KINETIC OF THE PHYSICAL QUALITY CHANGES DURING DEEP FAT FRYING OF SWEET POTATO CHIP

Investigation was carried out to study kinetics of moisture loss, oil uptake, lightness and textural changes during deep fat frying of sweet potato (Ipomoea batatas L.) chip. Sweet potato slides of 2mm thickness were fried in a laboratory scale fryer at different temperatures ranging from 120 to 150°C. The investigation showed that the moisture loss, oil uptake, lightness followed the first order kinetics equation while the textural change was displayed as two terms equation. The first term of textural change was the softening of tissue and the second one was the crust hardening process. The kinetic coefficients of the changes of all above parameters increased significantly (p < 0.05) with the increasing of temperature. The temperature dependency of rate constants for moisture loss, oil uptake, lightness and textural change values were described via Arrhenius equation (r > 0.98, p < 0.05). The activation energies of moisture loss, oil uptake, lightness and textural changes (softening of the tissue and crust hardening) were 13.54 ± 1.28, 10.47 ± 0.56, 34.01 ± 1.36, 1.11 ± 0.06 and 24.68 ± 1.47 KJ/mol respectively.