Investigation of drying kinetics, color, and rehydration parameters of broccoli florets dried with infrared radiation following blanching pretreatment

Abstract

In order to reduce the drying time of broccoli and to investigate rehydration and color changes associated with the drying process, infrared drying method and blanching pretreatment were used in this study. Boccoli florets were dried using infrared drying at power levels of 50, 62, 74 and 88 W to investigate drying kinetics. Blanching was used as a pretreatment and it was found that the blanched samples dried faster. Effective moisture diffusion coefficients were also calculated. While Deff values between 9.26 x 10-11 and 2.15 x 10-10 m2/s were observed for the control samples, this value varied between 1.10 x 10-10 and 2.87 x 10-10 m2/s for the blanched samples. The calculated activation energy values for the blanched and control samples are 2.11 and 2.0 kW/kg, respectively. The drying process was modeled using 12 different thin-layer drying models and it was found that the Midilli & Kucuk model best represented the process. Color analysis was performed by measuring L, a and b values as well as chroma, hue angle and total color change values. It was observed that increasing infrared power affected color parameters, leading to a decrease in L values and an increase in a and b values. In addition, blanching pretreatment preserved color to some extent. The rehydration behavior of dried samples was also analyzed. It was found that the highest rehydration capacity was achieved in blanched samples dried at 74 W.