Kinetics of Reshteh Khoshkar Color Changes During Atmospheric and Vacuum Deep-fat Frying

The effect of frying pressure on the kinetics of color changes during atmospheric and vacuum deep fat frying of Reshteh Khoshkar has been studied. The Hunter color parameters redness, yellowness, lightness and total color difference were used to estimate color changes during frying as a function of process. Lightness (L*) decreased from 85.37 to 75.01 with vacuum frying time, while redness (a*), yellowness (b*) and total color difference increased from -2.09, 4.92 and 0 to 1.22, 37.01 and 31.56, respectively. It was observed that the severity of colour change was higher in atmospheric frying process than the vacuum frying process. The changes in color parameters were modeled by zero-order, first-order and a combined kinetics model. The two first-order and combined kinetics models fitted properly the values of color changes during frying, with good coefficient of determination. The combined model used can describe the experimental colour parameters better than the other studied kinetics models.