Experimental Moisture Ratio Research Articles

Comprehensive study on potato drying in convective air dryer: experimental observations, mathematical modeling, and model validation

We studied the drying kinetics of sliced potatoes (Solanum tuberosum) using a tray dryer. An experiment was conducted on how the drying rate was impacted by air temperature, sample thickness, and air velocity. The study was conducted under varying temperature ranges (50°C, 60°C, and 70°C), air velocities (0.6 ms−1, 0.7 m s−1, and 0.8 m s−1), and potato slice thickness (2 mm, 4 mm, and 6 mm). The findings revealed that a higher air temperature was correlated with an increase in the drying rate, while thicker layers demonstrated a decrease in the drying rate. We further evaluated five mathematical models, with the Page Model emerging as the most suitable based on the lowest residual standard error (RSE) and Akaike's Information Criteria (AIC), which are 0.06421 and -1123.947, respectively. After plotting the predicted moisture ratio against the experimental moisture ratio, we observed an exceptional predictive accuracy (R2 > 0.99) across various conditions. These findings underscore the critical importance of precise parameter control for optimizing potato drying processes in industrial settings, providing valuable insights for enhanced efficiency and resource utilization. Further exploration into real-time optimization and scalability can extend the practical applications of this study.

Hot Air Drying of Brazilian Spinach Leaves

Brazilian spinach is one of the best leafy vegetables with tons of nutrients and has a range of health benefits. Its quality also determines the acceptance of customers to buy and consume it. The common method to extend the shelf life of the spinach is through drying treatment and preserving the color and texture quality of the leaves. Therefore, this study aimed to determine the drying characteristics of Brazilian spinach and investigate the effect of drying temperature on the color and texture quality of Brazilian spinach. Brazilian spinach leaves were dried using a hot air dryer under different temperatures (30, 50, 70 and 90°C). Results showed that the drying rate increased when temperature increased. It was found that the Midili model gave the best fitting to the experimental moisture ratio for a specific drying treatment. Drying the Brazilian spinach leaves at 50°C was the best condition for preserving their color and texture properties.

Investigating the Effects of Different Drying Methods on the Drying Kinetics and Proximate Composition of Zobo Calyces

Hibiscus sabdarrifa are cultivated and consumed as tea, whereas other hibiscus varieties are planted for the fibers they produce. Hibiscus sabdariffa known as roselle, is one of the underexploited food crops with nutritional and food industry processing potential. Thus, this study was undertaken to determine the effects of different drying methods (sun, solar and oven drying) and drying kinetics on the proximate composition of dried calyx (Proximate and Mineral composition) using AOAC Standard. The data obtained from this study was statistically analyzed using Tukey HSD (Tukey Honest Significant Difference). The values of the model constant and other Statistical parameters for moisture ratio were obtained. The two-term exponential model had the highest R2 and the lowest x2 and RMSE value. The model constants, the R2, x2 and RMSE for each model were obtained. The page model had the highest R2 and lowest x2 and RMSE and was selected as the best fit model for describing the drying kinetics zobo calyces in an oven dryer while Logarithmic model and Wang and Sing Model was selected for modeling of zobo calyces in sun and solar dryer respectively. The experimental and predicted moisture ratio values are very close to the each other given the R2 value and the straight-line graph when the predicted moisture ratio is plotted against the experimental moisture ratio. Sample dried with oven dryer gave the highest carotenoid and vitamin C content compared to other drying methods. Therefore, oven dryer is recommended for drying of zobo calyces as compared to sun and solar dryer.

Detection of moisture ratio and carotenoid compounds in mamey (Pouteria sapota) fruit during dehydration process using spectroscopic techniques.

This work presents the study of the moisture ratio and carotenoid compounds in dried mamey (Pouteria sapota) using non-invasive spectroscopic techniques. The drying behavior of mamey at 64°C by a homemade solar dryer is analyzed by fitting the experimental data to four different mathematical drying models. In addition, this result is compared with other drying techniques, namely by heat chamber with natural convection at temperatures of 50°C and 60°C. The results show that the Lewis model is the one that best fits the experimental moisture ratio curve of mamey. On the other hand, Near-Infrared and Terahertz spectroscopic techniques are used to estimate the moisture ratio, since water absorption is most sensitive at these frequencies. Fourier Transform Infrared-attenuated total reflectance and Raman spectroscopy are performed to detect the carotenoid compounds in dried mamey. This compound has important applications in the food industry and health benefits. To our knowledge, there are few studies on the dehydration of Pouteria sapota as well as its characterization using spectroscopic techniques for the detection of moisture ratio and carotenoid content; therefore, this study can be useful in agriculture and food sectors when detailed information about the cited parameters is needed.

Natural convective greenhouse vermicelli drying: Thermo-environ-econo-kinetic analyses

This article presents the performance of a low-cost, simple and sustainable natural convection greenhouse dryer (NCGHD) for vermicelli drying. Vermicelli samples of diameter (ø) 1.25, 2 and 3 mm have been dried until no moisture evaporation was observed. The values of convective and evaporative heat transfer coefficients for ø3 mm vermicelli samples were observed to be the highest (1.37 and 210.83 W/m2℃) followed by ø2 mm (1.02 and 87.93 W/m2℃) and ø1.25 mm (0.55 and 43.50 W/m2℃) samples. The overall greenhouse and energy efficiencies for ø3 mm vermicelli samples were also found highest (9.02 and 15.87 %) as compared to ø1.25 and 2 mm vermicelli samples. The increasing diameter of the vermicelli samples resulted in reduced payback period and energy payback time; and increased carbon credit earned. Midilli-Kucuk model showed the highest congruence with the data of experimental moisture ratio for vermicelli drying. Effective moisture diffusivity increased from 2.09×10−11 to 1.06×10−10 m2/s with the increasing vermicelli diameter from ø1.25 to 3 mm. The experimental uncertainty varied from 1.138 to 1.199 % for given vermicelli samples. This study would be insightful to researchers in designing the most sustainable vermicelli drying system with greater simplicity and performance; and lowest financial and energy requirements.

Soğan Dilimlerinin Kuruma Özelliklerinin Modellenmesinde Gen İfade Programlamasının (GEP) Kullanımı (Allium Cepa)

In this study, the drying properties of onion slices were experimentally investigated under the different drying temperatures of 45, 50, 55, and 60°C for different thicknesses of 2, 3, 4, and 5mm. The drying characteristics of the onion slices were significantly influenced by drying temperature. Thin slices with higher temperature dried in the shortest time while thick slices with low temperature took longer to dry. In modeling drying curves, the moisture ratio values of the onion slices were compared with five models commonly used in the literature. In addition, Gene Expression Programming (GEP) was used to model the drying characteristics of the onion slices, and mathematical formulas were derived to calculate moisture ratio values. The results indicated that the moisture ratio values predicted by all models agreed with the experimental moisture ratio values for onion slice samples at different temperatures. The scientific findings we obtained here showed that the two model provided a better simulation of onion slice drying kinetics than other models in different experimental temperature and thickness ranges. Also, the GEP model was able to usefully determine the moisture ratio of onion slices with appropriate accuracy in a shorter time without the need for complicated formulas.

Mathematical Modeling to Describe Drying Behavior of Kyoho (Vitis labruscana) Skin Waste: Drying Kinetics and Quality Attributes

Grape skin (Kyoho: Vitis labruscana), a by-product of processed grapes, was experimentally investigated for its drying behavior at different drying temperatures with five thin layer drying models. Moreover, we determined the effect of drying temperature on the bioactive capacity of Kyoho skin. The experimental moisture ratio decreased with increasing drying temperature. The drying process was predicted by mathematical models, such as Page (303.15 K: R2 = 0.9815, 333.15 K: R2 = 0.9685) and two-term (313.15 K: R2 = 0.9639, 323.15 K: R2 = 0.9737) models. Moisture diffusivity (Deff) ranged from 2.87 × 10−8 to 9.82 × 10−8 m2/s, with an activation energy (Ea) of 33.78 ± 1.06 kJ/mol. Total phenolic compounds (0.37 ± 0.04 to 0.23 ± 0.03 mg GAE/g) and antioxidant activities (DPPH• activity of 93.06 to 73.31%) of Kyoho skin were significantly affected by drying temperature. Thus, this study concluded that the drying process decreased the bioactive potential of grape skin; therefore, we recommend that the food processing industry needs to consider drying variables during the processing of grape skin-based value-added products for improved food production.

Application of Artificial Neural Network for Predicting the Drying Kinetics and Chemical Attributes of Linden (Tilia platyphyllos Scop.) during the Infrared Drying Process

This study analyzes the possibility of utilizing artificial neural networks (ANNs) to characterize the drying kinetics of linden leaf samples during infrared drying (IRD) at different temperatures (50, 60, and 70 °C) with sample thicknesses between 0.210 mm and 0.230 mm. The statistical parameters were constructed using several thin-layer models and ANN techniques. The coefficient of determination (R2) and root mean square error (RMSE) were utilized to evaluate the appropriateness of the models. The effective moisture diffusivity ranged from 4.13 × 10−12 m2/s to 5.89 × 10−12 m2/s, and the activation energy was 16.339 kJ/mol. The applied Page, Midilli et al., Henderson and Pabis, logarithmic, and Newton models could sufficiently describe the kinetics of linden leaf samples, with R2 values of >0.9900 and RMSE values of <0.0025. The ANN model displayed R2 and RMSE values of 0.9986 and 0.0210, respectively. In addition, the ANN model made significantly accurate predictions of the chemical properties of linden of total phenolic content (TPC), total flavonoid content (TFC), DPPH, and FRAP, with values of R2 of 0.9975, 0.9891, 0.9980, and 0.9854, respectively. The validation of the findings showed a high degree of agreement between the anticipated values generated using the ANN model and the experimental moisture ratio data. The results of this study suggested that ANNs could potentially be applied to characterize the drying process of linden leaves and make predictions of their chemical contents.

Effect of microwave‐assisted vacuum drying on the drying kinetics and quality parameters of Moringa oleifera leaves

AbstractMicrowave‐assisted vacuum drying (MAVD) has been studied to improve drying kinetics and physical and antioxidant properties of dried moringa leaves. Microwave power and vacuum level produced a significant reduction (p < .05) in drying time and improvement of drying rate. It was further confirmed by an increase in effective diffusivity value (Deff) by an increase in power and vacuum levels. The reliance of Deff on microwave power was further confirmed by an increase in activation energy from 13.564 to 17.31 W/g with an increased power level. Fitting experimental moisture ratio to the thin layer drying models revealed that the Midilli et al. model could better describe the MAVD of moringa leaves with the highest R2 values. Physical characteristics such as color and rehydration ratio were better for MAVD samples than hot air‐dried samples. Increased drying rate and rehydration ratio were due to the open porous structure of the moringa leaves dried by MAVD, as revealed from the SEM imaging. The vacuum level and power level were significant (p < .05) to the total color difference but the change in color at power levels of 270 and 450 W were insignificant (p > .05). Also, the vacuum level was significant (p < .05), and the microwave power level was insignificant (p > .05) to the rehydration ratio of the MAVD moringa leaves. Phenolic composition and antioxidant properties of MAVD moringa leaves showed increased phenolic content and improved antioxidant activity. Microwave power showed a significant effect (p < .05) on antioxidative properties, whereas vacuum level (p > .5) showed an insignificant effect. The highest power level of 450 W and vacuum level of 500 mmHg produced better quality moringa leaves with good physical and antioxidative properties.Practical ApplicationsDrying is the most common and oldest preservation method for storing food for a longer time. It is very much important to dry moringa leaves that have high moisture content and very less shelf‐life. But conventional drying methods cause great nutritional and textural changes. Microwave‐assisted vacuum dryer combines the advantage of quick and shorter drying of microwave system and lower temperature process as in vacuum system. This eventually reduces the drying time and temperature stress on the food product. This study aids in scale‐up and design a MAVD system for moringa leaves based on its drying kinetics. MAVD of moringa leaves was best modeled by Midilli et al. model. Evaluation of physical characteristics of leaves after drying and its comparison with hot air‐dried one revealed better color and rehydration property that is considered as the key character of dried samples. MAVD also produced increased antioxidant properties with good retention of phenolic components. So, the method of Microwave Assisted Vacuum Drying (MAVD) has got tremendous importance that could be industrially exploited in Moringa leaf processing plants.

Study of Water Desorption Isotherms from Cocoa Beans (Theobroma Cacao L.) of Cameroon

The aim of this work was the determination of desorption isotherms from cocoa beans at different temperatures (20°C, 30°C, 35°C, 40°C and 45°C), moisture ratio (10% and 90%). Gravimetric method and different temperatures were used to get the experimental moisture ratio at equilibrium. Experimental data were adjusted to mathematical isotherm models frequently used for the hygroscopic representation of agricultural products. Cocoa beans varied from 0 to 13% moisture ratio equilibrium. Obtained results showed that the moisture ratio at equilibrium decreases as temperature increases for the same relative humidity. Statistical parameters, modified the Oswin model, GAB, Iglesias Chirife Hasley and Chungs Pfost modified model better represented hygroscopic balance for cocoa beans than Henderson modified and Harkings Jura models. Desorption isotherm models are important for the determination of desorption energy and drying models. The desorption isotherms of cocoa beans were satisfactorily modeled by modified Oswin, GAB, Iglesias, Chirife, Halsey, and modified Chungs Pfost, which can be used as tools in the prediction and optimization of storage conditions in a wide range of water activities and temperatures.

Effect of drying air temperature on the drying characteristics and quality aspects of black ginger

This study focuses on investigating the effect of drying temperature on drying characteristics and quality aspects of black ginger dried in an electric dryer. The effect of inlet drying air temperature (40 °C–80 °C) on the drying time and drying rate of black ginger were investigated. It was observed that the drying time of black ginger was reduced by 64.2% when the drying temperature was increased to 80 °C from 40 °C. The experimental moisture ratio obtained at different drying air temperatures were compared with various thin layer drying models available in the literature. It was observed that moisture ratio predicted from Midilli and Kucuk model showed good fit with experimental drying curves at drying air temperature between 40 °C and 50 °C. The Two term model showed good fit at 60 °C and Diffusion approach model suited between 70 °C and 80 °C. It was observed that the selection of thin layer models was dependent on the inlet drying air temperature. The effective diffusivity of black ginger at 80 °C was 2.13 × 10−9 m2 s−1. Quality analyses of the samples were carried out in terms of total phenolic content (TPC) and antioxidant (AA) values. Maximum values of TPC (13.58 mg GAE/g of sample) and AA (81.06%) were reported at 60 °C. Hence, a trade-off between drying time and product quality is required in selecting the drying air temperature.

Infrared drying of Clinacanthus nutans leaves

Clinacanthus nutans herbal leaf was dried using an infrared dryer under different power levels (100 W, 200 W, and 300 W) and at different distances between infrared source and samples (10 cm, 20 cm, and 30 cm). Results showed that the drying rate increased when power levels increased and distances decreased. There were found that Midili and Kucuk, Modified Henderson and Pabis, Verma, Two Term, and Wang and Singh gave the best fitting to the experimental moisture ratio for a specific drying treatment. The moisture diffusivity values determined were 4 × 10−11 to 3.09 × 10−10 m2/ s and the activation energy values ranged from 30.81 to 50.58 W/g. Infrared drying can be an option for quick preservation technique for C. nutans herbal leaves as it gave a shorter drying time which could optimize the energy usage. Novelty impact statement The drying rate of C. nutans leaves was able to increase at a faster rate by infrared radiation as compared to the conventional methods. This result gave a significant reduction of drying time that may reduce energy consumption and enhance the physicochemical properties of the herb.

Impact of air temperature on drying characteristics and some bioactive properties of kiwi fruit slices

Drying kinetics, ascorbic acid content (AAC), total phenolic content (TPC), and antioxidant capacity (AC) of kiwifruits at different temperatures (60 ?C, 70 ?C, and 80) were investigated. The drying rate and effective moisture diffusivity of kiwifruits were the highest at 80 ?C. Additionally, the Parabolic model best predicts the experimental moisture ratio at 60 ?C and 70 ?C, while the Page model described the drying curve at 80 ?C. On the other hand, the AAC, TPC, and AC of kiwifruits were significantly influenced by temperature. Degradation of AAC increased with the increment in temperature, while TPC and AC were higher at the higher temperature. The range of the AAC, TPC, and AC of fresh and dried fruits were 165.59?12.58-462.81?11.53 mg/100 g DW, 747.66?16.09-1846.87?15.52 mg/100 g GAE DW, and 0.283?0.15-1.903?0.15 mmol TE/100 g DW, respectively. The highest AAC, TPC, and AC losses were calculated as 64.22%, 59.43%, and 85.13%, respectively.

Color changes and drying kinetics modeling of basil seed mucilage during infrared drying process

The physicochemical properties and color of dried seed mucilage (gums) depend on the condition and method of drying. So, in this study, the effects of infrared (IR) dryer system parameters such as IR power (150, 250, and 375 W), distance of mucilage from lamp surface (4, 8, and 12 cm), mucilage thickness (0.5, 1.0, and 1.5 cm) on drying kinetics and color indexes (L*a*b*) of basil seed mucilage (BSM) were examined in an IR dryer system. IR drying kinetic of BSM was modeled using mathematical approach. Thus, experimental moisture ratio data were fitted to 8 various empirical models. It was found that Page model has the best fit to show the kinetic behavior and acceptably described the IR drying behavior of BSM with the highest correlation coefficient values and the lowest standard error values. The average effective moisture diffusivity (Deff) increased from 1.69 × 10−9 to 9.21 × 10−9 m2/s with increasing lamp power from 150 W to 375 W, while it was decreased from 7.93 × 10−9 to 2.65 × 10−9 m2/s and 7.81 × 10−9 to 1.82 × 10−9 m2/s 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. The increasing in IR radiation power has a positive influence on the lightness (increasing L* index) of dried BSM and it reduced color changes index (ΔE) from 13.04 to 11.51. The results showed that IR drying method has great industrial potential in saving processing time as well as energy with better maintenance of color and quality of dried BSM.

The kinetics of thin-layer drying and modelling for mango slices and the influence of differing hot-air drying methods on quality

This study compared the thin-layer drying kinetics of hot-air methods, namely, convective oven drying (OVD), uncontrolled solar drying (UAD) and modified ventilation greenhouse solar drying (MVD). Additionally, the effects of these drying techniques on colour, rehydration characteristics and microstructure of Tommy Atkin mango slices were investigated. The experiments were conducted on mango slices of three different thicknesses: 3 mm, 6 mm and 9 mm. The drying curves generated from the experimental data revealed that the rate of drying increased with thickness and that a thickness of 3 mm is optimal. It was discovered that increased drying rates resulted in a decrease in the drying time. When 3 mm slices were dried using OVD and MVD, the duration of the drying process was reduced by 85% and 80%, respectively, in comparison to the samples dried under UAD conditions. Lemon juice pre-drying treatment had no significant (p < 0.05) effect on the drying rate or duration of the drying process. Non-linear regression analysis was used to optimise the drying coefficients by fitting the moisture ratio data to eleven suitable thin-layer models. The model parameters developed by Midilli et al. performed the best in terms of predicting the experimental moisture ratio (R2 = 0.9810-0.9981, χ2 = 1.465 × 10−6-3.081 × 10−5 and RMSE = 0.0003-0.0004). Additionally, increasing the slice thickness to 6 mm and 9 mm prolonged the drying times, resulting in significant changes in sample quality, including the total colour (ΔE), rehydration and microstructure. In comparison to OVD- and MVD-dried samples, UAD-dried samples exhibited the greatest colour change and had the highest rehydration ratio values. Also, the surface of the UAD-dried samples developed a more porous structure with distinct cracks. Based on the results, MVD was determined to be a viable alternative method for drying 3 mm mango slices on a large scale.

Mathematical modeling of the moisture ratio during drying of Yam (Dioscorea rotundata) in a hot air dryer

Drying is one of the major unit operation in food industry and it kinetics data is required for optimization. The aim of this study was to evaluate the effect of air temperature (50, 60, and 70°C), air velocity (0.5, 1, and 1.5 m/s), and slice thickness (3, 6, and 9 mm) on the moisture ratio of yam slice during drying. Ten (10) different empirical models were used in fitting the experimental moisture ratio data, the prediction performance was evaluated with sum of square error (SSE), coefficient of determination (R2) and root mean square error (RMSE). The model fitting shows that the Two term model was most performed based on R2, SSE, and RMSE value. This result can be use to control the drying systems for yam slice.

Drying characteristics and degradation kinetics in some parameters of goji berry (Lycium Barbarum L.) fruit during hot air drying

Drying kinetics, color properties, water-soluble vitamins, antioxidant capacity, total phenolic content, and thermal degradation kinetics of bioactive compounds in goji berries were investigated. Drying experiments were conducted at 50°C, 60°C, and 70°C. Page model was determined as the best model to predict experimental moisture ratio for all temperatures. Increment in drying temperature increased effective moisture diffusivity and drying rate values. Vitamins C and B6, antioxidant activity and total phenolic content were significantly reduced by drying. Thermal degradation of vitamins C and B6, antioxidant capacity and total phenolic content were found to fit the first order kinetic model.

Thin-layer drying model of Cosmos caudatus

Drying kinetic models and energy characteristics are well known tools to evaluate and predict the most suitable drying physiochemical conditions for a particular product. In this study, a thin-layer drying model was developed to best describe the drying kinetic behaviour of Cosmos caudatus. The drying experiments were conducted using a thermal convection oven and C. caudatus leaves were dried at five different temperatures (40, 50, 60, 70, 80?C). Six different thin-layer drying models were proposed and applied to select the best drying model by fitting to the experimental moisture ratio data. The proposed drying models included Page, Modified Page, Lewis, Henderson-Pabis, Two Term and Weibull, and the results were statically compared and evaluated based on their goodness of fit. Among these, the Page model was found to best represent the thin-layer drying behaviour of C. caudatus with 99.76%, 5.93?10-5, 9.68?10-5 for the coefficients determination (R2), reduced chi-square (?2), and root mean square error (RMSE), respectively. The average effective moisture diffusion coefficient (Deff) for the temperature 40 to 80?C ranged from 4.12?10-12 to 24.71?10-12 m2/s, while the activation energy (Ea) was calculated at 39.35 kJ/mol based on the Arrhenius?s equation.

Development of mathematical model for drying of crops under passive greenhouse solar dryer

The design and development of greenhouse dryer operating under passive mode is being reported in the present experimentation. The aim of the present study is to develop and fit a new proposed model for drying of tomato flakes and potato chips under greenhouse dryer operating under passive mode. The proposed model was compared with 6 different mathematical models and it was found that the proposed model highest coefficient of determination for both tomato flakes and potato chips followed by logarithmic model. Statistical evaluation of the predicted and experimental moisture ratio shows that the proposed model gives lowest root mean square error and chi square. The present result shows that the curve fitting ability of proposed model for both tomato flakes and potato chips is best compare to other model. However there is no other theoretical basis offered for the best curve fitting ability of the equation.

Mathematical and intelligent modeling of stevia (Stevia Rebaudiana) leaves drying in an infrared-assisted continuous hybrid solar dryer.

Drying characteristics of stevia leaves were investigated in an infrared (IR)‐assisted continuous‐flow hybrid solar dryer. Drying experiments were conducted at the inlet air temperatures of 30, 40, and 50°C, air inlet velocities of 7, 8, and 9 m/s, and IR lamp input powers of 0, 150, and 300 W. The results indicated that inlet air temperature and IR lamp input power had significant effect on drying time (p < .05). A comparative study was performed among mathematical, Artificial Neural Networks (ANNs), and Adaptive Neuro‐Fuzzy System (ANFIS) models for predicting the experimental moisture ratio (MR) of stevia leaves during the drying process. The ANN model was the most accurate MR predictor with coefficient of determination (R2), root mean squared error (RMSE), and chi‐squared error (χ2) values of 0.9995, 0.0005, and 0.0056, respectively, on test dataset. These values of the ANFIS model on test dataset were 0.9936, 0.0243, and 0.0202, respectively. Among the mathematical models, the Midilli model was the best‐fitted model to experimental MR values in most of the drying conditions. It was concluded that artificial intelligence modeling is an effective approach for accurate prediction of the drying kinetics of stevia leaves in the continuous‐flow IR‐assisted hybrid solar dryer.