Exergetic performance analysis of ohmic cooking process

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

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.

Effects of Vacuum Ohmic Evaporation on Some Quality Properties of Sour Cherry Juice Concentrates

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.

Energetic and exergetic performance analysis and modeling of drying kinetics of kiwi slices

This work focused on the effects of the moisture content, slices thickness and microwave power on aspects of energy and exergy, drying kinetics, moisture diffusivity, activation energy, and modeling of the thin layer drying of kiwi slices. Results showed that energy and exergy efficiency increased with increasing microwave power and decreasing slice thickness while values of energy efficiency (15.15-32.27 %) were higher than exergy efficiency (11.35-24.68 %). Also, these parameters decreased with a decrease in moisture content. Specific energy consumption varied from 7.79 to 10.02, 8.59 to 10.77 and 9.57 to16.20 to MJ/kg water evaporated for 3, 6 and 9 mm, respectively. The values of exergy loss were found to be in the range of 5.90 and 14.39 MJ/kg water and decreased as the microwave power increased and slice thickness decreased. Effective diffusivity increased with decreasing moisture content and increasing microwave power and slice thickness. Average effective moisture diffusivity of kiwi slices changes between 1.47 × 10(-9) and 39.29 × 10(-9) m(2)/s within the given variables range. Activation energy (17.96-21.38 W/g) showed a significant dependence on the moisture content. Although the Midilli model showed the best fit, Page's model was selected, since it had almost a similar performance but the model is simpler with two parameters instead of four.