Selection of drying techniques for Pingyin rose on the basis of physicochemical properties and volatile compounds retention

Awareness of edible rose being beneficial for health has attracted researchers in exploring different rose products. The study aimed to investigate effects of vacuum freeze drying (VFD), hot air drying (HAD), heat pump drying (HPD), relative humidity drying (RHD) and catalytic infrared drying (CID) on the physicochemical properties, and volatile organic compounds (VOCs) of Pingyin roses. Results showed that the VFD roses had significantly (p < 0.05) bright color, complete tissue cells, low shrinkage, and good plasma membrane permeability. CID roses showed the highest total phenols content (164.09 ± 0.88 mg/g) and the strongest antioxidant activity. Besides, the odor is the most crucial indicator for dried roses. VFD can well prevent the odor from diminishing/destroying and preserve the natural smell of rose. Thermal drying including HAD, HPD, RHD, and CID, could cause significant losses of VOCs. Consequently, the findings can provide the scientific basis for future large-scale production of dried rose products.