Impact of citric acid on the drying characteristics of kiwifruit slices

Kiwifruit slices were dried at four different air drying temperatures of 50, 55, 60 and 70ºC and at 2 m s-1 air velocity by using a cabinet dryer in this study. The drying, rehydration and colour characteristics were significantly influenced by pretreatment and drying temperature. The drying time decreased with the increase in drying temperature. The drying rate curves showed that the entire drying process took place in the falling rate period. Five well-known thin-layer models were evaluated for moisture ratios using nonlinear regression analysis. The results of regression analysis indicated that the Midilli & Kucuk model the best to describe the drying behaviour with the lowest c2 and RMSE values, and highest R2 value. The effective moisture diffusivity of the dried kiwifruit slices was calculated with Fick’s diffusion model, in which their values varied from 4.19×10–10 to 6.99×10-10 m2 s-1 over the mentioned temperature range. The dependence of effective diffusivity coefficient on temperature was expressed by an Arrhenius type equation. The calculated values of the activation energy of moisture diffusion were 10.37 and 19.08 kJ mol-1 for citric acid and control samples, respectively

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Thin layer mathematical modelling of white maize in a mobile solar-biomass hybrid dryer

Research in Agricultural Engineering ◽

10.17221/56/2020-rae ◽

2021 ◽

Author(s):

Joseph Oppong Akowuah ◽

Ato Bart-Plange ◽

Komla A. Dzisi

Keyword(s):

Thin Layer ◽

Type Equation ◽

Moisture Diffusivity ◽

Coefficient Of Determination ◽

Drying Rate ◽

Mean Square ◽

Drying Time ◽

Thin Layer Drying ◽

Drying Behaviour ◽

Kinetics Of

Performance of a tractor mounted solar-biomass hybrid dryer which utilise combined energy of solar and biomass was investigated. Drying behaviour of maize grains in the dryer was also investigated using 10 thin-layer mathematical models. The models were compared based on coefficient of determination (R2) and root mean square error (RMSE) values between experimental and predicted moisture ratios. Moisture content (MC) of grains in the dryer reduced from 19 ± 0.86% to 13 ± 0.4% (w.b.) in 5 h, compared to grains dried in open-sun which reached same MC in 15 hours. This resulted in average drying rate of 1.2 %·h–1 compared to 0.4 %·h–1 for grains dried in the open-sun leading to net savings in drying time of 67%. Overall mean temperature, 41.93 ± 2.7 °C in the dryer was 15.3 °C higher than the ambient temperature. Midilli Kucuk model was best to describe the thin-layer drying kinetics of maize in the dryer. It showed a good fit between the predicted and experimental data. The effective moisture diffusivity of grains dried in the dryer ranged between 1.45 × 10–11 m2·s–1 – 3.10 × 10–11 m2·s–1. An activation energy of 96.83 kJ·mol–1 was determined based on the Arrhenius-type equation.

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Optimization and Prediction of the Drying and Quality of Turnip Slices by Convective-Infrared Dryer under Various Pretreatments by RSM and ANFIS Methods

Foods ◽

10.3390/foods10020284 ◽

2021 ◽

Vol 10 (2) ◽

pp. 284

Author(s):

Ebrahim Taghinezhad ◽

Mohammad Kaveh ◽

Antoni Szumny

Keyword(s):

Energy Efficiency ◽

Color Difference ◽

Moisture Diffusivity ◽

Effective Moisture Diffusivity ◽

Diffusivity Coefficient ◽

Drying Process ◽

Anfis Model ◽

Drying Time ◽

Effective Moisture ◽

Response Variables

Drying can prolong the shelf life of a product by reducing microbial activities while facilitating its transportation and storage by decreasing the product weight and volume. The quality factors of the drying process are among the important issues in the drying of food and agricultural products. In this study, the effects of several independent variables such as the temperature of the drying air (50, 60, and 70 °C) and the thickness of the samples (2, 4, and 6 mm) were studied on the response variables including the quality indices (color difference and shrinkage) and drying factors (drying time, effective moisture diffusivity coefficient, specific energy consumption (SEC), energy efficiency and dryer efficiency) of the turnip slices dried by a hybrid convective-infrared (HCIR) dryer. Before drying, the samples were treated by three pretreatments: microwave (360 W for 2.5 min), ultrasonic (at 30 °C for 10 min) and blanching (at 90 °C for 2 min). The statistical analyses of the data and optimization of the drying process were achieved by the response surface method (RSM) and the response variables were predicted by the adaptive neuro-fuzzy inference system (ANFIS) model. The results indicated that an increase in the dryer temperature and a decline in the thickness of the sample can enhance the evaporation rate of the samples which will decrease the drying time (40–20 min), SEC (from 168.98 to 21.57 MJ/kg), color difference (from 50.59 to 15.38) and shrinkage (from 67.84% to 24.28%) while increasing the effective moisture diffusivity coefficient (from 1.007 × 10−9 to 8.11 × 10−9 m2/s), energy efficiency (from 0.89% to 15.23%) and dryer efficiency (from 2.11% to 21.2%). Compared to ultrasonic and blanching, microwave pretreatment increased the energy and drying efficiency; while the variations in the color and shrinkage were the lowest in the ultrasonic pretreatment. The optimal condition involved the temperature of 70 °C and sample thickness of 2 mm with the desirability above 0.89. The ANFIS model also managed to predict the response variables with R2 > 0.96.

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Estimation of Effective Moisture Diffusivity in Starchy Materials Following Hydrothermal Treatments

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.312-315.364 ◽

2011 ◽

Vol 312-315 ◽

pp. 364-369 ◽

Cited By ~ 4

Author(s):

Seyed Amir Bahrani ◽

Catherine Loisel ◽

Jean Yves Monteau ◽

Sid Ahmed Rezzoug ◽

Zoulikha Maache-Rezzoug

Keyword(s):

Reaction Rate ◽

Effective Diffusivity ◽

Moisture Diffusivity ◽

Reaction Model ◽

Reaction Rate Constant ◽

Diffusivity Coefficient ◽

Maize Starch ◽

First Order ◽

Melting Phenomenon ◽

Treatment Processes

Two hydrothermal treatment processes (DV-HMT and DIC treatment) were investigated on standard maize starch for three processing temperatures; 100, 110 and 120°C. The gravimetric change of starch powder during the treatment was analyzed by a simultaneous water diffusion and starch reaction model. The effective diffusivity coefficient (Deff) and reaction rate constant (k) were estimated by minimizing the error between experimental and analytical results. The values of Deff and k clearly increased with temperature. The degree of starch melting was evaluated for the two treatments using the first-order reaction model as a function of processing time. The results suggest that the absorption process is controlled by water–starch reactivity that induces melting phenomenon of starch crystallites, which progresses when temperature increases. The two hydrothermal treatments considerably differ: DIC being more prone to water absorption as demonstrated by the values of Deff and k.

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Investigation of influence of pre-treatment and low-temperature on drying kinetics, sorption properties, shrinkage and color of brown seaweeds (Saccharina Latissima)

Proceedings of 21th International Drying Symposium ◽

10.4995/ids2018.2018.7694 ◽

2018 ◽

Author(s):

Ignat Tolstorebrov ◽

Trygve Magne Eikevik ◽

Inna Petrova ◽

Yulia Shokina ◽

Michael Bantle

Keyword(s):

Relative Humidity ◽

Salt Content ◽

Sorption Isotherms ◽

Moisture Diffusivity ◽

Drying Kinetics ◽

Saccharina Latissima ◽

Diffusivity Coefficient ◽

High Accumulation ◽

Drying Time ◽

Brown Seaweeds

Drying kinetics of Saccharina latissima (raw and blanched) at low temperatures (10.0, 25.0 and 38.0 °C) was studied. The effective moisture diffusivity coefficient varied due to temperature alterations in the range between 1.4 and 4.5 10-10 m2/s for raw and 0.91 and 2.56 10-10 m2/s for blanched seaweeds. Significant changes in structural properties and chemical composition resulted in a much longer drying time of blanched seaweeds, when compared with raw. Drying temperature of 38.0 °C resulted in more brown color, when compared with other samples. Sorption characteristics of dried raw seaweeds depended on salt content and showed high accumulation of moisture at relative humidity of air of 80.0 %. The blanched seaweeds showed linear accumulation of moisture within increasing of relative humidity of drying air from 20.0 to 80.0 %, but high level of hysteresis was determined between sorption and desorption isotherms. The shrinkage development within dewatering of blanched and raw samples was also studied. Keywords: brown seaweeds, drying kinetics, sorption isotherms, color

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Improved Procedure for Natural Convection Garlic Drying

Acta Technologica Agriculturae ◽

10.2478/ata-2020-0015 ◽

2020 ◽

Vol 23 (2) ◽

pp. 92-98

Author(s):

Amor Bouhdjar ◽

Hakim Semai ◽

Amal Boukadoum ◽

Sofiane Elmokretar ◽

Azzedine Mazari ◽

...

Keyword(s):

Effective Diffusivity ◽

Diffusivity Coefficient ◽

Solar Drying ◽

Residual Moisture ◽

Drying Temperature ◽

Solar Systems ◽

Energy Consuming ◽

C 50 ◽

Increasing Temperature

AbstractVegetable drying is an energy consuming procedure despite the fact that it is the most efficient way to preserve agricultural products. This study investigates a new way to dry good quality garlic at lower cost. Thin garlic layer was submitted to free convection airflow at air drying temperature of 40 °C, 50 °C, and 60 °C. Using the slope method, effective diffusivity coefficient was determined at each drying temperature during the first and second falling drying rate periods. Considering the former, it increased with increasing temperature. In relation to latter, it decreased with the temperature increase. However, at low drying temperatures, process keeps on going to very low moisture content; and it develops to an asymptotic value at high temperatures, indicating that shrinking at high temperature prevents evaporation of some residual moisture. Considered separately, these temperatures do not reflect the conditions met in solar drying, since in solar systems, air temperature increases during the day with increasing solar radiation. Therefore, characterization of garlic drying by means of step temperature varying – the first hour of drying at 40 °C; the second hour of drying at 50 °C, and the remaining time of drying at 60 °C – might better correspond with conditions under solar drying and result in better understanding of the process.

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DRYING KINETICS AND CROSS-LINKING OF SULFUR PREVULCANIZED THICK NATURAL RUBBER LATEX FILM

Rubber Chemistry and Technology ◽

10.5254/rct.13.88908 ◽

2013 ◽

Vol 86 (1) ◽

pp. 57-67 ◽

Cited By ~ 3

Author(s):

Chen Jing ◽

Yang Lei ◽

Zhong Jieping ◽

Li Sidong ◽

Chen Yongjun ◽

...

Keyword(s):

Film Formation ◽

Natural Rubber Latex ◽

Type Equation ◽

Drying Kinetics ◽

Latex Film ◽

Cross Linking ◽

Drying Time ◽

Drying Temperature ◽

Drying Kinetic ◽

Link Density

ABSTRACT In order to investigate drying kinetics of thick natural latex (NR) samples after film formation and the effect on cross-linking of NR latex during the drying process, we employed drying experiment methods, swelling methods, and Fourier transform infrared spectroscopy (FTIR) methods to study the drying and vulcanizing characteristics of NR latex. The results show that the drying temperature and thickness of film have obviously affected drying characteristics. The drying kinetic equation is achieved by mathematic fitting, and the Henderson and Pabis model MR = a exp(−kt) was the best fitted model for the thick NR latex film. The effect of the drying temperature on the drying constant was assessed employing an Arrhenius type equation, which can be expressed as k = 6746 exp[−39.9 × 103/(RT)] (R = 8.314 J mol−1 K−1). The drying constant exponentially decreased with the increasing film thickness. At the beginning of drying, the cross-link density increases rapidly, and up to the maximum value, it would slightly decrease with the prolonged drying time, which the results of FTIR also agree with.

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Drying characteristics and quality evaluation in convective drying of Cissus quadrangularis Linn.

MATEC Web of Conferences ◽

10.1051/matecconf/201819203041 ◽

2018 ◽

Vol 192 ◽

pp. 03041

Author(s):

Setthawat Thanimkarn ◽

Ekkapong Cheevitsopon ◽

Jiraporn Sripinyowanich Jongyingcharoen

Keyword(s):

Quality Evaluation ◽

Moisture Diffusivity ◽

Convective Drying ◽

Total Phenolic ◽

Drying Time ◽

Drying Characteristics ◽

Drying Temperature ◽

Cissus Quadrangularis ◽

Lower Bulk Density

This study aimed to investigate the effect of drying temperature (40, 60, 80, and 100°C) on drying characteristics of Cissus quadrangularis Linn. (CQ) undergoing convective drying. Physical properties and phytochemicals of the dried CQ were also evaluated. CQ with the thickness of 5 mm was dried from about 10 to 0.1 g water/g dry matter. The results showed that increasing drying temperature increased drying rate (DR) and effective moisture diffusivity (Deff) and consequently decreased drying time. The drying time, maximum DR, and Deff were in the ranges of 85-1920 min, 0.0059-0.0248 g water/g dry matter·min, and 0.7302-9.1281×10-9 m2/s, respectively. Lower drying temperature could preserve quality of the dried CQ. Decreasing drying temperature resulted in greener and lower bulk density and shrinkage. The greatest total phenolic content (TPC) and quercetin content were obtained by drying the CQ at 60°C.

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Characteristics of Thin-Layer Infrared Drying of Apple Pomace With and Without Hot Air Pre-drying

Food Science and Technology International ◽

10.1177/1082013207078525 ◽

2007 ◽

Vol 13 (2) ◽

pp. 91-97 ◽

Cited By ~ 47

Author(s):

J. Sun ◽

X. Hu ◽

G. Zhao ◽

J. Wu ◽

Z. Wang ◽

...

Keyword(s):

Thin Layer ◽

Initial Moisture Content ◽

Effective Diffusivity ◽

Moisture Diffusion ◽

Apple Pomace ◽

Drying Time ◽

Infrared Drying ◽

Hot Air ◽

Thin Layer Drying ◽

Treated Apple

Thin-layer infrared drying characteristics of apple pomace, with and without hot air pre-drying, were studied with a laboratory scale infrared dryer. Moreover, ten commonly used mathematical models were used to fit experimental data. Logarithmic model and Page model were most adequate in describing thin-layer drying of fresh and pre-treated apple pomace respectively. The values of average effective diffusivity in drying the pre-treated apple pomace were about 1.3 times of that in the fresh apple pomace with the initial moisture content of 40% (wet basis).The values of activation energy of moisture diffusion were about 30 kJ/mol for the fresh and pre-treated apple pomace respectively. Infrared drying, combined with hot air pre-drying, can save 20% of drying time to remove the same amount of remained moisture as compared to the infrared drying alone. The above findings might be used for operation of drying apple pomace.

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Drying Kinetic Simulation of Clay Tiles Made from the Raw Material Having Less Clay Fraction

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1036.3 ◽

2014 ◽

Vol 1036 ◽

pp. 3-8

Author(s):

Miloš Vasić ◽

Zagorka Radojević

Keyword(s):

Clay Fraction ◽

Effective Diffusivity ◽

Moisture Diffusivity ◽

Effective Moisture Diffusivity ◽

Diffusivity Coefficient ◽

Moisture Movement ◽

Effective Moisture ◽

Drying Kinetic ◽

Clay Tiles

In order to describe the internal moisture rate and to take all different mechanisms of moisture movement into account, it is suitable to use effective diffusivity as a measure of moisture rate, irrespectively of the mechanisms really involved. This means that all different mechanisms and driving forces for internal moisture transport are lumped together and introduced into effective moisture diffusivity. Hence, diffusion equations are retained and reused with the effective diffusivity coefficient as a measuring parameter of internal moisture ratio. In our previous studies we have presented the calculation method which assumed constant diffusivity. The next goal was to estimate effective diffusivity at various moisture contents, in a real case of non-linear drying curves, and to predict drying kinetic. In our last study we have developed a model for determination of the variable effective diffusivity and identification of the exact transition points between possible drying mechanisms. In this paper we have tried to develop more accurate tool for determination of time dependent effective moisture diffusivity. An analytical model and computing procedure were developed to evaluate mass transfer properties and describe drying kinetic of clay tiles having less clay fraction. The proposed procedure was validated with experimental drying data. Presented results have demonstrated that the proposed dying model can be applied for the accurate description of experimental drying kinetics and a reliable estimation of effective diffusivity.

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Pretreatment enhanced the physical and antioxidant stability of dried Cordyceps militaris by different drying conditions

E3S Web of Conferences ◽

10.1051/e3sconf/202130202005 ◽

2021 ◽

Vol 302 ◽

pp. 02005

Author(s):

Dechapon Chaiya ◽

Chanthima Phungamngoen ◽

Sunee Eadmusik ◽

Wichien Sriwichai ◽

Ekkasit Subcharoen

Keyword(s):

Citric Acid ◽

Radical Scavenging Activity ◽

Antioxidant Properties ◽

Radical Scavenging ◽

Cordyceps Militaris ◽

Active Components ◽

Processing Efficiency ◽

Drying Time ◽

Drying Temperature ◽

Drying Technology

Cordyceps militaris has been treated as a functional food and supplementary food for several years. In recent studies, active components in Cordyceps militaris have received great attention and promoted health. Drying technology is a common method and it was applied to Cordyceps spp. many times for extending their shelf life and preserving their nutrients. A combination of pretreatment with drying technology could promote processing efficiency. The aim of this study is to study the effect of pretreatments (Soaking in 0.5% citric acid, boiling, steaming and desiccating) combined with drying method by vacuum dryer (VD) at 50, 60 and 70 °C on physical quality and antioxidant capacity in dried Cordyceps militaris. The result showed pretreatment by soaking in acid 0.5% citric acid, boiling and steaming took drying time more than those desiccating and untreated dried sample to desire the final moisture content (approximately 8% db.). Increasing of drying temperature in VD could reduce drying time. Desiccating prior to drying samples exhibited the highest L* value and the lowest of a* and b* values when compared with other pretreatments. High drying temperature tend to decrease L* value while a* and b* values are increasing. It was due to the occurring of browning reaction during drying process. Desiccating samples showed color value closest to fresh samples. These results were consistent with all photographs from digital camera. The glass transition temperature of all samples was about 39.43-45.82 °C and the highest value was found in the case of desiccating sample. Antioxidant properties, pretreatment by soaking in acid combined with drying at 70 °C by VD showed the highest content of phenolic compound, DPPH and superoxide radical scavenging activity. It was concluded that pretreatment could preserve important substances, for example, cordycepin and adenosine contents of Cordyceps militaris during drying.

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