Rheological behavior of sour cherry juices concentrated by ohmic and conventional evaporation processes under vacuum

ICIER, Filiz/0000-0002-9555-3390WOS: 000558531400001In this study, sour cherry juice was evaporated up to 65% total soluble solid content (TSSC) under vacuum (25 kPa) by ohmic-assisted vacuum evaporation (OAVE) and vacuum evaporation (VE). the effects of voltage gradients (10-14 V/cm) on the rheological behavior of sour cherry concentrates having different TSCC (30%-65%) were determined, and compared with those of VE. in general, the shear stress increased as the shear rate increased for all concentrations. Since the statistical error values of Power Law and Newton models were similar (p > .05), the most appropriate model describing the rheological behavior was chosen as Newton model being more nominative and mathematically simpler. the viscosity of concentrates (30%-65%) varied in the range of 0.003-0.119 Pa.s. the increase in the viscosity values depending on TSSC during evaporation was similar for both processes. Thus, OAVE could be beneficial alternative method to VE for the purpose of producing fruit juice concentrates having similar rheological properties. Practical applications It is an alternative evaporation method in the literature in recent years by integrating ohmic heating into the evaporation process. However, in order for the ohmic evaporation process to be an alternative, it is necessary to provide qualities of fruit juices similar to or better than the vacuum evaporation process. One of the most important features for the transportation of fruit juices in industrial transport lines is rheological properties. in this study, it is important to determine that the consistency of the product resulting from the use of ohmic heating support in evaporation does not differ from the conventional method. the data obtained in this publication will constitute an important data infrastructure for scaling OAVE operation to industrial systems as an alternative.Turkiye Bilimsel ve Teknolojik Arastirma KurumuTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114O117]; Ege Universitesi [2015/BIL/010]Turkiye Bilimsel ve Teknolojik Arastirma Kurumu, Grant/Award Number: 114O117; Ege Universitesi, Grant/Award Number: 2015/BIL/01

Applicability of ohmic heating assisted vacuum evaporation for concentration of sour cherry juice

WOS: 000407410100028Sour cherry juice having total soluble solids (TSS) of 19.2% was evaporated up to 65% TSS at vacuum (gauge pressure of 580 mm-Hg) by applying ohmic heating at three different voltage gradients (10-14 V/cm). Total process times were determined as 40, 55, 75, and 85 min for 14 V/cm, 12 V/cm, and 10 V/cm, and vacuum evaporation (VE), respectively. The change of moisture content during ohmic assisted vacuum evaporation and VE processes were investigated by seven different empirical models. The best fitting model was Midilli model for three different voltage gradients and VE. The electrical conductivity values at different voltage gradients varied between 0.41 and 1.13 S/m for different TSS contents. The changes of EC values were examined in detail for three different regions; heating up period, first evaporation period, and second evaporation period. EC increased until a critical % TSS content (32% TSS), then remained constant for certain time (until 45% TSS) depending on voltage gradient, and then it had tendency to decrease. Ohmic heat generation increased sharply during heating period, then decreased dramatically during evaporation periods. It is recommended that ohmic heating could be alternatively used as the heat source to shorten the process times of vacuum evaporation applied for concentration of fruit juices. (C) 2017 Elsevier Ltd. All rights reserved.TUBITAK (Turkish Scientific and Technology Committee) Project [114O117]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [2211-C Program]This study is a part of the Ph.D. Thesis titled as "Setting up and Performance Evaluation of Ohmic Heating Assisted Vacuum Evaporation System, and The Experimental Investigation And Mathematical Modelling of The Process", and financially supported by TUBITAK (Turkish Scientific and Technology Committee) Project No. 114O117, and the researcher (S. Sabani) was financially supported TUBITAK 2211-C Program

Modeling the electrical conductivity value of the model solution

Abstract The ohmic heating process is one of the novel electrical heating methods that are considered as fast, homogeneous and efficient heating. In this study, the details of the relationship between electrical conductivity (EC)-Temperature (Temp) and EC-pH-Temp at different Total Soluble Solid Content (TSSC) and different pH values were examined. Especially, the study explains details of the electrical conductivity value due to pH change (2, 2.5, 3, 3.5) and expressing EC change depending on the pH value of fruit and vegetable juices. At constant pH, EC values decrease with increasing TSSC values (10%, 20%, 30%, 40%, 50%, 60%) and decrease with increasing pH at constant TSSC value. When the relationship between Temp-EC is analyzed that the EC value increases as Temp increases in all cases and this increase is linear. It was found that the Temp-EC relationship was in high compatibility with an R2 value above 0.97. Also, in the Temp-EC-pH relationship, the R2 value was found to be an acceptable value above 0.95

Alternative Thawing Methods for the Blanched/Non-Blanched Potato Cubes: Microwave, Ohmic, and Carbon Fiber Plate Assisted Cabin Thawing

WOS: 000399308000055The effects of conventional-C, carbon fiber plate assisted cabinet heater-CPAC, ohmic-OT, and microwave thawing-MT techniques on changes of some quality characteristics and resistant starch (RS) content of potato (Solanum tuberosum L.) cubes (18 x 18 x 18 mm) were investigated. The effects of blanching prior to the freezing on thawing characteristics were also determined. The thawing times of non-blanched samples were determined as 23,580485 s, 5360 +/- 40 s, 205 +/- 18.25 s and 19.26 +/- 1.49 s for conventional, CPAC, OT, and MT methods, respectively. The blanching process increased the thawing times in general. OT and CPAC thawing methods served lower RS content for thawed potato samples. The potato cubes thawed by OT and MT were softer than C and CPAC thawed potato cubes (P<0.05). The highest color change was found for MT of blanched samples and conventional thawing of non-blanched samples. The electrical methods could be alternative thawing methods in terms of providing shorter thawing times and desirable changes on some quality characteristics. Practical ApplicationsThe conventional thawing of high amount of frozen food products have posed a problem for catering industry. The long thawing time, drip loss issues, quality loses and possible microbial spoilage are lacks of conventional thawing method. The electroheating methods such as ohmic, microwave and unique carbon fiber plate assisted cabinet heating were employed as alternative thawing techniques. Thawing time of potato cubes were shortened and quality characteristics, such as drip loss, texture profile, color properties and resistant starch (RS), were improved by novel thawing methods. The obtained results reveal that the application of alternative thawing methods may lead to decreasing of the operating cost due to shorter process time and minimizing the changes in color, texture and nutritional compounds.TUBTAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [2209]This study was partially supported by TUBTAK 2209 Project titled as "Thawing of Frozen Potato Cubes by Novel Thawing Methods" and all authors acknowledge to Kubilay CAKMAK for support

Infrared drying of dill leaves: Drying characteristics, temperature distributions, performance analyses and colour changes

Cokgezme, Omer Faruk/0000-0001-9806-2282; Cevik, Mutlu/0000-0003-4847-4910WOS: 000538276500001PubMed: 32501117Thin-layer drying behaviour of dill leaves samples under three different infrared radiation power intensities was investigated. Diffusion Approach was found to be the best model that describes the drying behaviour of dill leaves. Effective diffusivity values were 6.97 x 10(-9), 6.84 x 10(-9) and 8.96 x 10(-9) m(2)/s for power intensities of 1790, 1970 and 2070 W/m(2), respectively. According to the first and second law efficiencies, the infrared drying system was more efficient at higher power intensities (p < 0.05). However, the total colour change was maximum at the highest power intensity. For the investigated infrared drying conditions, 1970 W/m(2) was recommended as the best-infrared power intensity applied for drying of dill leaves by taking into account both performance analyses and quality changes

Performance analyses for evaporation of pomegranate juice in ohmic heating assisted vacuum system

WOS: 000401387500001Pomegranate juice having 17.5% total soluble solids (TSS) content was evaporated to 40%TSS by ohmic heating assisted vacuum evaporation (OVE; 7.5 V/cm, 10 V/cm and 12.5 V/cm) and vacuum evaporation (VE) methods. Thermodynamics' first law and second law analyses were conducted for different TSS contents (20-40%) by taking into account of two different control boundaries; in terms of process boundary (PB) and system boundary (SB). Energy efficiency, specific water removal rate (SWRR) and exergy efficiency reached maximum values for 30% TSS content, then it decreased. It was determined that energetic and exergetic efficiencies of SB were lower than those of PB. For the same TSS content, exergy efficiency value increased and improvement potential (IP) value decreased as the voltage gradient increased. Since highest energy consumption (5844.20 +/- 29.89 J) was determined at 40% TSS content for 7.5 V/cm (p < 0.05) this process condition need the improvement most. It can be concluded that OVE method used the energy more efficiently than VE method for the purpose of the concentration of pomegranate juice. (C) 2017 Elsevier Ltd. All rights reserved.TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [1140117]This study was a part of TUBITAK Project No. 1140117 of "Setting up and testing of ohmic heating assisted evaporation system, and investigation of its applicability on the concentration of pomegranate juice". The authors acknowledge TUBITAK TOVAG Group and Certurkler Machine Company