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Modelling the Drying Behaviour Of Salted Shark Fillets

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  036195,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.13922) @2003
Authors:   Clement K. Sankat, Saheeda Mujaffar
Keywords:   Shark, Drying, Fick’s Law, Drying Rate Constant, Diffusion Coefficient

Shark fillets (10 x 5 x 1 cm) which were previously osmotically treated in saturated brine solution (4h, 30C) were dried in a horizontal air flow cabinet oven at 40C (40% rh), 50C (25% rh) and 60C (15% rh) as well as under tropical ambient conditions (30C, 60% rh). The air speed in the oven was fixed at 1.5 m/s and under ambient laboratory conditions, less than 0.5 m/s. Sample weight, moisture content, salt content and water activity were measured as the slabs dried. Slab moisture content decreased logarithmically with drying time, and increasing the dry bulb temperature from 30C to 50C resulted in a greater decline in moisture content as well as lower equilibrium moisture values. Further increasing the temperature to 60C resulted in an initial increase in drying rate, followed by a dramatic decline due to case hardening of the slabs. Drying of slabs at 30C and 40C occurred in both the constant rate and falling rate periods. Drying at 50C and 60C occurred in the falling rate period only. The falling rate period occurred in two phases, each characterised by a rate constant (k1 and k2). k1-values estimated from plots of ln (M-Me/Mo-Me) increased from 0.0389 to 0.3051 h-1 as drying temperature increased from 30-60C. At the same temperatures, diffusion coefficients for the first falling rate period (D1) calculated according to Ficks Law increased from 1.1 x 10-6 to 8.6 x 10-6 cm2s-1. Activation energy estimated from an Arrhenius type equation averaged 55.6 KJ/mol.

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