MATHEMATICAL MODELLING OF DRYING KINETICS OF KINEMA

Abstract

Kinema is an indigenous food of Nepal traditionally prepared by natural fermentation of boiled soybeans covered with a sticky, colorless material accompanied by pungent odor of ammonia. The effects of temperature variation on the drying kinetics of kinema samples were studied. The present investigation was conducted at drying temperatures of 50ºC, 60ºC, 70oC and 80ºC in cabinet dryer and the drying kinetics of kinema were evaluated. The experimental data were fitted to five thin layer mathematical models including the Lewis, Page, Handerson and Pabis, Logarithmic and Midilli et al. models. These models were evaluated by comparing the coefficient of determination (R2 ), chi square (χ2), root mean square error (RMSE) and sum of standard error (SSE). The drying rate curve showed that the drying of kinema falls in falling rate period. The rate of drying continuously decreased as drying proceeded. Graphical and statistical analysis of result showed that Midilli et al. model was best fitted for cabinet drying with the value of R2 , RMSE, χ2 and SSE ranging from 0.982496-0.999538, 0.00784- 0.03271, 0.0000839- 0.001399 and 0.000923- 0.018192 respectively. The effective diffusivity was calculated using Fick’s diffusion equation and the value varied from 2.0258 × 10-10 m2 /s at 50oC to 9.4219 × 10-10 m2 /s at 80oC. Effective moisture diffusivity increased with increase in drying temperature. The activation energy was found to be 49.599 kJ/mol and the diffusivity constant was found to be 6.63× 10-6 m2 /s respectively.