The Effects of Electric Field and Ultrasound Pretreatments on the Drying Time and Physicochemical Characteristics of the Zucchini Chips.

Abstract

The aim of this study was to investigate the effects of electrical pretreatment (40V, 60 sec) and ultrasound blanching (35kHz, 80°C, 2 min) on the drying time, texture, color, and rehydration properties of zucchini which were dried by hot air and freeze dryers to 8% moisture content (wet basis). The synergistic effect of electrical and ultrasonical applications reduced the drying time (36%) to reach the target moisture content in hot air drying and provided fracturable, chewy, and edible hard zucchini chips. The highest lightness value was found as 86.04 at the group blanched ultrasonically and freeze dried chips.The greenness was found at most (-9.31) in the combined group of electrical pretreated, ultrasound assisted blanched and freeze dried sample group. The rehydration capacity of the dried samples increased significantly with the effect of ultrasound compared to the increase with the effect of electroplasmolysis application (P≤0.05). Zucchini chips with higher quality characteristics were produced by these combined applications. The electrical method can be alternatively used for drying pretreatments in the food industry with the advantage of decreasing the processing time and improving the textural and sensorial properties compared to the method of hot drying.