Tae Wha Moon

Seoul National University, Sŏul, Seoul, South Korea

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Publications (51)84.36 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Starches with high slowly digestible starch (SDS) contents were prepared by treating completely gelatinized waxy corn starch with amylosucrase. The structural properties of the prepared starches were then investigated. The content of SDS increased by up to 38.7% after amylosucrase modification, and the portion of chains with degree of polymerisation (DP) 25–36 increased, while the portion of chains with DP ⩽ 12 decreased. Amylosucrase-modified starches showed a weak B-type crystalline structure. A slight increase in the degree of relative crystallinity was observed with increased reaction time. The thermal properties, including melting temperature and enthalpy, of the amylosucrase-modified starches were higher than for the control starch. Although the amylosucrase-modified starches showed varying structural properties according to reaction time (1–45 h), their digestibilities did not change much after 6 h. By controlling the reaction time of the amylosucrase treatment, a tailored starchy food containing the desired amount of SDS can be produced.
    Food Chemistry 07/2014; 152:113–120. · 3.33 Impact Factor
  • Food science and biotechnology 02/2014; 23(1):23-31. · 0.70 Impact Factor
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    ABSTRACT: Understanding in vitro digestibility and release experiments with starch-entrapped calcium alginate microspheres provide the possibility of controlling starch digestibility in the human gastrointestinal tract. Native and amylosucrase (AS)-treated waxy corn starches (5000 U, 20 000 U, and control) were encapsulated with three different ratios of sodium alginate: 0.5, 0.7, and 1.0%. The slowly digestible and RS fractions of the encapsulated starch were 57.5 and 97.7%, respectively. After cooking, the proportions of these fractions still ranged from 55.7 to 96.1%, depending on the type of starch and concentration of sodium alginate, whereas the un-encapsulated starch contained between 2.9 and 48.3% slowly digestible and RS after cooking. In vitro release was studied in both uncooked and cooked encapsulated samples. When incubated in simulated gastric fluid, the beads swelled and started to float but did not erode, even after thermal treatment. Incubation in simulated intestinal and colonic fluids caused the beads to release starch in both uncooked and cooked starch-encapsulated samples. Encapsulated AS control and native waxy corn starch samples released much more starch than AS-modified starches. The total amount of starch released did not exceed 20% for uncooked samples and 25% for cooked samples.
    Starch - Starke 01/2014; 66(1-2). · 1.22 Impact Factor
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    ABSTRACT: Debranched water yam starch was subjected to repeated hydrothermal treatment (HTT), and its physicochemical and structural properties and digestion pattern were investigated. The B-type crystalline pattern of raw starch was recrystallized to B- and CA-type patterns by debranching and repeated HTT. The degree of relative crystallinity of debranched starch gradually increased and reached its maximum (43.3%) after five repetitions of HTT. The thermal transition temperatures and melting enthalpy of recrystallized starches increased progressively, reflecting the perfection of their crystalline structure, leading to the accumulation of boiling-stable crystalline structure under repeated HTT conditions. As a result, RS of HTT starches reached a very high level (>92.2%). The boiling-stable RS content depended on the repetition of this treatment and was maximized (81.0%) after five repetitions.
    Starch - Starke 07/2013; 65(7-8):679-685. · 1.22 Impact Factor
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    ABSTRACT: Forty-seven strains of Aspergillus oryzae isolates from Korean nuruks were compared for their brewing characteristics. A. oryzae YI-A6 and YI-A7 showed the highest acid α-amylase, glucoamylase, and carboxypeptidase activities, respectively. Sixteen isolates with high amylolytic or proteolytic enzyme activities were selected for investigation of their rice wine fermentation characteristics. After 12 days of brewing at 15°C, ethanol concentrations were 10.2–14.3% for A. oryzae strains. Fermentation rates were the highest for YI-A7. Most rice wine samples fermented with nuruk strains had lower concentrations of off-flavor compounds than the control did. All mean sensory attribute values significantly differed among samples. Pearson correlation coefficients showed that glucoamylase activity was positively correlated to both ethanol productivity and overall harmony (p<0.01). Thus, glucoamylase activity was identified as the best factor for screening Aspergillus strains for use in rice wine brewing.
    Food science and biotechnology 04/2013; 22(2):425-432. · 0.70 Impact Factor
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    ABSTRACT: Heat-moisture treatment (HMT) was optimised to increase the formation of slowly digestible starch (SDS) in waxy potato starch, and the structural and physiological properties of this starch were investigated. A maximum SDS content (41.8%) consistent with the expected value (40.1%) was obtained after 5 h 20 min at 120 °C with a 25.7% moisture level. Differential scanning calorimetry of HMT starches showed a broadened gelatinization temperature range and a shift in endothermal transition toward higher temperatures. After HMT, relative crystallinity decreased with increasing moisture level and X-ray diffraction patterns changed from B-type to a combination of B- and A-types. Hollow regions were found in the centres of HMT waxy potato starches. HMT intensity significantly influenced SDS level. This study showed that HMT-induced structural changes in waxy potato starch significantly affected its digestibility and the blood glucose levels of mice who consumed it.Highlights► We applied heat-moisture treatment (HMT) to waxy potato starch. ► Optimal conditions for HMT were established using response surface methodology. ► After HMT, starches with high SDS content were produced. ► HMT waxy potato starch was evaluated for its glucose response in mice.
    Food Chemistry 08/2012; 133(4):1222-1229. · 3.33 Impact Factor
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    ABSTRACT: Gelatinized water yam starch was subjected to hydrothermal treatment (25, 30, and 35% moisture content for 1, 8, 16, and 24 h at 100 °C) and characterized by X-ray diffractometry, solid-state ¹³C cross-polarization and magic-angle spinning nuclear magnetic resonance, differential scanning calorimetry, and digestibility analysis. The slowly digestible starch (SDS) content of the starch treated at 30% moisture content for 24 h reached 49.1%, 31.9% higher than that of the control starch. The B-type pattern of native starch was re-crystallized to the A-type by hydrothermal treatment. The SDS content showed negative correlations with T(o), T(p), T(c), and T(r), but showed a positive correlation with melting enthalpy. Furthermore, SDS was positively correlated with hydrothermal reaction time, moisture content, relative crystallinity, and the double-helix proportion. The structural changes in hydrothermally treated water yam starches resulted in the enhancement of SDS. PRACTICAL APPLICATION: The hydrothermally treated water yam starch could be used as a food ingredient for slow-energy supply or dietary fiber.
    Journal of Food Science 05/2012; 77(6):C574-C582. · 1.78 Impact Factor
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    ABSTRACT: The structural properties and digestibility of slowly digestible hydrothermally treated potato starch (SDS) were investigated. The potato starch with 20, 30 or 40% moisture content was heated at 100 °C for 30 min, and then kept at 30 °C or 70 °C for 12 h. The sample with 30% moisture content, heated and kept at 30 °C, produced the highest SDS content (37.5%). The modified products were analysed with scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry (DSC). The cross-section showed a large hollow area and X-ray patterns were altered from B- to a mixture of B- and A-type. DSC of the heated samples demonstrated a broader gelatinisation temperature range compared with the heated-and-stored samples. In vivo glucose responses with mice correlated with the in vitro starch digestibility experiments. This study showed that structural changes during hydrothermal treatment of potato starch significantly affected digestibility and blood glucose levels in mice.
    Carbohydrate Polymers 01/2011; 83(4):1879-1886. · 3.48 Impact Factor
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    ABSTRACT: This study investigated the technical feasibility of coating type 4 resistant starch (RS4) onto rice with the edible polymers locust bean gum (LBG) and agar. The coating solutions were prepared using LBG, agar, and a mixture of LBG and agar at three concentrations (0.01%, 0.1% and 1%). The raw milled rice was soaked in the prepared coating solutions, rolled in RS4 powder and dried. Microscopic observation revealed that the RS4 coating on the rice surface with 0.1% and 1% LBG–agar mixture had a resistance to washing and cooking and covered the whole surface of the rice with good adherence. The thickness of the RS4 coating on the rice surface with 0.1% and 1% LBG–agar mixture was approximately 74 and 233 μm, respectively. Compared with uncoated rice and rice mixed with RS4, the RS4-coated rice showed lower starch digestibility, a decreased glucose response and a slower rate of blood glucose decrease.
    International Journal of Food Science & Technology 12/2010; 45(12):2612 - 2621. · 1.24 Impact Factor
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    ABSTRACT: Enzymatic modification by amylosucrase (AS) from Neisseria polysaccharea was used on waxy rice, normal rice, waxy corn, normal corn, waxy potato, and normal potato starches to prepare the starches with a high content of slowly digestible starch (SDS) fraction. The AS-treated starches contained similar amounts of resistant starch, decreased rapidly digestible starch, and increased SDS compared to controls. After the AS treatment, the SDS contents increased by approximately 25% in waxy starches but about 8% in normal starches. The yields of the insoluble fraction of waxy starches were about 15% higher than those of normal starches. The branch chain length was increased by DP 13–19. The AS-treated starches showed a B-type X-ray diffraction pattern, 5–9 J/g for retrogradation enthalpy, 88–89 °C for peak temperature, and much larger moduli for their gels compared with raw starches.
    Carbohydrate Polymers 09/2010; 82(2):489-497. · 3.48 Impact Factor
  • Sang-Jun Lee, Tae Wha Moon, Jaehwan Lee
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    ABSTRACT: The explosive puffing process may provide characteristic physicochemical properties in red ginseng. The effects of explosive puffing on the changes of volatiles in red ginseng were investigated using headspace-solid phase microextraction (HS-SPME)-gas chromatograph (GC) with a mass selective detector (MS). Formation of porous structures and smaller pieces were clearly observed on the surface of puffed red ginseng by scanning electron microscopy. Total volatiles in puffed red ginseng increased by 87% compared to those in red ginseng. Hexanal, Delta-selinene, and beta-panasinsene were major volatiles in red ginseng, whereas aristolene, beta-panasinsene, and calarene were main volatiles in puffed red ginseng. Puffing process decreased volatiles from lipid oxidation including aldehydes, ketones, and 2-pentylfuran and increased terpenoids in red ginseng. Selective ion monitoring (SIM) mode for GC/MS results showed that 2-furanmethanol and maltol were present at the concentrations of 0.20% and 0.24%, respectively, in red ginseng and 5.86% and 3.99%, respectively, in puffed red ginseng. The explosive puffing process increased 2-furanmethanol and maltol in puffed red ginseng significantly (P < 0.05) with the changes of microstructures.
    Journal of Food Science 03/2010; 75(2):C147-51. · 1.78 Impact Factor
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    ABSTRACT: The structural characteristics of citric acid-treated rice starch, which was subjected to autoclaving and stored at a high temperature under acidic conditions, were investigated by high performance anion-exchange chromatography, multi-angle laser-light scattering, X-ray diffraction, differential scanning calorimetry (DSC), nuclear magnetic resonance, and scanning electron microscopy. The citric acid-treated rice starch contained chains of different lengths (DP 7−70) and had an A + V type polymorphism. The DSC thermogram of acid-treated rice starch showed a broad endothermic peak, which indicated that the structure of the acid-treated rice starch contained a number of double helices with various melting temperatures. Microscopic observation showed that the internal structure of the acid-treated starch displayed more or less spherical lumps that could be composed of short chains and amylose–lipid complex. The digestive properties of acid-treated rice starch were altered by heat processing such as cooking and autoclaving because crystalline regions were converted to amorphous regions or lamellae.
    Carbohydrate Polymers 10/2009; 78(3):588-595. · 3.48 Impact Factor
  • Ki Woo Kim, Seung Jun Choi, Tae Wha Moon
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    ABSTRACT: Charging artifacts and surface features of corn starch granules were investigated by scanning electron microscopy. Three types of industrial waxy corn starch granules with different levels of moisture content (0, 10.3, and 24.2%) were prepared and subjected to both secondary electron imaging and backscattered electron imaging. There were no significant charging artifacts in secondary electron images at 3 or 5 kV. However, imaging at higher magnifications and accelerating voltages much lower than 3 kV ranging from 0.1 to 1 kV did not show well-resolved structures. At higher accelerating voltages than 5 kV, charging was manifested as excessive brightness at specific areas and alteration of bright and dark lines in the direction of the raster pattern in secondary electron images of all the types of specimens tested. As the accelerating voltage increased up to 30 kV in secondary electron images, the charging also increased. Meanwhile, no charging was detected in all the backscattered electron images taken at different accelerating voltages. As the accelerating voltage increased in backscattered electron images, the resolution increased with less depth of focus. Consistent results were found in all the types of corn starch granules assayed in this study. These results suggest that a simple and rapid morphological analysis of moisturized starches can be performed by backscattered electron imaging without considerable heat drying of starches. Concomitantly, it allows for imposing a higher accelerating voltage to ensure better image resolution, facilitating morphological characterization of diverse starch granules as they are in native states.
    Micron 12/2008; 39(8):1160-1165. · 1.88 Impact Factor
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    ABSTRACT: Reaction conditions were optimized to increase the content of resistant starch in adlay starch using esterification with glutaric acid, and the physicochemical properties of the prepared glutarate starches were investigated. Different amounts of glutaric acid (0.1–0.5g/g starch, dry weight basis) were reacted with adlay starch at various temperatures (70–130°C) and reaction times (3–9h). The resistant starch levels increased with increased glutaric acid content, reaction temperature, and reaction time. The color difference was mainly affected by reaction time. The highest resistant starch content (RS 66%) was obtained using conditions of 0.4g glutaric acid/g starch, 115°C, and 7.5h, with a color difference of 10.24. After digestion with α-amylase and amyloglucosidase, the water-soluble fraction of glutarate starch had more oligosaccharides than high-amylose maize starch (RS 43%). FT-IR and solid-state NMR detected carbonyl groups in the glutarate starch, indicating the formation of cross-linkages through esterification. The granular structure of the glutarate starches was not destroyed and they retained birefringence. After heating with an excess of water, the granules kept their shape but lost their birefringence. The glutarate starches had low solubility in both cold and hot water, and the resistant starch contents were unchanged after heating due to the restriction of swelling by cross-linking. The glutarate starches had a similar chain-length distribution to raw starch, indicating that acid hydrolysis took place at branching points in the amorphous region. Furthermore, the glutarate starches possessed a weaker crystalline region, more diverse double helical chains, and lower enthalpy than raw starch.
    Carbohydrate Polymers 11/2008; 74(4):787-796. · 3.48 Impact Factor
  • Food science and biotechnology 08/2008; 17(4):705-712. · 0.70 Impact Factor
  • S J Choi, S E Lee, T W Moon
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    ABSTRACT: We examined the effects of NaCl and glucose on cold-set ovalbumin gelation. Cold-set gels were prepared by adding glucono-delta-lactone (GDL) to a 2% heated ovalbumin solution. For the gel prepared from ovalbumin heat-denatured with NaCl and glucose, the gel with 10 mM NaCl was most transparent and had high gel strength. Its maximum complex shear modulus (G*) and turbidity were 2.5 times greater and 3 times lower, respectively, than those of the gel without NaCl. The turbidity of the gel with the higher NaCl content increased steeply after the addition of GDL and did not change during the experimental period. The maximum G* of the gel exhibited positive correlations with the molar mass, radius, and surface hydrophobicity of soluble aggregates and the NaCl content, but the turbidity exhibited negative correlations with these factors. The presence of glucose did not significantly affect the turbidity or rheological properties of the gel. For the gel prepared by adding NaCl and glucose with GDL, the presence of glucose did not affect the turbidity, but the maximum G* decreased in inverse proportion to the glucose content. The turbidity of the gel with higher NaCl content (>or= 50 mM) was the greatest among all samples, and the increased turbidity was maintained throughout the measurements. The gels with 50 and 100 mM NaCl exhibited thixotropy during shearing at a constant shear rate. Therefore, the presence of NaCl and glucose during cold gelation could facilitate the preparation of cold-set gels having various properties for food applications.
    Journal of Food Science 07/2008; 73(5):C313-C322. · 1.78 Impact Factor
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    ABSTRACT: Corn starch was converted using alpha-1,4-glucanotransferase from Thermotoga maritima (Tm alpha GT), a hyperthermophilic bacterium, without inducing gelatinization, and the structural changes and physical properties of the modified starches were investigated. Enzyme modification was induced at 65 degrees C for 8, 16, or 24 h, and the morphology of the modified starches was observed with light and scanning electron microscopy. Granule integrity was mostly maintained after enzyme treatment, although some granules were partially fragmented as evidenced by enlarged surface pores and some cracks. The modified starches had lower apparent amylose levels than raw starch. The molecular weights of amylose and amylopectin molecules in the treated starches were lower than those of raw starch, and the amount of branched molecules, which had much lower molecular weights, also increased in the treated starches. The chain-length distribution of amylopectin showed an increased number of shorter branched chains. The modified starches showed a wider melting temperature range and a lower melting enthalpy than that of raw starch. The X-ray diffraction pattern of the modified starches showed typical A-type starch peaks, but the relative crystallinities were lower than that of raw starch. The solubility and paste clarity of the modified starches were much higher than those of raw starch. The modified starch gels maintained their rigidity over the whole frequency range tested and showed thermoreversibility between 4 and 75 degrees C. These results suggest that Tm alpha GT can be used to produce granular corn starch, which contains amylose and amylopectin having lower molecular weights and a thermoreversible gelation property.
    Journal of Food Science 05/2008; 73(3):C158-C166. · 1.78 Impact Factor
  • S J Choi, T W Moon
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    ABSTRACT: The molecular characteristics of ovalbumin aggregates formed by heating with NaCl and glucose were investigated with a multi-angle laser light scattering system. The presence of NaCl and glucose affected the formation and molecular structure of the aggregates. Specifically, glucose increased the denaturation temperature of ovalbumin due to thermal stabilization of the native state of ovalbumin, regardless of the content of added NaCl. The surface hydrophobicity of the aggregates was increased by the addition of NaCl, which induced the denaturation of ovalbumin at a lower temperature. Aggregates with a larger weight-average molar mass (M(w)) and root mean square radius (R(g)) formed from heat-denatured ovalbumin with NaCl and glucose. The presence of NaCl during heat denaturation caused the formation of aggregates with a larger M(w) (1.9 x 10(5) and 3.5 x 10(6) g/mol for 0 and 10 mM NaCl, respectively) and R(g) (14.8 and 80.4 nm for 0 and 10 mM NaCl, respectively). Over a certain amount of NaCl, the addition of more glucose resulted in the formation of more aggregates with greater M(w) and R(g) values. In sum, the thermostability of ovalbumin was affected primarily by glucose, but the molecular characteristics of the soluble aggregates formed by heat denaturation varied primarily with NaCl content.
    Journal of Food Science 04/2008; 73(2):C41-C49. · 1.78 Impact Factor
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    Cereal Chemistry 01/2008; 85(1):65-69. · 1.25 Impact Factor
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    ABSTRACT: The Arabidopsis AHL gene encodes a 3'(2'),5'-bisphosphate nucleotidase (BPNTase) involved in the reductive sulfate activation pathway. A bacterial expression vector containing AHL cDNA was randomly mutagenized with hydroxylamine and transformed into the E. coli cysteine auxotrophic mutant cysQ. Bacterial colonies that did not show evidence of complementation, i.e. those that exhibited slower growth on cysteine-free medium, were selected for further study. Sequencing of the AHL cDNA in one such clone revealed the conversion of cytosine 635 (C635) to thymine, resulting in an Alanine (A212) to Valine substitution. This microbial complementation procedure is useful in BPNTase structure-activity studies for biotechnological applications.
    Biotechnology Letters 07/2007; 29(6):913-8. · 1.85 Impact Factor

Publication Stats

377 Citations
84.36 Total Impact Points

Institutions

  • 1999–2014
    • Seoul National University
      • • Department of Agricultural Biotechnology
      • • National Instrumentation Center for Environmental Management - NICEM
      • • Department of Food and Animal Biotechnology
      Sŏul, Seoul, South Korea
  • 2006–2008
    • University of Seoul
      Sŏul, Seoul, South Korea