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Achieving the desired level of caramelisation in a date powder requires considerable effort. Consequently, an assessment was conducted on efficacy of thin-layer infrared dehydration for date paste. Various parameters were considered, including airflow velocities of 0.5, 1.0, and 1.5 m.s-1, radiation intensities of 0.076, 0.1528, and 0.228 W.cm-2, and date paste layer thicknesses of 3 mm and 5 mm. The study's findings indicated a positive correlation between drying rate and lowering airflow velocity and a negative correlation between drying time and decreasing airflow velocity, the thickness of date paste, and rising intensity of infrared. The effective moisture diffusivity (Deff) was caculated by employing Fick's diffusion equation. For all situations under investigation, the mean values were within the range of 3.94 × 10-11 m2.s-1 to 6.01 × 10-10 m2.s-1. A relationship has been established between Deff and moisture content. Seven distinct mathematical models were subjected to rigorous validation by applying non-linear regression analysis, aiming to accurately characterise the drying process of date paste. The modified two-term model provided the most accurate forecast of the drying process for date paste layers.

In order to reduce the drying time of broccoli and to investigate rehydration and color changes associated with the drying process, infrared drying method and blanching pretreatment were used in this study. Boccoli florets were dried using infrared drying at power levels of 50, 62, 74 and 88 W to investigate drying kinetics. Blanching was used as a pretreatment and it was found that the blanched samples dried faster. Effective moisture diffusion coefficients were also calculated. While Deff values between 9.26 × 10−11 and 2.15 × 10−10 m2/s were observed for the control samples, this value varied between 1.10 × 10−10 and 2.87 × 10−10 m2/s for the blanched samples. The calculated activation energy values for the blanched and control samples are 2.11 and 2.0 kW/kg, respectively. The drying process was modeled using 12 different thin-layer drying models and it was found that the Midilli & Kucuk model best represented the process. Color analysis was performed by measuring L, a and b values as well as chroma, hue angle and total color change values. It was observed that increasing infrared power affected color parameters, leading to a decrease in L values and an increase in a and b values. In addition, blanching pretreatment preserved color to some extent. The rehydration behavior of dried samples was also analyzed. It was found that the highest rehydration capacity was achieved in blanched samples dried at 74 W. [ABSTRACT FROM AUTHOR]

Achieving the desired level of caramelisation in a date powder requires considerable effort. Consequently, an assessment was conducted on efficacy of thin-layer infrared dehydration for date paste. Various parameters were considered, including airflow velocities of 0.5, 1.0, and 1.5 m·s-1, radiation intensities of 0.076, 0.1528, and 0.228 W·cm-2, and date paste layer thicknesses of 3 mm and 5 mm. The study's findings indicated a positive correlation between drying rate and lowering airflow velocity and a negative correlation between drying time and decreasing airflow velocity, the thickness of date paste, and rising intensity of infrared. The effective moisture diffusivity (Deff) was caculated by employing Fick's diffusion equation. For all situations under investigation, the mean values were within the range of 3.94 × 10-11 m2·s-1 to 6.01 × 10-10 m²·s-1. A relationship has been established between Deff and moisture content. Seven distinct mathematical models were subjected to rigorous validation by applying non-linear regression analysis, aiming to accurately characterise the drying process of date paste. The modified two-term model provided the most accurate forecast of the drying process for date paste layers. [ABSTRACT FROM AUTHOR]

Blueberry is a small fruit, which has a very high amount of antioxidant substances. It is con-sumed either in fresh or dried form. In this study, the effect of vacuum on the oven thin-layer drying of blueberries was investigated. The kinetic parameters of effective moisture diffusivity (Deff) and activation energy (Ea) values were calculated. Moreover, the drying curves were modelled with the most known mathematical modelling equations given in the literature. For oven and vacuum oven drying, the drying temperatures were selected as 60, 70 and 80°C. The drying times were seen to decrease by increasing the drying temperature and with the effect of vacuum. The highest drying time was observed as 420 minutes in oven drying at 60°C. The effect of vacuum decreased this drying time to 240 minutes. Deff values were calculated to elucidate the underlying mass transfer mechanisms by using Fick’s 2nd law, which were found to be between 1.14-2.83×10-9 m²/s for oven drying and increased to 2.54-4.33×10-9 m²/s by the addition of vacuum. Likewise, activation energy was increased from 25.93 to 43.98 kJ/mol by vacuum addition. Twelve mathematical models were applied to the drying curve data and among them, Alibas model for both oven drying and vacuum-assisted oven drying gave the coefficient of determination (R²) values that were higher than 0.997. As a result, the vacuum addition was seen to yield lower drying times and higher kinetic parameters for the oven drying of blueberries. [ABSTRACT FROM AUTHOR]

This study investigates the applicability of the Peleg model to the osmotic dehydration of various sweet potato variety samples in sugar beet molasses, addressing a notable gap in the existing literature. The osmotic dehydration was performed using an 80% sugar beet molasses solution at temperatures of 20 °C, 35 °C, and 50 °C for periods of 1, 3, and 5 h. The sample-to-solution ratio was 1:5. The objectives encompassed evaluating the Peleg equation's suitability for modeling mass transfer during osmotic dehydration and determining equilibrium water and solid contents at various temperatures. With its modified equation, the Peleg model accurately described water loss and solid gain dynamics during osmotic treatment, as evidenced by a high coefficient of determination value (r2) ranging from 0.990 to 1.000. Analysis of Peleg constants revealed temperature and concentration dependencies, aligning with previous observations. The Guggenheim, Anderson, and de Boer (GAB) model was employed to characterize sorption isotherms, yielding coefficients comparable to prior studies. Effective moisture diffusivity and activation energy calculations further elucidated the drying kinetics, with effective moisture diffusivity values ranging from 1.85 × 10−8 to 4.83 × 10−8 m2/s and activation energy between 7.096 and 16.652 kJ/mol. These findings contribute to understanding the complex kinetics of osmotic dehydration and provide insights into the modeling and optimization of dehydration processes for sweet potato samples, with implications for food processing and preservation methodologies. [ABSTRACT FROM AUTHOR]

Abstract The primary objective of this investigation, the influence of chemical, combined chemical, hybrid pre-treated samples and the addition of inert material into turkey berry samples through the fluidized bed dryer was studied at processing air temperature of 70 0C and an inlet air flow of 4.2 m/s, as well as compared to sun drying. Results showed that the Hybrid-II treatments as well as the addition energy carrier method reduced drying time around by 12 times and 10 times compared to open sun-dried samples. The Hybrid-II pre-treatment method resulted in the quickest drying procedure, and it was completed in 330 minutes. In addition, the lowest shrinkage of around 39%, tolerable color change, and the maximum retention of vitamin-C were achieved compared to both OSD and un-treated samples. The Midilli and coauthors (2002) [1] model was fitted, the most preferable model for predicting the drying characteristics of Turkey berry.

The objective of this study is mainly to analyze the drying kinetic parameters, effective diffusivity, and thermodynamic performance indicators (energy, exergy, heat, and mass transfer coefficients) of tea under different drying conditions of different drying temperatures (DT) and thin layer thicknesses (TT). Experimental drying was conducted at drying temperatures of 70°C, 80°C, and 90°C with thin layer thicknesses of 10 mm, 15 mm, and 20 mm. The results show that a higher drying temperature and a lower thin layer thickness can increase evaporation moisture content and shorten drying time. By evaluating and comparing the fitting of five drying models adopted by the coefficient of determination (R2) and chi-square (χ2), it can be found that the logarithmic model is the best to describe drying behavior. The effective moisture diffusivity shows a positively correlated trend with the increase in DT and TT, with the value of activation energy ranging from 14.030 to 22.344 kJ mol-1 K-1. The specific moisture evaporation rate (SMER), energy efficiency, exergy efficiency, and sustainability index (SI) descend as the TT increases at all DT; the specific energy consumption (SEC) and improvement potential (IP) rate perform in an opposite manner, but the TT remains unchange. The conclusion drawn from the thermodynamic parameters is opposite to the aforementioned. As the TT increases, the heat and mass transfer coefficients show a significant decrease trend. In addition, the heat and mass transfer coefficients are given as functions of DT and TT, and further knowledge shows that the mass transfer coefficient is positively correlated with DT but the heat transfer coefficient is negatively correlated. In conclusion, this article provides new insights into the effects of drying characteristics, energy consumption characteristics and heat and mass transfer characteristics in the process of tea drying under different drying conditions, and provides certain theoretical reference bases for promoting the optimization of industrialized tea drying production machinery design and drying process optimization. [ABSTRACT FROM AUTHOR]

Mango puree was foamed using hydroxypropyl methylcellulose to achieve foam densities ranging from 0.3 to 0.8 g/cm3. Subsequently, these mango foams were dried at temperatures ranging from 60 to 80 °C. The experimental results showed that mango foam drying was in the falling rate period. The effective moisture diffusivity (Deff) was well described by the Arrhenius equation, with the pre-exponential factor (D0) and activation energy (Ea) closely related to the void area fraction in mango foam. This relationship led to higher Deff and shorter drying times at higher void area fractions. The minimum loss of total phenolics content (TPC) was observed in mango foams with an initial foam density of 0.3 g/cm3 dried at 60ºC, with only a 7% loss. Increasing drying temperatures to reduce drying time did not mitigate TPC loss. Similarly, the minimum reductions in antioxidant activities, as measured by both the 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid and ferric reducing antioxidant power assays, were observed in mango foams with an initial foam density of 0.3 g/cm3 dried at 60 °C, with values of 14% and 18%, respectively. Dried mango foams with lower densities exhibited more pronounced color changes due to the presence of more sponge-like voids. However, the drying temperature did not significantly affect the product color. In addition, dried mango foams with lower initial foam densities displayed a more brittle and spongy texture. [ABSTRACT FROM AUTHOR]

BACKGROUND: Convective hot air drying of cocoyam is risk-free and inexpensive to a significant level. However, hot air drying causes negative changes to the color, texture, flavor and nutritional content of cocoyam as a result of the prolonged drying. Recently, the innovative technology of ultrasound pretreatment has been applied in food processing to reduce the processing time, conserve energy and preserve the quality of the food product. Thus, there is need to investigate the effect of ultrasound pretreatment with distilled water (UDW) and ultrasound with osmotic dehydration (UOD) for different ultrasonic times (10-30 min) on the drying kinetics of cocoyam slices during convective hot air drying. Ultrasound pretreatment was applied at a frequency of 20 kHz and an output power of 600 W for UDW and UOD. The ultrasound-pretreated samples were further dried in a convective hot-air drying oven at 70 °C. RESULTS: UDW and UOD samples, respectively, had a 25% and 46% reduction in drying time compared to untreated samples. The UOD samples had the lowest activation energy (10.697 x 10³ kJ), as well as the highest moisture diffusivity (3.782 x 10-10m² s-1) and mass transfer coefficient (2.006 x 10-8m s-1), among the untreated and UDW samples. Wang and Singh, Page and Peleg models were found to be the most fitted models with respect to the drying characteristics of cocoyam for untreated, UDW and UOD samples, respectively. CONCLUSION: Ultrasound pretreatment technology is a potential non-thermal process that can be incorporated as a pretreatment method in the convective drying of cocoyam to reduce processing time, conserve energy and enhance cocoyam product shelf life. [ABSTRACT FROM AUTHOR]

Untreated banana peels biomass of 15 x 10, 30 x 20 and 60 x 40 mm sizes were dried at 60 oC while untreated and pretreated (hot water and sulphite treated) biomass of 10 x 10 mm size were dried at 80 – 140 oC, to find out the influence of surface area, pretreatment and temperature on convective hot air oven drying of the biomass. The rate of drying of banana peels increased with increasing surface area and temperature while hot water and sulphite pretreatments reduced the time needed for drying. The drying operation occurred primarily in the falling-rate phase. Effective moisture diffusivities for the drying operations were in the range 5.19 x 10-10 – 1.55 x 10-8 m2 s-1. The activation energies for drying untreated, sulphite treated and hot water treated peels were 24.7, 21.4 and 21.3 kJ mol-1, respectively. The biomass drying kinetics was well described by the Weibull model. Specific energies needed for drying the 15 x 10, 30 x 20 and 60 x 40 mm banana peels biomass at 60 oC were 157.9 – 335.6 kWh/kg while those required for drying both untreated and pretreated 10 x 10 mm sized banana peels biomass at 80 – 140 oC were 33.5 – 93.9 kWh/kg. The rate of drying banana peels in hot air oven can be considerably improved and the energy needed for drying appreciably reduced by increasing the peel surface area, drying at higher temperatures and pretreating the biomass with hot water or sulphite solution.

Jatropha curcas L. seeds are good sources of industrial-grade oil for biodiesel production and feedstock for thermochemical conversion to other biofuels. Freshly harvested seeds are wet and susceptible to deterioration due to enzymatic and microbial activities, excess moisture also limits the efficiencies of biofuel production processes. Hence, they require moisture removal by drying pre-treatment before storage and further industrial processing. Drying characteristics and moisture transfer properties of Jatropha seeds are also needed for the design, analysis and optimization of the process. Jatropha curcas seeds were dehydrated in a convective hot-air dryer at 80 - 140 °C using 1.5 m s − 1 air velocity. Dehydration rates and energy consumption were evaluated from the dehydration data. Coefficients of diffusion and mass transfer as well as activation energy were estimated by the Crank, Dincer-Dost, Biot-Lag factor (Bi-G), Biot-Drying constant (Bi-S), Biot-Dincer (Bi-Di) and Biot-Reynolds (Bi-Re) moisture transfer models. The dehydration kinetics of the seeds were also defined by thin-layer dehydration models. The dehydration rate was enhanced by drying at higher temperatures and occurred in the falling-rate phase. The energies needed to dehydrate the seeds were 0.155 – 0.184 kWh/kg fresh seed at 80 – 140 °C. Diffusion coefficients, moisture transfer coefficients and activation energies evaluated by the models were 0.975 – 3.013 × 10−8 m2 s − 1, 0.316 × 10−6 – 4.88 × 10−6 m s − 1 and 16.1 - 26.8 kJ mol−1 at 80 – 140 °C, respectively. Dincer-Dost, Bi-G, Bi-S, Bi-Di and Bi-Re moisture transfer models aptly predicted dimensionless moisture content profile. The Weibull model was the thin-layer drying model that best described the dehydration kinetics of the seeds. Moisture transfer properties and drying rate of Jatropha seeds can be enhanced and energy requirement minimized by drying seeds at higher temperatures, thus reducing the overall cost of processing seeds and boosting the profitability of biofuel production from the seeds.

This study was conducted to investigate the drying kinetics and internal and external mass transfer characteristics of walnuts for an understanding of the drying mechanism. The drying characteristics, mass transfer characteristics, and color of walnut during hot air drying (HAD) were investigated under different initial moisture content (IMC) (0.35, 0.39, and 0.43 g water/g wet mass) and drying temperatures (50, 60, 70, and 80 °C). The results indicated that the IMC and drying temperature both have significant effects on the drying process of walnut, showing the higher the IMC, the longer the preheating time, the smaller the effective moisture diffusivity (Deff) and mass transfer coefficient (hm), and the longer the drying time, but reverse results for drying temperature. The values of Deff and hm for walnut ranged from 4.94 × 10−10 to 1.44 × 10−9 m2/s and 1.24 × 10−7 to 3.90 × 10−7 m/s, respectively. The values of activation energy for moisture diffusion and mass transfer ranged from 21.56 to 23.35 kJ/mol and 28.92 to 33.43 kJ/mol, respectively. Multivariate linear prediction models were also established for estimating the Deff and hm as a function of the HAD process parameters. The drying temperature has a greater effect on the walnut kernel lightness than the IMC. The Verma et al model could be used to describe the HAD process of the walnut. The findings contribute to the understanding of moisture transfer mechanisms in walnuts and have practical value for the evaluation and improvement of drying systems. [ABSTRACT FROM AUTHOR]

The present study optimized the drying temperature (50–80°C) for potato slices based on color, texture, and visual observations. At an optimized temperature (60°C), a 2D axisymmetric finite element method (FEM) was developed in COMSOL Multiphysics to predict the heat and mass transfer (HMT) in a disk‐shaped potato slice. The nonisotropic shrinkage was predicted for the potato slice by the arbitrary Lagrangian–Eulerian approach. The experimental dehydration results revealed that axial shrinkage (27.44%) was 2.5 times higher than radial shrinkage (67.39%). The simulated outcomes based on FEM revealed the realistic visualization of spatial heat transfer, moisture migration, and nonisotropic slice deformation. The predicted moisture content, surface temperature, and shrinkage properties were in good agreement with the experimental results. The shrinkage behavior was further validated using artificial neural network (ANN) to simulate the slice shrinkage. Results showed that both the COMSOL and ANN approaches can precisely predict the shrinkage‐dependent HMT model. The ANN model outperformed the COMSOL determined by mean absolute error, mean square error (MSE), root MSE, and Chi‐square (χ2) values. The successful application of the presented approach for determining dehydration characteristics may have potential for quality assessment and management of different fruits and vegetables. Practical applications: This journal article explores the practical industrial applications of combining finite element method (FEM)‐based heat and mass transfer model and artificial neural networks (ANNs) to improve the efficiency and quality of food drying processes. FEM is employed to simulate and predict the realistic visualization of heat and mass transfer phenomena along with non‐isotropic shrinkage, while ANN serves as a data‐driven modeling tool for process control and prediction. The integration of these two technologies offers significant advantages in the food industry, including quantification of precise temperature and moisture content, as well as to monitor the drying process of various food products, reduced energy consumption, and time. [ABSTRACT FROM AUTHOR]

Pea drying studies were assessed to learn more about the kinetics and properties of drying in a hot-air dryer. Research was done on impact of temperatures and pre-treatments on drying behaviours. The drying rate graphs demonstrated that the entire drying procedure took place when rates were declining. To properly understand the experimental data, four mathematical models (Henderson & Pabis, Page, Wang & Singh, and Aghbashlo et al.) were used. The Page model was discovered to be the ideal one to depict peas' curves of drying. The identification of the Page model as the most suitable for depicting pea drying curves underscored the applicability in modeling drying behaviors in similar agricultural products. With Fick's second law of diffusion, effective moisture diffusivity (Deff) sorted from 2.45x10-10 to 6.55x10-10 m2/s at given temperature. Deff was expressed as a function of temperature with an Arrhenius type equation. For samples from Potas, Blanch, and Control codes, the activation energy for moisture diffusion was computed as 21.48, 22.82, and 22.32 kJ/mol, respectively. The computation of activation energy for moisture diffusion for different samples offered practical information for optimizing drying processes under various conditions. The results showed the importance of pea drying kinetics and practical implications for industry on drying efficiency and product quality. [ABSTRACT FROM AUTHOR]

Drying is an important process that increases the shelf life of agricultural products. It is a process whereby the activities of most decay causing microbes are either deactivated or reduced to safe levels. This work determined the drying kinetics of Periwinkle Meaty within the drying temperature range of 50°C through to 100°C using a laboratory convective oven. Drying data was fitted to five thin layer drying models such as artificial neural network (ANN), page, Henderson-pabis, Lewis and a newly developed model (NDM). The various related thin layer drying model constants and coefficients were obtained using non-linear regression statistical methods. The result shows that drying took place almost entirely within the falling rate period. The temperature dependent effective diffusivity was shown to be in values that ranged from 1.49 x 10-6 to 6.30 x 10-7 m² s-1 in the temperature range applied in this work. And the related activation energy was found to be 15.43 kJ mol-1. The fitting results also showed the ANN and NDM closely followed by the Henderson-Parbis' as suitable for predicting the thin layer drying kinetics of periwinkle meaty. [ABSTRACT FROM AUTHOR]

Sengon wood beams are widely used as a wood packaging material. According to the International Standards for Phytosanitary Measures (ISPM), wood packaging materials must be pests-free. One method for eliminating problems with wood is by heat treatment or drying. This research aims to determine the kinetics of isothermal drying of sengon wood blocks using a combination of infrared and hot air heating. The drying process is carried out at temperatures of 70, 80 and 90 °C, air velocity of 1, 2 and 3 m/s until the final moisture content of the wood reaches 19%. The experimental data were fitted to four drying models, and analyzed using non-linear regression to determine the most suitable model and evaluated through the coefficient of determination (R2), chi-square (X2), and root mean square error (RMSE). The research results revealed that the temperature of the wood core reached 56 oC the fastest at a temperature of 90 oC and an air velocity of 3 m/s in 45 minutes. The highest R2 coefficient 0.9998 is found on the model page at a drying temperature of 70°C and an air velocity of 3 m/s with the lowest X, RMSE values of 0.00001 and 0.0025 respectively. The effective moisture diffusivity of sengon wood particles increased from 1.80x10-6 to 2.47x10-6 m2/min due to the increase in temperature treatment from 70 to 90 °C. The largest diffusion activation energy at an air velocity of 3 m/s is 23.92 kJ/mol. [ABSTRACT FROM AUTHOR]

Solar drying is a method employed to expedite moisture reduction and enhance preservation capacity, characterized by intricate heat and mass transfer processes, challenging the micro-level description of drying kinetics. This study aims to optimize solar drying conditions for kola fish using a double slope solar dryer. An empirical investigation was conducted in three modes viz: open sun drying, natural convection solar dryer and forced convection solar drying. The research underscores the advantages of forced convection drying, showcasing a notable reduction of 4 h in drying time in comparison to natural convection. Furthermore, natural convection surpassed open sun drying, yielding an impressive 18-hour time-saving. An empirical model was formulated to establish the relationship between surface temperature and influential parameters, including insolation, air temperature, and ambient temperature. This model exhibited a high degree of reliability, featuring a correlation coefficient of 0.982 and a narrow standard deviation of 0.028, enabling precise surface temperature predictions under various conditions. The study delved into the effective moisture diffusivity range of kola fish, pinpointing it within the range of 5.16 × 10–9 to 5.29 ×10–8 m2/s. This understanding of intrinsic moisture migration during drying contributes to process optimization. Furthermore, the determination of the activation energy for kola fish drying, which ranged from 28.34 to 38.83 kJ/mol, elucidates the temperature-dependent nature of drying kinetics and underlying energy-driven mechanisms. These revelations significantly enhance the comprehension and advancement of controlled solar drying techniques for kola fish. [ABSTRACT FROM AUTHOR]

This study investigated experimentally and numerically the influence of ultrasound pre-treatment on the drying kinetics of sliced carrot samples. Drying experiments were performed under different conditions, including scenarios with and without ultrasound pre-treatment at drying temperatures of 30 °C, 40 °C, and 50 °C. A diffusion-based-drying model was developed to study the impact of ultrasound pre-treatment on drying kinetics. The effective moisture diffusivity of carrots was expressed as a function of moisture content and temperature. Given the complexity of the dehydration process in carrot slices, which depends on the spatiotemporal variations in moisture content and temperature, and is challenging to monitor experimentally, the effective moisture diffusivity is computed by minimizing the discrepancy between numerical predictions and experimental moisture-content changes over time. This study revealed that ultrasound pre-treatment significantly enhanced the moisture diffusivity of the samples, increasing it by 43% to 90% at drying temperatures of 40 °C and 50 °C, respectively. To apply this analysis of ultrasound pre-treatment in large-scale dryers where thousands of slices may be involved, the proposed diffusion model was simplified to a characteristic drying-curve model. Afterwards, this characteristic drying-curve model was incorporated into a belt-dryer model. The results indicated a 12% reduction in the length of the belt dryer when ultrasound pre-treatment was applied. Additionally, the color of carrot samples was preserved better with ultrasound pre-treatment. On the basis of these results, the application of ultrasound pre-treatment in the hot-air drying of carrot slices was favored, both in terms of improved drying kinetics and quality aspects. [ABSTRACT FROM AUTHOR]

Longer process times in conventional drying methods can be improved by using rapid technologies. Infrared drying is one of these faster methods. Consumer awareness on health and wellness products has increased and boosted with Covid-19 pandemic. Therefore, the consumption trend of snack products formulated with natural ingredients has increased. It is estimated that this trend will continue to rise. In accordance with this, fruit leather production from dates was done by infrared drying and the effect of cooking time on drying behavior was investigated. Firstly, dates were washed and seeds were removed, then water was added at a ratio of 1:2.5 (dates:water), and cooked for 30, 45 and 60 min. Samples were pressed and dried at 10 mm thickness. Drying curves showed first-order drying kinetics and effective moisture diffusivity (Deff) of fruit leathers were found as 1.53×10-9, 1.70×10-9 and 1.74×10-9 m²/s for 30, 45 and 60 min of cooking time, respectively. [ABSTRACT FROM AUTHOR]

Jackfruit seeds can be considered a valuable bioresource that can be efficiently used as biomass for bioenergy, but it requires a pre-treatment step using drying. Although studies have shed some light on its drying behaviour, there is still a remarkable gap in knowledge regarding the fundamental drying characteristics of jackfruit seeds biomass in the context of renewable energy. In this work, thermal characterisation and drying kinetics of jackfruit seeds were investigated. The drying experiments were conducted in a convective dryer at particle level under different inlet air velocities and temperatures. The shrinking phenomenon was evaluated during the experiments using the digital images analyses technique and the measurements of the thickness, width, and length of the samples. The evolution of the volumetric shrinkage with drying time was determined and results were taken into account in the mathematical modelling of the process based on the diffusion theory. The model was solved numerically by the finite difference method and the predicted values were compared with the results from the analytical solution of the diffusive model. It was shown that there were no significant differences between the modelling approaches studied, which suggested that the analytical solution can be used for simplifications purposes in optimisation and design studies. The effective diffusivity ranged from 4.60 × 10−10 to 6.30 × 10−10 m2 s−1 and activation energy from 28.40 to 29.13 kJ mol−1. The volumetric shrinkage ranged from 41.86 to 68.84% and the shrinking coefficient from 0.449 to 0.569. Particle sphericity ranged from 0.67 to 0.52 during drying. • Differential Scanning Calorimetry and Thermogravimetric Analysis characterisation. • Determination of the shrinking parameters of the solid during drying process. • Analytical solution of the diffusive model and estimation of transport parameters. • Numerical solution of the diffusive model considering solids shrinkage. [ABSTRACT FROM AUTHOR]

Effective drying methods for agricultural products have been a major global concern. A study on modeling the effect of dryer configurations on the thin-layer solar drying kinetics of ogbono seeds was presented in this paper. Ogbono seeds were dried using a solar drying system, which was a forced convection distributed type solar collector, equipped with a sun-tracking mechanism. The seeds were dried at four different tilt angles of 0, 5, 10, and 15°; two absorber plate thicknesses of 1.5 mm and 2.7 mm; and a constant air velocity of 2 m s-1. The drying data obtained from the experiment was fitted to six thin-layer drying predictive models. The effective moisture diffusivities at varying treatments as well as the activation energy of the ogbono seeds were determined. Results from the experiment revealed that the drying kinetics of the seeds varied with the different tilt angles and plate thicknesses. All six drying models fitted fairly accurately with the drying data of ogbono seeds. However, the Wang and Singh model with the highest coefficient of determination (R²) value of 0.9994 and least root mean squared error (RMSE) value of 0.007 was the best-fitted model for the thin-layer solar drying of ogbono seeds. The effective moisture diffusivities determined for the seeds ranged from 2.03 x 10-11 to 3.24 x 10-11 m² s-1. The research results revealed that these values increased with the absorber plate thickness of the dryer. The activation energy of 59.724 kJ mol-1 was determined for the ogbono seeds. The results obtained from this research showed that a solar drying system in alliance with a good predictive model could be employed in food processing industries for better dryer designs and more efficient product drying. [ABSTRACT FROM AUTHOR]

Untreated banana peels biomass of 15 x 10, 30 x 20 and 60 x 40 mm sizes were dried at 60 oC while untreated and pretreated (hot water and sulphite treated) biomass of 10 x 10 mm size were dried at 80 - 140 oC, to find out the influence of surface area, pretreatment and temperature on convective hot air oven drying of the biomass. The rate of drying of banana peels increased with increasing surface area and temperature while hot water and sulphite pretreatments reduced the time needed for drying. The drying operation occurred primarily in the falling-rate phase. Effective moisture diffusivities for the drying operations were in the range 5.19 x 10-10 - 1.55 x 10-8 m² s-1. The activation energies for drying untreated, sulphite treated and hot water treated peels were 24.7, 21.4 and 21.3 kJ mol-1, respectively. The biomass drying kinetics was well described by the Weibull model. Specific energies needed for drying the 15 x 10, 30 x 20 and 60 x 40 mm banana peels biomass at 60 oC were 157.9 - 335.6 kWh/kg while those required for drying both untreated and pretreated 10 x 10 mm sized banana peels biomass at 80 - 140 oC were 33.5 - 93.9 kWh/kg. The rate of drying banana peels in hot air oven can be considerably improved and the energy needed for drying appreciably reduced by increasing the peel surface area, drying at higher temperatures and pretreating the biomass with hot water or sulphite solution. [ABSTRACT FROM AUTHOR]

The delightful pungency, aromatic compounds and phytochemicals in some spices make them indispensable in local food systems and native medicine, hence, driving a robust market in many parts of the world. The understanding of their drying characteristics is very important for processing and adding value, and a thin layer drying study is a proven method for achieving this. In this study, changes in the moisture content, moisture ratio, drying rate and effective diffusivity of alligator peppers, ginger and turmeric were investigated at three drying temperatures 50, 60, and 70 °C following standard procedures. Five models were proposed to simulate the drying process. Non-linear regression was used to establish the coefficient of determination (R2), sum of square error (SSE) and root mean square error (RMSE) for each model to determine the model of the best fit. The Page model gave the best fit for ginger while the logarithmic model was best fitted for alligator peppers and turmeric. The effective diffusivity ranged from 1.79-3.08 × 10-9, 8.44-9.74 × 10-9, and 4.06-6.49 × 10-9 m2.s-1 for alligator peppers, ginger and turmeric, respectively. The activation energy ranged from 16.5-22 kJ.mol-1.K-1 for the three spices. These findings promise improvement in the drying, processing and handling of spices, thereby boosting the obtainable income from the value chain.

Phaleria macrocarpa (Scheff.) Boerl. or 'Mahkota Dewa' is a popular plant found in Malaysia as it is a valuable source of phytochemicals and therapeutic properties. Drying is an essential step in the storage of P. macrocarpa fruits at an industrial level to ensure their availability for a prolonged shelf life as well as preserving their bioactive compounds. Hence, this study evaluates the effect of different temperatures on the drying kinetics, extraction yield, phenolics, flavonoids, and antioxidant activity of P. macrocarpa fruits. The oven-drying process was carried out in this study at temperatures of 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C. Six thin-layer drying models (i.e., Lewis, Page, Henderson and Pabis, two-term exponential, Logarithmic, and Midilli and Kucuk models) were evaluated to study the behaviour of oven-dried P. macrocarpa fruits based on the coefficient of determination ( R 2 ), root mean square error ( R M S E ), and chi-square ( χ 2 ). The quality of the oven-dried P. macrocarpa fruits was determined based on their extraction yield, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (2,2-diphenyl-1-picrylhydrazyl) using ultrasound-assisted extraction. The results showed that the time for moisture removal correspondingly increased in the oven-dried P. macrocarpa fruits. Apparently, the Midilli and Kucuk model is the most appropriate model to describe the drying process. The range of effective moisture diffusivity was 1.22 × 10 − 8 to 4.86 × 10 − 8   m 2 / s , and the activation energy was 32.33 kJ/mol. The oven-dried P. macrocarpa fruits resulted in the highest extraction yield (33.99 ± 0.05%), TPC (55.39 ± 0.03 mg GAE/g), TFC (15.47 ± 0.00 mg RE/g), and DPPH inhibition activity (84.49 ± 0.02%) at 60 °C based on the significant difference (p < 0.05). A strong correlation was seen between the antioxidant activity, TPC, and TFC in the oven-dried P. macrocarpa fruits. The current study suggests that the oven-drying method improved the TPC, TFC, and antioxidant activity of the P. macrocarpa fruits, which can be used to produce functional ingredients in foods and nutraceuticals. [ABSTRACT FROM AUTHOR]

The target of this study was to examine the influence of ultrasound pretreatment and edible coatings (xanthan, guar, and wild sage seed gums) on the total phenols content, antioxidant potential, mass transfer rate, effective moisture diffusivity (Deff), and rehydration rate of sweet cherries (SC). For the edible coating of SC, a 0.2% gum solution (xanthan, guar, and wild sage seed) was prepared and the SC were dipped into the aqueous solution. Also, the ultrasound process (40 kHz and 150 W) was performed in an ultrasonic bath for 3 min. The gums coating increased the total phenols content, antioxidant properties, and drying time and decreased the Deff values. The highest value of DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging activity (61.04 ± 2.09%) was observed on coated SC by guar gum. The mean drying times for uncoated, xanthan gum-coated, guar gum-coated, and wild sage seed gum-coated SC were 130, 160, 175, and 140 min, respectively. In this study, the SC Deff as determined by the second Fick law varied from 1.39 × 10−9 m2/s to 2.46 × 10−9 m2/s. The Midilli model gave the best results for describing single-layer drying of SC. The mean rehydration ratio for uncoated, xanthan gum-coated, guar gum-coated, and wild sage seed gum-coated SC were 141.81, 167.26, 176.21, and 156.87 %, respectively. Considering the total phenols content, antioxidant activity, and rehydration ratio, edible coating and ultrasonic pretreatment will be more promising for SC pretreatment before drying and other processes.

This article is a comparison of the date fruits drying performance of two most simple and common type of solar dryers. A simple even span type forced convection greenhouse dryer (FCGHD) and a forced convection cabinet solar dryer (FCCSD) were developed and tested under the climate of Hisar, India. The average values of convective heat transfer coefficients (HTC) were calculated as 0.46 and 0.53 W m−2 °C−1 for FCGHD and FCCSD, respectively. The respective average evaporative HTC was evaluated as 64.58 and 276.06 W m−2 °C−1. The drying efficiency and specific energy consumption for date fruits drying under FCCSD were, respectively, 55.2% higher and 37.87% lower than that of FCGHD. Amongst seven considered thin layer drying models, Midilli–Kucuk model showed the highest commensuration to the experimentally evaluated drying data of moisture ratio for date fruits. Higher values of effective moisture diffusivity and lower values of activation energy were observed under FCCSD. The economic prospective of both the drying arrangements has also been presented. [ABSTRACT FROM AUTHOR]

The objective of this article was to investigate the drying kinetics, effective moisture diffusivity, and quality of pitaya in the heat pump drying process. The experiment was conducted at a drying temperature of 50–70°C, slice thickness of 8–10 mm, and a relative humidity of 10–30%. The results showed that the heat pump drying of pitaya was a deceleration process. The drying temperature has the greatest influence on the drying rate. The drying time decreased by 28.57% with the drying temperature increased from 50 to 70°C, while that increased the least by 12% with the slice thickness dropped from 10 to 8 mm. Six drying models were analyzed comparatively based on experimental data, and calculations indicated that the Avhad and Marchetti model could better describe the moisture migration law during the heat pump drying process of pitaya. The optimal drying kinetics model was established to predict the change of moisture content under different drying conditions, and the average error of the model compared with the experimental values was 5.56%. In addition, the effective moisture diffusivity of pitaya ranged from 6.4167 × 10−10 to 9.8156 × 10−10 m2/s, and the drying temperature had a remarkable influence on the effective moisture diffusivity while the slice thickness had the least. According to the Arrhenius equation, the drying activation energy of pitaya under the experimental conditions was 19.628 kJ/mol. Moreover, the effect of drying temperature on browning degree and surface microstructure was also analyzed. The conclusions of this article provide theoretical support for the analysis of water migration laws and the optimization of the pitaya heat pump drying process.

Pepino is an exotic fruit that contains high vitamin C and is known to have many beneficial effects on health. In this study, thin layer drying and color changes of pepino fruit by infrared (IR) and microwave (MW) methods were investigated. Effective moisture diffusions and activation energy were calculated from the drying data. Uniformly sliced pepino fruit was processed without peeling. While IR drying processes were performed at 60, 70, and 80 °C temperatures in 210, 165, and 120 minutes, respectively, MW drying processes were completed at 25, 16, and 6 minutes at 140, 210, and 350 W power levels. While the initial average moisture content was 18.5702 kg water/kg dry, the lowest moisture content was determined as 0.3250 at 80 °C in IR and 0.1263 water/kg dry matter×min at 350 W at MW. Effective moisture diffusions (Deff) for IR were calculated between 6.69 × 10-10 - 1.23 × 10-9 m2/s, while for MW it was found between 8.75 × 10-9 - 3.75 × 10-8 m2/s. The activation energy (Ea) was 29.80 kJ/mol for IR and 33.30 kW/kg for MW. In addition, it was determined that color preservation was better in the IR method, and local burns were observed in the samples in the microwave method.

In the present work, a forced convective hybrid photovoltaic thermal (PV-T) solar dryer assisted with an evacuated tube collector (ETC) is set up to investigate the thin layer drying of potato slices. The drying experiment is compared with the traditional sun drying method without PV-T system under the meteorological conditions of Thanjavur, Tamilnadu. The initial moisture content of potato slices used for the study is 91% (wb). The drying experiment was carried out at different air temperature levels of 50, 55 and 60 °C. Nine numerical models are used to study the drying kinetics of untreated potato slices. Using IBM SPSS 23 statistical package, non-linear regression analysis was performed to estimate correlation coefficient (R2), reduced chi-square (χ2) and root mean square error (RMSE). The model developed by Midilli et al., is the most appropriate one to describe potato slices thin layer drying behavior in a hybrid dryer. The effective moisture diffusivity (Deff) determined using Fick’s second law of diffusion was found to vary from 2.12463×10-8 to 2.79233×10-8 m2/s. The activation energy (Ea) determined using the Arrhenius equation was found to be 16.4276 KJ/mol for drying of potato slices.

In this research, the effect of ultrasound time and dryer type (hot -air and infrared) on the drying time, effective moisture diffusivity coefficient and rehydration of wheat sprouts were investigated and drying kinetics were modeled. To apply ultrasound pre - treatment, the sprouts were placed inside the ultrasonic bath machine for 0, 5, 10, and 15 minutes, and after leaving the machine and removing extra moisture, the samples in thin layers were placed in the hot -air (with a temperature of 70°C) and infrared (power of 250 W) dryers. The results showed that sonication up to 5 minutes, causes an increase in moisture removal rate from the sprouts, an increase in the effective moisture diffusivity coefficient, and as a result, reduces the drying time. By increasing sonication time from zero to 5 min, the average drying time of sprouts in the hot -air and infrared dryers decreased from 126.7 min to 120.0 min, and from 25.7 min to 21.3 min, respectively. The average drying time of the samples in the hot -air dryer was 150.8 min and in the infrared dryer was 28.0 min. Also, the average effective moisture diffusivity coefficient calculated for the samples placed in the hot - air dryer was equal to 1.65×10 -10 m²S-1 and for the infrared dryer it was equal to 8.59×10-10m² s-1 . The time of ultrasound and drying treatment had significant effects on the rehydration of samples, and the value of this parameter was higher for samples dried in the hot -air dryer. In order to investigate the drying kinetics of wheat sprouts, mathematical models were fitted to the experimental data, and the Page model with two parameters (k and n) was chosen as the best model based on the highest accuracy. Generally, 5 minutes pre -treatment by ultrasound and then using an infrared dryer is the best condition for drying wheat sprouts. [ABSTRACT FROM AUTHOR]

The drying of sea bass was examined using oven and infrared (IR) at 60–80°C, and microwave (MW) at 140–350W. Effective moisture diffusivities and activation energies were determined, and mathematical models were applied to the data. Moisture content was found as 1.8571 kg water/kg dry matter and reduced to 0.1009–0.0798, 0.0767–0.0520, and 0.0783–0.066 kg water/kg dry matter for oven, IR, and MW, respectively. Drying times were found as 300–180, 315–135, and 18–5 for oven, IR, and MW, respectively. The most compatible models found as Midilli and Kucuk for oven, Aghbashlo et al. for IR, and Alibas for MW. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the drying kinetics and internal and external mass transfer characteristics of walnuts for an understanding of the drying mechanism. The drying characteristics, mass transfer characteristics, and color of walnut during hot air drying (HAD) were investigated under different initial moisture content (IMC) (0.35, 0.39, and 0.43 g water/g wet mass) and drying temperatures (50, 60, 70, and 80 °C). The results indicated that the IMC and drying temperature both have significant effects on the drying process of walnut, showing the higher the IMC, the longer the preheating time, the smaller the effective moisture diffusivity (Deff) and mass transfer coefficient (hm), and the longer the drying time, but reverse results for drying temperature. The values of Deff and hm for walnut ranged from 4.94 × 10−10 to 1.44 × 10−9 m2/s and 1.24 × 10−7 to 3.90 × 10−7 m/s, respectively. The values of activation energy for moisture diffusion and mass transfer ranged from 21.56 to 23.35 kJ/mol and 28.92 to 33.43 kJ/mol, respectively. Multivariate linear prediction models were also established for estimating the Deff and hm as a function of the HAD process parameters. The drying temperature has a greater effect on the walnut kernel lightness than the IMC. The Verma et al model could be used to describe the HAD process of the walnut. The findings contribute to the understanding of moisture transfer mechanisms in walnuts and have practical value for the evaluation and improvement of drying systems.

In this study, the effects of infrared (IR) dryer system parameters such as IR power, the distance of mucilage from lamp surface, mucilage thickness on drying kinetics and, color indexes (L*, a*, b* and ΔE) of wild sage seed mucilage (WSSM) were investigated in an IR dryer system. Experimental moisture ratio (MR) data were fitted to 7 various empirical thin-layer models. It was found that the Page model has the best fit to show the kinetic behavior and acceptably described the IR drying behavior of WSSM with the lowest mean square error (MSE), root mean square error (RMSE), mean absolute error (MAE), and standard error (SE) values and the highest correlation coefficient (r) value. The values of MSE, RMSE, and MAE for all experiments were in the range of 0.1×10-3-1.1×10-3, 1.04×10-2-3.25×10-2 and 8.7×10-3-27.1×10-3, respectively. The average effective moisture diffusivity (Deff) increased from 4.61×10-9 m2s-1 to 15.8×10-9 m2s-1 with increasing lamp power from 150 W to 375 W, while it was decreased from 14.4×10-9 m2s-1 to 5.16×10-9 m2s-1 and 13.2×10-9 m2s-1 to 4.31×10-9 m2s-1 with increasing the distance of mucilage from 4 to 12 cm and the reduction of mucilage thickness from 1.5 to 0.5 cm, respectively. Increasing in IR radiation power has a positive influence on the yellowness (increasing 19.78% in b* index) of dried WSSM. Also, it increased the color changes index (ΔE) from 16.05 to 17.59.

The thin-layer olive pomace vacuum drying behavior was experimentally investigated for 3 gauge pressures; -130, -200, -250 mbar, and for various sample thicknesses 5, 10 and 15 mm. Nine thin layer mathematical models were used to fit olive cake vacuum drying. Olive pomace vacuum drying took place in the falling rate period at all pressures and for all thicknesses, no constant rate period was observed. Among the selected models, the Diffusion Approach was found to be the most appropriate model better describing the olive pomace drying behavior. The drying rate is correlated to the depression under the thin layer and its thickness. ANOVA-Pareto variance analysis showed the predominance of gauge pressure over layer thickness on drying time and drying rate. The diffusivity coefficient increased linearly over the depression range, from 3.37657E-09 to 4.03063E-06 m²/s, as obtained using Fick's second law. [ABSTRACT FROM AUTHOR]

To improving energy efficiency and increasing quality of dried product, a infrared dryer was constructed that can be used to dry fruits and vegetables. In this study, drying kinetics modeling of garlic in an infrared dryer was investigated. The effect of samples distance from the radiation lamp in three levels of 5, 7.5 and 10 cm and the effect of garlic slices thickness in the in three levels of 3, 6 and 9 mm on the mass transfer rate and effective moisture diffusivity coefficient during the dry process of garlic was investigated. To determine the appropriate kinetics model in the drying process, the drying curves can be analyzed under the defined conditions. Therefore, in this research, to investigate on the drying kinetics of garlic slices, the standard models were fitted to the experimental data. By increasing the distance of the samples from the heat source from 5 to 10 cm, the average drying time of garlic increased from 35.8 minutes to 37.3 minutes. By increasing the thickness of the samples from 3 to 9 mm, the average drying time of garlic increased from 22.7 minutes and 50.9 minutes. The effect of sample distance from infrared heat lamp and sample thickness on changes in effective moisture diffusivity coefficient of garlic was investigated and results showed that this coefficient values were increased with decreasing in distance and increasing samples thickness. By reducing sample distance from the lamp from 10 to 5 cm, it was observed that the effective moisture diffusivity coefficient increased from 2.71×10-9 m²s-1 to 3.63×10-9 m²s-1. The average effective moisture diffusivity coefficient of garlic slices for thicknesses of 3, 6, and 9 mm were 0.94×10-9 m²s-1, 2.72×10-9 m²s-1, and 5.54×10-9 m²s-1, respectively. In drying process modeling of garlic, the Midilli model with the highest coefficient of determination and the lowest error, had closer results to the experimental data than the other models. [ABSTRACT FROM AUTHOR]

The moisture content and shrinkage of a sample are often ignored when determining its effective moisture diffusivity (EMD), which will result in a larger error in simulating the dynamic moisture diffusion process during drying. This work aimed to determine the EMDs of cortex and core in axial and radial directions considering the combined influence of moisture content and shrinkage of material. The drying and shrinkage characteristics of cortex and core were investigated under different hot air drying conditions, and the EMDs of the cortex and core in different drying stages were determined by the slope method considering the moisture content and shrinkage. The results showed that the EMDs were dependent on the carrot component rather than its directions. The EMDs of the core and cortex were different. It decreased slowly at the early drying stage, and decreased sharply at the later drying stage, and increased with the hot air temperature increasing. A third order polynomial relationship was established to correlate the EMDs with the moisture content and hot air temperature (R2 > 0.9460), and was verified by experiments. The maximum weighted absolute percentage error of the moisture content from simulation and experiment was only 6.11%, more accurate than that based on a constant effective moisture diffusivity (CEMD) for characterizing the intrinsic moisture diffusion in carrot during drying. Practical applications: The EMD is an important parameter that characterizes intrinsic moisture diffusion in material and often used for modeling and calculation in food drying. The investigation methods developed in this study can be applied for determining the EMD of samples with shrinkage and variable moisture content. This study would be helpful for understanding the moisture transfer mechanism and optimizing operation conditions in carrot drying industry. [ABSTRACT FROM AUTHOR]

An active indirect solar dryer (AISD) has been used to conduct drying experiments of beetroot slices without a thermal storage unit (TSU) (mode-I) and with TSU (mode-II) using paraffin wax as a phase change material. The performance analysis and drying curves of beetroot slices were assessed in both modes and compared. The average drying efficiency and drying rate were enhanced by 48.63% and 41.72% in mode-II compared to mode-I. Two-term exponential and modified Page models were the best models for beetroot slices in mode-I and mode-II, respectively. The specific energy consumption was estimated to be 1.706 and 0.96 kWh/kg, the average moisture diffusivity was 7.11 × 10−9 and 7.22 × 10−9 m2/s, and the mean mass transfer coefficients were 3.56 × 10−3 and 3.64 × 10−3 m/s, respectively. The specific moisture extraction rate was 0.586 and 1.041 kg/kWh and the mean heat transfer coefficient was 4.103 and 4.2 W/m2K, in mode-I and mode-II, respectively. The collector outlet temperature is increased by 2.5 to 10.7°C when the heat is discharged from TSU. In comparison to mode-I, the performance of AISD is superior in mode-II, exhibiting better drying performance due to TSU in the drying section in mode-II. [ABSTRACT FROM AUTHOR]

In this study, Kemer eggplants (Solanum melongena L.) were examined in terms of system performance and energy efficiency after drying at constant air temperature and different operating systems developed on a heat pump dryer. The air velocity and the drying time have a negative correlation was observed. In addition, the Midilli & Kucuk model was the most appropriate model to explain the experimental data of dried eggplant samples obtained from this study. Effective moisture diffusivity was calculated between 6.08 × 10−10 and 7.30 × 10−10 m2/s depending on air velocity values. The reduction of the eggplant slices from 12.158 (g water/g dry matter (dm)) moisture value to 0.645 (g water/g dm) moisture value took 236 min at 1 m/s air velocity with the application of Serial Condenser and Parallel Evaporator Drying System (SCPEDS). The Serial Condenser Drying System (SCDS) was found to yield both the highest average condenser capacity with 2.256 kW and the highest system performance coefficient with 3.181. The brightness values (L) of dried eggplant samples increased compared to the fresh eggplant samples. The closest brightness value to the fresh samples was determined as 84.7 in the drying experiments with the air velocity of 0.5 m/s and the SCPEDS system. The other color parameters (b, C and h°) decreased during drying. The highest total color change value (8.05) was obtained with SCPEDS system at 1.0 m/s. The highest browning index value (63.48) was reached in the drying experiments performed with the SCDS system at 0.75 m/s. [ABSTRACT FROM AUTHOR]

The delightful pungency, aromatic compounds and phytochemicals in some spices make them indispensable in local food systems and native medicine, hence, driving a robust market in many parts of the world. The understanding of their drying characteristics is very important for processing and adding value, and a thin layer drying study is a proven method for achieving this. In this study, changes in the moisture content, moisture ratio, drying rate and effective diffusivity of alligator peppers, ginger and turmeric were investigated at three drying temperatures 50, 60, and 70 °C following standard procedures. Five models were proposed to simulate the drying process. Non-linear regression was used to establish the coefficient of determination (R²), sum of square error (SSE) and root mean square error (RMSE) for each model to determine the model of the best fit. The Page model gave the best fit for ginger while the logarithmic model was best fitted for alligator peppers and turmeric. The effective diffusivity ranged from 1.79–3.08 × 10–9, 8.44–9.74 × 10–9, and 4.06–6.49 × 10–9 m² ·s–1 for alligator peppers, ginger and turmeric, respectively. The activation energy ranged from 16.5–22 kJ·mol–1·K–1 for the three spices. These findings promise improvement in the drying, processing and handling of spices, thereby boosting the obtainable income from the value chain. [ABSTRACT FROM AUTHOR]

The performance, thermal parameters and drying kinetics of muskmelon are calculated in an indirect natural convection solar dryer (INCSD) and indirect forced convection solar dryer (IFCSD). The initial moisture content (MC) of muskmelon slices was 12.4156 kg/kg of db (db) and it declined to 0.1605 db in 15, 18 and 22 h in IFCSD, INCSD and open sun drying (OSD), respectively. The estimated collector and drying efficiencies (ηcl and ηdr) were 58.5 and 9.39% in INCSD and the same were 66.37 and 12.11% in IFCSD, respectively. The specific moisture extraction rate (SMER) was 0.544 and 0.6204 kg/kWh in INCSD and IFCSD, respectively. The Verma model was relevant to fit the drying characteristics of muskmelon in INCSD, IFCSD and OSD. The thermal parameters such as effective moisture diffusivity (Defm), surface transfer coefficients (hht and hmt) and activation energy (Eac) were also determined for both setups. The average increment of 13.45% on ηcl, 28.97% on ηdr, 14.04% on SMER, 24.08% on Defm, 55.36% on hht, 55.16% on hmt, and 24.83% on Eac were observed in IFCSD than INCSD. The Eac of muskmelon slices was 38.06 and 28.61 kJ/mol in INCSD and IFCSD, respectively. Uncertainty analysis was performed and error bars were included in all the plots. [ABSTRACT FROM AUTHOR]

The influence of pretreatment methods like physical, chemical, combined physical, and hybrid treatments on the Turkey berry (Solanum torvum) fruits to enhance the water diffusion during drying was assessed due to removing a waxy layer on the peel. Pretreated and untreated samples were dried at 70 ⁰C and 4 m/s of air flow in a fluidized bed dryer. Fruits pretreated with combined abrasion and blanching have the lowest drying time and good vitamin C content retention of 36%. The highest drying rate of 0.396 kg water/kgdb min−1, maximum effective moisture diffusivity of 6.002 x 10-10 m2/s, and volumetric shrinkage ratio of 0.68 were obtained for fruits that undergone combined physical pretreatment along with drying. The maximum change in color ΔE = 14.75 and Chroma ΔC = - 10.53 were obtained for the untreated samples.