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- MakaleAçık Erişim2024Scopus SJRQ1Design of Ohmic Thawing Cell with Hydrostatic Pressure Units: Application in Minced Beef
Döner, Deniz; Çokgezme, Ömer Faruk; Çevik, Mutlu; İçier, Filiz
The thawing process is a common processing method used in the meat industry. To ensure provide food safety and protect meat quality, the thawing process should be carried out carefully. Ohmic thawing (OT) is one of the novel thawing methods. In this study, a custom-designed ohmic thawing prototype was set up and used to thaw frozen minced beef samples in different shapes (X: 13 × 4 × 3 cm3; Y: 13 × 6 × 2 cm3; Z: 13 cm height × 3.91 cm diameter) at 3 different voltage gradients (10–13-16 V/cm) by using 3 different electrode designs (E1, titanium foil; E2, needle type titanium electrode; E3, titanium embossed). The optimum OT condition resulting in a high-quality product with the highest process efficiency was determined. As an optimization procedure, a three-level general factorial design was performed. Thawing time, drip loss, thawing ratio, maximum temperature, ohmic power consumption, energy efficiency, and exergy efficiency values were used as responses. The cylindrical sample shape resulted in higher changes in quality and decreased performance of the process. The optimum ohmic thawing condition was a 16 V/cm voltage gradient for Y-shaped samples by using an E2 electrode design. The thawing time for the optimum condition was 2074s corresponding ohmic power consumption of 15.84 W. The drip loss during thawing was measured at 1.20%. The maximum temperature reached during the thawing process was recorded as 15.90 °C. Energy efficiency and exergy efficiency values were greater than 35%. Based on these results, the overall desirability of the ohmic thawing method was evaluated as 0.755. The obtained desirability value indicated the ohmic thawing method to be highly efficient and effective in achieving optimal thawing outcomes. The results of this study could give valuable information on the design of industrial-scale ohmic heating units to be used with solid foods, especially for thawing purposes.
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İncele - Kitap BölümüAçık Erişim2024Recent trends in evaporation techniques
Icier, Filiz; Doner, Deniz; Cokgezme, Omer Faruk; Sabanci, Serdal; Cevik, Mutlu
Increasing energy costs of the food industry and the necessity to reduce emissions of greenhouse gases orient the researchers to find alternative solutions to increase energy efficiency, and to decrease waste and environmental damage. Hence, the use of novel technologies comes to the fore. Since volumetric heating could be provided by Ohmic and microwave heating methods, a heating medium is not required. Thus it is possible to reduce undesirable changes in quality attributes by eliminating contact with hot surfaces and providing rapid heating. The negative effects on the environment could also be reduced owing to both utilization of efficient energy for the heating process and the elimination of wastewater. Alternative nonthermal methods including ultrasound, membrane filtration, pulsed electric field, and electroplasmolysis techniques could also be applied. In this chapter, recent studies on the evaporation techniques, regarding their system setups, effects on the quality characteristics, and performance evaluations are reviewed.
- MakaleAçık Erişim2021Scopus SJRQ1Influences of sample shape, voltage gradient, and electrode surface form on the exergoeconomic performance characteristics of ohmic thawing of frozen minced beef
Çokgezme, Ömer Faruk; Döner, Deniz; Çevik, Mutlu; Kemahlıoğlu, Ali Varsın; İçier, Filiz
In the present study, it was aimed to investigate the exergoeconomic performance of ohmic thawing (OT) system during the thawing of frozen minced meat (lean beef). The effects of the sample shape (X: 13 × 4 × 3 cm, Y: 13 × 6 × 2 cm, Z: cylinder with a height of 13 cm and diameter of 3.91 cm), electrode surface form (titanium foil with smooth surface, titanium electrode with needle-type surface and titanium electrode with pyramid-type surface), and voltage gradients (10, 13, and 16 V/cm) were investigated. Lower exergoeconomic values were obtained for the cylindrical shape compared to the rectangular prism. The lowest exergy efficiency value (12.45 ± 0.42), is was obtained for the cylindrical shape at 10 V/cm voltage gradient with titanium foil electrode. The needle-type surface electrodes had higher performance values than other electrodes. The exergoeconomic performance increased as the voltage gradient increased. The lowest unit exergy cost (72.40 ± 2.8) was obtained for rectangular prism shape at 16 V/cm with needle-type electrode. The comprehensive exergoeconomic evaluation in this study exhibited the energy utilization effectiveness and unit exergy cost of OT.
AtıfScopus32WoS28OpenAlex30İncele - MakaleYalnız künye2021Scopus SJRQ1Numerical simulation of temperature histories of frozen minced meat having different fat contents during ohmic thawing
Cevik, Mutlu; Icier, Filiz
The ohmic thawing (OT) of minced meat sample was mathematically modelled using different numerical methods (Finite Difference-FD and Finite Volume-FV) for different process conditions (voltage gradients of 10, 13 and 16 V/cm and fat contents of meat sample as 2%, 10% and 18%). FD method was successful to predict the temperature changes for both heating and phase change regions. FV method was performed by using two different heat generation functions; depending on process time (UDF-1) or the center temperature (UDF-2). The description of the change of heat generation term depending on process time (UDF-1) in the ANSYS module was more successful with the experimental data compared to the description of the change of heat generation term depending the center temperature (UDF-2). Although FV model is more complex than FD model it can be applied for simulation of detailed temperature distributions. On the other hand, FD model can be applied for practical predictions of temperature histories for center temperatures in simple geometries. It is thought that the simulation of OT performed at different conditions with the FD and the FV methods would contribute valuable data in the design of household ohmic thawing/cooking systems for solid food materials.
AtıfScopus25WoS21OpenAlex21İncele - MakaleYalnız künye2020Scopus SJRQ2Characterization of viscoelastic properties of minced beef meat thawed by ohmic and conventional methods
Cevik, Mutlu; Icier, Filiz
Frozen minced meat samples having fat contents of 2%, 10% and 18% were thawed using different methods (refrigeration thawing at ambient temperature of +4 ℃, under running cold water (+4 ℃) thawing, ohmic thawing for 10, 13 and 16 V/cm). Viscoelastic properties were determined by using rheological tests (oscillation and creep/recovery tests). Storage modulus, loss modulus, complex modulus, loss tangent, dynamic viscosity and complex viscosity values of minced meat samples increased as fat content increased. As frequency value increased, the modulus values of meat samples increased but dynamic and complex viscosity values of the samples decreased. The minced meat samples thawed by different methods had recoverable compliance values. The compliance values of meat samples during creep region can be well characterized by Burgers model. Ohmic thawing can be used as an alternative thawing method since it resulted in similar rheological properties of minced meat samples compared to refrigeration thawing at ambient temperature of +4 ℃ and under running cold water (+4℃) thawing.
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İncele - MakaleAçık Erişim2020Scopus SJRQ1Thermal Image Processing Technique for Determination of Temperature Distributions of Minced Beef Thawed by Ohmic and Conventional Methods
Döner, Deniz; Çokgezme, Ömer Faruk; Çevik, Mutlu; Engin, Mustafa; İçier, Filiz
In the present study, the effectiveness of ohmic thawing (OT) on temperature distribution (TD) was evaluated by using a non-destructive measurement method: thermal imaging (TI). The effects of both OT process parameters and sample properties on TD of thawed minced beef were determined. Thermal images were taken from the central cross-sectional area of a thawed sample. In the first part of the study, the effects of OT system parameters (voltage gradient; 10–13–16 V/cm and electrode type; E1:titanium foil electrode with a smooth surface, E2: needled-type titanium electrode, E3: titanium electrode with pyramid surface shaped) and sample shape (X: 13 × 4 × 3 cm3; Y: 13 × 6 × 2 cm3; Z: 13 cm height × 3.91 cm diameter) were analyzed in detail. The best thawing condition (electrode type E2 and sample shape Y) was determined by taking into account of thawing time and TD properties obtained from a developed TI processing technique. In the second part of the study, the effects of OT process on TD properties of minced beef having different fat contents (2–10–18%) were compared with those of two different conventional thawing processes (stationary cold ambient + 4 °C -RT and under cold running water + 4 °C -WT). The percentage of thawed portions in central section was above 68% for OT and varied between 12 and 54% for CT. Rectangular-shaped samples had more homogeneous temperature distributions than cylindrical samples (p < 0.05). TI could be used to control the process by non-destructive monitoring of temperature during OT.
AtıfScopus36WoS31OpenAlex35İncele - MakaleYalnız künye2019Scopus SJRQ2Effects of Vacuum Ohmic Evaporation on Some Quality Properties of Sour Cherry Juice Concentrates
Sabancı, Serdal; Icier, Filiz
Sour cherry juice (SJ) having total soluble solid (TSS) content of 19.2 % was concentrated to 65 % TSS by applying vacuum ohmic evaporation (VOE) and vacuum evaporation (VE) methods under constant absolute pressure (25 kPa). Total monomeric anthocyanin content (TMAC) of sour cherry concentrate (65 % TSS) was found in the range of 1561.67–1777.38 mg/L whereas total phenolic content (TPC) varied in the range of 9,071.22–78,347.53 mg/L concentrate. TPC and TMAC values of juice concentrates were affected less from VOE process compared to VE (p < 0.05) while there was no significant difference between the total antioxidant activities of SJ concentrates obtained by both methods (p > 0.05). TMAC and TPC values increased as the voltage gradient applied increased (p < 0.05). VOE process preserved the color properties of juice concentrates better compared to the VE process. It was concluded that VOE method could be an alternative fast evaporation method to obtain high-quality fruit juice concentrates.
AtıfScopus35WoS31OpenAlex34İncele - MakaleYalnız künye2017Scopus SJRQ1Ohmic heating assisted vacuum evaporation of pomegranate juice: Electrical conductivity changes
Icier, Filiz; Yildiz, Hasan; Sabanci, Serdal; Cevik, Mutlu; Cokgezme, Omer Faruk
A novel electrical heating method, named as ohmic heating, was successfully integrated to vacuum evaporation system, and pomegranate juice was concentrated until its total soluble dry matter content reached to 40% by applying three different voltage gradients (7.5, 10, and 12.5 V/cm) at 180 mm Hg absolute pressure in this system. Total evaporation times were determined as 152, 78, and 53 min at the voltage gradients of 7.5, 10, and 12.5 V/cm, respectively. The concentration time of pomegranate juice was shortened about 56% by ohmic heating relative to conventional evaporation. The electrical conductivity values were increased up to reach 25% TSDM for 7.5 V/cm and at 35% TSDM for 10 V/cm, then showed a decreasing pattern. However, it was constant (0.55 ± 0.01 S/m) during evaporation process at 12.5 V/cm. It is recommended that the ohmic heating method could be successfully integrated to vacuum evaporation process to shorten the processing time significantly. Industrial relevance Ohmic heating has been utilized as alternative method for the purpose of heating, pasteurization, cooking etc., and relatively better products can be obtained by ohmic heating. Nowadays, energy efficient systems are needed in concentrated juice production. The integration of ohmic heating to the conventional vacuum systems could serve the production high quality juice concentrates with efficient use of energy. In present study, ohmic heating assisted vacuum evaporation of pomegranate juice was conducted, successfully. This method decreased the total process time for juice concentration, which is critically important for industrial scale productions. This novel method can be implemented to the fruit juice production lines by taking into account of design characteristics of ohmic systems such as electrical conductivity changes depending on both temperature and total soluble solids concentration. The effects of main process parameter, named as voltage gradient, on electrical conductivity changes during electrical heating assisted evaporation process has been also reported in the present study.
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