or fructose are added.

ACS Style

Hyun Lee; Shufang Li; Kejia Gu; Dojin Ryu. Reduction of Ochratoxin A during the Preparation of Porridge with Sodium Bicarbonate and Fructose. Toxins 2021, 13, 224 .

AMA Style

Hyun Lee, Shufang Li, Kejia Gu, Dojin Ryu. Reduction of Ochratoxin A during the Preparation of Porridge with Sodium Bicarbonate and Fructose. Toxins. 2021; 13 (3):224.

Chicago/Turabian Style

Hyun Lee; Shufang Li; Kejia Gu; Dojin Ryu. 2021. "Reduction of Ochratoxin A during the Preparation of Porridge with Sodium Bicarbonate and Fructose." Toxins 13, no. 3: 224.

Journal article
Published: 19 January 2021 in Food Chemistry
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Ochratoxin A (OTA) is a nephrotoxin produced by many species in two fungal genera of Aspergillus and Penicillium under virtually all agricultural environments. Hence, OTA occurs frequently in agricultural commodities and their downstream products worldwide. In this study, thermal stability of OTA in the presence of sugars commonly added to food products including glucose, fructose, and sucrose was investigated by analyzing their reaction products with HPLC–FLD and LC–MS/MS. Samples were heated at three different temperatures (100, 125, and 150 °C) in 10-min intervals for up to 60 min in the absence of food matrix. Analysis showed increased OTα and OTα-amide and decreased OTA isomer (14-R-OTA) formation when OTA was heated with sugars. Among the sugars tested, adding fructose resulted in significantly lower OTA levels than glucose, sucrose, or no sugar added control. Addition of fructose also shifted OTA degradation product profile to less toxic OTα-amide, instead of OTA isomer which has similar toxicity to OTA. These results suggest that added sugars influenced the levels of OTA and its degradation products formed during thermal processing, and may provide a means to reduce the toxicity of OTA in food.

ACS Style

Kejia Gu; Dojin Ryu; Hyun Jung Lee. Ochratoxin A and its reaction products affected by sugars during heat processing. Food Chemistry 2021, 348, 129038 .

AMA Style

Kejia Gu, Dojin Ryu, Hyun Jung Lee. Ochratoxin A and its reaction products affected by sugars during heat processing. Food Chemistry. 2021; 348 ():129038.

Chicago/Turabian Style

Kejia Gu; Dojin Ryu; Hyun Jung Lee. 2021. "Ochratoxin A and its reaction products affected by sugars during heat processing." Food Chemistry 348, no. : 129038.

Journal article
Published: 27 May 2020 in Food Control
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Ochratoxin A (OTA) is a possible human carcinogen commonly occurring in many agricultural commodities, particularly in oats and their processed products. Due to its heat stability, OTA has been found in thermally processed food products including breakfast cereals and cereal grains. In this study, the reduction of OTA during roasting of oats was investigated under conditions similar to the industrial applications including addition of sugars. Oat grains were conditioned to achieve a uniform moisture content (16% wet weight basis, wb) and OTA (100 μg/kg wb). Then, the grains were roasted at 120 °C and 180 °C for 30 min and 60 min, respectively. The concentration of OTA in roasted oat-based cereals was decreased by 2–18% with increasing roasting temperature and time. The reduction of OTA was greater when oat grains were roasted with reducing sugars, i.e., glucose (11%) and fructose (15%), compared with oat-based cereal samples with no added sugar (10%). In addition, previously identified degradation products of OTA such as OTA isomer, OTα, and OTα amide were not formed during roasting. These results indicate that increased reduction of OTA in oats can be achieved by roasting with sugars, which can be readily applicable in commercial production of oat-based snack foods.

ACS Style

Hyun Jung Lee. Stability of ochratoxin A in oats during roasting with reducing sugars. Food Control 2020, 118, 107382 .

AMA Style

Hyun Jung Lee. Stability of ochratoxin A in oats during roasting with reducing sugars. Food Control. 2020; 118 ():107382.

Chicago/Turabian Style

Hyun Jung Lee. 2020. "Stability of ochratoxin A in oats during roasting with reducing sugars." Food Control 118, no. : 107382.

Journal article
Published: 25 February 2020 in Foods
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An analytical method to measure solubilized orthophosphate ions (HPO42− and PO43− ) from the water-insoluble food additives calcium phosphate dibasic (DCP) and calcium phosphate tribasic (TCP) in processed foods was optimized by comparing ion chromatography (IC) coupled with DS6 conductivity detector (Cond.) and high-performance liquid chromatography (HPLC) with Evaporative light scattering detector (ELSD) methods. The ion-pairing HPLC method could analyze calcium and phosphate ions successively. However, this method exhibited low reproducibility after approximately 48 hours of measurements. The IC method was established as an effective method of measuring orthophosphate ions with high reproducibility using distilled water and KOH solution as the mobile phase with a Dionex column. Matrix-based limit of detections (LOD) and limit of quantifications (LOQ) for snacks and cereals were estimated in the range of 0.01–0.91 µg/mL and 0.21–2.74 µg/mL, respectively. In inter-day and intra-day tests, the calculated precision (%RSD) and accuracy (recovery %) ranged from 0.5% to 6.6% and 82% to 117%, respectively, in both food samples. The levels of DCP or TCP could be analyzed in various positive food samples, and the developed IC method demonstrated good applicability in the analysis of DCP and TCP in collected processed foods.

ACS Style

Minjung Song; Juhee Park; Jihyun Lee; Heejae Suh; Hyunjung Lee; Dojin Ryu; Chan Lee. New Analytical Approach for the Determination of Calcium Phosphate Dibasic and Tribasic in Processed Food by Comparison of Ion Chromatography with High-Performance Liquid Chromatography. Foods 2020, 9, 248 .

AMA Style

Minjung Song, Juhee Park, Jihyun Lee, Heejae Suh, Hyunjung Lee, Dojin Ryu, Chan Lee. New Analytical Approach for the Determination of Calcium Phosphate Dibasic and Tribasic in Processed Food by Comparison of Ion Chromatography with High-Performance Liquid Chromatography. Foods. 2020; 9 (3):248.

Chicago/Turabian Style

Minjung Song; Juhee Park; Jihyun Lee; Heejae Suh; Hyunjung Lee; Dojin Ryu; Chan Lee. 2020. "New Analytical Approach for the Determination of Calcium Phosphate Dibasic and Tribasic in Processed Food by Comparison of Ion Chromatography with High-Performance Liquid Chromatography." Foods 9, no. 3: 248.

Journal article
Published: 29 June 2019 in Toxins
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Ochratoxin A (OTA) is a widespread mycotoxin produced by several species of the genera Aspergillus and Penicillium. OTA exists in a variety of foods, including rice, oats, and coffee and is hepatotoxic, with a similar mode of action as aflatoxin B1. The precise mechanism of cytotoxicity is not yet known, but oxidative damage is suspected to contribute to its cytotoxic effects. In this study, human hepatocyte HepG2 cells were treated with various concentrations of OTA (5–500 nM) for 48 h. OTA triggered oxidative stress as demonstrated by glutathione depletion and increased reactive oxygen species, malondialdehyde level, and nitric oxide production. Apoptosis was observed with 500 nM OTA treatment. OTA increased both the mRNA and protein expression of phase I and II enzymes. The same results were observed in an in vivo study using ICR mice. Furthermore, the relationship between phase I and II enzymes was demonstrated by the knockdown of the aryl hydrocarbon receptor (AhR) and NF-E2-related factor 2 (Nrf2) with siRNA. Taken together, our results show that OTA induces oxidative stress through the phase I reaction regulated by AhR and induces apoptosis, and that the phase II reaction is activated by Nrf2 in the presence of oxidative stress.

ACS Style

Hye Soo Shin; Hyun Jung Lee; Min Cheol Pyo; Dojin Ryu; Kwang-Won Lee. Ochratoxin A-Induced Hepatotoxicity through Phase I and Phase II Reactions Regulated by AhR in Liver Cells. Toxins 2019, 11, 377 .

AMA Style

Hye Soo Shin, Hyun Jung Lee, Min Cheol Pyo, Dojin Ryu, Kwang-Won Lee. Ochratoxin A-Induced Hepatotoxicity through Phase I and Phase II Reactions Regulated by AhR in Liver Cells. Toxins. 2019; 11 (7):377.

Chicago/Turabian Style

Hye Soo Shin; Hyun Jung Lee; Min Cheol Pyo; Dojin Ryu; Kwang-Won Lee. 2019. "Ochratoxin A-Induced Hepatotoxicity through Phase I and Phase II Reactions Regulated by AhR in Liver Cells." Toxins 11, no. 7: 377.

Research article
Published: 01 June 2019 in Phytopathology®
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The plant pathogen Fusarium culmorum represents an inoculum source capable of contaminating grains with deoxynivalenol in the Inland Northwest region of the United States. A multilevel modeling approach utilizing varying intercepts for different sampling quadrats, fields, and iterations in the dataset was performed to characterize differences in isolation frequency of F. culmorum collected during a 2-year soil survey. Differences in the isolation frequency of F. culmorum varied the most by sampled field followed by quadrat and iteration, respectively. Higher relative elevation within the sampling region of a field limited the amount of F. culmorum recovered. The effect of annual climate variables was investigated using combinations of single-variable and multivariable model equations with linear and polynomial terms. The same data analysis approach was applied to an external dataset of F. culmorum isolation frequencies in grains from fields across eastern Australia. These results represent a case study for investigating variability within datasets containing overdispersed fungal counts and incorporating climate summaries as predictor variables.

ACS Style

Andrew Robinson; Dojin Ryu; Hyun Jung Jung Lee. Utility of a Multilevel Modeling Approach to Investigate Differences in Isolation Frequency of Fusarium culmorum in Agricultural Soil Across the Inland Pacific Northwest. Phytopathology® 2019, 109, 1062 -1073.

AMA Style

Andrew Robinson, Dojin Ryu, Hyun Jung Jung Lee. Utility of a Multilevel Modeling Approach to Investigate Differences in Isolation Frequency of Fusarium culmorum in Agricultural Soil Across the Inland Pacific Northwest. Phytopathology®. 2019; 109 (6):1062-1073.

Chicago/Turabian Style

Andrew Robinson; Dojin Ryu; Hyun Jung Jung Lee. 2019. "Utility of a Multilevel Modeling Approach to Investigate Differences in Isolation Frequency of Fusarium culmorum in Agricultural Soil Across the Inland Pacific Northwest." Phytopathology® 109, no. 6: 1062-1073.

Journal article
Published: 14 May 2019 in Food Control
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Ochratoxin A (OTA) is one of the most important mycotoxins due to its widespread occurrence and toxicity, including nephrotoxicity and potential carcinogenicity to humans. OTA has been detected in a wide range of agricultural commodities and their processed products such as infant cereals and breakfast cereals. Extrusion processing, which is widely used in the manufacture of infant and breakfast cereals, may reduce mycotoxin levels to varying degrees. Hence, the effects of extrusion cooking process on the stability of OTA in spiked (100 μg/kg) oat flakes and rice flour was investigated by using a laboratory-scaled twin-screw extruder. In addition, the effect of twin-screw extrusion and addition of baking soda (0, 0.5, and 1.0% weight of total solids) on the reduction of OTA in oats and rice was investigated. The reductions of OTA in the artificially contaminated oat flakes upon extrusion cooking were in the range of 40–43% whereas the reductions in rice flour ranged from 78 to 82%. The reductions of OTA during extrusion with added baking soda were up to 65% and 72% in oats and rice, respectively. These results suggest that OTA in rice and oats may be reduced significantly by extrusion cooking process, which can be applied to commercial production of infant cereals and breakfast cereals. In addition, baking soda may also help to reduce OTA levels in oats during thermal processing.

ACS Style

Dojin Ryu; Ryan Joseph Kowalski; Girish Ganjyal; Hyun Jung Lee. Reduction of ochratoxin A in oats and rice by twin-screw extrusion processing with baking soda. Food Control 2019, 105, 21 -28.

AMA Style

Dojin Ryu, Ryan Joseph Kowalski, Girish Ganjyal, Hyun Jung Lee. Reduction of ochratoxin A in oats and rice by twin-screw extrusion processing with baking soda. Food Control. 2019; 105 ():21-28.

Chicago/Turabian Style

Dojin Ryu; Ryan Joseph Kowalski; Girish Ganjyal; Hyun Jung Lee. 2019. "Reduction of ochratoxin A in oats and rice by twin-screw extrusion processing with baking soda." Food Control 105, no. : 21-28.

Journal article
Published: 03 October 2018 in Food and Chemical Toxicology
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Because ochratoxin A (OTA) is widely found in foods, people are susceptible to OTA exposure. The mechanism leading to renal toxicity induced by OTA remains unclear. The aim of this study was to investigate OTA-induced toxicity in human proximal tubule HK-2 cells. OTA decreased cell viability, and the expression of kidney injury molecule-1 (KIM-1), a kidney damage marker, was increased when HK-2 cells were exposed to OTA. Additionally, OTA treatment of cells increased intracellular reactive oxygen species and malondialdehyde and decreased glutathione levels. OTA-treated cells induced the aryl hydrocarbon receptor (AhR) and pregnane X receptor (PXR) genes followed by induction of the cytochrome P450 1A1 (CYP1A1), CYP1A2, and CYP3A4 genes representing phase I enzyme. The mRNA expression of phase II enzymes such as heme oxygenase-1, nicotinamide adenine dinucleotide phosphate-quinone oxidoreductase 1, and glutamate cysteine ligase catalytic subunit were upregulated by activation of NF-E2-related factor 2 (Nrf2) translocation by treatment with OTA. The response of OTA-orally administered mice also showed marked increases in these enzymes as well as KIM-1. These results indicate that OTA induces phase I and II enzymes through the AhR, PXR, and Nrf2 signaling pathways in HK-2 cells, which may lead to modulation of proximal tubule injury.

ACS Style

Hyun Jung Lee; Min Cheol Pyo; Hye Soo Shin; Dojin Ryu; Kwang-Won Lee. Renal toxicity through AhR, PXR, and Nrf2 signaling pathway activation of ochratoxin A-induced oxidative stress in kidney cells. Food and Chemical Toxicology 2018, 122, 59 -68.

AMA Style

Hyun Jung Lee, Min Cheol Pyo, Hye Soo Shin, Dojin Ryu, Kwang-Won Lee. Renal toxicity through AhR, PXR, and Nrf2 signaling pathway activation of ochratoxin A-induced oxidative stress in kidney cells. Food and Chemical Toxicology. 2018; 122 ():59-68.

Chicago/Turabian Style

Hyun Jung Lee; Min Cheol Pyo; Hye Soo Shin; Dojin Ryu; Kwang-Won Lee. 2018. "Renal toxicity through AhR, PXR, and Nrf2 signaling pathway activation of ochratoxin A-induced oxidative stress in kidney cells." Food and Chemical Toxicology 122, no. : 59-68.

Short communication
Published: 06 August 2018 in Food Control
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Ochratoxin A (OTA) represents one of the most widespread mycotoxins in agricultural commodities in the world and is considered as a possible human carcinogen with its potent nephrotoxicity. Since OTA is stable under most food processing conditions, it has been detected in a variety of cereal grains and their processed products. We investigated the effect of explosive puffing process on the reduction of OTA in rice and oats. Moisture content of rice and oat grains were adjusted to 15% (wet weight basis, wb) and OTA was spiked at 100 μg/kg. Then the grains were processed by explosive puffing at 0.5, 0.7, and 0.9 MPa. The moisture content of puffed rice and oat snacks were in the ranges of 5 – 8% wb and 6 – 10% wb, respectively, and the moisture content in the puffed products were decreased with increasing pressure. In addition, decreased bulk density and increased degree of redness (a) were observed with increased explosive puffing pressure. The reduction of OTA concentration in puffed rice and oats were decreased with increasing explosive puffing pressures in the ranges of 15 – 28% and 38 – 52%, respectively. These results suggest that OTA in rice and oat may be reduced significantly by explosive puffing process, which can be applied to commercial production of cereal-based snack foods.

ACS Style

Hyun Jung Lee; Singeun Kim; Hyung Joo Suh; Dojin Ryu. Effects of explosive puffing process on the reduction of ochratoxin A in rice and oats. Food Control 2018, 95, 334 -338.

AMA Style

Hyun Jung Lee, Singeun Kim, Hyung Joo Suh, Dojin Ryu. Effects of explosive puffing process on the reduction of ochratoxin A in rice and oats. Food Control. 2018; 95 ():334-338.

Chicago/Turabian Style

Hyun Jung Lee; Singeun Kim; Hyung Joo Suh; Dojin Ryu. 2018. "Effects of explosive puffing process on the reduction of ochratoxin A in rice and oats." Food Control 95, no. : 334-338.

Journal article
Published: 30 August 2017 in Journal of Food Protection
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Ochratoxin A (OTA) is one of the most important mycotoxins owing to its widespread occurrence and toxicity, including nephrotoxicity and potential carcinogenicity to humans. OTA has been detected in a wide range of agricultural commodities, including cereal grains and their processed products. In particular, oat-based products show a higher incidence and level of contamination. Extrusion cooking is widely used in the manufacturing of breakfast cereals and snacks and may reduce mycotoxins to varying degrees. Hence, the effects of extrusion cooking on the stability of OTA in spiked (100 μg/kg) oat flake was investigated by using a laboratory-scale twin-screw extruder with a central composite design. Factors examined were moisture content (20, 25, and 30% dry weight basis), temperature (140, 160, and 180°C), screw speed (150, 200, and 250 rpm), and die size (1.5, 2, and 3 mm). Both nonextruded and extruded samples were analyzed for reductions of OTA by high-performance liquid chromatography, coupled with fluorescence detection. The percentage of reductions in OTA in the contaminated oat flakes upon extrusion processing were in the range of 0 to 28%. OTA was partially stable during extrusion, with only screw speed and die size having significant effect on reduction (P < 0.005). The highest reduction of 28% was achieved at 180°C, 20% moisture, 250 rpm screw speed, and a 3-mm die with 193 kJ/kg specific mechanical energy. According to the central composite design analyses, up to 28% of OTA can be reduced by a combination of 162°C, 30% moisture, and 221 rpm, with a 3-mm die.

ACS Style

Hyun Jung Lee; Samjhana Dahal; Enrique Garcia Perez; Ryan Joseph Kowalski; Girish M. Ganjyal; Dojin Ryu. Reduction of Ochratoxin A in Oat Flakes by Twin-Screw Extrusion Processing. Journal of Food Protection 2017, 80, 1628 -1634.

AMA Style

Hyun Jung Lee, Samjhana Dahal, Enrique Garcia Perez, Ryan Joseph Kowalski, Girish M. Ganjyal, Dojin Ryu. Reduction of Ochratoxin A in Oat Flakes by Twin-Screw Extrusion Processing. Journal of Food Protection. 2017; 80 (10):1628-1634.

Chicago/Turabian Style

Hyun Jung Lee; Samjhana Dahal; Enrique Garcia Perez; Ryan Joseph Kowalski; Girish M. Ganjyal; Dojin Ryu. 2017. "Reduction of Ochratoxin A in Oat Flakes by Twin-Screw Extrusion Processing." Journal of Food Protection 80, no. 10: 1628-1634.

Journal article
Published: 01 February 2017 in Food Control
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ACS Style

Fadwa Al-Taher; Jack Cappozzo; Jerry Zweigenbaum; Hyun Jung Lee; Lauren Jackson; Dojin Ryu. Detection and quantitation of mycotoxins in infant cereals in the U.S. market by LC-MS/MS using a stable isotope dilution assay. Food Control 2017, 72, 27 -35.

AMA Style

Fadwa Al-Taher, Jack Cappozzo, Jerry Zweigenbaum, Hyun Jung Lee, Lauren Jackson, Dojin Ryu. Detection and quantitation of mycotoxins in infant cereals in the U.S. market by LC-MS/MS using a stable isotope dilution assay. Food Control. 2017; 72 ():27-35.

Chicago/Turabian Style

Fadwa Al-Taher; Jack Cappozzo; Jerry Zweigenbaum; Hyun Jung Lee; Lauren Jackson; Dojin Ryu. 2017. "Detection and quantitation of mycotoxins in infant cereals in the U.S. market by LC-MS/MS using a stable isotope dilution assay." Food Control 72, no. : 27-35.

Journal article
Published: 23 January 2017 in Journal of Food Protection
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Ochratoxin A (OTA) is a possible human carcinogen and occurs frequently in cereal grain, soy, and other agricultural commodities. Infants and young children may be more susceptible to contaminants than adults because of their lower body weight, higher metabolic rate, reduced ability to detoxify food toxicants, and more restricted diet. The purpose of this study was to investigate the occurrence and levels of OTA in infant formula and infant cereal products available in the U.S. market. In the present study, 98 powdered infant formula (milk- and soy-based) samples and 155 infant cereal (barley-, rice-, oat-, wheat-, and mixed grain–based) products were collected from different retail locations in the United States over a 2-year period. OTA levels were determined by liquid chromatography–tandem mass spectrometry. Although OTA was not detected in any of the infant formula samples, 47 (30%) of 155 infant cereals were contaminated with OTA in the range of 0.6 to 22.1 ng/g. At present, there is no regulatory limit for OTA in the United States. However, all of the positive samples were above the maximum level set by the European Commission (0.5 ng/g) for OTA in baby foods. OTA was detected in all types of infant cereals, but the highest incidence and concentrations were found in oat-based infant cereals (59%), followed by mixed grain cereals (34%). Increased surveillance and monitoring of OTA levels in grains used in infant foods may be needed to reduce exposure of infants and young children to OTA from cereal products.

ACS Style

Jack Cappozzo; Lauren Jackson; Hyun Jung Lee; Wei Zhou; Fadwa Al-Taher; Jerry Zweigenbaum; Dojin Ryu. Occurrence of Ochratoxin A in Infant Foods in the United States. Journal of Food Protection 2017, 80, 251 -256.

AMA Style

Jack Cappozzo, Lauren Jackson, Hyun Jung Lee, Wei Zhou, Fadwa Al-Taher, Jerry Zweigenbaum, Dojin Ryu. Occurrence of Ochratoxin A in Infant Foods in the United States. Journal of Food Protection. 2017; 80 (2):251-256.

Chicago/Turabian Style

Jack Cappozzo; Lauren Jackson; Hyun Jung Lee; Wei Zhou; Fadwa Al-Taher; Jerry Zweigenbaum; Dojin Ryu. 2017. "Occurrence of Ochratoxin A in Infant Foods in the United States." Journal of Food Protection 80, no. 2: 251-256.

Review article
Published: 09 January 2017 in Journal of Agricultural and Food Chemistry
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Cereal grains and their processed food products are frequently contaminated with mycotoxins. Among many, five major mycotoxins of aflatoxins, ochratoxins, fumonisins, deoxynivalenol, and zearalenone are of significant public health concern as they can cause adverse effects in humans. Being airborne or soilborne, the cosmopolitan nature of mycotoxigenic fungi contribute to the worldwide occurrence of mycotoxins. On the basis of the global occurrence data reported during the past 10 years, the incidences and maximum levels in raw cereal grains were 55% and 1642 μg/kg for aflatoxins, 29% and 1164 μg/kg for ochratoxin A, 61% and 71,121 μg/kg for fumonisins, 58% and 41,157 μg/kg, for deoxynivalenol, and 46% and 3049 μg/kg for zearalenone. The concentrations of mycotoxins tend to be lower in processed food products; the incidences varied depending on the individual mycotoxins, possibly due to the varying stability during processing and distribution of mycotoxins. It should be noted that more than one mycotoxin, produced by a single or several fungal species, may occur in various combinations in a given sample or food. Most studies reported additive or synergistic effects, suggesting that these mixtures may pose a significant threat to public health, particularly to infants and young children. Therefore, information on the co-occurrence of mycotoxins and their interactive toxicity is summarized in this paper.

ACS Style

Hyun Jung Lee; Dojin Ryu. Worldwide Occurrence of Mycotoxins in Cereals and Cereal-Derived Food Products: Public Health Perspectives of Their Co-occurrence. Journal of Agricultural and Food Chemistry 2017, 65, 7034 -7051.

AMA Style

Hyun Jung Lee, Dojin Ryu. Worldwide Occurrence of Mycotoxins in Cereals and Cereal-Derived Food Products: Public Health Perspectives of Their Co-occurrence. Journal of Agricultural and Food Chemistry. 2017; 65 (33):7034-7051.

Chicago/Turabian Style

Hyun Jung Lee; Dojin Ryu. 2017. "Worldwide Occurrence of Mycotoxins in Cereals and Cereal-Derived Food Products: Public Health Perspectives of Their Co-occurrence." Journal of Agricultural and Food Chemistry 65, no. 33: 7034-7051.

Journal article
Published: 01 January 2017 in Food Chemistry
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Ochratoxin A (OTA) is a fungal metabolite and putative carcinogen which can contaminate a variety of foods such as cereals, wine, and nuts. Commercial ELISA kits are known to give false-positive results for OTA concentrations when phenolic compounds are present. Pistachios represent a food matrix rich in phenolic compounds potentially contaminated with OTA, and were used to model OTA cross-reactivity. Polyvinylpolypyrrolidone (PVPP) was incorporated during extraction of OTA using a commercial ELISA protocol. HPLC methods were used to confirm that PVPP does not interact with OTA and levels of gallic acid and catechin remaining in pistachio extracts decreased with increasing PVPP application. Cross-reactivity of extracts also decreased with increasing PVPP application, and color loss was used as an indicator of anthocyanin removal. Incorporating PVPP into ELISA protocols allows for the continued use of rapid immunological methods in food matrices containing phenolic compounds.

ACS Style

Andrew L. Robinson; Hyun Jung Lee; Dojin Ryu. Polyvinylpolypyrrolidone reduces cross-reactions between antibodies and phenolic compounds in an enzyme-linked immunosorbent assay for the detection of ochratoxin A. Food Chemistry 2017, 214, 47 -52.

AMA Style

Andrew L. Robinson, Hyun Jung Lee, Dojin Ryu. Polyvinylpolypyrrolidone reduces cross-reactions between antibodies and phenolic compounds in an enzyme-linked immunosorbent assay for the detection of ochratoxin A. Food Chemistry. 2017; 214 ():47-52.

Chicago/Turabian Style

Andrew L. Robinson; Hyun Jung Lee; Dojin Ryu. 2017. "Polyvinylpolypyrrolidone reduces cross-reactions between antibodies and phenolic compounds in an enzyme-linked immunosorbent assay for the detection of ochratoxin A." Food Chemistry 214, no. : 47-52.

Journal article
Published: 01 October 2016 in Journal of Food Protection
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Ochratoxin A (OTA) represents one of the most widespread mycotoxins in agricultural commodities in the world and is considered a possible human carcinogen with its potent nephrotoxicity. OTA is stable under most food processing conditions; however, higher-temperature treatment may reduce OTA content in foods. Since OTA can be found in processed products destined for both human and animal consumption, factors affecting its stability or reduction during thermal processes were investigated here. The reduction of OTA was measured during various heating times (up to 60 min) at different temperatures (100, 125, 150, 175, and 200°C) in aqueous buffer solutions at different pHs (pH 4, 7, and 10). Quantification of OTA was carried out using high-performance liquid chromatography with fluorescence detection. The results showed that the rate and extent of OTA reduction were dependent on pH, processing time, and temperature; greater than 90% OTA reduction was achieved at 200°C for all treatments except pH 4. After processing under an alkaline condition (pH 10) at 100°C for 60 min, about 50% of the OTA was lost, while after 60 min under neutral and acidic conditions at 100°C, significant reductions of OTA were not shown.

ACS Style

Samjhana Dahal; Hyun Jung Lee; Kejia Gu; Dojin Ryu. Heat Stability of Ochratoxin A in an Aqueous Buffered Model System. Journal of Food Protection 2016, 79, 1748 -1752.

AMA Style

Samjhana Dahal, Hyun Jung Lee, Kejia Gu, Dojin Ryu. Heat Stability of Ochratoxin A in an Aqueous Buffered Model System. Journal of Food Protection. 2016; 79 (10):1748-1752.

Chicago/Turabian Style

Samjhana Dahal; Hyun Jung Lee; Kejia Gu; Dojin Ryu. 2016. "Heat Stability of Ochratoxin A in an Aqueous Buffered Model System." Journal of Food Protection 79, no. 10: 1748-1752.

Corrected and republished article
Published: 13 November 2015 in Journal of Food Science
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Aflatoxins, ochratoxins, fumonisins, deoxynivalenol, and zearalenone are of significant public health concern as they can cause serious adverse effects in different organs including the liver, kidney, and immune system in humans. These toxic secondary metabolites are produced by filamentous fungi mainly in the genus Aspergillus, Penicillium, and Fusarium. It is challenging to control the formation of mycotoxins due to the worldwide occurrence of these fungi in food and the environment. In addition to raw agricultural commodities, mycotoxins tend to remain in finished food products as they may not be destroyed by conventional processing techniques. Hence, much of our concern is directed to chronic health effects through long-term exposure to one or multiple mycotoxins from contaminated foods. Ideally risk assessment requires a comprehensive data, including toxicological and epidemiological studies as well as surveillance and exposure assessment. Setting of regulatory limits for mycotoxins is considered necessary to protect human health from mycotoxin exposure. Although advances in analytical techniques provide basic yet critical tool in regulation as well as all aspects of scientific research, it has been acknowledged that different forms of mycotoxins such as analogs and conjugated mycotoxins may constitute a significant source of dietary exposure. Further studies should be warranted to correlate mycotoxin exposure and human health possibly via identification and validation of suitable biomarkers.

ACS Style

Hyun Jung Lee; Dojin Ryu. Advances in Mycotoxin Research: Public Health Perspectives. Journal of Food Science 2015, 80, T2970 -T2983.

AMA Style

Hyun Jung Lee, Dojin Ryu. Advances in Mycotoxin Research: Public Health Perspectives. Journal of Food Science. 2015; 80 (12):T2970-T2983.

Chicago/Turabian Style

Hyun Jung Lee; Dojin Ryu. 2015. "Advances in Mycotoxin Research: Public Health Perspectives." Journal of Food Science 80, no. 12: T2970-T2983.

Journal article
Published: 01 July 2015 in Journal of Food Protection
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Cereal grains are a significant source of ochratoxin A (OTA) in the human diet. Multiple ochratoxigenic Aspergillus and Penicillium spp. have been reported as contaminants on various cereal grains around the world, although relatively few species dominate in any given location. Efforts to mitigate the risk of fungal contamination and OTA accumulation can be made pre- and postharvest. Still, a rapid and reliable screening method is sought that can be used to predict the OTA level of a sample and to inform risk assessments prior to processing. In this study, we assessed the efficacy of two OTA-related indices for OTA level prediction. Infestation rates were determined by direct plating for freshly harvested and stored barley, durum, and hard red spring wheat samples (n = 139) with known OTA levels. Presumptive ochratoxigenic isolates were tested for their ability to produce OTA. The nonribosomal peptide synthase (otanpsPN) involved in OTA biosynthesis was used to quantify ochratoxigenic fungi in barley and wheat. Viable Penicillium verrucosum was present in 45% of the samples. In total, 62.7% (n = 110) of the P. verrucosum isolates tested produced OTA on dichloran yeast extract sucrose 18% glycerol agar. Both OTA level and infestation rate (r = 0.30), as well as OTA level and otanpsPN concentration (r = 0.56), were weakly correlated. Neither infestation rate nor otanpsPN concentration is a reliable predictor of OTA level in a sample.

ACS Style

Julie Kuruc; Justin Hegstad; Hyun Jung Lee; Kristin Simons; Dojin Ryu; Charlene Wolf-Hall. Infestation and Quantification of Ochratoxigenic Fungi in Barley and Wheat Naturally Contaminated with Ochratoxin A. Journal of Food Protection 2015, 78, 1350 -1356.

AMA Style

Julie Kuruc, Justin Hegstad, Hyun Jung Lee, Kristin Simons, Dojin Ryu, Charlene Wolf-Hall. Infestation and Quantification of Ochratoxigenic Fungi in Barley and Wheat Naturally Contaminated with Ochratoxin A. Journal of Food Protection. 2015; 78 (7):1350-1356.

Chicago/Turabian Style

Julie Kuruc; Justin Hegstad; Hyun Jung Lee; Kristin Simons; Dojin Ryu; Charlene Wolf-Hall. 2015. "Infestation and Quantification of Ochratoxigenic Fungi in Barley and Wheat Naturally Contaminated with Ochratoxin A." Journal of Food Protection 78, no. 7: 1350-1356.

Research article
Published: 23 February 2015 in Journal of Agricultural and Food Chemistry
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Ochratoxin A (OTA) has been found in all major cereal grains including oat, wheat, and barley worldwide and considered as a potential concern in food safety. A total of 489 samples of corn-, rice-, wheat-, and oat-based breakfast cereal were collected from U.S. retail marketplaces over a two-year period, and OTA was determined by high-performance liquid chromatography. Overall, 205 samples (42%) were contaminated with OTA in the range from 0.10 to 9.30 ng/g. The levels OTA were mostly below of the European Commission Regulation (3 ng/g) except in 16 samples of oat-based cereals. The incidence of OTA was highest in oat-based breakfast cereals (70%, 142/203), followed by wheat-based (32%, 38/117), corn-based (15%, 15/103), and rice-based breakfast cereals (15%, 10/66). On the basis of the incidence and concentration of OTA, oats and oat-based products may need greater attention in further surveillance programs and development of intervention strategies to reduce health risks in consumers.

ACS Style

Hyun Jung Lee; Dojin Ryu. Significance of Ochratoxin A in Breakfast Cereals from the United States. Journal of Agricultural and Food Chemistry 2015, 63, 9404 -9409.

AMA Style

Hyun Jung Lee, Dojin Ryu. Significance of Ochratoxin A in Breakfast Cereals from the United States. Journal of Agricultural and Food Chemistry. 2015; 63 (43):9404-9409.

Chicago/Turabian Style

Hyun Jung Lee; Dojin Ryu. 2015. "Significance of Ochratoxin A in Breakfast Cereals from the United States." Journal of Agricultural and Food Chemistry 63, no. 43: 9404-9409.