Cold plasma pretreatment – A novel approach to improve the hot air drying characteristics, kinetic parameters, and nutritional attributes of shiitake mushroom

Cold plasma (CP) is a promising novel technology, which can widely be applied to accelerate the drying process and preserve the nutritional values in the foodstuff. Therefore, the aim of this study was to explore the effect of CP pretreatments on hot air drying of shiitake mushroom. Direct CP and cold plasma-activated water (CPAW) was used to treat the mushrooms before drying at 50, 60, and 70 °C. Scanning electron microscopic reports exhibited that both CP and CPAW pretreatment significantly changed the surface topography of shiitake by generating intracellular spaces, larger cavities, and less density, which in turn facilitated the drying process of shiitake. Both CP and CPAW pretreatment accelerated the mass transfer during the drying process, resulting in lower activation energy, drying time and energy requirement compared to Control. Mathematical modeling studies revealed that Page, Parabolic, Logarithmic as well as Midilli and others were the best models to adequately describe the drying kinetics of shiitake. Furthermore, CP pretreatments were better capable of preserving the phenolics, flavonoids, and antioxidant activity than Control. While CP-pretreated mushrooms preserved the highest amount of phenolics (463.30 mg/100 g), flavonoids (100.70 mg/100 g), and DPPH-relative inhibition activity (0.201). Conclusively, CP, as an effective pretreatment strategy, can repeatedly be applicable for the drying of agro-products in terms of improving the drying parameters, energy management as well as protecting the nutritional compounds.