Cold plasma technique as a pretreatment for drying fruits: Evaluation of the excitation frequency on drying process and bioactive compounds.

The present work aims to evaluate the effect of different excitation frequency (200, 500 and 800 Hz) of cold plasma technique as a pretreatment for drying tucumã. SEM images showed changes on the pretreated tucumã's surface, favoring the drying rate and diffusivity of water as well as reducing the drying time. Marginal variation of color and reduced drying time were observed in the samples treated using 200 and 800 Hz. The pretreatment improved the concentration of phenolic (45.3 mg GAE g-1) and antioxidant compounds (799.8 µM ET) (p-value < 0.05). Carotenoids were more sensitive to the drying time, presenting significant degradation at 500 Hz. For this reason, the propose pretreatment based on the application of cold plasma technique for drying foods can preserve/improve their nutritional quality.