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.

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.

Pasteurization of fermented red pepper paste by ohmic heating

Cho, W.I.,Yi, J.Y.,Chung, M.S. Elsevier Science 2016 INNOVATIVE FOOD SCIENCE AND EMERGING TECHNOLOGIES Vol.34 No.-

<P>Ohmic heating was applied to a Korean traditional fermented food containing red pepper paste, called Gochujang with low thermal conductivity (0.458 W/m.K), by varying frequencies (40-20,000 Hz) and applied voltages (20-60 V). Contrary to conduction heating, the entire sample was heated uniformly, and the specific heating rate was found to be highly dependent on the frequency, peaking at 5 kHz and 60 V. The results showed that complex differential equation and the Runge-Kutta fourth-order method are suitable for simulating the temperature profile during ohmic heating. The deactivation of vegetable cells of Bacillus strains on fermented red pepper paste by ohmic heating was indicated by a 99.7% reduction, compared with conduction heating for 8 min at 100 degrees C producing a 81.9% reduction. The organoleptic and physicochemical qualities of the samples pasteurized by ohmic heating were nearly the same as those of raw samples, and higher than those of conventionally heated samples. Industrial relevance: The present study designed and implemented a novel sterilization process based on a static ohmic heating system with low-frequency AC at the laboratory scale for fermented red pepper paste with a low thermal conductivity (0.458 W/m.K). The developed system was used to investigate the mechanisms and characteristics underlying the induction of ohmic heating and then, tested the pasteurization effect against microorganisms in fermented red pepper paste. Comparing with conventional heating processes, ohmic heating could provide rapid and uniform heating, thereby is more suitable for pasteurization and sterilization of viscous foods as fermented red pepper paste on industrial thermal processing. (C) 2016 Elsevier Ltd. All rights reserved.</P>

옴 가열이 대두 단백질의 열변성에 미치는 영향

차윤환 ( Yun Hwan Cha ) 한국식품영양학회 2011 韓國食品營養學會誌 Vol.24 No.4

Ohmic heating uses electric resistance heat which occurs equally and rapidly inside food when an electrical current is passed throught. In this study, we observed the physical & chemical characteristics changes which occurs in soybean protein during heating denaturation by using ohmic and conventional heating. After the ohmic heating process, we could not find any change of the primary protein structure in the denaturated soy protein samples. However, the rate of imbibed water(RIW) of the ohmic samples was 2 times faster than that of the conventional samples. Also the ANS-surface hydrophobicity was decreased, which is very closely related to RIW. In the differential scanning calorimeter(DSC) analysis result, all 7S soyprotein fraction samples were completely denaturated by ohmic and conventional heating. However, the 11S samples were completely denatured only by ohmic heating. According to the DSC result, we decided that soyprotein was damaged by temperature and electrical current during ohmic heating. The damage of electrical current was a cause of the charcteristic changes.

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.

Evaluation of energy efficacy and texture of ohmically cooked noodles

Jo, Yeon-Ji,Park, Sung Hee Elsevier 2019 Journal of food engineering Vol.248 No.-

<P><B>Abstract</B></P> <P>The feasibility of ohmic heating for cooking instant noodles was evaluated using a customized ohmic system. Temperature come-up time, heat transfer ratio (<I>HT</I> <SUB> <I>nls</I> </SUB>), system performance coefficient (<I>SPC</I>), and textural qualities were evaluated as a function of different electric fields (10, 12.5, 15, and 17.5 V/cm) and temperature holding times (30, 60, 90, and 120 s). Temperature come-up time to 100 °C was 3.9 ± 0.1, 2.5 ± 0.1, 2.1 ± 0.2, and 1.3 ± 0.1 min at electric fields of 10, 12.5, 15 and 17.5 V/cm, respectively. Temperature come-up time decreased significantly with an increase in electric field. The highest <I>HT</I> <SUB> <I>nls</I> </SUB> of 0.89 was observed at 15 V/cm. An electric field of 15 V/cm with a 90 s holding time yielded the greatest <I>SPC</I> of 0.63 ± 0.05 and the most preferable textural qualities for hardness. Our study shows the potential of ohmic heating to rapidly cook instant noodles with good textural qualities and energy efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Investigate the ohmic cooking for noodles as a function of electric fields (10–17.5 V/cm) and holding times (30–120 s). </LI> <LI> Ohmic heating enabled rapid cooking of instant noodles using electric field and internal energy generation. </LI> <LI> Energy efficacy of ohmic heating was promising since most of electrical energy was converted to heat. </LI> <LI> Heat transfer between noodles and soup was expedited at higher electric field application. </LI> <LI> Ohmic heating showed its potential to produce good textural quality of noodles. </LI> </UL> </P>

Leakage of Cellular Materials from Saccharomyces cerevisiae by Ohmic Heating

( Sung Won Yoon ),( Chung Yung J. Lee ),( Ki Myung Kim ),( Cherl Ho Lee ) 한국미생물 · 생명공학회 2002 Journal of microbiology and biotechnology Vol.12 No.2

The ohmic heating of foods for sterilization provides a shorter come-up time compared to conventional thermal processes. The electric fields as well as the heat generated by ohmic heating facilitate germicidal effects. In the present study, the effect of ohmic heating on the structure and permeability of the cell membrane of yeast cells, Saccharomyces cerevisae, isolated from Takju (a traditional Korean rice-beer), was investigated. The ohmic heating was found to translocate intracellular protein materials out of the cell wall, and the amount of exuded protein increased significantly as the electric field increased from 10 to 20 V/cm. As higher frequencies were applied, more materials were exuded. Compared to conventional heating, more amounts of proteins and nucleic acids were exuded when these cells were treated with ohmic heating. The molecular weights of the major exuded proteins ranged from 4 kDa to 18 kDa, as analyzed by Tricine-SDS PAGE. A TEM study also confirmed the leakage of cellular materials, thus indicating irreversible damage to the cell wall by ohmic heating. It was, therefore, concluded that the electric fields generated by ohmic heating induced electroporation, causing irreversible damage to the yeast cell wall and promoting the translocation of intracellular materials.

Resistance of <i>Escherichia coli</i> O157:H7 ATCC 35150 to ohmic heating as influenced by growth temperature and sodium chloride concentration in salsa

Kim, Sang-Soon,Lee, Jae-Ik,Kang, Dong-Hyun Elsevier 2019 FOOD CONTROL Vol.103 No.-

<P><B>Abstract</B></P> <P>Salsa is a liquid-solid food containing jalapeño and serrano peppers, which result in multistate outbreak in 2008. Storage temperature and sodium chloride (NaCl) concentration of salsa vary depending on the climate, season, and type of product. In this regard, effect of growth conditions, namely, low temperature (15 °C) or NaCl concentration (4.5%) on the resistance of <I>Escherichia coli</I> O157:H7 ATCC 35150 to ohmic heating was identified in this study. Cells of <I>E. coli</I> O157:H7 ATCC 35150 grown under different growth conditions was inoculated into prepared salsa sample, and then subjected to ohmic heating. Mechanisms of resistance acquisition were identified by transcriptional responses, membrane fatty acid changes and confirmed with propidium iodide (PI) uptake values. Resistance of the pathogen to ohmic heating decreased when growth temperature decreased from 37 °C to 15 °C while increased resistance was observed for this pathogen when grown with 4.5% NaCl. Several heat stress related genes such as <I>dnaK</I>, <I>rpoH</I>, <I>grpE</I>, <I>groES</I>, <I>htpG</I>, and <I>htpX</I> were up-regulated (≥5 fold change) as growth temperature decreasedwhile <I>groEL</I>, <I>dnaK</I>, <I>rpoH</I> were up-regulated when grown with high NaCl concentration in the present study. The ratio of unsaturated fatty acids (USFA) to saturated fatty acids (SFA) of pathogen increased slightly (+0.16) or significantly (+0.79) with increasing NaCl concentration or decreasing temperature, respectively. These results indicate that the cell membrane of the pathogen grown at low temperature was more susceptible to heat than when grown under optimal conditions or high NaCl concentration. Cell membrane damage measured by PI uptake values of the pathogen grown with high NaCl concentration were not significantly different from those of the control (<I>p</I> > 0.05), while the values were significantly higher for the pathogen grown at low temperature and subjected to ohmic heating (<I>p</I> < 0.05). Based on these results we suggest that resistance of the pathogen grown at low temperature to ohmic heating decreased because of dominant cell membrane damage compared to induced heat stress related genes. The cell membrane damage was dominant by means of an increased ratio of USFA to SFA. On the other hand, pathogen resistance increased when grown in medium of high NaCl concentration because of induced heat stress related genes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Growth conditions influenced the resistance of pathogen to ohmic heating. </LI> <LI> Several heat stress related genes were induced by extreme growth conditions. </LI> <LI> The ratio of unsaturated fatty acids was significantly changed by growth conditions. </LI> <LI> Cell membrane damage of pathogen grown with different conditions was verified. </LI> </UL> </P>