Moisture Diffusivity and Activation Energy for High Velocity Hot Air Drying of Chicken Meat

Microwave and steam blanching as pretreatments to hot air drying of orange-fleshed sweet potato (OFSP) were studied. The air-drying experiment was performed at constant temperature of 70°C and airflow of 1.0 m/s. The effective moisture diffusivity varied from 1.5 × 10 − 9 to 4.4 × 10 − 9 m2/s, and 1.1 × 10 − 10 to 7.9 × 10 − 10 m2/s, for the microwave and blanched assisted hot air drying, respectively. The activation energy obtained for the various microwave-assisted hot air drying was 29.1 W/mm for 4 min, 68.1 W/mm for 3 min, and 79.7 W/mm for 2 min. Ascorbic acid degradation and formation of brown pigments in the OFSP slices were lower in microwave than in steam blanch-assisted drying. Microwave-assisted drying of OFSP is best governed by Page model, M R = exp − k t n , while the blanch-assisted followed the logarithmic model, M R = a exp − k t + c . To produce better quality OFSP flour, it is recommended to cut the tubers into 3 mm slices, microwave at a power of 630 W for 2 min or blanch for 1 min, 43 seconds prior to hot air drying.

Download Full-text

Effective moisture diffusivity during hot air solar drying of tomato slices

Research in Agricultural Engineering ◽

10.17221/33/2014-rae ◽

2016 ◽

Vol 62 (No. 1) ◽

pp. 15-23 ◽

Cited By ~ 7

Author(s):

H. Samimi Akhijani ◽

A. Arabhosseini ◽

M.H. Kianmehr

Keyword(s):

Moisture Diffusivity ◽

Effective Moisture Diffusivity ◽

Slice Thickness ◽

Solar Drying ◽

Air Velocity ◽

Hot Air Drying ◽

Chi Square ◽

Air Drying ◽

Hot Air ◽

Effective Moisture

Mathematical modelling and effective moisture diffusivity of tomato (Lycopersicon esculentum) was studied during hot air solar drying. An experimental solar dryer with a swivel collector was used for experiments. The collector followed the solar radiation using a precious sensor. Drying experiments were performed in a thin layer hot air drying at slice thicknesses of 3, 5 and 7 mm and air velocities of 0.5, 1 and 2 m/s. The experimental data were fitted to different mathematical moisture ratio models and the Page model was selected as the best model according to correlation coefficient R2, chi-square χ2 and root mean square error (RMSE) parameters. The maximum values of moisture diffusivity was 6.98 × 10–9 m2/s at air velocity of 2 m/s and slice thickness of 7 mm while the minimum value of the moisture diffusivity was 1.58 × 10–9 m2/s at air velocity of 0.5 m/s and slice thickness of 3 mm.

Download Full-text

Effect of Temperature and Microwave Power Levels on Microwave Drying Kinetics of Zhaotong Lignite

Processes ◽

10.3390/pr7020074 ◽

2019 ◽

Vol 7 (2) ◽

pp. 74 ◽

Cited By ~ 4

Author(s):

Pengfei Zhao ◽

Chenhui Liu ◽

Wenwen Qu ◽

Zhixiu He ◽

Jiyun Gao ◽

...

Keyword(s):

Activation Energy ◽

Thin Layer ◽

Apparent Activation Energy ◽

Microwave Power ◽

Microwave Drying ◽

Hot Air Drying ◽

Air Drying ◽

Hot Air ◽

Thin Layer Drying ◽

Rate Period

Microwave drying is a promising and effective way to drying and upgrading lignite. The influence of temperature (100–140 °C) and microwave power levels (500–800 W) on thin-layer drying characteristics of Zhaotong lignite under microwave irradiation were investigated. Fourteen thin-layer drying models were used to analyze the microwave drying process while six thin-layer drying models were used to analyze the hot-air drying process. The microwave drying processes at all temperature (100–140 °C) or low microwave power levels (500–700 W) exhibited four periods: a warm-up period, a short constant period, the first and second falling rate period, while one falling rate period was found during hot-air drying. The effective diffusion coefficient of lignite were calculated and it increases with increasing temperature and microwave power levels. During microwave drying, the two-term exponential model is the most suitable model for all applied conditions, while the Modified Page model is the most suitable model to describe the hot-air drying experiments. The apparent activation energy were determined from Arrhenius equation and the values for the first and second falling rate period are 3.349 and 20.808 kJ·mol−1 at different temperatures, while they are 13.455 and 19.580 W·g−1 at different microwave power levels. This implies the apparent activation energy is higher during the second falling rate period, which suggest that the dewatering of absorbed water is more difficult than capillary water. The value of apparent activation energy in hot-air drying is between the first and second falling rate period of microwave drying. Results indicate that microwave drying is more suitable to dewatering free water and capillary water of lignite.

Download Full-text

Investigation of the Effect of Combined Drying for Rainbow Trout Fillets and Comparison with Hot-air Drying

Turkish Journal of Fisheries and Aquatic Sciences ◽

10.4194/1303-2712-v20_9_05 ◽

2020 ◽

Vol 20 (9) ◽

pp. 701-709

Author(s):

Osman Ismail ◽

Ozlem Gokce Kocabay

Keyword(s):

Regression Analysis ◽

Moisture Diffusivity ◽

Vacuum Drying ◽

Drying Method ◽

Drying Process ◽

Hot Air Drying ◽

Air Drying ◽

Hot Air ◽

Effective Moisture ◽

Ultrasonic Assisted

In this study, drying kinetics, chemical composition and surface color for fillets samples, namely Rainbow trout (Oncorhynchus mykiss) subjected to combined drying (ultrasonic assisted vacuum drying) and hot-air drying were compared at full length between 50-70°C. Drying process carried out entirely in the falling rate period. The results suggested that the moisture content was influenced by the combined drying method and the drying temperature. The shortest drying time was obtained using combined drying method at 70°C. The combined drying method made shorter the drying process and enhanced the effective moisture diffusivity by comparison with hot-air drying method. The activation energies were observed using a modified Arrhenius type equation as of 2.392 and 4.83 kW kg-1 for combined and hot-air drying, respectively. Quality characteristics of fillets samples were specified as physical (moisture content, color values) and chemical (protein, fat and ash). Seven different drying models were considered for moisture ratios using nonlinear regression analysis. The consequences of regression analysis stated that the Midilli et al., model best fits data set. According to the results, the highest effective moisture diffusivity was determined in the fillets dried with the ultrasonic assisted vacuum drying method and they increased with increasing drying temperatures. Ultrasonic treatment accelerated the vacuum drying process for the fillets. Also, the ultrasonic assisted vacuum drying method is a better technology to preserve the original material and prevent thermal damage.

Download Full-text

Thin Layer Modelling of Microwave-Convective Drying of Tomato Slices

International Journal of Food Engineering ◽

10.1515/ijfe-2012-0205 ◽

2013 ◽

Vol 9 (1) ◽

pp. 75-90 ◽

Cited By ~ 13

Author(s):

Tilahun S. Workneh ◽

Moruf O. Oke

Keyword(s):

Activation Energy ◽

Thin Layer ◽

Microwave Power ◽

Hot Air Drying ◽

Air Drying ◽

Hot Air ◽

Thin Layer Drying ◽

Rate Period ◽

Air Ventilation ◽

Best Fit

AbstractThe thin layer drying behaviour of tomato slices dried using microwave power densities of 1.13, 2.08 and 3.11 W/g combined with air ventilation (50°C) and hot air drying at 40, 50, 70 and 80°C was investigated. The tomato slice dried faster when subjected to microwave heating coupled with hot air ventilation. Drying time decreased considerably with increase in microwave power density and with increase in hot air temperature. Drying took place in a constant rate period followed by the falling rate period after a short heating period. The drying data were fitted to Newton (Lewis), Page, Henderson and Pabis, Logarithmic, Wang and Singh and Parabolic equations. The Parabolic model (R2 = 0.9999; χ2 = 0.0085; MBE = 0.0182 and RMSE = 0.0691) gave the best fit to predict the hot air ventilation drying of tomato slices while the Logarithmic model (R2 = 0.9951; χ2 = 0.0024; MBE = −0.0319 and RMSE = 0.0477) gave the best fit for microwave-assisted hot air drying of tomato slices. The values of the effective diffusivity coefficients of the tomato slices varied between 1.68 × 10–9 and 5.22 × 10–8 m2/s while the activation energy was 27.09 kJ/mol. The lower activation energy indicates that drying of tomato slices requires less energy and is hence a cost and energy-saving method. Microwave drying at 1.13 and 2.08 W/g maintained superior colour quality of the tomato slices.

Download Full-text

Microwave Assisted Convective Air Drying of Sugarloaf Pineapples (Ananas Comosus)

Applied Engineering in Agriculture ◽

10.13031/aea.14380 ◽

2021 ◽

Vol 37 (5) ◽

pp. 763-774

Author(s):

Ernest Ekow Abano

Keyword(s):

Air Temperature ◽

Microwave Power ◽

Moisture Diffusivity ◽

Hot Air Drying ◽

Drying Time ◽

Air Drying ◽

Microwave Assisted ◽

Hot Air ◽

Effective Moisture ◽

Drying Conditions

HighlightsMicrowave pretreatment before drying reduced drying time significantly.Microwave-assisted drying increased the effective moisture diffusivity coefficient.Microwave pretreatment before convective hot-air drying improved quality parameters.The Middili et al. (2002) model best fitted the microwave-assisted drying of sugarloaf pineapples.Abstract. This study’s objective was to provide the optimum drying conditions to produce quality dried sugarloaf pineapples using microwave pretreatments before the conventional hot air drying. For this, the effect of microwave power (385 to 697 W), microwave time (2 to 4 min), and air temperature (50°C to 70°C) on the drying kinetics and quality of sugarloaf pineapple were evaluated using the Box Behnken response surface methodology. To reach a 17.44±0.09% kg/kg dry matter moisture content, we found the optimum drying conditions for sugarloaf pineapples to be 697 W microwave power for 2.26 min before convective hot air drying at a temperature of 64.75°C. The predicted drying time, ascorbic acid content, and browning index were 13.68 h, 20.89 mg/100 g, and 0.099 Abs unit at this optimum condition, respectively. The pineapple slices’ effective moisture removal rate pretreated with microwave before drying was higher than the control and was between 6.42 × 10-10 m2/s and 11.82 × 10-10 m2/s while ones without a microwave were between 3.54 × 10-10 m2/s and 8.78 × 10-10 m2/s for drying at air temperature between 50°C and 70°C. It was discovered that the Midilli et al. (2002) model was the most appropriate thin layer model for microwave-assisted drying of sugarloaf pineapples. The pineapple slices’ drying rate potential generally increased with microwave power and pretreatments time but not the corresponding increase in the air temperature. Drying time for microwave-assisted drying was in the range of 11 to 20 h, while the ones without microwaves were between 18 and 24 h. Therefore, microwaves should be considered a pretreatment step to the industrial production of sugarloaf pineapple to reduce drying time and produce better quality products. Keywords: Drying, Hot air, Microwave, Moisture diffusivity, Sugarloaf pineapple.

Download Full-text

Hot-air Drying Kinetics of Yam Slices under Step Change in Relative Humidity

International Journal of Food Engineering ◽

10.1515/ijfe-2015-0340 ◽

2016 ◽

Vol 12 (8) ◽

pp. 783-792 ◽

Cited By ~ 19

Author(s):

Hao-Yu Ju ◽

Qian Zhang ◽

A.S. Mujumdar ◽

Xiao-Ming Fang ◽

Hong-Wei Xiao ◽

...

Keyword(s):

Relative Humidity ◽

Weibull Model ◽

Moisture Diffusivity ◽

Drying Kinetics ◽

Drying Rate ◽

Rehydration Ratio ◽

Hot Air Drying ◽

Drying Time ◽

Air Drying ◽

Hot Air

Abstract The drying kinetics and mathematical modeling of hot-air drying of yam slices were investigated under two-stage relative humidity (RH) control strategy with 60 °C and 1.5 m/s as its constant drying temperature and air velocity, respectively. Results indicate high RH in the initial stage results in high sample’s temperature that enhances water diffusion in the falling rate drying period. Within the scope of current work, change in RH in the later drying period has insignificant influence on sample’s temperature rise while low RH can accelerate the drying rate. Compared to drying at constant 20 % RH at the same drying air temperature, the drying strategy of using 40 % RH over the first 15 min and then lowing to 20 % RH for the remainder time yields a shorter drying time. Weibull model adequately described the moisture content variation with time for all experiments with the scale parameter ranging from 105.02 to 122.38 min and the values of shape parameters from 0.988 to 1.183. The effective moisture diffusivity determined from the Weibull model varied from 2.032 to 2.610×10−8 m2/s. The rehydration ratio increased as the overall drying time was reduced. Microstructure examination shows that higher RH in the initial drying stage can lead to a more porous microstructure which enhances drying, while fast drying rate in the initial drying period generates a crust layer which hinders drying.

Download Full-text

Study of Mathematical Models in Hot Air Drying of Herbs in Herbal Compress Ball

MATEC Web of Conferences ◽

10.1051/matecconf/201818701002 ◽

2018 ◽

Vol 187 ◽

pp. 01002 ◽

Cited By ~ 1

Author(s):

Boochita Wongpanit ◽

Sumitta Chotikamas ◽

Supacharee Roddecha ◽

Prapakorn Tantayotai ◽

Malinee Sriariyanun

Keyword(s):

Mathematical Models ◽

Curcuma Longa ◽

Moisture Diffusivity ◽

Effective Moisture Diffusivity ◽

Suitable Model ◽

Hot Air Drying ◽

Air Drying ◽

Hot Air ◽

Effective Moisture ◽

Zingiber Cassumunar

Herbal compress ball is currently one of important products of Thailand for exporting sales worldwide. It is used in Thai traditional medical treatment and spa to reduce muscle pain and relaxation. This research aimed to generate the mathematical models representing the behaviors of herbs in hot air drying to extend shelf life for exporting sales. Here, six types of herbs, including Prai (Zingiber cassumunar Roxb.), Turmeric (Curcuma longa Linn.), Lemongrass (Cymbopogon citratus), Kaffir lime (Citrus hystrix), Soap Pod leaves (Acacia concinna) and Tamarind Leaves (Tamarindus indica Linn.) were dried in different temperature at 60, 70, and 80 °C. Fours drying models, Page, Henderson and Pabis, and Logarithmic and Fick's second law equation were applied with experimental data of drying herbs to predict the rate of diffusion of water. The results showed that the Page model is the most suitable model due to the highest decision coefficient (R2) but the lowest Root Mean Square Error (RMSE). The effective moisture diffusivity (Deff) of the herbs in herbal compress ball was increased with increased the drying temperature. The size of the herb particle translated inversely with effective moisture diffusivity (Deff) value.

Download Full-text

Effects of Osmotic Dehydration on the Hot Air Drying of Apricot Halves: Drying Kinetics, Mass Transfer, and Shrinkage

Processes ◽

10.3390/pr9020202 ◽

2021 ◽

Vol 9 (2) ◽

pp. 202

Author(s):

Ivan Pavkov ◽

Milivoj Radojčin ◽

Zoran Stamenković ◽

Krstan Kešelj ◽

Urszula Tylewicz ◽

...

Keyword(s):

Activation Energy ◽

Osmotic Dehydration ◽

Effective Diffusivity ◽

Drying Process ◽

Air Velocity ◽

Hot Air Drying ◽

Drying Time ◽

Air Drying ◽

Hot Air ◽

Kinetics Of

This study aimed to determine the effects of osmotic dehydration on the kinetics of hot air drying of apricot halves under conditions that were similar to the industrial ones. The osmotic process was performed in a sucrose solution at 40 and 60 °C and concentrations of 50% and 65%. As expected increased temperatures and concentrations of the solution resulted in increased water loss, solid gain and shrinkage. The kinetics of osmotic dehydration were well described by the Peleg model. The effective diffusivity of water 5.50–7.387 × 10−9 m2/s and solute 8.315 × 10−10–1.113 × 10−9 m2/s was calculated for osmotic dehydration. Hot air drying was carried out at 40, 50, and 60 °C with air flow velocities of 1.0 m/s and 1.5 m/s. The drying time shortened with higher temperature and air velocity. The calculated effective diffusion of water was from 3.002 × 10−10 m2/s to 1.970 × 10−9 m2/s. The activation energy was sensitive to selected air temperatures, so greater air velocity resulted in greater activation energy: 46.379–51.514 kJ/mol, and with the osmotic pretreatment, it decreased to 35.216–46.469 kJ/mol. Osmotic dehydration reduced the effective diffusivity of water during the hot air drying process. It also resulted in smaller shrinkage of apricot halves in the hot air drying process.

Download Full-text