Kinetics of potato drying using fluidized bed dryer

Abstract

The effect of air temperature and two different shapes (cuboidal and cylindrical) with 3 aspect ratio of each shape on the drying kinetics of potato (Solanum tuberosum) in fluidized bed dryer was investigated. Drying was carried out at 50, 60 and 70°C at 7 m/s air velocity. Drying data were analysed to obtain effective diffusivity of moisture transfer. During drying moisture transfer from potato were described by Fick's diffusion model. Two mathematical models were fitted to experimental data. The Page model gave better fit than simple exponential model. The Arrehnious activation energy value expresses the effect of temperature on diffusivity.Keywords Potato . Fluidised bed drying . Cuboidal and cylindrical shape . Aspect ratio . Diffusivity . Activation energy The popular potato products are potato chips, potato powder, potato flakes and potato granule. Potato granules are used for preparation of different variety of crispy food products like namkeen, bhujiya, soup curry and snack foods. It can be used for making sweetened food. Few organized and several private sectors produce potato granules with other processed food products. It is necessary to dry the product with minimum cost, energy and time. In fluidized bed drying, drying time is shortened due to intensive heat and mass transfer between drying air and particles being dried and overheating is prevented (Giner and Calvelo 1987). The drying of vegetables in a fluidized bed dryer produces dry vegetable pieces of excellent quality in a much shorter time than in continuous belt dryers (Bobic and Baumani 2002).During drying, shapes and sizes of food particulates constantly change as a result of water removal and moisture diffusion from particulates. The knowledge of changes in shape and size during fluidized bed drying is very much required for designing of processing, drying, handling and packaging equipments for food industry. Even though, considerable work is done on drying of various fruits and vegetables, the information on drying kinetics of vegetables is scanty, particularly for potato shapes. Drying is affected by nature of product, type of dryer, parameters of drying kinetics such as moisture ratio, temperature, air velocity, drying rate, drying constant as moisture diffusivity. The moisture migration during this period is controlled by diffusion. The rate of moisture movement is described by an effective diffusivity. So it is necessary to study the effect of shapes and effect of temperature on drying kinetics.Therefore the present investigation was undertaken to study the effect of product shape on drying kinetics of potato particulates drying behaviour with the help of models and to estimate the Arrehnious activation energy during potato drying. ModelingThe empirical model and Page's model were used to investigate the effect of shapes and their aspect ratio on drying characteristic of food. The basic model is known

Drying kinetics of dill leaves in a convective dryer

“…Several authors had attempted to determine mathematical models for estimation of the moisture ratio and drying rate of food and biological materials during the drying process in eg potato (Bakal et al, 2011), Cuminum cyminum (Zomorodian and Moradi, 2010), carrot (Doymaz, 2004), sweet cherry (Doymaz and Ismail, 2011), and berberies (Gorjian et al, 2011). Some researchers have studied the effective moisture diffusion and energy of activation in a thin layer drying of different agricultural products such as squash seeds (Chayjan et al, 2011), onion slices (Pathare and Sharma, 2006), or milky mushroom (Arumuganathan et al, 2009).…”

“…Fluidization is defined as suspending the vegetable bed (dill leaves, Anethum sowa L.) in air flow. With gradually increasing airflow through a bed of vegetable, fixed bed, minimum fluidized bed (semifluidized bed), bubbling fluidized bed and transportation will be created, respectively (Chayjan et al, 2011).Several authors had attempted to determine mathematical models for estimation of the moisture ratio and drying rate of food and biological materials during the drying process in eg potato (Bakal et al, 2011), Cuminum cyminum (Zomorodian and Moradi, 2010), carrot (Doymaz, 2004, sweet cherry (Doymaz and Ismail, 2011), and berberies (Gorjian et al, 2011). Some researchers have studied the effective moisture diffusion and energy of activation in a thin layer drying of different agricultural products such as squash seeds (Chayjan et al, 2011), onion slices (Pathare and Sharma, 2006), or milky mushroom (Arumuganathan et al, 2009).…”

Evaluation of Energy Aspects of Apple Drying in the Hot-Air and Infrared Dryers

“…The moisture ratio rapidly reduces due to a reduction of the heat transfer resistance inside the material and increase of the mass transfer area. With increasing of the drying time, the hardened layer imposes a barrier against the dissipation of moisture across the product's surface and prolongs its departure from the product and so, moisture ratio slowly decreases (Bakal et al, 2011;Doymaz and Ismail, 2011). The effectiveness of increasing the drying air temperature in apple drying at thickness of 3 mm and constant air velocity (1 m sec…”

Drying Kinetics of Sandge, an Indian Traditional Food Adjunct in Air Convective Drying

“…The effect of air temperature, air velocity, relative humidity and material size have been studied and simulation models proposed by various investigators for thin layer drying of many agricultural products [13][14][15][16][17][18][19][20][21][22] [ . Although the literature on the studies of drying characteristics of raw agricultural products is available, but few studies have been reported on the drying kinetics of processed food products.…”