Combined effects of pulsed electric field and ultrasound pretreatments on mass transfer and quality of mushrooms

Abstract

This study aimed to investigate the effects of pulsed electric field (PEF), ultrasound (US), and combined pretreatments (PEF-US) on mass transfer, rehydration capacity, microstructure, and nutritional quality of shiitake mushrooms (Lentinus edodes). The results indicated that pretreatments could accelerate mass transfer during the hot-air drying process at 65 °C, resulting in lower drying time and energy requirement than control. Meanwhile, the low-field nuclear magnetic resonance (LF-NMR) analysis revealed better rehydration capacity of the pretreated groups than the untreated group. The results of scanning electron microscopy (SEM) demonstrated that pretreatments significantly changed the cell structure by developing intracellular space and larger cavities and facilitating the drying and rehydration process of mushrooms. Additionally, the physiochemical analysis illustrated that pretreatment could preserve the color and nutritional quality more effectively than the untreated groups. Of the pretreatment groups, the shortest drying time was observed in the combined (PEF-US) group (4.7 h). The PEF-US pretreated mushroom also exhibited the highest phenolics (224.17 μg/μL) and soluble sugar (3.90 mg/mL) levels. Overall, the study concluded that the combined pretreatment group (PEF-US) was a promising pretreatment method for hot-air drying of mushroom products to improve the drying efficiency, product quality control, and nutritional value protection.