Hot Air Convective Drying Research Articles

A comparative study on the efficiency of two modeling approaches for predicting moisture content of apple slice during drying

AbstractThe efficiency of two different modeling approaches for predicting moisture content of apple slices during drying were evaluated and compared. The experiments were performed at four air‐drying temperatures and at three levels of air velocity in the convective hot air dryer. Moisture content of apple during drying was predicted using theoretical model and Artificial Neural Networks (ANNs) models. The theoretical model was developed by solving heat and mass transfer equations simultaneously using numerical technique. A multilayer perceptron (MLP) neural network and radial basis function (RBF) network were used to develop neural network modeling. The agreement between the experimental results and the theoretical model predictions was quite good by considering the shrinkage dependent effective diffusivity in the model. Among different ANN structures, the best results were obtained for the MLP network with two hidden layers based on the statistical criteria (the coefficient of determination [R2] and mean squared error [MSE]). Although both two approaches could reasonably forecast the moisture content of apple slice during drying, the ANN model demonstrated better goodness of fit than theoretical model.Practical applicationMoisture content and water activity are important parameters in production of dried fruit, which have traditionally been measured by destructive and time‐consuming methods. Hence, quick tools are required to evaluate the moisture concentration and monitor changes during drying. Modeling can be considered as a helpful tool for prediction of moisture content as a function of time and space. The results of this study show that the two types of models can successfully predict changes in moisture content during drying. Applying these models at the commercial level can reduce variability in product quality and improve repeatability of the drying process.

Artificial neural network modelling approach of drying kinetics evolution for hot air oven, microwave, microwave convective and freeze dried pineapple

This study presents the dehydration characteristics of the drying of the pineapple slice. Hot air oven (60 °C), microwave (100 W), microwave convective (600 W, 40 °C) and freeze drying (0.1 mbar, − 40 °C) of pineapple slice through artificial neural network (ANN) modeling approach (Backpropagation algorithm for feed-forward network). Considering the sample thickness of 0.15 cm, effective moisture diffusivity is calculated. To study the reconstitution property of the product, the rehydration ratio is considered at 20 °C, 40 °C, 60 °C and 80 °C. The microwave convective drying (96 min) is the fastest while the freeze drying is slowest (20 h). The coefficient of correlation through the ANN model for hot air oven, microwave, microwave convective and freeze dried sample are 0.99936, 0.9994, 0.99948, and 0.99926 respectively. In terms of rehydration ratio, freeze drying (5.49) is found best followed by microwave (4.62), hot air (4.50), and microwave convective drying (2.00). At 80 °C the coefficient of rehydration value attains the maximum of 0.969 for freeze dried sample, whereas the minimum value of 0.369 is observed at 20 °C for the microwave-convective dried sample. From the observations obtain it may be stated that the ANN model predicts the dehydration kinetics adequately for the entire drying process. Freeze dried product appears to be the best in terms of reconstitution properties.

Influence of UV-B Pretreatments on Kinetics of Convective Hot Air Drying and Physical Parameters of Mushrooms (Agaricus bisporus)

The present study aimed to investigate the effects of ultraviolet-B (UV-B) pretreatments on selected physical properties (shrinkage, rehydration, color, texture) and drying kinetics and to model the drying kinetics of hot air dried mushrooms using several mathematical models, such as the Henderson–Pabis, logarithmic, two-term, Verma, Wang and Singh, Midilli, and modified Henderson–Pabis models. Results showed that the use of UV-B pretreatment before mushroom drying reduced shrinkage, color changes, firmness, and drying time and increased rehydration and the effective moisture diffusion coefficient. The amount of activation energy increased from 16.55 ± 1.3 kJ/mol (control sample) to 18.27 ± 2.2 kJ/mol (UV-B treated samples for 30 min), 19.72 ± 1.4 kJ/mol (UV-B treated samples for 60 min), and 21.9 ± 1.9 kJ/mol (UV-B treated samples for 90 min). However, increasing the drying temperature increased the shrinkage and firmness of samples. The modified Henderson–Pabis model with the highest correlation coefficient (R2) and lowest root mean square error (RMSE) and chi-square (χ2) showed the best fit for every drying curve, proving to be an excellent tool for the prediction of drying time.

High precision laboratory dryer for thin layer and bulk drying with adjustable temperature, relative humidity and velocity of the drying air

Convective hot air drying is one of the most common post-harvest processes within the agricultural sector and a standard process in the food industry. The technique is used on fruits and vegetables in order to increase their added value or to extend their shelf life. Drying is highly dependent on the condition of the drying air in terms of temperature, relative humidity and velocity and on the thickness of the product layer. The influence of these drying parameters on the drying behavior and quality is product-specific and has to be investigated in laboratory experiments due to the high costs for full-scale evaluation. For this purpose, a high precision laboratory dryer was developed in order to achieve controlled and stable climate conditions during the drying of light bulk material.To avoid temperature drift of the load cell during drying, a temperature-controlled sensor housing was applied. To further stabilize the signal, it was corrected with the instantaneous temperature.The high precision laboratory dryer HPD TF1 could be potentially useful to establish drying curves for defined temperature, relative humidity and velocity of the drying air. Further potential applications are the establishment of sorption isotherms or the determination of diffusion coefficients of various materials.

Microwave-assisted hot air convective drying of whole cranberries subjected to various initial treatments

The aims of study were to evaluate the effect of: (i) initial treatments such as sonication (S), convective freezing (F), sonication combined with freezing (SF), microwave-vacuum (MWV), microwave-vacuum combined with convective freezing (MWVF) and cryogenic freezing (N) as well as; (ii) replacement of hot air convective drying (HACD) with microwave vacuum drying (MWVD) in the final stage of drying on: the drying kinetics, average drying rates (DRAVG), the content of bioactive compounds and antioxidant activity of osmotically dehydrated whole cranberries. HACD of fruits took from 740 to 950 min. The use of microwaves instead of hot air in the final stage of drying (HACD + MWVD) reduced the drying time, which took from 80 to 493 min. DRAVG of HACD + MWVD was more than one order of magnitude larger than DRAVG of HACD. The use of microwaves during initial treatment and drying resulted in the shortest drying time, i.e. 20 min and the highest DRAVG, i.e. 0.092 kg H2O/kg DM/min. HACD + MWVD resulted in significantly higher contents of bioactive compounds and antioxidant activity of fruits than HACD. Among different pretreatments used in the present study, sonication and freezing (S, F, SF) gave the best results in terms of drying time and final product quality.

Model development and optimization of process conditions for color properties of tomato in a hot‐air convective dryer using box–behnken design

his study was conducted to improve on the retention of color properties of dried tomato fruits. Process conditions were optimized using response surface methodology (RSM). A three-level-four-variable Box–Behnken design was used for the optimization which involved 68 samples in triplicate, the variables were drying-air temperature, slice thickness, cultivar, and pre-drying treatment. The results indicated that quadratic models best described the behavior of color properties of tomato in hot-air convective dryer with R2 of 0.8080 and 0.7955 for hue angle color value (HACV) and color difference (CD), respectively. The process conditions significantly influenced the HACV and CD of dried tomato fruits. Through the RSM, the optimal process conditions for HACV and CD were as follows: drying-air temperature 50°C, slice thickness 5.11 mm, cultivar 1.75 (Tiwantiwa), and pre-drying treatment of honey and sugar solution with a desirability value of 0.838. HACV and CD obtained under these conditions were 39.55° and 33.64, respectively. Practical applications Tomato is one of the most important fruits and vegetables, and natural sources of lycopene and vitamin C. Drying is an important process used in the preservation of the fruit toward wastages minimization and also involved in the production of antioxidant food supplements. Color is a major criterion consumers usually consider to either accept or reject processed vegetables in the market. Through optimization of the process conditions involved in drying, the retention of color properties and overall quality were improved. This research showed great potential as related to selection of cultivar and development of new natural resources to be used as pre-drying treatment.

Hybrid drying of Murraya koenigii leaves: anti-diabetic and anti-ageing activities

This study aims to compare the anti-diabetic and anti-ageing effect of the Murraya koenigii leaves by using the drying method of convective hot-air drying (40, 50 and 60 °C) and two hybrid drying methods through microwave vacuum-drying (6, 9 and 12 W/g) and convective hot-air pre-drying followed by microwave vacuum finishing-drying (50 °C followed by 9 W/g), in addition to the freeze-drying, which was used as a control method. The anti-diabetic activity was evaluated by using α-amylase and α-glucosidase inhibition method, while the anti-ageing activity was measured by using acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition effect. The results indicated that the dried leaves of M. koenigii were more selective towards α-glucosidase inhibition with the percentage ranging from 7.92 to 23.57% at the concentration of 62.52 ± 22.18 to 20.39 ± 2.01 mg dried leaves/mL. Concerning the anti-ageing activity, the inhibition effect of AChE was significantly weaker compared to BChE inhibition, revealing that the dried M. koenigii leaves were more selective towards BChE inhibition with the percentage ranged from 79.47 to 87.07%. Furthermore, the Page model and diffusion models showed a good fitting of the model to the empirical data of drying kinetics with the highest coefficient of determination (0.9996; 0.9995) and the lowest values of root-mean-square error (0.0102; 0.0090) and Chi-square coefficients (0.0010; 0.0008). Overall, microwave vacuum-drying is the recommended drying method to be used for M. koenigii leaves due to its promising result obtained for the inhibition of α-glucosidase and BChE.

Novel Sensing Technologies During the Food Drying Process

Instantly sensing the food quality attributes is a prerequisite to regulate the drying process for final product quality improvement. Novel sensing technologies have been “pushed” to food drying engineering from other research disciplines. Electronic nose, computer vision, hyperspectral imaging, near-infrared, nuclear magnetic resonance, and dielectric properties have been “transplanted” for this purpose. Various physicochemical attributes of food quality, including flavors, moisture contents, colors, shapes, texture, and chemical contents, have been sensed during the food drying process. Sun and solar drying, hot air convective drying, freeze drying, and microwave drying have been involved in these attempts. Numerous data processing and analysis techniques have been employed to make clear the meaning of multivariate variables for the above technologies. With the assistance of these technologies, a great diversity of drying processes have been modulated and food product quality had been improved. To promote their industrial application, more research is required to be conducted and more practical sensing method development is suggested along this direction.

Drying characteristics of yam slices (Dioscorea rotundata) in a convective hot air dryer: application of ANFIS in the prediction of drying kinetics

This study applied Adaptive Neuro-Fuzzy Inference System (ANFIS) to predict the moisture ratio (MR) during the drying process of yam slices (Dioscorea rotundata) in a hot air convective dryer. Also the effective diffusivity, activation energy, and rehydration ratio were calculated. The experiments were carried out at three (3) drying air temperatures (50, 60, and 70 °C), air velocities (0.5, 1, and 1.5 m/s), and slice thickness (3, 6, and 9 mm), and the obtained experimental data were used to check the usefulness of ANFIS in the yam drying process. The result showed efficient applicability of ANFIS in predicting the MR at any time of the drying process with a correlation value (R2) of 0.98226 and root mean square error value (RMSE) of 0.01702 for the testing stage. The effective diffusivity increased with an increase in air velocity, air temperature, and thickness and the values (6.382E -09 to 1.641E -07 m2/s). The activation energy increased with an increase in air velocity, but fluctuate within the air temperatures and thickness used (10.59–54.93 KJ/mol). Rehydration ratio was highest at air velocity×air temperature×thickness (1.5 m/s×70 °C × 3 mm), and lowest at air velocity × air temperature×thickness (0.5 m/s×70 °C × 3 mm). The result showed that the drying kinetics of Dioscorea rotundata existed in the falling rate period. The drying time decreased with increased temperature, air velocity, and decreased slice thickness. These established results are applicable in process and equipment design, analysis and prediction of hot air convective drying of yam (Dioscorea rotundata) slices.

Hybrid Drying of Murraya koenigii Leaves: Energy Consumption, Antioxidant Capacity, Profiling of Volatile Compounds and Quality Studies

This study aims to reduce the amount of specific energy consumed during the drying of fresh Murraya koenigii leaves by comparing four drying methods: (1) convective hot-air drying (CD; 40, 50 and 60 °C); (2) single-stage microwave-vacuum drying (MVD; 6, 9 and 12 W/g); (3) two-stage convective hot-air pre-drying followed by microwave-vacuum finishing–drying (CPD-MVFD; 50 °C, 9 W/g); and (4) freeze-drying as a control in the analysis sections. The drying kinetics were also modelled using thin-layer models. The quality parameters of dried M. koenigii leaves were measured including total polyphenolic content (TPC), antioxidant capacity (ABTS and FRAP), profiling of volatile compounds, colour analysis and water activity analysis. Results showed that CPD-MVFD effectively reduced the specific energy consumption of CD at 50 °C by 67.3% in terms of kilojoules per gram of fresh weight and 48.9% in terms of kilojoules per gram of water. The modified Page model demonstrated excellent fitting to the empirical data obtained. FD showed promising antioxidant activity. The major contributor of antioxidant capacity was TPC. The volatile compounds profiled by gas chromatography-mass spectrometry, namely, β-phellandrene (31%), α-pinene (19.9%), and sabinene (16%) were identified as the major compounds of dried M. koenigii leaves. Colour analysis showed MVD’s high performance in preserving the colour parameters of M. koenigii leaves under all conditions. The colour parameters were correlated to the antioxidant capacity and TPC. Water activity analysis showed that the water activity of M. koenigii leaves for all drying methods indicating that the conditions were microbiologically and shelf-stable. Pearson correlation showed the colour parameters of the leaves had a strong correlation to TPC. Overall, MVD showed promising energy consumption reduction and recovery in TPC and volatile compounds.

PEMODELAN MATEMATIK KANDUNGAN AIR PADA PENGERINGAN APEL

Drying is one of the most significant method in food preservation. This study was conducted to investigate mathematical models of thin layer drying of apple slices. The kinetic of thin layer drying of apple slices was experimentally investigated in a hot air convective dryer. Crank solution for difusion in slab model and Lewis model for drying in thin layer were used to predict the drying profile. Drying characteristic of apple slices were determined using ambient air at 50 oC and 0,4167 m/s linier velocity. The result showed that Lewis model was more convenient for short-period drying, whereas the Crank solution model was more appropiate for long- periode drying.

Drying Characteristics of Blackberry Fruits in a Convective Hot-air Dryer

In this study, blackberry fruits were dried in a pilot-scale hot-air dryer to identify the drying characteristics of the fruits. The air velocity was set as 1 m·s−1, and the temperature range was set as 54 to 75 °C. Fick’s law of diffusion was used to describe heat transfer during the decreasing rate period. Effective diffusivity values were calculated, and the Arrhenius constitutive model was used to describe the temperature dependence of these values. The Page, logarithmic, approximation of diffusion, two-term, and Midilli et al. models were used to fit the experimental data. A nonlinear regression analysis was used to calculate rate constants and model coefficients. The present findings revealed that among the tested models, the Midilli et al. model best described the experimental data; therefore, it was concluded that the model could be used to describe the drying characteristics of blackberry fruits.

Ultrasonication assisted salt-spices impregnation in black carrots to attain anthocyanins stability, quality retention and antimicrobial efficacy on hot-air convective drying.

The present study aims at optimisation of enhanced solute impregnation through ultrasonication (US) at 37 kHz using central composite design of response surface methodology (RSM). Black carrots were blanched at 98 °C/3 min followed by immersion in salt-spices based solutions for 8 h, treated with bath sonication at specific intervals (2, 4 & 6 h) for 5, 10 and 15 min. Responses for optimum water loss (WL), solute gain (SG), anthocyanins retention, texture and highest antioxidant activity were optimized in effect of NaCl%, spices mix% and US time. The suggested models were of good fit while lack of fit as non-significant (p < 0.0500). Best combination was compared for anthocyanins retention on pressure-cooking (120 °C/15 psi) with fresh, blanched, salt-spiced without US subjected to hot-air convective drying (55 °C/5 h). Ultrasonication-assisted salt-spiced convective dried (USPCD) carrots retained highest anthocyanin content (41%) post cooking which correlated with increased glass transition (Tg) and antimicrobial efficacy (as zone of inhibition) in comparison to fresh, blanched convective dried (BCD) and salt-spiced convective dried (SPCD) carrots. FTIR spectra suggested the correlation of textural effects with pectin degradation and solute impregnation. XRD spectra revealed changes in pectin (2θ = 22.06°) and NaCl crystallinity peaks at 2θ = 27.49, 31.86, 45.62, 56.68, 66.45 and 75.43°, owing to the processing of black carrots. The spectra also confirmed higher solute impregnation in USPCD than SPCD carrots. Scanning electron micrographs of USPCD also indicated higher impregnation through smallest pores visible in longitudinal section of carrot tissue structure, which also appeared to be polymeric network filled with higher solutes than SPCD. Taken together, US assisted solute impregnation might have provided protection to the anthocyanins degradation as well as retention of other quality parameters on processing.

Influence of drying temperature and pretreatment on the drying characteristics and quality of dried cashew (Anacardium occidentale L.) apple slices

This study evaluated the mineral content, browning extent, proximate content, the sensory analysis in the yellow variety of cashew apple slices, for both fresh and after being subjected to pretreatment, at three different drying temperatures. Fresh cashews were harvested, sliced into 7 mm thickness, pretreated by dipping the slices into ascorbic acid and dried at the temperature of 45 °C, 55 °C and 65 °C using the hot air convective dryer at a constant air velocity of 0.8 m/s. During the drying the weight loss was measured initially at an interval of every 30 minutes for the first five hours and later at an hour hour interval. The analysis of minerals content (magnesium and calcium) and proximate analysis which included pH, color, vitamin C content, and tannin content was carried out. In addition, sensory evaluation for taste, texture, aroma, appearance and overall acceptability was carried out according to the 9-point hedonic scale using raw cashew apple as a control. For each of the plots for the drying curves from the mechanical drying test, they are mostly in the failing rate period. The results showed that the moisture loss from the cashew slices increased with increase in drying temperature and time of drying. It was observed that drying temperature has an influence on the proximate content, browning extent and mineral content of the cashew slices. An increase in temperature leads to high losses of vitamin C, less browning effect and high losses of tannin. The result of the sensory evaluation revealed that the pretreated sample dried at a temperature of 55 °C was the most acceptable.

Salinity effects on ultrasound-assisted hot air drying kinetics of sewage sludge

The influences of salt concentrations (0, 0.0214, 0.178, 0.265, 0.438 and 0.731 mol kg−1) and freeze/thawing treatment on the drying characteristics of sewage sludge were examined in a series of ultrasound-assisted (150 W) hot air convective dryer experiments at 80–130 °C. The average drying rate of the conventional sludge and hypersaline sludge sample through freezing/thawing treatment increased. The drying rates of saline sewage sludge decreased as the salt concentration increased. The average drying rate of the hypersaline sludge decreased by 8.6 percent compared to the conventional one. The apparent activation energy of the conventional and hypersaline sludge in the first falling rate stage of the drying were 14.27 and 15.61 kJ mol−1, respectively. Moreover, surface cracking dynamics formed as a result of drying were investigated. Our results show that the surface crack ratio during ultrasound assisted hot-air convection drying of conventional sewage sludge increased by 6.1 percent compared to that of the hot-air convection drying alone.

Characterisation of the Convective Hot-Air Drying and Vacuum Microwave Drying of Cassia alata: Antioxidant Activity, Essential Oil Volatile Composition and Quality Studies

The preservation of active constituents in Cassia alata through the removal of moisture is crucial in producing a final product with high antioxidant activity. This study aims to determine the influences of various drying methods and drying conditions on the antioxidant activity, volatiles and phytosterols content of C. alata. The drying methods used were convective drying (CD) at 40 °C, 50 °C and 60 °C; freeze drying; vacuum microwave drying (VMD) at 6, 9 and 12 W/g; and two-stage convective pre-drying followed by vacuum microwave finish drying (CPD-VMFD) at 50 °C and 9 W/g. The drying kinetics of C. alata are best described by the thin-layer model (modified Page model). The highest antioxidant activity, TPC and volatile concentration were achieved with CD at 40 °C. GC–MS analysis identified the presence of 51 volatiles, which were mostly present in all samples but with quantitative variation. The dominant volatiles in fresh C. alata are 2-hexenal (60.28 mg 100 g−1 db), 1-hexanol (18.70 mg 100 g−1 db) and salicylic acid (15.05 mg 100 g−1 db). The concentration of phytosterols in fresh sample was 3647.48 mg 100 g−1 db, and the major phytosterols present in fresh and dried samples were β-sitosterol (1162.24 mg 100 g−1 db). CPD-VMFD was effective in ensuring the preservation of higher phytosterol content in comparison with CD at 50 °C. The final recommendation of a suitable drying method to dehydrate C. alata leaves is CD at 40 °C.

Thermal properties of fresh and dried cranberry (Vaccinium macrocarpon) fruits determined by differential scanning calorimetry and thermogravimetric analysis

AbstractThe aim of this study was to determine selected thermal properties of cranberries based on DSC and TGA curves, and to compare the properties of fresh cranberries, the dry matter of cranberries, cranberries processed by hot‐air convective drying (HACD) at 80°C, and cranberries processed by microwave‐vacuum drying (MWVD) at 150 W. Thermal analysis techniques can be used to determine the thermal stability of fruits and indicate the best temperature of processing, which can minimize the thermal‐oxidative damage, as well as extend the shelf life of fruits. Dry matter of cranberries was analyzed at −30°C to 500°C. The first endothermic peak was determined at −14.7°C, the last endothermic peak at 362.3°C. The area under the DSC curve was 874.8 J/g, and mass loss was 64.70%. The temperature of the first and last endothermic peak was determined at 4.8 and 84.6°C (fresh fruits), −10.6°C and 86.0°C (HACD), 2.0°C, and 84.5°C (MWVD), respectively. The area under the DSC curve was determined at 4970.0 J/g (fresh fruits), 525.1 J/g (HACD), and 518.5 J/g (MWVD), and mass loss reached 65.54% (fresh fruits), 1.84% (HACD), and 4.27% (MWVD).Practical applicationsThe results of this study expand our knowledge about the thermal properties of the dry matter of cranberries, fresh cranberries, cranberries processed by hot‐air convective drying (HACD) at 80°C and by microwave‐vacuum drying (MWVD) at 150 W. Differential scanning calorimetry (DSC) proved to be a useful technique for determining the temperature of endothermic phase transition peaks and the area under the DSC curve of cranberries. Thermogravimetric analysis (TGA) supported the determination of mass loss during the measurements. Processing of food products, including drying can change their thermophysical and chemical properties. These changes can affect the thermal stability of dried products, which can be seen in the course of DSC and TGA curves. In this study, the temperature, at which the phase transitions of cranberries occur, was indicated. On this basis, the optimal processing temperature can be selected to preserve the berries content. The best temperature of fruit processing can minimize the thermal‐oxidative damage and extend shelf life of cranberries. Similar thermal stability of cranberries dried by hot‐air convection (HACD) at 80°C, and fruits dried by microwave‐vacuum (MWVD) at 150 W was found. The obtained findings can be further expanded by calculating the specific heat of cranberries.

Thin Layer Drying Kinetics of Wheat Grain in a Convective Hot-Air Dryer

Thin Layer Drying Kinetics of Wheat Grain in a Convective Hot-Air Dryer

The effect of freezing on the hot air and microwave vacuum drying kinetics and texture of whole cranberries

The aim of this study was to evaluate the effect of convective and cryogenic freezing, hot air convective drying (HACD) at 60, 70, 80, and 90 °C and microwave vacuum drying (MWVD) at 100, 150, 200, 300, 450, and 500 W on the drying kinetics and texture of whole cranberries. Effective moisture diffusivities and drying rates were higher, whereas drying times were shorter for the samples dried by MWVD compared with the samples processed by HACD. The drying kinetics of cranberries during MWVD was discussed based on the hypothesis postulating that changes in the drying rate of cranberries during MWVD can be explained by and correlated with changes in the pressure gradient on material surface. Cranberries processed by MWVD were characterized by significantly greater hardness, gumminess, and chewiness in comparison with HACD samples. MWVD was found to be an effective method for producing dried snacks characterized by hard and crispy texture and considerable resistance to stress associated with manufacturing, packaging, storage, and delivery. HACD produced brittle fruit that were difficult to store and transport and were not fully suitable for direct consumption. Convective freezing before MWVD improved the overall appearance of cranberries, whereas cryogenic freezing combined with high temperature HACD adversely influenced the drying rate and produced dried cranberries with suboptimal overall appearance.

Mathematical and Kinetic Modelling for Convective Hot Air Drying of Sweet Potatoes (&amp;lt;i&amp;gt;Ipomoea batatas L&amp;lt;/i&amp;gt;)

The kinetic modelling of thin layer drying is performed with various agricultural products such as seeds, grains, fruits and some plant species with economic importance. Sweet Potato (Ipomoea batatas L) is a widely consumed, and its industrialization is on the increase. The thin layer drying kinetics of sweet potato were experimentally investigated in a convective hot air dryer. Comparison was made between the experimental and model predicted moisture ratio by nonlinear regression analysis. Furthermore, the effect of drying temperature and slice thickness on the selected model constants was evaluated. From the experimental data obtained, it was observed that moisture ratio of the potato sample was directly proportional to the mass of the sample while the time of drying was inversely proportional and these two parameters (mass and time) were used to develop a mathematical model for the thin layer drying of sweet potatoes using a convective hot air dryer. The mathematical model developed was validated. The experimental data fitted the developed mathematical model and gave the Sum of Squares (SSE) value of 0.0001296 and coefficient of determination (R2) as unity. The parameters obtained from the kinetic modelling of the selected models studied could be used in designing low cost dryers for optimum drying conditions.