Drying Of Slices Research Articles

Drying kinetics and activation energy for solar drying of ginger slices

Drying is one of the oldest and most important preservation method for food in which by reducing the water activity the shelf life can be increased. In the present investigation, fresh ginger was pretreated in calcium oxide solution at different concentrations. Solar drying at three temperature levels viz., 55, 65 and 75o C at loading densities of 0.147 g/cm2, 0.176 g/cm2, 0.206 g/cm2 respectively were used for the investigation. Results of study revealed that the total time required for ginger drying in solar dryer curtails with rise in drying air temperature and increased as loading density increased. The activation energy was observed to be 20.45 kJ mol-1, 29.06 kJ mol-1 and 17.6 kJ mol-1 for 0.147 g/cm2, 0.176 g/cm2 and 0.206 g/cm2 loading density respectively. Also, the diffusivity increased with increase in temperature from 45 to 65 oC.

Drying quality and energy consumption efficient improvements in hot air drying of papaya slices by step-down relative humidity based on heat and mass transfer characteristics and 3D simulation

Convective hot air drying technology is widely used for fruits and vegetables drying process due to its simplicity in usage, small investment, and convenience in operation. However, it is generally considered energy-intensive process with lower drying efficiency and quality because of unprecise control of drying process. In order to solve these problems, step-down relative humidity (RH) hot air drying technology was applied for papaya drying to improve drying efficiency and quality and reduce energy consumption. The effect of constant RH (20%, 30%, 40%, and 50%) and step-down RH of 50% with different holding times (10, 30, 60, and 90 min) and then decrease to 20% on heat and mass transfer process, drying quality, and energy consumption was examined. Results showed that decreasing RH contributed to improvement in the drying rate (DR). Compared to constant RH of 20%, the drying time under initial RH of 50% for 30 min followed by 20% RH shortened by 21.4%. Additionally, under this RH control strategy, the rehydration ratio (RR) and energy consumption achieved their maximum (7.71 ± 0.06) and minimum value (0.015 ± 0.001 kJ/g), respectively. During initial drying stage, high RH improved convective heat transfer coefficient (ht ) values and material temperature increased quickly. Furthermore, high RH contributed to maintaining pore structure formation, which benefited moisture diffusion. When RH was reduced, low RH enhanced convective mass transfer coefficient (hm ) significantly, resulting in rapid diffusion of internal moisture at high temperature, as well as rapid moisture evaporation from the surface. Therefore, step-down RH hot air drying was verified to improve drying of papaya slices, making it energy efficient process. The findings in current work indicate step-down relative humidity strategy is a promising technique to enhance hot air drying process, quality, and energy efficiency of papaya slices.

Drying kinetics and quality properties of Mellaki ( Pyrus communis L.) pear slices dried in a novel vacuum‐combined infrared oven

In a specially designed infrared oven equipped with a two-way infrared heating and vacuum pump systems, the effects of drying parameters (100–300 W infrared powers and 100–250 mmHg vacuum pressures) on drying kinetics and quality properties of pear slices were comprehensively studied. The samples dried at 300 W had high HMF values (12.73–95.68 mg/kg d.m). The highest sensory scores were observed in pear slices dried at 300 W and 250 mmHg. Six different mathematic models were taken into account to analyze the drying characteristics of pear slices, with the Wang and Singh model (R2 = 0.9996, χ2 = 0.0004, and RSME = 0.0062) presenting the best prediction of the drying behavior. The effective moisture diffusivity values were 1.1829–4.6684 × 10−8. The activation energies for 100 and 250 mmHg vacuum applications were 44.21 and 43.89 kJ/mol, respectively. It was concluded that a vacuum-combined infrared dryer (300 W, 250 mmHg) could be a fast and economic method for drying pear slices. Novelty impact statement A combination of 300 W infrared power and 250 mmHg vacuum pressure was the fastest combination for the drying of pear slices and gave the highest score in sensory evaluation. The Wang & Singh model exhibited the best results in fitting the experimental data. As a result, the vacuum-combined infrared technology was improved the drying efficiency and quality of dried pear.

Mathematical Modeling of Thin Layer Drying of Onion Slices

Mathematical Modeling of Thin Layer Drying of Onion Slices

Electrohydrodynamic drying of fruit slices: Effect on drying kinetics, energy consumption, and product quality

The effect of electrohydrodynamic drying on the drying kinetics, energy consumption, and quality was studied for apple and strawberry slices with different thicknesses from 1 to 4 mm. Effective diffusivity and energy consumption were quantified via direct measurements, while visual quality attributes, such as color and shrinkage were determined through image analysis. It was found that effective diffusivity was independent of thickness, around 0.5×10-11 m2/s for apples and 0.24×10-11 m2/s for strawberries. The average specific energy consumption increased with the fruit thickness from 601.13 kJ/kg (1 mm) to 1433.83 kJ/kg (4 mm) for apple slices and from 1324.17 (3 mm) to 1756.71 kJ/kg (4 mm) for strawberry slices. The effect of EHD drying on apple color was significantly smaller than conventional hot-air drying. The impact of EHD drying on the shrinkage of apple slices was about 85%, and for strawberry slices, about 90%, which was higher than in hot-air drying. It can be concluded that EHD is effective for drying thin fruit slices due to the low energy consumption and better quality.

Experimental investigation and drying kinetics of mixed type solar dryer with thermal energy storage material for drying of apple slices

ABSTRACT The current study covers drying of 500 g of apple slices of uniform thickness by forced convection mixed solar drying unit integrated with paraffin wax and natural sand as energy storage (thermal) material. The experimental setup consists of solar collector (for heating inlet air) and drying chamber in which heated air removes moisture content of apple slices from 80 to 21.7% (wet basis) in 3.5 h during April 2021. The average moisture diffusivity for lower tray was 1.018 × 10−8 m2/s which was 16.3% and 28.6% greater than upper tray and open sun drying, respectively. The average drying rate for lower tray (0.5318 kg water/kg dried product/h) was higher than upper tray and open sun drying. At the same drying time of 3.5 h, the final moisture content in lower tray, upper tray and open sun drying were obtained as 21.7%, 22.64% and 25.61%, respectively, which indicates that present solar drying is better than open sun drying. The average drying exergy efficiency was obtained as 48.14% with maximum value as 74%. The maximum (& average) drying efficiency and collector efficiency were 13% (& 5.56%) and 83.3% (& 66.39%), respectively. Wang and Singh model was found the best suitable among 14 thin layer drying models.

Characteristics and mathematical modeling of apple slice drying in an electrohydrodynamic system with a needle‐plate electrode

AbstractThe drying of apple slices in an electrohydrodynamic (EHD) system with a needle‐plate electrode was characterized and mathematically modeled at voltages of 30, 40, and 50 kV and with distances between needles of 5, 6, and 7 cm. The results showed that the drying rate, effective water diffusion coefficient, and rehydration ratio of the apple slices, and specific energy consumption of drying, all increased with increasing voltage. Initially, there was a period when the drying rate was approximately constant in the low‐voltage EHD, but not in the high voltage conditions. At the same voltage, the drying rate was highest when the distance between needles was 6 cm. The voltage and distance between needles had a significant (p < .05) interactive effect on the effective water diffusion coefficient and specific energy consumption, but not on the rehydration ratio. General mathematical models for drying can be used to represent the drying behavior of apple slices. The Midilli and Kucuk model and the Logarithmic model had the best fits, with correlation coefficients of 0.998803 and 0.998267, respectively. Predictive functions for the moisture ratio of apple slices based on voltage and distance between needles were established and verified. The results indicated that the Logarithmic model could more accurately predict the moisture ratio of apple slices dried using the EHD method.Practical ApplicationsAs a new drying technology, electrohydrodynamic (EHD) drying has unequaled advantages. According to the results, using the appropriate voltage and distance between needles improves not only drying efficiency, but also the rehydration ratio of apple slices, which reflects the quality of dried products. The Logarithmic model can accurately predict the EHD drying behavior of apple slices, which is of great significance in optimizing actual production.

Influence of ethanol and ultrasound on drying, bioactive compounds, and antioxidant activity of strawberries (Fragaria × ananassa)

This study aimed to evaluate the use of ethanol (ET) and ultrasound (US) in convective drying of strawberry slices, as well as the effect on physicochemical, bioactive, and antioxidant parameters. For this, strawberry slices with a thickness of 0.005 m were pretreated with ET (in different volume fractions), US, and a combination of both. Drying kinetics were performed for control strawberry slices (without ET and US) and pretreated with 50% ethanol (ET50), 50% ethanol and ultrasonic (ET50US), 100% ethanol (ET100), and 100% ethanol and ultrasonic (ET100US) at a temperature of 60 °C. Empirical and diffusive models were fitted to the experimental data to describe the drying kinetics, and the fresh and dried slices were analyzed according to the parameters of water activity (aw), water content, total phenolic compounds (TPC), total anthocyanins (ATS), vitamin C and antioxidant activity (AA) (ABTS•+, DPPH•, and FRAP). The use of the ET100US combination provided an increase in the moisture transport process, higher drying rate, shorter process time (570 min), and reduction of aw to a safe value (aw <0.5), however, it sharply degraded the TPC, ATS, and AA. The ET50US pre-treatment even with a drying time of 690 min was the most efficient, since the values of TPC, ATS, and vitamin C suffered smaller reductions, where the AA varied in only 10.32%, 13.78% and 6.54% for the methods ABTS•+, DPPH•, and FRAP, respectively when compared to fresh strawberry. In this sense, it can be stated that the pre-treatment with 50% ethanol and ultrasound (ET50US) showed less reduction in the degradation of bioactive and antioxidant properties, and in the minimization of drying time for strawberry slices.

Thin Layer Modelling of Indirect and Mixed-Mode on-Farm Drying of Selected Vegetables

The thin layer drying characteristics of tomato and okra slices dried using mixed-mode on-farm solar dryer, indirect mode on-farm solar dryer and open sun drying. The tomato and okra slices dried faster when dried under the mixed-mode on-farm solar dryer. Drying time was reduced considerably using the on-farm solar dryers. The drying data were fitted into Lewis, Henderson and Pabis, and page equations. The Page model (R2=0.9365, 0.9623; X2= 0.0067, 0.0000579; RMSE= 0.0086, 0.0020 and MBE= -0.008, -0.002) gave the best prediction for the mixed-mode drying and indirect mode drying of tomato slices respectively. In the same vein Page model (R2=0.9202, 0.933o; X2= 0.00091, 0.000730; RMSE= 0.0265, 0.0244 and MBE= -0.0088, -0.0074) gave the best prediction for the mixed-mode drying and indirect mode drying of okra slices respectively. Effective moisture diffusivity of tomato slices varied between -7.4724 X 10-08 and -1.6439 X 10-07 while that of okra varied between -3.12 X 10-07 and -8.08 X 10-07. The indirect mode dryer gave the best quality of dried tomato and okra.

Investigating shrinkage corrected drying characteristics, rehydration, color profile and microstructural evolution during solar drying of pineapple slices

AbstractThe study describes the solar drying characteristics of pineapple slices with incorporation of shrinkage and influence of drying and rehydration on structural alterations, color profile and microstructure. Samples were dried in mixed mode solar dryer at an air velocity of 0.5 m/s, with recorded average solar radiation, ambient and drying chamber temperature of 665 W/m2, 33°C and 65°C, respectively, from initial moisture content of 89.9% to a final moisture content of 23% in 6.5 h. Samples showed 43.7% higher drying rate and 82.25% lesser moisture diffusivity on consideration of shrinkage. Moisture diffusivity was increased with a reduction in moisture content during drying on ignoring the shrinkage, while it was initially increased and then gradually reduced at later hours when shrinkage effect was considered. The slices showed overall shrinkage of 86.95% during drying but could recover only 35–45.57% of its volume during rehydration. The water absorption and volume recovery were consistently higher at rehydration temperature of 60°C followed by 45°C and 30°C. Solar dried and rehydrated samples demonstrated overall color change of 16.80 ± 1.15 and 5.87 ± 2.5–7.56 ± 1.43, respectively. Scanning electron micrographs of solar dried samples presented collapsed cellular matrix but rehydrated samples showed porous microstructure indicating regaining of honeycomb network.Practical ApplicationsSolar drying is an essential sustainable approach to reduce the tremendous post‐harvest losses of fruits and it also offers the advantages of energy cost saving, higher affordability level and greater payback power to farmers. Present study explored the drying characteristics, followed by rehydration characteristics and effect of drying and rehydration on quality attributes of pineapple slices. Therefore, results are helpful for food processors and engineers in optimization of drying and rehydration processes to obtain best quality products, shelf‐life extension of perishable fruits. Solar dried pineapple slices will give better returns to farmers. Moreover, dried pineapple can be utilized as dried chips/snacks, powder, etc. and also can be further rehydrated to reconstitute for utilization in different value added food products like ice‐cream, cakes, flakes, granules etc.

MATHEMATICAL MODELLING AND OPTIMIZATION OF MELON SLICE DRYING WITH RESPONSE SURFACE METHODOLOGY IN A HEAT PUMP DRYING SYSTEM

The objective of this study was to optimize the process conditions (in terms of air temperature, air velocity and thickness of the slices) using response surface methodology (RSM) to achieve minimum specific energy consumption and maximum moisture diffusivity during drying of melon slices with a closed loop heat pump drying (HPD) system. An optimum drying temperature of 45 °C, air velocity of 1 m/s and slice thickness of 5.04 mm were recommended with following predicted responses close to experimental values: drying time 216.58 min, total energy consumption 2.94 kWh, coefficient of performance heat pump (COPhp) 3.08, coefficient of performance system (COPws) 2.75, specific moisture extraction rate (SMER) 0.22 kg/kWh, drying rate 2.53, L* value 82.53, a* value -1.83 and b* value 25.82. The most suitable models to represent the drying behavior of optimum melon slices was chosen Wang &amp; Sing. Effective moisture diffusivities (Deff) of the melon slices were ranging from 7.075E-10 - 1.843E-07 m2s-1 and increasing drying air temperature, drying air velocity and slice thickness led to an increment of Deff.

DEHYDRATION BEHAVIOR AND THERMODYNAMIC ANALYSIS OF KIWIFRUIT SLICES IN CONVECTIVE TRAY DRYER

The present study was concerned with convective drying of kiwifruit slices. The influences of drying air temperature and flow rate on dehydration behavior of the samples and thermodynamic performance of the process were investigated. The results showed that the process duration was significantly decreased with the increasing temperature and flow rate. The entire dehydration process took place in the falling rate period and no constant period was observed. Using the nonlinear regression procedure, four well-known mathematical models were fitted into the experimental drying curves and the Midilli model represented the best description. The results of thermodynamic analyses indicated that, following the increment in air temperature, the energy utilization and energy utilization ratio values increased from 2.91 to 15.05 kJ s-1 and from 0.24 to 0.47, respectively. The exergy loss and exergy efficiency were specified to be in the ranges of 50-280 J s-1 and 55.89% to 84.13%, respectively. The exergy improvement potential rate and sustainability index varied from and from 12.28 J s-1 to 36.39 J s-1 and from 12.28 J s-1 to 36.39 J s-1, respectively. Generally, despite of energetic indices, higher temperatures of drying air resulted in better exergetic performance.

Energy consumption computing of cold plasma‐assisted drying of apple slices (Yellow Delicious) by numerical simulation

AbstractEnergy consumption is a great challenge during fruit drying. New techniques such as cold plasma are used as pretreatment or the main treatment for food drying. In this work, apple drying with cold plasma was investigated with COMSOL simulation. Two treatments were designed: (a) traditional air drying at 60°C and 0.5 m/s airflow, and (b) cold plasma treatment at 100 W, and 60 Hz with laminar airflow at 60°C and 0.5 m/s. The samples were two apple slices with a 6 cm diameter and 0.3 cm thickness. Results show that plasma technology without airflow does not have an effective role in drying. But the combination of plasma and airflow drying reduced the drying time from the 9,600 s to 3,600 s. The plasma‐treated samples reached a constant moisture content faster than the air‐dried samples. The energy consumption of drying with plasma was 85‐fold lower than a traditional air‐drying method. The shrinkage of plasma‐treated samples was low and the total shrinkage was near the undried sample (0.008). Cold plasma probably can reduce the energy consumption, drying time, and final drying costs of fresh food drying.Practical applicationDrying with a combination of methods can reduce the processing time. In this work, the plasma technology was combined with air drying and the results show lower process time, lower shrinkage, and lower energy consumption. Plasma technology in combination with traditional air drying can reduce the drying time of food material from 9,600 s to 3,600s. The energy consumption of plasma drying was significantly lower than air drying. It can be concluded from these results that this drying method can be applied to study the drying of different types of food material.

Evaluation of the effect of the operational parameter on unripe banana (Musa cavendishii) flour production: case study at Arba Minch

Abstract In recent times, there are huge postharvest losses in banana production due to low market price, overproduction, lack of proper storage facilities and inadequate supply chain management. The transformation of fresh bananas to Unripe Banana flour has got immense potential to cope up with the postharvest losses of banana and it adds value to fresh bananas. Due to high availability of minerals such as potassium, calcium, iron and also the presence of high dietary fiber and resistant starch in unripe banana, they promote colon health and act as nutritious food source. In relation to this, the effect of the three types of pretreatment techniques on production of flour from unripe banana and their quality characteristics were analyzed. Drying of banana slices was conducted after performing pre-treatments like optimal osmotic solution variables, sodium meta-bisulfite (SMS), and hot water (at 100 °C). Both the untreated (control) and treated samples was oven dried at 45, 60, and 75 °C for a day (24 h). After complete drying, the banana slices were milled into a powder. For the study of optimum osmotic parameters, the design-Expert (software version 7.0.0) at three level full factorial design was employed. The optimum conditions of minimal solid gain percentage (5.66%) at maximum water loss (29.16%) were obtained at 30 °Brix sugar concentration, 60 °C socking temperature and 90 min soaking time.

열처리와 비열처리 방법에 따른 양파 및 마늘 건조 슬라이스의 품질 특성

In the present study, the application of suitable thermal and nonthermal pretreatment methods was explored to develop a dried products comprising onion and garlic slices. Pretreatment was performed via blanching for 30 sec, steaming for 1 min, dipping in warm water (45°C) for 30 min, and dipping in cold water (8°C) for 1 hr. Furthermore, physicochemical and microbiological analyses were performed in conjunction with sensory evaluations. The group subjected to pretreatment via cold-water dipping exhibited the lowest moisture content and water activity with a negligible redness, yellowness, and browning index. Furthermore, the results of sensory evaluation revealed that this group exhibited relatively high color and overall acceptability. The group subjected to pretreatment via blanching presented severe browning and shape distortion. The samples in the group subjected to pretreatment via cold-water dipping did not exhibit a significant difference in pH; furthermore, the number of microorganisms during storage was lower than that in the control group. It was concluded that the hot-air drying of onion and garlic slices after cold-water dipping resulted in an increase in drying efficiency and the suppression of browning, without inducing major component changes. The facile technique demonstrated in the present study is expected to be fast and cost-effective, thereby facilitating practical application in farms.

Drying of garlic slices by electrohydrodynamic‐hot air method

AbstractIn this study, garlic slices were dried with a new drying method, electrohydrodynamic‐hot air combined drying system, under different temperatures (55 and 60°C) and voltages (15, 20, 25, and 30 kV), and the effects of drying conditions on drying time, color parameters, rehydration capacity, energy values, and microstructure were investigated. In addition, experimental data were fitted into 10 different mathematical models that are widely used to select the appropriate model that could describe the drying behavior of garlic slices. The longest drying time required for constant moisture content was observed under 30 kV‐60°C treatment for 100 min, while the shortest drying time was observed under 15 kV‐55°C treatment for 160 min. Verma et al., Diffusion Approach, and Newton models were determined so as to find the most suitable model for the drying behavior of thin‐layer dried garlic samples at different temperatures and voltages. Increasing drying temperature caused a decrease in the a* and b* values of the garlic samples. The lowest energy consumption during the drying of the garlic slices was found at 30 kV‐55°C treatment combination. It was observed that the temperature and kV values have impact on the product microstructures.Practical ApplicationDrying is the preservation process to extend the shelf life of products. The traditional method is the most used one in the drying industry. The low energy efficiency of this method and the loss of quality due to the high contact of the hot air with the product have led to the research of new methods. Therefore, the electrohydrodynamic method is used as a new approach that results in high energy efficiency and a high‐quality product. As a result, integrating the electrohydrodynamic system into the hot air drying method will reduce the contact of the hot air with the product, thus prevents the negative effect of temperature and provides better quality products. In addition, this system can increase the drying efficiency and energy economy by reducing the drying time and energy consumption in drying procedure of garlic samples.

Evacuated tube solar and sun drying of beetroot slices: Comparative assessment of thermal performance, drying kinetics, and quality analysis

In this research work, the thermal performance of an evacuated tube solar dryer (ETSD) was investigated at no-load and with load of beetroot slices for drying. The experiments were performed in both ETSD and sun drying to compare drying kinetics, mass transfer phenomena, colour changes, and retention of bioactive compounds of beetroot slices. At no-load condition, maximum ambient and drying chamber temperature achieved were 41.50 °C and 75 °C respectively. The initial moisture content was found to be 84.05% which reduced to 9.25% and 13.56% in ETSD and sun-drying, respectively. Average drying rate was found to be 8.5 g water/g dry solid. hr and 7.94 g water/g dry solid. hr. in ETSD and sun-drying respectively. Weibull and Midilli kucuk models precisely described the drying kinetics of beetroot slices in ETSD and sun-drying, respectively. The effective moisture diffusivity range, activation energy, and maximum mass transfer coefficient of beetroot slices dried in ETSD were 1.01 × 10-7 to 2.45 × 10-7 m2/s, 27.60 kJ/mole, and 3.23 × 10-4 m/s respectively while for sun drying these parameters are 1.19 × 10-7 to 2.24 × 10-7 m2/s, 57.15 kJ/mole, and 3.18 × 10-4 m/s. Betalain pigment retention was higher by 63.98% in ETSD drying than sun drying. The colour changes were found to be higher in sun drying. The average phenolic content and antioxidant capacity were higher by 31.07% and 21.87% in ETSD as compared to sun drying. Therefore, the ETSD can effectively dry other food commodities with reduced drying time and significant retention of quality attributes.

Drying of lotus rhizome slices: Influence of drying conditions on Fourier transform infrared spectroscopy, rheology, functional, and physicochemical characteristics of lotus rhizome powder

AbstractFresh lotus rhizome has a limited harvesting duration and is prone to browning leading to fast decomposition. Lotus rhizome powder (LRP) can be an innovative substitute to unravel this difficulty, valorize the product and improve its export potential. Microwave blanched lotus rhizome (LR) slices revealed the logarithmic model as the best drying model of fresh LR slices. Water activity (Aw) portrayed strong dependence on drying time; color parameters, a* increased, while L* and b* decreased with slice thickness. Water and oil absorption capacity (WAC and OAC) of lotus rhizome powder (LRP) changed from 4.95 to 1.68 g/g and 2.99 to 0.52 g/g, respectively, with a sharp increase in OAC of samples dried at 80°C. Storage modulus (G′) was higher than loss modulus (G″). Samples of 3 mm thickness dried at 50, 60 and, 70°C had the lowest flow behavior index (n) of 0.2219. Fourier transform infrared spectra of LRP displayed regions of polyphenols with slight deviations for different drying temperatures. It was concluded that 3 mm thick slices dried at 60–80°C required lesser time and possessed better WAC, OAC, and color values.Practical ApplicationsRecently, vegetable powders have driven the attention of food process engineers due to their stability and wide nutritional gamut. Thus, it is attempted to develop and characterize the Lotus (Nelumbo nucifera Gaertn) rhizome powder which will not only make it readily available but will find its practical utilization as an ingredient in food formulations. Lotus rhizome powder is a unique blend of nutrients and bioactive components; therefore, it is important to understand its properties, drying behavior, and engineer the powder development with maximum functionality. Primarily, the lotus rhizome being a perishable vegetable, can be improved for shelf‐life stability and safety. Secondarily, the lotus rhizome powder can be incorporated as the functional ingredient, in flavoring, food, and pharmaceutical industry. Therefore, it is of prime significance to add value to this aquatic vegetable to make it an ideal food resource in the future.

DRYING, COLOUR AND REHYDRATION CHARACTERISTICS OF ORANGE SLICES UNDER INFRARED RADIATION HEATING

The effect of different infrared (IR) powers on drying of orange slices was investigated in infrared dryer. The orange slices dried at 62, 74 and 88 W infrared powers and constant slice thickness of 6 mm. Results showed that drying, colour and rehydration characteristics of orange slices were greatly influenced by infrared power. The drying data were fitted with five mathematical models available in the literature. Based on the statistical tests applied to make an assessment, the model of Midilli and Kucuk was found to satisfactorily explain drying kinetics of orange slices for all drying conditions. The Fick’s diffusion model was used to calculate the effective moisture diffusivity (Deff) of orange slices. The value of Deff varied from 1.59×10-10 to 2.49×10-10 m2/s. It was found that the effective moisture diffusivities increased with increasing IR power. Activation energy was estimated by a modified Arrhenius type equation as 2.11 kW/kg. As the infrared power increased, the rehydration ratio was found to be reduced. Furthermore, with increase of infrared power, the values of a and DE increased, whereas the values of L, b and C decreased.

Evaluating of Microwave Drying for Hawthorn Slice as Alternative to Convective Drying

HIGHLIGHTS Microwave drying lead to improve the drying characteristics of Hawthorn slices. Page model was found as the best described the microwave drying data. Microwave drying at 360 W can be applied as an effective technology for drying of hawthorn slices.