A novel approach to evaluate the temperature during drying of food products with negligible external resistance to mass transfer

Barati, E.; Esfahani, Javad Abolfazli

doi:10.1016/j.jfoodeng.2012.07.028

Cited by 24 publications

(8 citation statements)

References 26 publications

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“…This result of ANOVA of 95% confidence level indicates that the RH, in the range of 20-40%, had insignificant effect on the drying time of yam slices. The result was consistent with the previous works of Curcio et al [39] and Barati and Esfahani [40] for drying of carrot and mango, respectively. It should be mentioned that, if the entire drying process occurred in a falling rate period, the drying rate would be mainly controlled by the internal resistance to the diffusion of water, and therefore the RH would have less effect on the drying rate.…”

Section: Drying Characteristic Under Different Constant Rh Levelssupporting

confidence: 93%

“…This might indicate that the internal moisture diffusion phenomenon controlled the drying process. Similar results were reported for the drying of yam slice [40] , carrot cubes, [21] and liquorice root respectively. [41] Figure 3 also shows also that for RH of 30% and 40%, there were two distinct drying periods that named warm-up period and a falling drying rate period.…”

Section: Drying Characteristic Under Different Constant Rh Levelssupporting

confidence: 87%

“…[31] In addition, when the value of Bi number is greater than 30, drying process is totally diffusion-controlled. [40] Moreover, moisture transfer coefficient (k) was calculated using Eq. (12).…”

Section: Determination Of Effective Diffusivity and Mass Transfer Coementioning

confidence: 99%

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Drying characteristics and modeling of yam slices under different relative humidity conditions

El‐Mashad

Fang

et al. 2015

Drying Technology

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The drying characteristics of yam slices under different constant relative humidity (RH) and step-down RH levels were studied. A mass transfer model was developed based on Bi-Di correlations containing a drying coefficient and a lag factor to describe the drying process. It was validated using experimental data. Results showed that the drying air with constant RH levels of 20%, 30%, and 40%, temperature of 60 o C and air velocity of 1.5 m/s had insignificant effect on drying time. This phenomenon was likely attributed to the fact that higher RH lead to rapidly increment of sample's temperature. Afterwards, higher sample's temperature could provide an additional driving force to water diffusion and thereby promoted the moisture movement which could minimize the negative effect of lower drying rate in the initial drying stage. Applying air with 40% RH for 15 min in the initial stage achieved the desired color and reduced the drying time by 25% compared to Downloaded by [University of Otago] at 12:28 07 October 2015 2 the drying time under continuous dehumidification from an initial RH of 40%. Using the developed Bi-Di correlation, the estimated Biot number, effective moisture diffusivity and mass transfer coefficient ranged from 0.1024 to 0.1182, from 1.1133×10 -10 to 8.8144×10 -9 m 2 /s and from 1.8992×10 -9 to 1.7364×10 -7 m/s, respectively. A rather high correlation coefficient of determination (R 2 ranged from 0.9871 to 0.9971) was determined between the experimental and predicted moisture contents. The present findings contributed to a better understanding of the effect of relative humidity on drying characteristics. The developed Bi-Di correlation provided a new method to determine the effective diffusivity of moisture in drying. A, B constants in Eq. (14)A p the surface area of the particles exposed to hot air (m 2 ) Bi Biot number for moisture transfer (dimensionless) Di Dincer number (dimensionless) DR drying rate (g·g -1 ·h -1 ) Fo Fourier number for moisture transfer (dimensionless) G lag factor (dimensionless) k moisture transfer coefficient (m·s -1 ) Downloaded by [University of Otago] at 12:28 07 October 2015 3 L characteristic dimension, slab half-thickness (m) M moisture content (dry basis) MR moisture ratio (dimensionless) MR exp,i the ith experimental moisture ratio MR e the equilibrium moisture ratio MR pre,i the ith predicted moisture ratio N the number of observation R 2 correlation coefficient RH relative humidity (%) S drying coefficient (s -1 ) T drying air temperature ( o C) t drying time (h) v flow velocity of drying air (m·s -1 ) μ characteristics coefficient depending on the product geometry CIELAB Parameters

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Section: Drying Characteristic Under Different Constant Rh Levelssupporting

confidence: 93%

Section: Drying Characteristic Under Different Constant Rh Levelssupporting

confidence: 87%

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Drying characteristics and modeling of yam slices under different relative humidity conditions

El‐Mashad

Fang

et al. 2015

Drying Technology

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“…; Alibas ). Heat transfer to the inner sections of foods is limited because of the low thermal conductivity of food materials in hot air drying (Barati and Esfahani ). The desire to eliminate the disadvantages of hot air drying, prevent significant quality loss and improve drying efficiency has resulted in the increasing use of microwave rays in the drying of foodstuffs.…”

Section: Introductionmentioning

confidence: 99%

Drying Characteristics and Processing Parameters for Microwave-Vacuum Drying of Kiwifruit (A ctinidia deliciosa ) Slices

Tian

Zhao

et al. 2015

Journal of Food Processing and Preservation

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This study experimented on microwave-vacuum (MWV) drying of kiwifruit (Actinidia deliciosa) slices as a way to improve drying productivity and the quality of dried fruit. The effects of microwave power density, sample thickness and vacuum degree on the drying characteristics of kiwifruit slices were studied. The results showed that these three factors had significant effects on the vitamin C and chlorophyll contents and on the rehydration capacity of dried kiwifruit slices, as well as the total drying time. The processing parameters of MWV drying of kiwifruit slices were optimized by using Box-Behnken design with a quadratic regression model built by response surface methodology. The optimum processing parameters were experimentally determined as microwave power density at 7.7 W, sample thickness of 6.0 mm and MWV drying for 11.5 min at a vacuum degree of −90 kPa. High-quality dried kiwifruit slices can be created under these conditions using this drying process. PRACTICAL APPLICATIONSKiwifruit (Actinidia deliciosa) has become a popular fruit because of its bright green flesh, high level of vitamin C and because it contains a wide variety of phytonutrients, including carotenoids, lutein, phenolics, flavonoids and chlorophyll. It needs some form of preservation to extend its shelf life. Microwave-vacuum (MWV) drying is a novel alternative that combines the advantages of both microwave drying and vacuum drying. The objectives of this study were to investigate the effect of microwave power density, sample thickness and vacuum degree on the MWV drying characteristics and quality of MWV-dried kiwifruit slices, and to evaluate a suitable drying model for describing the drying process. In addition, the process parameters of MWV drying were optimized by response surface methodology. This present study provides the theoretical basis for industrial-scale production.

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“…El procesamiento o transformación de las frutas amplía su vida útil y su disponibilidad, y además permite utilizar excedentes de otras líneas de producción, como ocurre en las industrias que elaboran jugos, confituras y productos deshidratados. Las técnicas convencionales de procesamiento de estos productos han sido objeto de numerosos trabajos, en los que se intentaron optimizar las condiciones de tratamiento de modo de reducir el consumo energético de los procesos, las temperaturas y los tiempos de tratamiento (Barati & Esfahani, 2013;Barba et al, 2015). Sin embargo, muchos ingredientes alimentarios y productos son sensibles a las temperaturas de procesamiento y por ende, vulnerables a cambios químicos, físicos y microbiológicos.…”

Section: Introductionunclassified

Aplicación de tecnologías emergentes al procesamiento de frutas con elevada calidad nutricional. – Una revisión

Gamboa

Rodríguez

Carvajal

et al. 2016

Rev. colomb. investig. agroindustriales

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El incremento a nivel mundial del procesamiento de frutas, debido a la mejora en las técnicas de preservación, transporte y a los sistemas de comercialización y distribución, permite ofrecer al consumidor un abanico cada vez más amplio de alimentos saludables, en creciente demanda. Sin embargo, la mayoría de los constituyentes de interés de los alimentos son sensibles a la temperatura y vulnerables a cambios químicos, físicos ymicrobiológicos. Los tratamientos convencionales aplicados en la industria suelen facilitar las pérdidas de compuestos, a la vez que consumen altos niveles de energía, tiempo y agua. Es por ello que en los últimos años un gran número de tecnologías alternativas que permiten el procesamiento a temperaturas bajas o medias surgieron como potenciales tratamientos para inactivar enzimas y microorganismos con mínimos efectos perjudiciales sobre los parámetros de calidad de los alimentos. Los estudios enfocados al procesamiento de frutas permiten obtener una amplia información sobre el comportamiento de dichas materias primas durante diferentes tratamientos, para contribuir a la elaboración de alimentos de calidad, seguros y saludables queconserven, en la medida de lo posible, los atributos nutricionales y sensoriales característicos de los productos frescos.

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A novel approach to evaluate the temperature during drying of food products with negligible external resistance to mass transfer

Cited by 24 publications

References 26 publications

Drying characteristics and modeling of yam slices under different relative humidity conditions

Drying characteristics and modeling of yam slices under different relative humidity conditions

Drying Characteristics and Processing Parameters for Microwave-Vacuum Drying of Kiwifruit (A ctinidia deliciosa ) Slices

Aplicación de tecnologías emergentes al procesamiento de frutas con elevada calidad nutricional. – Una revisión

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