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Ohmic Heating for Tofu Making—A Pilot Study  [PDF]
Cheng-Chang Lien, Yu-Chieh Shen, Ching-Hua Ting
Journal of Agricultural Chemistry and Environment (JACEN) , 2014, DOI: 10.4236/jacen.2014.32B002

The aim of this study is to explore the relationship between temperature and electrical conductivity of soya milk under ohmic heating in tofu making. The soya milk of 10 Brix was heated to a steady temperature of 90?C. The applied voltage was increased and the temperature rising rate was investigated for adequate heating profiles in tofu making. Experimental results showed that the electrical conductivity of soya milk is proportional to the heating time. The temperature rising rate was increased from 1.46?C to 3.82?C/min as a result of increased voltage. Hence ohmic heating could be an efficient, convenient heating measure in tofu making.

Ohmic Heating Suspends, not Reverses, the Cooling Contraction of Hot Jupiters  [PDF]
Yanqin Wu,Yoram Lithwick
Physics , 2012, DOI: 10.1088/0004-637X/763/1/13
Abstract: We study the radius evolution of close-in extra-solar jupiters under Ohmic heating, a mechanism that was recently proposed to explain the large observed sizes of many of these planets. Planets are born with high entropy and they subsequently cool and contract. We focus on two cases: first, that ohmic heating commences when the planet is hot (high entropy); and second, that it commences after the planet has cooled. In the former case, we use analytical scalings and numerical experiments to confirm that Ohmic heating is capable of suspending the cooling as long as a few percent of the stellar irradiation is converted into Ohmic heating, and the planet has a surface wind that extends to pressures of ~10 bar or deeper. For these parameters, the radii at which cooling is stalled are consistent with (or larger than) the observed radii of most planets. The only two exceptions are WASP-17b and HAT-P-32b. In contrast to the high entropy case, we show that Ohmic heating cannot significantly re-inflate planets after they have already cooled. This leads us to suggest that the diversity of radii observed in hot jupiters may be partially explained by the different epochs at which they are migrated to their current locations.
Influence of Ohmic Heating on Advection-Dominated Accretion Flows  [PDF]
G. S. Bisnovatyi-Kogan,R. V. E. Lovelace
Physics , 1997, DOI: 10.1086/310826
Abstract: Advection-dominated, high-temperature, quasi-spherical accretion flow onto a compact object, recently considered by a number of authors, assume that the dissipation of turbulent energy of the flow heats the ions and that the dissipated energy is advected inward. It is suggested that the efficiency of conversion of accretion energy to radiation can be very much smaller than unity. However, it is likely that the flows have an equipartition magnetic field with the result that dissipation of magnetic energy at a rate comparable to that for the turbulence must occur by Ohmic heating. We argue that this heating occurs as a result of plasma instabilities and that the relevant instabilities are current driven in response to the strong electric fields parallel to the magnetic field. We argue further that these instabilities heat predominantly the electrons. We conclude that the efficiency of conversion of accretion energy to radiation can be much smaller than unity only for the unlikely condition that the Ohmic heating of the electrons is negligible.
Protein removal from fish mince washwater using ohmic heating
Kobsak Kanjanapongkul,Tipaporn Yoovidhya,Suvit Tia,Pisit Wongsa-Ngasri
Songklanakarin Journal of Science and Technology , 2008,
Abstract: A static ohmic heating system was developed to remove protein from fish mince (threadfin bream) washwatercollected from a surimi production plant in order to improve water quality. The samples were heated under different electricfield strengths (EFS, 20, 25, and 30 V/cm) until reaching the desired temperature (50, 60, and 70oC), and further held at thattemperature for a certain time (0, 15, and 30 minutes). Heating the samples to 70oC resulted in a better protein removal whencompared to 50 and 60oC. After heating to 70oC, the samples were centrifuged. The analysis of the supernatant obtained showsthe reduction of protein, COD, BOD, TS, and TDS to 42%, 25%, 23%, 44%, and 61%, respectively. The electrical conductivityof the samples showed a linear relationship with temperature and the temperature demonstrated a parabolic relationshipwith heating time. EFS and holding time have no significant effect on protein removal.
Extended Heat Deposition in Hot Jupiters: Application to Ohmic Heating  [PDF]
Sivan Ginzburg,Re'em Sari
Physics , 2015,
Abstract: Many giant exoplanets in close orbits have observed radii which exceed theoretical predictions. One suggested explanation for this discrepancy is heat deposited deep inside the atmospheres of these "hot Jupiters". Here, we study extended power sources which distribute heat from the photosphere to the deep interior of the planet. Our analytical treatment is a generalization of a previous analysis of localized "point sources". We model the deposition profile as a power law in the optical depth and find that planetary cooling and contraction halt when the internal luminosity (i.e. cooling rate) of the planet drops below the heat deposited in the planet's convective region. A slowdown in the evolutionary cooling prior to equilibrium is possible only for sources which do not extend to the planet's center. We estimate the Ohmic dissipation resulting from the interaction between the atmospheric winds and the planet's magnetic field, and apply our analytical model to Ohmically heated planets. Our model can account for the observed radii of many inflated planets which have equilibrium temperatures $\approx 1500\textrm{ K}-2500\textrm{ K}$, and are inflated to a radius $\approx 1.5 R_J$. However, some extremely inflated planets remain unexplained by our model. We also argue that Ohmically inflated planets have already reached their equilibrium phase, and no longer contract. Following Wu & Lithwick (2013) who argued that Ohmic heating could only suspend and not reverse contraction, we calculate the time it takes Ohmic heating to re-inflate a cold planet to its equilibrium configuration. We find that while it is possible to re-inflate a cold planet, the re-inflation timescales are longer by a factor of $\approx 30$ than the cooling time.
Journal of Engineering Science and Technology , 2011,
Abstract: Experiments were conducted to study the enhancement of carrot juice recovery using 2-stage pressing with ohmic heating. The study was designed using Response Surface Methodology employing the Box-Behnken design. The independent variables were: duration of first pressing (1, 2, 3 min.), voltage gradient (15, 20, 25 V/cm) and final temperature (60, 70, 80oC). Control experiments, without any ohmic heating between the 2-stage pressing, were also conducted for the purpose of comparison. Total juice recovery and juice quality were the dependent variables. Mathematical analysis for multistage pressing was applied to 2-stage expression process. The total juice recovery increased with increase in the duration of 1st pressing. Maximum enhancement in juice recovery in 2-stage expression with ohmic heating over control was 13.76%. The total solids ranged between 7.55 to 11.12% and increased with increase in the duration of 1st pressing. Total soluble solids were in the range of 3.6 to 6.6oBrix and increased at lower voltage gradient and higher final temperature. The ohmic heating did not cause much change in the colour of juice. The study indicated that maximum juice recovery of 98.9% can be obtained with 1st pressing of 2.72 min., ohmic heating up to a final temperature of 65.6oC under a voltage gradient of 15 V/cm followed by 2nd pressing of 10 min.
Does ohmic heating influence the flow field in thin-layer electrodeposition?  [PDF]
Matthias Schr?ter,Klaus Kassner,Ingo Rehberg,Josep Claret,Francesc Sagués
Physics , 2002, DOI: 10.1103/PhysRevE.66.026307
Abstract: In thin-layer electrodeposition the dissipated electrical energy leads to a substantial heating of the ion solution. We measured the resulting temperature field by means of an infrared camera. The properties of the temperature field correspond closely with the development of the concentration field. In particular we find, that the thermal gradients at the electrodes act like a weak additional driving force to the convection rolls driven by concentration gradients.
Temperature non-uniformities and risk of overheating at a direct ohmic heating of foods  [cached]
Jaromir Stancl,Michal Novy,Rudolf Zitny
Bulletin of Applied Mechanics , 2008,
Abstract: This paper is concerned with temperature non-uniformities especially the estimation of the risk of runaway and overheating at direct ohmic heating of food. The runaway criterion Rw, reflecting the role of temperature dependent electric conductivity and thermal resistance, is suggested. The influence of cooling, singularities at electrodes and fouling layer are analyzed, assuming properties of typical food materials (meat, milk) and typical process parameters. Results indicate that the risk of runaway at a very fast heating can be reduced by cooling a part of surface perpendicular to the intensity of electric field (cooled electrodes). It is further shown, that even if a small irregularity of the electrode surface (e.g. natural roughness) has a strong effect on the local intensity of electric field, temperature effects are seen only if the height of irregularities is comparable with the distance of electrodes (>5%). On the other hand, even very thin fouling layer at an electrode causes significant overheating, as soon as its electric conductivity is low.
Milk Tofu Onde Quality  [cached]
Dwi Ningsih
Journal of Animal Production , 2002,
Abstract: The study on “The Quality of Milk Tofu Onde” observed from its crispiness,colour,taste and texture was conducted to socialise the product of milk. Onde is a kind of snack which is popular in Indonesia and it easy to produce with simple eguipment. As much as 562.5 gs fresh milk tofu, 562.5 gs wither milk tofu and 1500 gs of wheat flour for the purpose of study. Data on crispiness, colour, taste and texture of milk tofu ande expressed in score, were obtained through 20 panelists and was analized with Randomized Group Design followed by an orthogonal polynomial teast. The first factors were sort of tofu (T) e.i fresh milk tofu and wither milk tofu. The second factors were level of tofu (S) e.i 50 percent, 75 percent and 100 percent of wheat flour or their proportion (g) were (125:125); (187.5:62.5); (100:0). The study showed that milk tofu onde from wither milk more crispy significantly (P>0.01) than those from fresh milk. The level of tofu gave a significant effect (P>0.01) on crispiness. This was shown by a quadrater regression of : Y1 = c9.0712 + 0.5093X c 0.0030X2 and Y2 = c3.3865 + 0.4949X c 0.0033X2 for fresh milk tofu and wither milk tofu respectively. Milk tofu onde from wither milk more brownnes significantly (P>0.01) than those fron fresh milk. The level of tofu gave a significant effect (P>0.01) on colour. This was shown by a linier regression of Y1 = 8.4244 + 4.4625x and Y2 = 8.7734 + 10.0745X for fresh milk tofu and wither milk tofu respectively. Milk tofu onde from wither milk more delicious significantly (P>0.01) than those from fresh milk. The level of tofu gave a significant effect (P>0.01) on taste. This was shown by a linier regressions of Y1 = 8.3383 + 0.0422 X and by a quadrater regression of Y2 = 3.5200 + 0.5156 X – 0.0033 X2 for fresh milk tofu and wither milk tofu respectively. Texture of milk tofu onde from fresh milk more dense significantly (P>0.01) than tose from wither milk. The level of tofu gave a significant effect (P>0.01) on texture. This was shown by a linier regressions of Y1= 5.4150 + 11.9630 X and Y2= 10.7880 + 1.5633 X for fresh milk tofu and wither milk tofu respectively. The study indicated that milk tofu onde from wither milk being more crispy, brownness, delicious and denseless texture than those from fresh milk. The best level of milk tofu was 75% on daugh. (Animal Production 4(1): 11-20 (2002)Key words : “Milk tofu onde”, crispiness
A statistical approach to define some tofu processing conditions
Benassi, Vera de Toledo;Yamashita, Fábio;Prudencio, Sandra Helena;
Ciência e Tecnologia de Alimentos , 2011, DOI: 10.1590/S0101-20612011000400011
Abstract: the aim of this work was to make tofu from soybean cultivar brs 267 under different processing conditions in order to evaluate the influence of each treatment on the product quality. a fractional factorial 25-1 design was used, in which independent variables (thermal treatment, coagulant concentration, coagulation time, curd cutting, and draining time) were tested at two different levels. the response variables studied were hardness, yield, total solids, and protein content of tofu. polynomial models were generated for each response. to obtain tofu with desirable characteristics (hardness ~4 n, yield 306 g tofu.100 g-1 soybeans, 12 g proteins.100 g-1 tofu and 22 g solids.100 g-1 tofu), the following processing conditions were selected: heating until boiling plus 10 minutes in water bath, 2% dihydrated caso4 w/w, 10 minutes coagulation, curd cutting, and 30 minutes draining time.
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