Impact of gliding arc plasma pretreatment on drying efficiency and physicochemical properties of grape

The effect of cold plasma pretreatment with different durations 10, 20, 30, 40, 50, and 60 s on the mass transfer rate and quality of grape fruit during hot-air drying at 60 degrees C and 1.5 m/s were studied. It was found that cold plasma pretreatment significantly increased effective moisture diffusivity, reducing the drying time and energy consumption by up to 26.27% and 26.30%, respectively. Longer exposure resulted in smaller shrinkage and higher rehydration ratio. Furthermore, plasma pretreatment resulted in improved quality of dried grapes, in particular higher total phenolic content, antioxidant activity, and vitamin C retention by up to 3.06-30.53%, 7.31-62.29%, and 17.87-168.73%, as compared to the untreated ones. Among all pretreatments, 50 s exposure was preferred due to the minimal energy consumption and the least effect on the samples color.