Modelling the drying characteristics of the traditional Indonesian crackers "kerupuk"

Abstract

An oven drying method was used to dry traditional Indonesian crackers, popularly known as kerupuk, applying drying temperatures of 50, 60 and 70°C and three different flavours, i.e., garlic, chili and seaweed. Newton, Page, Two terms, Midilli, Logarithmic and Henderson & Pabis mathematical models were used to fit the best model while the standard error of estimate (SSE), root mean square error (RMSE) and coefficient of correlation (r) were chosen as the criteria to determine the equation of the best fit drying model. The Midilli model was the best fit for all the kerupuk flavours. The effective moisture diffusivity was in the range of 1.0413 × 10–10–1.6363 × 10–10 m2·s–1 for the garlic flavour, 1.0007 × 10–10–1.5619 × 10–10 m2·s–1 for the chili flavour and from 1.0000 × 10–10 to 1.6228 × 10–10 m2·s–1 for the seaweed flavour. The activation energy of the garlic flavour, chili flavour and seaweed flavour kerupuk are 20.64, 20.64 and 22.57 kJ·mol–1, respectively. Furthermore, in the present study, the physical properties, i.e., the colour and hardness of the kerupuk crackers after the drying process was investigated.