Effect of combined ethanol and ultrasound pretreatment on energy consumption and bioactive compounds of rose petals in hot air drying

This study evaluates the impact of ultrasound (US), ethanol (ET), and combined ultrasound-ethanol (ET/US) pretreatments on the drying efficiency and quality of Rosa damascena petals during hot air drying. All pretreatments significantly reduced the drying time and specific energy consumption (p < 0.05). The highest reduction in drying time (52.38%) and specific energy consumption (64%) was observed for the ET/US pretreatment. Ultrasound alone (US30) and in combination with ethanol (ET/US) significantly improved rehydration ability and essential oil yield (up to 1.31%, p < 0.05). Furthermore, the ET/US treatment preserved more antioxidant activity, total phenolic content, and flavonoid content compared to other pretreatments and control (p < 0.05). The results of this study can show new perspectives for using the potential of ethanol- ultrasound as a cost-effective and energy-efficient method for industrial drying sensitive medicinal plants. Future studies could explore its scalability and applicability to other aromatic or perishable botanical species.