Diffusivity, shrinkage and simulated drying of litchi fruit (Litchi Chinensis Sonn.)

Abstract Litchi ( Litchi Chinensis Sonn .) is an important commercial fruit in Thailand and Vietnam. Litchi fruit is consumed both as fresh and dried products. Also most of the export of litchi is in the form of dried whole litchi fruit. Thermo-physical properties and drying model of litchi fruit is important for optimum design of litchi dryer. This paper presents moisture diffusivity, shrinkage and finite element simulated drying of litchi fruit. The moisture diffusivities of litchi were determined by minimizing the sum of square of deviations between the predicted and experimental values of moisture content of thin layer drying under controlled conditions of air temperature and relative humidity. The components in the form of cylinder for seed and seed stalk and slab for seed coat, shell and flesh were dried in thin layers at the air temperatures of 50, 60, 70 and 80 °C and relative humidity in the range of 10–25%. The mean diffusivity of flesh, seed and shell of litchi fruit increased with temperature and was expressed by the Arrhenius-type equation, but the diffusivities of seed coat and seed stalk were independent of temperature. The moisture diffusivities of seed coat and seed stalk were much lower than those of the other parts of the litchi. The shrinkage of litchi fruit has also been determined experimentally and it was expressed as a function of moisture reduction. A two-dimensional finite element model has been developed to simulate moisture diffusion in litchi fruit during drying. Shrinkage of the flesh and different component diffusivities of litchi during drying were also taken into account. The finite element model was programmed in Compaq Visual FORTRAN version 6.5. This finite element model satisfactorily predicts the moisture diffusion during drying. Moisture contents in the different components in the litchi fruit during drying were also simulated. This study provides an understanding of the transport processes in the different components of the litchi fruit.

[1]  Rose Marie Pangborn,et al.  Principles of Sensory Evaluation of Food , 1965 .

[2]  R. B. Pandit,et al.  Finite element analysis of microwave heating of potato––transient temperature profiles , 2003 .

[3]  Alberto M. Sereno,et al.  Modelling shrinkage during convective drying of food materials: a review , 2004 .

[4]  L. Segerlind.  Applied Finite Element Analysis , 1976 .

[5]  B. K. Bala,et al.  Measurement and Modeling of Moisture Sorption Isotherm of Litchi (Litchi Chinensis Sonn.) , 2010 .

[6]  Serm Janjai,et al.  Finite element simulation of drying of mango , 2008 .

[7]  José Bon,et al.  Mathematical Modeling of Drying Kinetics for Apricots: Influence of the External Resistance to Mass Transfer , 2007 .

[8]  Somchart Soponronnarit,et al.  DIFFUSION MODELS OF PAPAYA AND MANGO GLACe’ DRYING , 2000 .

[9]  J. Altenbach,et al.  Segerlind, L. J., Applied Finite Element Analysis. New York‐London‐Sydney‐Toronto, John Wiley & Sons 1976. XIII, 422 S., £ 12.60 , 1979 .

[10]  I. I. Ruiz-López,et al.  Mathematical Simulation of the Effective Diffusivity of Water during Drying of Papaya , 2007 .

[11]  P. K. Chattopadhyay,et al.  Moisture diffusion modeling of parboiled paddy accelerated tempering process with extended application to multi-pass drying simulation , 2008 .

[12]  Sergio A. Giner,et al.  Wheat drying kinetics. Diffusivities for sphere and ellipsoid by finite elements , 2002 .

[13]  C.-C. Jia,et al.  Development of Computer Simulation Software for Single Grain Kernel Drying, Tempering, and Stress Analysis , 2002 .

[14]  B. A. Souraki,et al.  Axial and radial moisture diffusivity in cylindrical fresh green beans in a fluidized bed dryer with energy carrier: Modeling with and without shrinkage , 2007 .

[15]  H. S. Ramaswamy,et al.  ANN-Based Models for Moisture Diffusivity Coefficient and Moisture Loss at Equilibrium in Osmotic Dehydration Process , 2007 .

[16]  Larry J. Segerlind,et al.  Modeling Simultaneous Heat and Mass Transfer in an Isotropic Sphere-A Finite Element Approach , 1991 .

[17]  Werner Mühlbauer,et al.  Drying characteristics of copra and quality of copra and coconut oil , 1996 .

[18]  B. K. Bala,et al.  Moisture Diffusivity Determination of Different Parts of Longan Fruit , 2007 .

[19]  M. Hasatani,et al.  Modeling of Diffusion in Ellipsoidal Solids: A Comparative Study , 2004 .

[20]  B. K. Bala,et al.  Finite Element Simulation of Drying of Longan Fruit , 2008 .

[21]  B. K. Bala.  Drying and Storage of Cereal Grains , 1997 .

[22]  S. Kaleemullah,et al.  Modelling of thin-layer drying kinetics of red chillies , 2006 .

[23]  Bart Nicolai,et al.  Estimation of effective diffusivity of pear tissue and cuticle by means of a numerical water diffusion model , 2006 .

[24]  Mohammad Nurul Alam Hawlader,et al.  Drying of Guava and Papaya: Impact of Different Drying Methods , 2006 .

[25]  W. Jomaa,et al.  Moisture diffusivity and drying kinetic equation of convective drying of grapes , 2002 .

[26]  Vincenza Calabrò,et al.  Simulation of food drying: FEM analysis and experimental validation , 2008 .

[27]  M. Kazemeini,et al.  Moisture diffusivity and shrinkage of broad beans during bulk drying in an inert medium fluidized bed dryer assisted by dielectric heating , 2009 .

[29]  R. Mascheroni,et al.  DIFFUSIVE DRYING KINETICS IN WHEAT, PART 2: APPLYING THE SIMPLIFIED ANALYTICAL SOLUTION TO EXPERIMENTAL DATA , 2002 .

[30]  N. D. Patil.  EVALUATION OF DIFFUSION EQUATION FOR SIMULATING MOlSTURE MOVEMENT WITHIN AN INDIVIDUAL GRAIN KERNEL , 1988 .

[31]  Miklós Neményi,et al.  Investigation of simultaneous heat and mass transfer within the maize kernels during drying. , 2000 .