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Frozen minced beef meat samples having different fat contents of 2, 10, and 18% were thawed until their center temperature reached −1 °C in the ohmic thawing system. Ohmic thawing was conducted by applying different voltage gradients (10, 13, and 16 V/cm) at ambient temperature of 4 ± 0.5 °C. Effective electrical conductivity (EEC) values of the samples at −1 °C were 0.5774 ± 0.0558, 0.4231 ± 0.0510, and 0.3933 ± 0.0693 S/m for 2, 10, and 18% fat contents, respectively. The change of effective electrical conductivity with temperature was linear for temperature range of −18 °C/−9.5 °C while it was exponential for temperature range of −9.5 °C/−4 °C. Above −4 °C, the polynomial model was best model describing the change of EEC with temperature. Ohmic thawing process could be applied as an alternative novel technology for thawing of meat and meat products. It is thought that the results of present study would contribute valuable information to open literature. Practical applications Researchers have given attention on investigation of alternative thawing methods for foods in recent years. Ohmic thawing has high energy efficiency, causes low drip loss and does not produce any waste water. Since it is controlled by heat generation caused due to passing of alternative current through food, the information on change of its electrical conductivity is crucial. The minced beef sample has heterogeneous structure such as muscle, connective, and adipose tissues. Thus, its effective electrical conductivity (EEC) varies depending on its composition. In this study, the relations between temperature and EEC of minced beef samples having different fat contents were determined for four different temperature ranges existed during ohmic thawing at different voltage gradients. EEC was very low at temperatures below −4 °C, and then it sharply increased above this temperature. Results of present study would give valuable information to food industry for setting up industrial scale ohmic thawing systems for meat and meat products.

Thin-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 × 10−9, 6.84 × 10−9 and 8.96 × 10−9 m2/s for power intensities of 1790, 1970 and 2070 W/m2, 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/m2 was recommended as the best-infrared power intensity applied for drying of dill leaves by taking into account both performance analyses and quality changes.

The verjuice sample (14.5 ± 0.2% total soluble solid [TSS] content) was concentrated (at 102 ± 2°C evaporation temperature) until reach 50% TSS content by applying ohmic heating at 13, 15, 17, and 19 V/cm voltage gradients. The total process times up to 50% TSS content were determined as 2,100, 1,500, 1,200, and 1,020 s for 13, 15, 17, and 19 V/cm, respectively. The electrical conductivity values increased until reach 32% TSS content and then showed a decrease until the final TSS content. The total energy consumption values increased as the voltage gradient decreased. The total power and specific water removal ratio (SWRR) values decreased as the voltage gradient decreased. The efficiency of ohmic heating assisted concentration process increased with the applied voltage gradient and it ranged from 71.27 to 75.22%. By evaluating the effects of ohmic heating conditions applied in the present study on total process time, total energy consumption, and process efficiency, 19 V/cm voltage gradients could be recommended to be optimum evaporation conditions of verjuice concentration in case of decreasing process time and higher energy efficiency. Practical applications Fruit juices are generally concentrated to extend their shelf life. Therefore, for concentration purposes, various techniques, such as thermal evaporation, freezing methods, and membrane techniques, are applied in the fruit juice industry. This technique has some disadvantages, such as high energy requirements, the formation of undesirable compounds, high initial investment cost, and high failure rate to reach the desired total soluble solid content. The ohmic heating method, which is among the alternative heating methods, has advantages such as high energy efficiency, shorter processing time, higher product quality, and not causing wastewater. As a result of this study, it is thought that the verjuice samples were successfully concentrated up to 50% TSS content by using the ohmic heating method and this method can be used as an alternative method instead of the traditional method due to higher process efficiency and shorter process time.

BACKGROUND: Vacuum evaporation (VE) process is widely utilized in fruit juice evaporation to preserve quality attributes of final product. However, it has some disadvantages such as possible degradation of aroma components or volatile fatty acids due to long process time, and low energy efficiency of process. Pomegranate juice having 17.5% total soluble solid (TSS) content was evaporated to 40% TSS by ohmic heating assisted vacuum evaporation (OVE; 7.5, 10 and 12.5 V cm −1 ) and VE in the present study. The effects of the evaporation methods on pH, titratable acidity and colour values, antioxidant activity (AA), total monomeric anthocyanin (TMA), total phenolic content (TPC), hydroxymethylfurfural (HMF) and invert sugar content of pomegranate juice concentrates were compared. RESULTS:The colour properties, TMA, TPC and AA values of pomegranate juice concentrates evaporated by OVE were more influenced than those evaporated by VE. The degradation of sugars was minimized for OVE processes at high voltage gradients (10 and 12.5 V cm −1 ), and HMF content of pomegranate juice concentrated by OVE was lower than VE. CONCLUSION: It is thought that electrochemical reactions occurred because of the use of titanium electrodes during the OVE process caused these quality changes in pomegranate juice concentrates having high acidity. Hence, it was concluded that the utilization of relatively more electrochemically inert electrodes should be investigated in further studies to better evaluate the of influence of OVE method on quality attributes of different fruit juices.where subscript '0' indicated colour properties of raw material, and subscript 'i' indicated colour properties of juice concentrates. Statistical evaluationStatistical evaluations were performed by using SPSS 16.0 (IBM, USA) program. The difference between the effects of evaporation methods on colour properties, TPC, total and invert sugar content, TMA, HMF and AA were determined by using analysis of variance (ANOVA) test. The confidence interval was chosen as 95%.

In this study, licorice root was successfully dried using two different radiative dryers (Carbon fiber-assisted cabin drying-CFACD and infrared drying-ID), and their effects on some drying characteristics, quality properties, and energy-exergy efficiency were investigated. Page and Verma models were the best models describing the drying behavior of licorice root for CFACD and ID methods, respectively. ID protected total phenolic content (TPC) better than CFACD while the changes of color properties were higher for ID. Energy and exergy efficiencies of CFACD were 40.20 ± 0.20% and 31.87 ± 0.10%, respectively, while these values were 10.39 ± 0.33% and 9.99 ± 0.27% for ID, respectively. Practical applications The radiative heating method has advantages such as shorter drying time, highenergy efficiency, and high heat transfer coefficient compared to convective drying methods. Infrared drying (ID) is known as the common energy efficient drying method for food materials while the information on the performance of other type of radiative carbon fiber assisted drying (CFACD) systems is limited. In this study, the use of carbon fiber assisted cabin dryer for drying of licorice was evaluated by comparing other radiative type infrared dryer. The drying characteristics of licorice samples having high amount of phenolic contents were compared both in terms of quality and energy performance characteristics of dryers. Energy and exergy efficiencies of CFACD were found to be higher than ID. In addition, more homogeneous temperature distribution and less color change were obtained in the CFACD process. It was determined that the CFACD process could be recommended for drying of licorice samples rather than ID.

Pectin is usually extracted by exposure to a high temperature and a specific pH value by conventional methods. However, due to reasons such as low energy efficiency of the process and damage to the pectin, alternative thermal and non-thermal methods are used in the pectin extraction process. In this study, the effect of different processing times (0, 5, 15, 30, 60, 120, 180 min) on pectin extraction was investigated for grapefruit, lemon, and orange samples at 80 C. Besides, it was determined that the electrical conductivity value ranged between 1.46-2.06 S/m during heating, the electrical conductivity value of the pH solution adjusted with sulfuric acid. Accordingly, it was figured out that the total amount of energy consumed increases as the process holding time increases. However, it was determined that there was a decrease in the average power value by turning on-off the system. Practical ApplicationPectin is one of the additives used in many areas in the food industry. Pectin is now produced especially from agricultural waste peel. During this production, it is subjected to long processes at certain pH and certain temperatures. With the present study, determination of pectin yield over a wide period of time by using ohmic heating process and total ohmic heating energy was determined. In this way, it is thought that a serious contribution will be made to the literature and industry regarding different industrial agricultural waste peel (orange, grapefruit, lemon) during pectin production. | INTRODUCTIONIn the food industry, some parts of food as the peel, stem, and core, and so forth, are released to the environment as waste. The amount of waste left to the environment increases rapidly every year due to the increase in population, urbanization, and developments in industry (Güzel & Akpınar, 2017). Wastes are divided into three groups as domestic wastes, industrial wastes, and agricultural wastes according to their usage and occurrence. This increase in agricultural and industrial wastes has led researchers to work on the recovering of these wastes. Some of the most important of these wastes are grapefruit, lemon, and orange wastes.