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Effect of continuous pulsed electric fields treatments on quality of apple juice (사과주스의 품질에 미치는 pulsed electric field 연속 처리효과)

  • Ahn, Seong-Hwan;Lim, Jeong-Ho;Kim, Young-Ho;Chung, Suk Jin;Park, Kee-Jai
    • Korean Journal of Food Preservation
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    • v.20 no.5
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    • pp.650-658
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    • 2013
  • Apple juices were sterilized by continuous pulsed electric field (PEF) treatments of pulse width of 25 ${\mu}s$ at electric field intensity of 20.0 kV/cm, and with the varied pulse frequencies of 35 Hz (40 kJ/L), 55 Hz (70 kJ/L), 72 Hz (100 kJ/L) and 85 Hz (130 kJ/L). The PEF treatments of apple juice reduced the microbial counts from 5.3 log CFU/mL of initial state to 3.0 log CFU/mL after PEF treatment at energy density of 130 kJ/L. Also yeast and fungi after PEF treatments were reduced from 5.3 log CFU/mL to 3.0 log CFU/mL and Escherichia coli were from 5.3 log CFU/mL of initial state to 4.7 log CFU/mL to < $10^1$ CFU/mL. The soluble solids and free sugars did not significantly differ (p<0.05) depending on conditions of PEF treatment. The total phenolic contents and antioxidant activity such as the DPPH and ferric reducing antioxidant power (FRAP) by PEF treatments were significantly partly reduced, but the PEF-reduced value came in smaller quantities than the heat treatment at $65^{\circ}C$. The iterative PEF treatments with pulse width of 25 ${\mu}s$ and pulse frequency of 85 Hz at electric field intensity of 20.0 kV/cm showed limited in microbial reduction. Also, total phenolic contents and antioxidant activity such as DPPH and FRAP, significantly decreased depending on treatment numbers of PEF (p<0.05).

ON THE MEAN VALUES OF DEDEKIND SUMS AND HARDY SUMS

  • Liu, Huaning
    • Journal of the Korean Mathematical Society
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    • v.46 no.1
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    • pp.187-213
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    • 2009
  • For a positive integer k and an arbitrary integer h, the classical Dedekind sums s(h,k) is defined by $$S(h,\;k)=\sum\limits_{j=1}^k\(\(\frac{j}{k}\)\)\(\(\frac{hj}{k}\)\),$$ where $$((x))=\{{x-[x]-\frac{1}{2},\;if\;x\;is\;not\;an\;integer; \atop \;0,\;\;\;\;\;\;\;\;\;\;if\;x\;is\;an\;integer.}\$$ J. B. Conrey et al proved that $$\sum\limits_{{h=1}\atop {(h,k)=1}}^k\;s^{2m}(h,\;k)=fm(k)\;\(\frac{k}{12}\)^{2m}+O\(\(k^{\frac{9}{5}}+k^{{2m-1}+\frac{1}{m+1}}\)\;\log^3k\).$$ For $m\;{\geq}\;2$, C. Jia reduced the error terms to $O(k^{2m-1})$. While for m = 1, W. Zhang showed $$\sum\limits_{{h=1}\atop {(h,k)=1}}^k\;s^2(h,\;k)=\frac{5}{144}k{\phi}(k)\prod_{p^{\alpha}{\parallel}k}\[\frac{\(1+\frac{1}{p}\)^2-\frac{1}{p^{3\alpha+1}}}{1+\frac{1}{p}+\frac{1}{p^2}}\]\;+\;O\(k\;{\exp}\;\(\frac{4{\log}k}{\log\log{k}}\)\).$$. In this paper we give some formulae on the mean value of the Dedekind sums and and Hardy sums, and generalize the above results.

Effect of Combined Treatment of Aqueous Chlorine Dioxide with Ultraviolet-C on the Quality of Red Chicory and Pak Choi during Storage (이산화염소수와 Ultraviolet-C 병합 처리에 따른 레드 치커리와 청경채의 저장 중 품질에 미치는 영향)

  • Kim, Hyun-Jin;Song, Hyeon-Jeong;Song, Kyung-Bin
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.40 no.2
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    • pp.245-252
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    • 2011
  • The combined effects of 10 kJ/$m^2$ ultraviolet-C (UV-C) with 50 ppm aqueous chlorine dioxide ($ClO_2$) on the qualities of red chicory and pak choi were examined. After the treatment, the samples were stored at $4{\pm}1^{\circ}C$ for 7 days. The combined treatment of $ClO_2$/UV-C reduced the initial populations of total aerobic bacteria in the red chicory and pak choi by 2.64 and 2.55 log CFU/g, respectively, compared to those of the control. Also, the populations of yeast and molds in the red chicory and pak choi by combined treatment were reduced by 2.41 and 2.00 log CFU/g, respectively. In addition, after 7 days of storage the total aerobic bacteria populations in the red chicory and pak choi were reduced to 3.71 and 3.93 log CFU/g, compared to 6.31 and 6.62 log CFU/g for the control, resulting in a significant decrease. Hunter L, a, and b values of red chicory and pak choi were not significantly different among the treatments. Non-thermal treatment caused a negligible change in sensory evaluation. These results suggest that the combined treatment of 50 ppm $ClO_2$ with 10 kJ/$m^2$ UV-C can be useful for maintaining the qualities of red chicory and pak choi.

Inactivation of Escherichia coli, Saccharomyces cerevisiae, and Lactobacillus brevis in Low-fat Milk by Pulsed Electric Field Treatment: A Pilot-scale Study

  • Lee, Gun Joon;Han, Bok Kung;Choi, Hyuk Joon;Kang, Shin Ho;Baick, Seung Chun;Lee, Dong-Un
    • Food Science of Animal Resources
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    • v.35 no.6
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    • pp.800-806
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    • 2015
  • We investigated the effects of a pulsed electric field (PEF) treatment on microbial inactivation and the physical properties of low-fat milk. Milk inoculated with Escherichia coli, Saccharomyces cerevisiae, or Lactobacillus brevis was supplied to a pilot-scale PEF treatment system at a flow rate of 30 L/h. Pulses with an electric field strength of 10 kV/cm and a pulse width of 30 µs were applied to the milk with total pulse energies of 50-250 kJ/L achieved by varying the pulse frequency. The inactivation curves of the test microorganisms were biphasic with an initial lag phase (or shoulder) followed by a phase of rapid inactivation. PEF treatments with a total pulse energy of 200 kJ/L resulted in a 4.5-log reduction in E. coli, a 4.4-log reduction in L. brevis, and a 6.0-log reduction in S. cerevisiae. Total pulse energies of 200 and 250 kJ/L resulted in greater than 5-log reductions in microbial counts in stored PEF-treated milk, and the growth of surviving microorganisms was slow during storage for 15 d at 4℃. PEF treatment did not change milk physical properties such as pH, color, or particle-size distribution (p<0.05). These results indicate that a relatively low electric-field strength of 10 kV/cm can be used to pasteurize low-fat milk.

Logarithmic temperature dependence of resistivity in CVD graphene

  • Takehana, Kanji;Imanaka, Yasutaka;Watanabe, Eiichiro;Oosato, Hirotaka;Tsuya, Daiju;Kim, Yongmin;An, Ki-Seok
    • Current Applied Physics
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    • v.17 no.4
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    • pp.474-478
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    • 2017
  • Logarithmical increase of the longitudinal resistivity (${\rho}_{xx}$) between 10 K and 80 K and its saturation at low temperature were observed in the graphene synthesized by the chemical vapor deposition (CVD) with various applied gate voltage. In the two-dimensional system, it is considerably difficult to identify the origin of the logarithmic temperature (Log-T) increase of the resistivity, because there are three corrections to exhibit the Log-T behavior: the weak localization, the electron-electron interaction (EEI) in the disordered system and the Kondo effect. In order to distinguish the origin of the Log-T behavior, we contrived a new method utilizing the magnetotransport property in tilted magnetic fields. As a result, we have assigned the Log-T behavior in the CVD graphene to the correction of the EEI.

Stability of Tris(2-cyclohexylaminoethyl)amine-Zn(II) Complex (Tris(2-cyclohexylaminoethyl)amine-Zn(II) 착물의 안정성)

  • Yong Woon Shin;Hyun Sook Baek;Jae-Kyung Yang;Jineun Kim;Moo Lyong Seo
    • Journal of the Korean Chemical Society
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    • v.47 no.2
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    • pp.121-126
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    • 2003
  • Tris(2-cyclohexylaminoethyl)amine (L) was synthesized by the Schiff base condensation reaction of tris(2-aminoethyl)amine with cyclohexanone, followed by reduction. The thermodynamic characteristics, mole ratio and formation constant of [Zn(II)-L] complex were measured by the cyclic voltammetry and isothermal titration. In the case of Zn(II), well-defined cathodic and anodic peak were obtained at -1.02V and -0.48V vs Ag/AgCl , respectively. For the [Zn(II)-L] complex, both peaks were obtained at -1.19V and -0.45V vs Ag/AgCl, respectively. In addition, the peak height gradually increases as the scan rate increases, suggesting that the currents obtained were diffusion - controlled. The mole ratio and stability constant of the complex measured cyclic voltammerty were 1:1 and logK$_f$= 5.8, respectively. And the mole ratio and stability constant of the complexe calculated by isothermal titration method was 1:1 and logK =5.4, respectively. ${\Delta}$H, ${\Delta}$G and T${\Delta}$S for the complex formation were -53.0 kJ/mol, -31.1 kJ/mol, and -21.9 J/K at 25 ${\circ}$C, respectively.

Effect of UV-C Irradiation on Inactivation of Escherichia coli O157:H7 and Listeria monocytogenes on Washed Carrot during Storage (UV-C 조사가 세척 당근의 저장 중 E. coli O157:H7과 Listeria monocytogenes의 생육저해 및 품질에 미치는 영향)

  • Kim, Ju-Yeon;Kim, Eun-Kyo;Shin, Cho-Long;Song, Kyung-Bin
    • Korean Journal of Food Preservation
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    • v.16 no.5
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    • pp.636-643
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    • 2009
  • Inactivation by UV-C irradiation of Escherichia coli O157:H7 and Listeria monocytogenes inoculated onto washed carrots was examined. Carrot samples were inoculated with 6-7 log CFU/mL of E. coli O157:H7 or L. monocytogenes, treated with doses of 0, 1, 3, 5, or $10\;kJ/m^2$ UV-C, and stored at $4{\pm}1^{\circ}C$ for 8 d. The populations of E. coli O157:H7 and L. monocytogenes significantly decreased with increasing irradiation dose (p<0.05). In particular, E. coli O157:H7 and L. monocytogenes populations fell significantly by 2.35 and 2.38 log CFU/g at $10\;kJ/m^2$, respectively, compared to control values. UV-C irradiation inhibited color changes and decreased the whiteness index in carrot during storage, compared to controls. Sensory evaluation results showed that UV-C-treated carrots had better sensory characteristics than did the control. Therefore, the results suggest that UV-C irradiation could be useful to improve the microbial safety and sensory qualities of fresh-cut carrots during storage.

Constituents of the Aerial Parts of Lonicera etrusca Growing in Saudi Arabia

  • Alqasoumi, Saleh I.;Al-Rehaily, Adnan J.;Abdel-Kader, Maged S.
    • Natural Product Sciences
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    • v.15 no.3
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    • pp.121-124
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    • 2009
  • Phytochemical investigation of the aerial parts of Lonicera etrusca resulted in the isolation of three iridoids including two aglycones, loganin aglycone (log-1) (1) and lonicerin (log-2) (2), and the known common glycoside loganin (4). The study also afforded a coumarin derivative, 7-hydroxycoumarin (3), and a flavonoid glycoside, luteolin-7-O-$\beta$-D-glucoside (5). The structures were determined utilizing physical, chemical and spectral methods.

Effect of UV-C Irradiation on the Inactivation of Listeria monocytogenes and Lipid Oxidation in Hamburger Patties during Storage (UV-C 조사가 햄버거 패티 저장 중 Listeria monocytogenes의 생육저해 및 지질산화에 미치는 영향)

  • Kim, Hyun-Jin;Kim, Seul-Ki;Chun, Ho-Hyun;Song, Kyung-Bin
    • Korean Journal of Food Preservation
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    • v.17 no.3
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    • pp.425-429
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    • 2010
  • Inactivation by UV-C irradiation of Listeria monocytogenes cocktail inoculated on hamburger patties was examined. Hamburger patty samples were inoculated with 6-7 log CFU/mL of L. monocytogenes cocktail, and then exposed to doses of 0, 1, 5, or $10kJ/m^2$ of UV-C light, followed by storage at $4{\pm}1^{\circ}C$ for 7 d. Microbiological evaluation indicated that the populations of L. monocytogenes decreased significantly (p<0.05) as irradiation dose increased. In particular, L. monocytogenes populations decreased by 2.03 log CFU/g after exposure to 10 $kJ/m^2$, compared with control samples. The thiobarbituric acid-reactive substance levels of hamburger patty samples increased during storage, regardless of UV-C irradiation status. These results indicate that UV-C irradiation may be useful in improving the microbial safety of hamburger patties during storage.

Effect of UV-C Irradiation on the Quality of Red Pepper Powder during Storage (UV-C 조사가 고춧가루의 저장 중 품질에 미치는 영향)

  • Chun, Ho-Hyun;Kim, Ju-Yeon;Kim, Hyun-Jin;Song, Kyung-Bin
    • Korean Journal of Food Preservation
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    • v.16 no.3
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    • pp.454-458
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    • 2009
  • The effect of UV-C irradiation on microbial growth and quality of red pepper powder during storage was examined. Red pepper powder was irradiated with doses of 27, 54, or $108\;kJ/m^2$ and stored at $20^{\circ}C$ for 4 weeks. UV-C treatment of red pepper powder decreased the populations of total aerobic bacteria and Bacillus cereus in proportion to radiation dose. In particular, total aerobic bacteria and B. cereus populations decreased by 1.03 and 0.90 log CFU/g after irradiation at $108\;kJ/m^2$, respectively, compared with control values. UV-C irradiation caused negligible changes in the Hunter color L, a, or b values. Sensory quality results on red pepper powder were not significantly different between treatments. Therefore, UV-C irradiation can be used to inhibit microbial growth in red pepper powder, without impairing quality during storage.