Thin-layer drying behaviour of mint leaves

Doymaz, İ̇brahim

doi:10.1016/j.jfoodeng.2005.03.009

Cited by 244 publications

(220 citation statements)

References 24 publications

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“…Resultados semelhantes foram obtidos em diversos trabalhos, quando se avaliou a taxa de secagem, de folhas de plantas medicinais ou aromáticas, em diferentes condições do ar de secagem, ocorrendo redução no tempo em resposta à elevação da temperatura (Goneli et al, 2014;Oliveira et al, 2013;Prates et al, 2012;Doymaz, 2014;Martinazzo et al, 2007;Doymaz, 2006). Na Figura 4 são apresentados os valores do coeficiente de difusão efetivo para as diferentes temperaturas do ar de secagem das folhas de jenipapo.…”

Section: Resultsunclassified

“…Recentemente diversos trabalhos têm sido desenvolvidos para investigar o comportamento, durante a secagem de diferentes espécies de plantas medicinais e aromáticas, por meio do ajuste de modelos matemáticos (Akpinar, 2006;Doymaz, 2006;Martinazzo et al, 2007;Martinazzo et al, 2010;Dias et al, 2011;Doymaz, 2011;Radünz et al, 2011;Prates et al, 2012;Reis et al, 2012;Oliveira et al, 2013;Doymaz, 2014;Rodríguez et al, 2014)and air velocity of 1 m/s. A theoretical diffusion model and eight different empirical models were fitted to the experimental data.…”

Section: Introductionunclassified

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Cinética de secagem e difusividade efetiva em folhas de jenipapo (Genipa americana L.)

Silva

Resende

Virgolino

et al. 2015

Rev. bras. plantas med.

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1Recebido para publicação em 28/08/2014 Aceito para publicação em 14/04/2015 RESUMO: O jenipapo (Genipa americana L.) é uma espécie nativa com importância medicinal, sendo amplamente utilizada no Brasil. Em função da necessidade de conhecimento à cerca do pré-processamento desta espécie, este trabalho foi desenvolvido com o objetivo de avaliar a cinética de secagem de folhas de jenipapo (G. americana L.), bem como determinar a difusividade efetiva da água durante o processo. As folhas foram coletadas com teor de água inicial de 2,30±0,05 (decimal b.s.), e submetidas à secagem em três condições de temperatura do ar (35,3; 46,0 e 65,0°C) até atingirem o teor de água de equilíbrio. Aos dados experimentais, ajustaram-se doze modelos matemáticos, recomendados para representar o processo de secagem de produtos agrícolas. As magnitudes do coeficiente de determinação (R 2 ), do erro médio relativo (P), do erro médio estimado (SE) e do teste do qui-quadrado (χ²), foram utilizadas para verificar o grau de ajuste dos modelos. Os modelos de Henderson e Pabis modificado e Midilli apresentaram ajustes adequados aos dados experimentais, sendo o modelo de Midilli, em função de sua simplicidade, escolhido para representar a cinética de secagem das folhas de jenipapo. Aumentando a temperatura do ar de secagem de 35,3 para 46,0 e 65,0ºC houve redução no tempo de secagem das folhas de jenipapo de 91,1 para 62,5 e 24,2 horas, respectivamente. O coeficiente de difusão efetivo aumenta com a elevação da temperatura, e esta relação é descrita pela equação de Arrhenius, que apresenta energia de ativação para a difusão líquida de 33,9 kJ mol -1 . Palavras-chave:Modelo de Midilli, desidratação, plantas medicinais, energia de ativação ABSTRACT: Drying kinetics and effective diffusivity in jenipapo sheets (Genipa americana L.). The jenipapo (Genipa americana L.) is a native species with medicinal importance and is widely used in Brazil. Due to the need for knowledge about the preprocessing of this species, this work was developed to evaluate the drying kinetics of the jenipapo leaves (G. americana L.), and also to determine the effective diffusivity of water during the process. The leaves were collected with an initial moisture content of 2.30 ± 0.05 (decimal db), and dried in three conditions of air temperature (35.3, 46.0 and 65.0°C) until they reach the equilibrium moisture content. The experimental data set were twelve mathematical models, recommended to represent the drying process of agricultural products. The magnitudes of the coefficient of determination (R²), the mean relative error (P), the average estimated error (SE) and the chi-square (X²), were used in order to verify the adequacy level of the models. The Henderson, modified Pabis and Midilli models presented appropriate adjustments to the experimental data, with the model Midilli, due to its simplicity, chosen to represent the drying kinetics of the jenipapo leaves. By increasing the temperature of the drying air from 35.3 to 46.0 and 65.0ºC, there was a reduction in the dryin...

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Section: Resultsunclassified

Section: Introductionunclassified

Cinética de secagem e difusividade efetiva em folhas de jenipapo (Genipa americana L.)

Silva

Resende

Virgolino

et al. 2015

Rev. bras. plantas med.

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“…The drying process was repeated for various foaming composition at operational temperature 40, 60, 80 and 100°C and thickness 2,3 and 5 mm. The foam mat was assumed as thin layer and moisture diffusivity (D w ) was estimated from the following equation (Doymaz 2006;Crank 1975):…”

Section: Drying Experimentsmentioning

confidence: 99%

Application of foam-mat drying with egg white for carrageenan: drying rate and product quality aspects

et al. 2013

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Drying is a significant step in the production of carrageenan. However, current drying process still deals with too long drying time and carrageenan quality degradation. The foam mat drying is an option to speed up drying process as well as retaining carrageenan quality. In this case, the carrageenan was mixed with egg white (albumin) as foaming agent and methyl cellulose for foam stabilizer. The foam will break the carrageenan gels and creates the porous structure resulting higher surface area for water transfer. This research studied the effect of egg white and methyl cellulose on carrageenan drying at various air temperature, and thickness. As a response, the water content versus time was observed and the drying rate was estimated. Meanwhile, the carrageenan texture was verified by X-RD (X-Ray Diffraction) and TEM (Transmission Electron Microscopy). Results showed that the presence of egg white stablized by methyl cellulose can speed up drying rate as well as retaining the crystalline structure of carrageenan. The higher albumin content, the faster drying rate. However, the addition of albumin and methyl cellulose restricted not more than 30 % in the mixture for keeping carrageenan quality and purity. By adding egg white 20 % and methyl cellulose 10 %, the water diffusion and drying rate can be two fold compared with carrageenan drying without foam. The improvement can be higher at the higher temperature and thinner carrageenan sheets.

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“…Pretreatment, subsequent drying and rehydration may induce changes in the structure and composition of plant tissues (Lewicki 1998) which affect the organoleptic properties upon rehydration. A number of studies for drying of fruits and vegetables have been reported by various authors (Maskan et al 2002;Togrul and Pehlivan 2002;Doymaz 2006;Akpinar 2006;Eren and Kaymak-Ertekin 2007;Mudgal and Pandey 2009;Shalini et al 2009). Rahman et al (2005), Kadam et al (2008), Singh et al (2008), Lidho (2008), Pardeshi et al (2009) have identified that the structure of dried foods depends on the drying methods and conditions such as temperature, relative humidity, air velocity and initial physico-chemical characteristics of the product.…”

Section: Introductionmentioning

confidence: 99%

Optimization of drying process parameters for cauliflower drying

2011

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The different sizes (3, 4 and 5 cm) of hybrid variety of cauliflower (variety no. 71) were dehydrated in thin layer at three temperatures of 55, 60 and 65°C with velocities of 40, 50 and 60 m/min. Dehydrated samples were analyzed for vitamin C, rehydration ratio and browning. Statistical analysis indicated that drying time was dependent on initial size of cauliflower, drying air temperature and velocity, but rehydration ratio was significantly affected by the combined effect of temperature and airflow velocity. Vitamin C content of the dried cauliflower samples were significantly affected by temperature only and non enzymatic browning was function of temperature, airflow velocity, and combined effect of temperature and airflow velocity. Optimization of the drying process parameters for the given constraints resulted in 60.10 0 C, 59.28 m/min, 3.35 cm. The predicted responses for the optimized combination of process parameters were time, vitamin C content, rehydration ratio, and browning values of 491.22 min (time), 289.86 mg/100 g (Vitamin C), 6.91 ( rehydration ratio), and 0.14 (browning), respectively with the desirability factor of 0.787.

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Thin-layer drying behaviour of mint leaves

Cited by 244 publications

References 24 publications

Cinética de secagem e difusividade efetiva em folhas de jenipapo (Genipa americana L.)

Cinética de secagem e difusividade efetiva em folhas de jenipapo (Genipa americana L.)

Application of foam-mat drying with egg white for carrageenan: drying rate and product quality aspects

Optimization of drying process parameters for cauliflower drying

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