Modeling of moisture, color and texture changes in sesame seeds during the conventional roasting

Roasting is the basic unit operation in the sesame paste production. Sesame seeds were roasted using conventional method at 120, 150, and 180 °C for 120 min. The effect of heating time and temperatures on the moisture content, color and texture of sesame seeds were investigated. The changes occurred in the moisture content, color values (L-, a-, and b-) and textural properties (hardness and fracturability) of sesame seeds were simulated using exponential, kinetic and polynomial models. Two parameter exponential and Page models provided the satisfactory description for the moisture content changes. The variations in the color parameters of sesame seeds during conventional roasting were adequately simulated by cubic polynomials. The zero-order kinetic model satisfactorily described the reduction in the hardness and fracturability of sesame seeds. The one-step nonlinear regression analysis was used to determine the temperature dependence of the model coefficients. The temperature dependence of moisture and color models was described by linear function relationship, but Arrhenius-type relationship was used for textural models. The activation energy for sesame seeds was estimated to be 6.9 and 9.8 kJ/mol for hardness and fracturability changes, respectively over the temperature range of the study.