호화점 이하에서 옴가열이 감자 전분의 열적특성에 미치는 영향

차윤환,Cha, Yun-Hwan 한국식품영양학회 2012 韓國食品營養學會誌 Vol.25 No.4

Ohmic heating uses electric resistance heat which occurs equally and rapidly inside of food when electrical current is flown into. In other study, we researched about soybean protein's characteristic changes by ohmic heating. Nevertheless treated same temperature, denaturation of soybean protein were accelerated by ohmic heating than conventional heating. In this time, we studied thermal property change of potato starch by ohmic heating besides conventional heating. For this purpose, potato starch was heated at same subgelatinization temperature by ohmic and conventional heating. And thermal properties were tested using DSC. Annealing of starch is heat treatment method that heated at 3~4% below the gelatinization point. DSC analysis results of this study, the $T_o$, $T_p$, $T_c$ of potato starch levels were increased, whereas $T_c{\sim}T_o$ was narrowed. This thermal property changes appear similar to annealing's result. It is thought the results shown in this study, because the heating from below the gelatinization point. 6, 12, 24, 72, and 120 hours heating at $55^{\circ}C$ for potato starch, $T_o$, $T_p$, $T_c$ values continue to increased with heating time increase. The gelatinization temperature of raw potato starch was $65.9^{\circ}C$ and the treated starch by conventional heating at $55^{\circ}C$ for 120 hr was $72^{\circ}C$, ohmic was $76^{\circ}C$. The gelatinization range of conventional (72 hr) was $10^{\circ}C$, ohmic was $8^{\circ}C$. In case of 24 hours heating at 45, 50, 55, 60, $65^{\circ}C$ for potato starch, the result was similar to before. $T_o$, $T_p$, $T_c$ values continue to increased and gelatinization range narrowed with heating temperature increase. In case of conventional heating at $60^{\circ}C$, the results of gelatinization temperature and range were $70.1^{\circ}C$ and $9.1^{\circ}C$. And ohmic were $74.4^{\circ}C$ and $7.5^{\circ}C$. When viewed through the results of the above, the internal structure of starch heated by ohmic heating was found that the shift to a more stable form and to increase the homology of the starch internal structure.

Comparison of pH effects on ohmic heating and conventional heating for inactivation of Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium and Listeria monocytogenes in orange juice

Kim, S.S.,Kang, D.H. Academic Press, etc 2015 FOOD SCIENCE AND TECHNOLOGY -ZURICH- Vol.64 No.2

The objective of the current study is to identify the influence of acidity on ohmic heating compared to conventional heating for inactivation of food-borne pathogens in orange juice. For conventional heating, the heating rate was not significantly different (P > 0.05) regardless of pH and pathogens were inactivated more effectively at lower pH. However, different patterns were observed for ohmic heating. Although temperature and electrical conductivity were not greatly affected by lowering pH, temperature increased more rapidly with increasing pH due to higher electrical conductivity. Also, the inactivation patterns were significantly different (P < 0.05) from conventional heating. While Salmonella Typhimurium was inactivated most rapidly at pH 2.5, Escherichia coli O157:H7 and Listeria monocytogenes were inactivated most rapidly at pH 4.5. When pathogens were exposed to each heating method at a fixed temperature, additional effects of ohmic heating were not observed. Also, the overall quality of orange juice subjected to ohmic heating was not greatly affected at any pH level. Therefore, increasing as well as lowering pH can also be considered effective ways to optimize pasteurization of orange juice when using ohmic heating. The different characteristics of ohmic heating compared to conventional heating indicate the necessity of a new approach.

옴가열이 전분의 외부와 내부 구조에 미치는 영향

차윤환,Cha, Yun-Hwan 한국식품영양학회 2015 韓國食品營養學會誌 Vol.28 No.1

Ohmic heating uses electric resistance heat which occurs equally and rapidly inside food when the electrical current is transmitted into. Prior to the study, we have researched the potato starch's thermal property changes during ohmic heating. Comparing with conventional heating, the gelatinization temperature and the range of potato starch treated by ohmic heating are increased and narrowed respectively. This result is appeared equally at wheat, corn and sweet potato starch. At this study, we treated potato, wheat, corn and sweet potato starch by ohmic/conventional method and observed change of external structure by microscope and internal structure by X-ray diffractometer. Conventional heated at $55^{\circ}C$ potato starch was not external structural changes. But ohmic heated potato starch is showed largely change. Some small size starch particle were broken or small particles are made of larger particle together or small particles caught up in the large particle. Changes in ohmic heated potato starch at $60^{\circ}C$ was greater. The inner matter came to an external particle burst inside and only the husk has been observed. The same change was observed in the rest of the starch. The change of internal structure of potato starch was measured using X-ray diffraction patterns. There was no significant difference between ohmic and conventional heating at $55^{\circ}C$. But almost every peak has disappeared ohmic at $60^{\circ}C$. Especially $5.4^{\circ}$ peak to represent the type B was completely gone. When viewed from the above results, external changes with change in the internal crystal structure of the starch particles were largely unknown to appear. In conclusion, during ohmic heating changes of starch due to the electric field with a change in temperature by the heating was found to have progressed at the same time.

옴가열이 전분의 열적 특성과 흡수력에 미치는 영향

차윤환,Cha, Yun-Hwan 한국식품영양학회 2014 韓國食品營養學會誌 Vol.27 No.1

Ohmic heating uses electric resistance heat which occurs equally and rapidly inside food when the electrical current is transmitted into. Prior to the study, we have researched the potato starch's thermal property changes during ohmic heating. Comparing with conventional heating, the gelatinization temperature and the range of potato starch treated by ohmic heating are increased and narrowed respectively. Herein, we have studied thermal property changes of wheat, corn, potato and sweet potato starch by ohmic heating as well as conventional heating. And then we measure the water holding capacity of starches. Annealing of starch is a heat treatment method heated at 3~4% below the gelatinization point. This treatment changes the starch's thermal property. In the DSC analysis of this study, the $T_o$, $T_p$, $T_c$ of all starch levels have increased, and the $T_c$-$T_o$ narrowed. In the ohmic heating, the treatment sample is extensively changed but not with the conventional heating. From the ohmic treatment, increases from gelatinization temperature are potato ($8.3^{\circ}C$) > wheat ($5.3^{\circ}C$) > corn ($4.9^{\circ}C$) > sweet potato ($4.5^{\circ}C$), and gelatinization ranges are potato ($7.9^{\circ}C$), wheat ($7.5^{\circ}C$), corn ($6.1^{\circ}C$) and sweet potato ($6.8^{\circ}C$). In the case of conventional treatment, water holding capacity is not changed with increasing temperature but the ohmic heating is increased. Water holding capacity is related to the degree of gelatinization for starch. This result show that when treated with below gelatinization temperature, the starches are partly gelatined by ohmic treatment. When viewing the results of the above, ohmic treatment is enhanced by heating and generating electric currents to the starch structure.

옴가열이 전분의 Pasting 특성에 미치는 영향

차윤환 ( Yun-hwan Cha ) 한국식품영양학회 2017 韓國食品營養學會誌 Vol.30 No.4

Ohmic heating is an internal heating method based on the principle that when an electrical current passes through food, electric resistance heat is uniformly generated internally by food resistance. Previous studies indicate that the thermal properties, external structure, internal structure, and swelling power of ohmic heat treated starch of various starches, such as potato, wheat, corn, and sweet potato, differed from those of conventional heating at the same temperature. In this study, the pasting property of starch, treated with ohmic and conventional heating, were measured by RVA (Rapid Visco-Analyzer). Our results show that as the ohmic heating temperature increased, the PV (Paste Viscosity) of the starch decreased significantly, and the PT (Pasting Temperature) increased. Changes in PV and PT indicate that the swelling of starch remains unchanged by ohm heating. The HPV (Hot Paste Viscosity), CPV (Cold Paste Viscosity) and SV (Setback Viscosity) of ohmic heated starch also differed from the conventional heated starch. The pasting property is similar to the viscosity curve of common cross-linked modified starch. In this experiment, we further confirm the similarity with modified starch and its usability.

電子레인지와 在來式 加熱方法에 따른 微生物 死滅效果에 關한 比較硏究

李曉敬,李容旭 서울大學校保健大學院 1991 國民保健硏究所硏究論叢 Vol.1 No.1

To assess the lethal effect of microwave treatment and conventional healing on bacterial strains, E.coli, Candida tropicalis and Bacillus subtilis were used as test microorganisms. And the lethal effect of two methods was evaluated by measuring the death rates of bacteria. Also, the experiments about the damage of cell membrane and the possibility of mutation were conducted to analyze the factors involved in the death of E.coli by the treatment of microwave. The results of the experiment were as follows: 1. Microwave treatment was more effective to kill E.coli and Candida tropicalis in diluted medium than conventional heating. Conventional heating, however, was more effective to kill Bacillus subtilis forming heat-resistant spores than microwave treatment. 2. Results from the increase of absorbance at 260nm and the injury by sodium chloride of microwave-treated E.coli indicated that microwave treatment should cause the damage of cell membrane in killing of microorganism. 3. The possibility of mutation by microwave treatment could be excluded through the experiment of no autotropic conversion in prototropic E.coli.

재래식 열과 마이크로파 에너지에 의해 열처리된 무기고분자의 결정화 거동에 관한 연구

박성수,차무경,류봉기,신학기,박희찬 한국세라믹학회 1997 한국세라믹학회지 Vol.34 No.9

This study investigated the crystallization behavior in PbO-ZnO-B2O3-TiO2 system sealing glass, inorganic polymer heat-treated by conventional heat and microwave energy. After determining heat-treated temperature for crystallization and characteristic points by DTA analysis, samples were heat-treated in a classical electric furnace and a home-style microwave oven (LG Electronic Co., 2.45 GHz, 700 W). A microwave heat-treated sample had the growth of PbTiO3 crystal at 45$0^{\circ}C$, 2$0^{\circ}C$ lower than that of a conventionally heat-treated sample. Also, it had crystallinity about 20% higher than the conventionally heat-treated sample. At 49$0^{\circ}C$, the size of PbTiO3 crystal in the conventionally heat-treated sample was larger than that in the microwave heat-treated sample due to longer heat-treated time.

옴가열이 전분의 레올로지 특성에 미치는 영향

차윤환,Cha, Yun-Hwan 한국식품영양학회 2019 韓國食品營養學會誌 Vol.32 No.4

Ohmic heating is a heating method based on the principle when an electrical current passes through food. Since this method is internal, electrical current damage occurred during heating treatment. The results of ohmic heated starch's external structure, X-ray diffraction, DSC analysis and RVA were differed from those of conventional heating at the same temperature. Several starches changed more rigid by structure re-aggregation. This change in starch was caused by change of physical, chemical, rheological property. The rheology of ohmic heated potato and corn starch of different heated methods were compared with chemically modified starch. After gelatinization, sample starch suspension (2%, 3%) measured flow curves by rheometer. Cross-linked chemically modified starch's shear stress was decreased with degree of substitution reversibly. Ohmic heated more dramatic, at $60^{\circ}C$. Potato starch's shear stress was less than commercial high cross-linked modified starch. Flow curves of potato starches measured at $4^{\circ}C$, $10^{\circ}C$, $20^{\circ}C$. Showed that Ohmic heated potato starch's shear stress ranging between $4^{\circ}C$ and $20^{\circ}C$ was narrower than modified starch. According to this study, ohmic heated potato starch can be used by decreasing viscosity agent like cross-linked modified starch.

토마토재배용 플라스틱온실의 이중피복방법에 따른 광합성유효광량자속 투과 및 열관류 특성

이현우 ( Lee H. W ),심상연 ( Sim S. Y. ),김영식 ( Kim Y. S. ) 한국농공학회 2010 한국농공학회논문집 Vol.52 No.5

This study was conducted to provide design data for deciding covering method in double layers greenhouse. The variation of photosynthetic photon flux (PPF) and heat flow in air inflated and conventional double layers greenhouse was analyzed. The PPF of air inflated double covering greenhouse was less than that of conventional greenhouse during summer season because the more PPF comes into conventional greenhouse through roof vent which was rolled up for ventilation. The air inflated double layers covering greenhouse was superior to conventional type in the aspect of controlling inside temperature down owing to lower irradiation. The PPF of air inflated greenhouse was greater than that of conventional greenhouse during winter season because the transmittance of conventional greenhouse decreased by dust collected on inside plastic film nearly closed for insulation. Considering the PPF not sufficient for tomato growing in winter, the air inflated double covering system with the greater transmittance was better than conventional covering system. When the inside air of air inflated greenhouse was injected into space between the double layers of covering, the PPF of air inflated greenhouse was much less than the conventional greenhouse because the transmittance of air inflated double covering decreased due to condensation of highly humidified inside air. It was concluded that the more dried outside air should be used for inflating double layers covering. The heat insulation performance of air inflated double covering system was superior to conventional double covering system when comparing the overall heat transfer coefficients for each covering method. However the differences among the overall heat transfer coefficients depending on difference between inside and outside temperatures of greenhouse were great, it is necessary to conduct additional experiment for investigating the overall heat transfer coefficient to design the double layers covering.

Effects of step change of heating source on synthesis of zeolite 4A from coal fly ash

Jae Kwan Kim,Hyun Dong Lee 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.5

Effects of step change of heating sources on the crystallization of zeolite 4A from coal fly ash by hydrothermal reaction were investigated with emphasis on the change in the crystallinity of the synthesized zeolite 4A. Most of the Si and Al components were effectively transformed into zeolite 4A by step change of the first conventional heating and then the second microwave heating of synthesis mixture dissolved from coal fly ash, and maximum crystallinity of zeolite 4A obtained was 91%. The first conventional heating also plays an important role in enhancing the nuclei formation that Si and Al in synthesis mixture reacted to form ring-like structures for combining sodalites, and further to small zeolite 4A seeds. The secondmicrowave heating increases the crystallization rates from small zeolite 4A nuclei to more zeolite 4A crystals. The cation exchange capacity (CEC) of the zeolite 4A crystallized by step change of heating source from the conventional to the microwave was 5.5 meq/g compared to 5.7 meq/g for commercial zeolite 4A. Test results showed that removal efficiency of heavy metals by zeolite 4A synthesized from fly ash was more than 98% and similar to commercial zeolite 4A.