Deep fat frying of tortilla chips: an integrated approach

Abstract

Tortilla chips were prepared from commercial nixtamilized dry masa flour. They were baked and then fried in fresh and used partially hydrogenated soybean oil for 5, 10, 15, 20, 25, 30, 45 and 60 seconds at 1500C and 1900C. A commercial batch fryer was used. Heat and mass transfer during deep fat fryer of tortilla chips were analyzed in this study. The effects of oil degradation and frying oil temperature on the rate of moisture loss and oil absorption, and on the physical and thermal properties of tortilla chips during frying were investigated. Viscosity, effective thermal conductivity, and specific heat of the frying oil were also measured. Density, effective thermal conductivity, and specific heat of tortilla chips decreased during frying. After 60 seconds of frying the oil tended to concentrate around the puffed areas of the tortilla chips. The formation of the sponge-like network and the crust of the tortilla chip started around the first IO seconds of frying. Thermal and physical properties of the tortilla chips such as density, effective thermal conductivity, and texture should be analyzed before and after 10 seconds of flying. At this time most of the tortilla chip is fully gelatinized and the crust starts to develop at the surface. Results after IO seconds were in better agreement with the models investigated. An increase in oil deterioration and in the flying temperature seem to cause an increase in the water evaporation rate from the tortilla chip and an increase in the total amount of oil absorbed by the tortilla chip during frying. The convective heat transfer coefficient decreased with oil degradation and increased with temperature. Viscosity of the frying oil increased with oil degradation and decreased with temperature. Effects of oil degradation and oil temperature on tortilla chips' properties such as density, effective thermal conductivity, and specific heat were not clearly established, and need further investigation.