Determination of Simultaneous Heat and Mass Transfer Parameters of Tulumba Dessert During Deep-Fat Frying

Abstract

The heat transfer ( h) of "Tulumba" dough was investigated depending on the water loss during frying at 150-180C. The plots of dimensionless temperature and concentration ratios against time were used to determine heat and mass transfer parameters. The mechanism of moisture transfer was studied. Effective mass transfer coefficient increased linearly, whereas effective moisture diffusivity increased exponentially with rising frying temperature. Moisture diffusivity were 1.77, 2.15, 2.69 and 3.59 x 10(-7) m(2)/s, and mass transfer coefficient were 3.009, 3.225, 3.445 and 3.695 x 10(-6) m/s for 150, 160, 170 and 180C, respectively. An Arrhenius type of relationship was found between temperature and the effective moisture diffusivity, so activation energy was calculated at 36.58 kJ/mol. On the other hand, higher oil temperature decreased the effective heat transfer coefficient during deep-fat frying. The maximum value was determined 182.41 W/m(2) C at 150C and the minimal value as 125.715 W/m(2) C at 180C.