• Food Science and Biotechnology
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• 제15권4호
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• pp.499-505
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• 2006

Clostridium botulinum spores are widely distributed in nature. Type A and proteolytic type B bacteria produce heat-resistant spores that are primarily involved in most of the food-borne botulism outbreaks associated with low-acid canned foods. Food-borne botulism results from the consumption of food in which C. botulinum has grown and produced neurotoxin. Growth and toxin production of type A and proteolytic type B in canned foods can be prevented by the use of thermal sterilization alone or in combination with salt and nitrite. The hazardousness of C. botulinum in low-acid canned foods can also be reduced by preventing post-process contamination and introducing hazard analysis and critical control point (HACCP) practices during production. Effectiveness of non-thermal technologies such as high pressure processing with elevated process temperatures on inactivation of spores of C. botulinum will be discussed.

• 한국축산식품학회지
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• 제32권6호
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• pp.713-717
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• 2012

The objective of this study was to evaluate the effect of sodium habituation on thermal resistance of Staphylococcus aureus in various ready-to-heat (RTH) sauces. The strain mixture of S. aureus strains KACC10768, KACC10778, KACC11596, KACC13236 and NCCP10862 was habituated up to 9% of NaCl. The inocula of NaCl-habituated and non-habituated S. aureus were inoculated in 5 g portions of pork cutlet, meat and Carbonara sauces at 7 Log CFU/g, and the samples were vortexed vigorously. The inoculated samples were then exposed to 60 and $70^{\circ}C$ in a water-bath, and survivals of total bacteria and S. aureus were enumerated on tryptic soy agar and mannitol salt agar, respectively, every 30 min for 120 min. At 60oC, the cell counts of total bacteria and the significant difference in survivals between sodium-habituated and non-habituated S. aureus were observed only in the Carbonara sauce; the tailing effect, which is the period of no reduction of bacterial cell counts, was observed in pork cutlet, meat and Carbonara sauces subjected to $60^{\circ}C$. At $70^{\circ}C$, total bacterial populations and sodium-habituated and non-habituated S. aureus cell counts in meat and Carbonara sauce also significantly decreased (p<0.05) after 30 min of heat treatment, followed by the obvious tailing effect. Sodium-habituated S. aureus cell counts in meat and Carbonara sauces were higher (p<0.05) than those of non-habituated S. aureus at $70^{\circ}C$. The results indicate that sodium habituation of S. aureus cells may increase the thermal resistance of the pathogen in RTH sauces; moreover, heating RTH sauces for a short time before serving may not sufficiently decrease the cell counts of S. aureus, particularly for sodium-habituated strain.

• Journal of Microbiology and Biotechnology
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• 제20권7호
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• pp.1077-1085
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• 2010

With an emphasis on its thermal behavior with different pHs and salts, the kinetic and thermodynamic parameters of the purified polygalacturonase (PG) from E. carotovora subsp. carotovora (Ecc) BR1 were studied, as the characterization of an enzyme is significant in the context of burgeoning biotechnological applications. The thermodynamic parameters for polygalacturonic acid hydrolysis by the purified PG were ${\Delta}H^*$=7.98 kJ/mol, ${\Delta}G^*$=68.86 kJ/mol, ${\Delta}S^*$=-194.48 J/mol/K, ${\Delta}G_{E-S}$=-1.04 kJ/mol, and ${\Delta}G_{E-T}$=-8.96 kJ/mol. In addition, its turnover number ($k_{cat}$) was 21/sec. The purified PG was stable within a temperature range of $20-50^{\circ}C$ and was deactivated at $60^{\circ}C$ and $70^{\circ}C$. The thermodynamic parameters (${\Delta}H^*$, ${\Delta}G^*$, ${\Delta}S^*$) for the irreversible inactivation of the PG at different temperatures ($30-60^{\circ}C$) were determined, where the effectiveness of various salts and different pHs (4-8) for the thermal stability of the PG were also characterized. The efficacy of various salts for the thermal stability of the PG was in the following order: $MgCl_2$ > $BaCl_2$ > KCl > $CaCl_2$ >NaCl. Therefore, the present work presents the biochemical, substrate hydrolysis thermodynamics and the thermal stabilization parameters of the PG from Ecc.

• 한국식품위생안전성학회지
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• 제23권2호
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• pp.157-162
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• 2008

열수(Hot water)를 이용 조제분유 및 선식 준비 시 살균효과를 실험한 결과 $60^{\circ}C$ 이상에서 살균 효과를 나타내었으나 조제분유와 선식에 열수를 가하였을 때 발생하는 온도 저하와 조제분유 및 선식 등의 분말 식품에서 biofilm을 생산하여 내열성이 증가되는 E. sakazakii의 특성을 고려하여 $70^{\circ}C$ 이상의 열수로 조제분유 및 선식 등을 용해하여야 할 것으로 판단된다. 마이크로웨이브를 이용 E. sakazakii의 살균 효과를 실험한 결과 E. sakazakii를 제어하기 위하여 100 mL의 경우 90초 이상 가열하거나 온도측정이 곤란한 경우에는 최초 끓는 시점까지 가열한 후 냉각하여 섭취하여야할 것으로 조사되었다. 용해된 조제분유 및 선식의 저장 안정성을 평가하기 위해 $5{\sim}35^{\circ}C$에 48시간 동안 보관하며 E. sakazakii의 성장곡선을 실험한 결과 $5^{\circ}C$, $10^{\circ}C$ 냉장온도에서는 48시간까지 증식이 미약하였다. 그러나 냉장 온도에서 사멸하지 않고 미약하게 증식하는 E. sakazakii의 특성을 고려하여 조제분유 및 선식의 냉장 보관은 24시간 이내로 제한하여 섭취하여야 할 것으로 판단된다.

• 한국식품과학회지
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• 제47권5호
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• pp.593-598
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• 2015

This study determined the thermal resistance of Bacillus cereus, Escherichia coli O157:H7, and Listeria monocytogenes in multi-grain soymilk and proposes processing conditions that meet the national standard for retort food products in Korea. D and z values were calculated from thermal inactivation kinetic curves after heating at 55, 60, and $65^{\circ}C$. The D value for B. cereus at $55^{\circ}C$ was the highest (22.8 min), followed by that for E. coli O157:H7 (18.8 min) and L. monocytogenes (17.6 min). At $60-65^{\circ}C$, the order was L. monocytogenes ($D_{60-65^{\circ}C}=3.4-0.9min$), E. coli O157:H7 (3.0-0.3 min), and B. cereus (1.2-0.3 min). The z values for these species were 5.2, 5.5, and $7.7^{\circ}C$, respectively. The Korean national standard for retort food products was achieved by thermal processing at $124{\pm}2^{\circ}C$ for 0.3-2.2 min. This study provides useful data for ensuring both the microbiological safety and product quality of multi-grain soymilk products.

• 한국식품과학회지
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• 제12권3호
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• pp.209-215
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• 1980

파파이야 라텍스를 $(NH_4)_2SO_4$,분획 및 CM-cellulose column을 통과시켜 두개의 획분으로 분리하고 각 획분 별로 pH 7.0, $60{\sim}90^{\circ}C$에서 열 불활성 실험을 행하고 다음과 같은 열역학적인 자료를 얻었다. 1. fraction I 의 z-value는 $25^{\circ}C$이었고 $70^{\circ}C$에서 활성화 엔탈피 (enthalpy of activation) 89.5 kJ/mol, 활성화엔트로피 (entropy of activation) -44.0 kJ/mol K, 활성화 자유에너지(free energy of activation) 104.6 kJ/mol이었다. 2. fraction II 의 z-value는 $23^{\circ}C$이고 $70^{\circ}C$에서 활성화 엔트로피 -22.0 kJ/mol K, 활성화 자유에너지 104.2 kJ/mol이었다. 3. fraction I과 fraction II를 혼합한 경우의 z-value는 $24.6^{\circ}C$, $70^{\circ}C$에서 활성화 엔탈피 90.9 kJ/mol, 활성화 앤트로피 -38.8 J/mol K, 활성화 자유에너지 104.2 kJ/mol이었다. 4. 조 추출액의 z-value는 $23.2^{\circ}C$이고 $70^{\circ}C$에서 활성화 엔트로피 113.8 kJ/mol, 활성화 엔트로피 22.0 kJ/mol K, 활성화자유에너지 106.2 kJ/mol이었다. 이상의 결과에서 fraction I 이 fraction II 보다 열에 안정하다고 볼 수 있었고 파파이야 라텍스에 있는 단백질 분해 효소의 열 안정성은 주로 fraction I 에 기인하는 것 을 알 수 있었다.

• 한국식품과학회지
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• 제34권6호
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• pp.1067-1072
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• 2002

팽이 및 만가닥버섯의 가공 기술 개발의 일환으로 수행되진 본 연구는 가공 전 처리 공정으로서의 blanching 조건을 확립하기 위해 두 버섯 peroxidase의 열적 특성 결과를 기초 자료로 삼았다. 효소 활성 측정은 Gorin과 Heidema의 방법을 변형하여 사용하였고, 생 버섯으로부터 추출한 조효소핵을 열처리했을 경우 팽이버섯은 $75^{\circ}C$, 3분, 만가닥버섯의 경우 $80^{\circ}C$, 1분 이상의 온도, 시간 조건에서 peroxidase의 불활성이 유발됨을 알았다. 이때 팽이 및 만가닥버섯 peroxidase의 활성에너지$(E_a)$는 59.58 kcal/mol, 43.05 kcal/mol이며 z값은 $9.0^{\circ}C,\;12.4^{circ}C$였다. 반면 Blanching에 의한 두 버섯 peroxidase의 활성화에너지($E_a$)와 z값은 각각 7.97 kcal/mol, 6.55 kcal/mol와 $59.8^{\circ}C,\;74.1^{circ}C$로 나타났다. 이는 peroxidase 자체의 열적 특성과 blanching에 의해 유발된 peroxidase의 열적 특성이 다르다는 것을 보여주는 것으로 blanching시에는 버섯자체와 버섯내의 성분들에 의해 열에 대한 저항성이 증대되어 z값이 높아지는 결과를 유발, 활성화에너지($E_a$)가 감소하는 결과로 나타났다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.30-33
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• 2004

Shallow p+-n junctions were formed by low-energy ion implantation and dual-step annealing processes The dopant implantation was performed into the crystalline substrates using $BF_2$ ions. The annealing was performed with a rapid thermal processor and a furnace. FA+RTA annealing sequence exhibited better junction characteristics than RTA+FA thermal cycle from the viewpoint of junction depth. A new simulator is designed to model boron diffusion in silicon, which is especially useful for analyzing the annealing process subsequent to ion implantation. The model which is used in this simulator takes into account nonequilibrium diffusion, reactions of point defects, and defect-dopant pairs considering their charge states, and the dopant inactivation by introducing a boron clustering reaction. Using a resonable parameter values, the simulator covers not only the equilibrium diffusion conditions but also the nonequilibrium post-implantation diffusion. Using initial conditions and boundary conditions, coupled diffusion equation is solved successfully. The simulator reproduced experimental data successfully.

• 한국축산식품학회지
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• 제39권6호
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• pp.863-876
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• 2019

The thermal-death times of Listeria monocytogenes were determined in inoculated restructured goat steak at 60℃, 65℃, and 70℃ of sous-vide temperatures. D-values of L. monocytogenes in inoculated restructured goat steak ranged from 7.27 min at 60℃ to 0.46 min at 70℃. Times need to yield at least a 6 log reduction of L. monocytogenes at their temperatures for this product were 47, 12, and 3 min, respectively. After sous-vide, all microbial counts in non-inoculated samples were not detectable, except the aerobic and anaerobic mesophilie and lactic acid bacteria counts were lower than 2 Log CFU/g. For sous-vided and grilled sous-vided samples, sous-vide loss and surface shrinkage were the lowest in samples sous-vided at 60℃ for 47 min (p<0.05). These samples demonstrated the lowest CIE L^*, shear force, hardness, gumminess and chewiness and the highest CIE a^* and hue angle (p<0.05). Therefore, sous-vide at 60℃ for 47 min provided convenient ready-to-cook restructured goat steak for microbiology safety and optimization of physicochemical quality.

• KSBB Journal
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• 제13권5호
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• pp.502-510
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• 1998

Stabilization of antibody, which is specific to Salmonella typhimurium antigens, present in dry states on membranes was accomplished, and its shelf-life, i.e., duration for maintaining minimum 90% of the initial activity, under optimal conditions was determined. To prepare two major components of an immuno-strip, the antibody was not only immobilized on nitrocellulose membrane surfaces but also placed within the pores of glass fiber membrane after conjugating it with old colloids as signal generator. Among potential stabilizers of the immuno-components, a disaccharide, trehalose, showed a significant protection effect of immunoglobulin structure from thermal energy. Optimal concentrations of trehalose for the respective component were significantly different (8-fold higher for the antibody-gold conjugate than for the immobilized antibody), which probably resulted from distinct densities and configurations of antibody present on the membranes. An additional requirement for the gold conjugate was freeze-drying of this substance such that the conjugate can be readily resolubilized upon contact with aqueous medium. By using the components prepared under optimal conditions, immuno-strips were constructed and exposed to thermal energy. Signals with less than 10% decrease in the intensity were maintained for approximately 21 days at 60$^{\circ}C$. Compared to previous reports, this result represented a 2-year shelf-life at room temperature. it was, however, two times longer if determined from thermal acceleration tests based on the theory of inactivation rate of protein. Such discrepancy between the two estimates could be mainly attributed to errors in accurately controlling temperatures and also to changes in the physical properties of membranes due to a high thermal energy.