Far-infrared Assisted Heat Pump Drying of Edible Roses Petals and the Product Quality Analysis

In order to explore the feasibility of far-infrared assisted heat pump drying of edible rose petals and the influence of far-infrared assisted heat pump drying on the quality of edible roses. In this paper, far-infrared assisted heat pump technology was used to dry edible rose petals, and the effects of different heat pump temperatures (40, 50, 60 ℃) and far-infrared assisted methods (far-infrared is in the whole, forward or backward process of heat pump drying respectively) were investigated. Drying characteristics, energy consumption, and the effect on the quality and biologically active ingredients of roses were discussed. The study found that when the heat pump temperature was 60 ℃ and dried for 45 minutes, the unit energy consumption and dehumidification was the largest, which was 2.73 g/(kW·h). This moment was determined to be the time point for dividing the drying process and the back process. The results showed that when the heat pump temperature was 60 ℃, the far-infrared power was 4 kW, and the far-infrared back-end assisted heat pump was used for drying, the drying time was the shortest and the total energy consumption was the lowest. After drying for 120 minutes, the moisture content was 11.59%. Compared with the single heat pump drying, the drying time was shortened by 33.33%, and the total energy consumption was reduced by 36.18%. The proanthocyanidins, vitamin C and polysaccharide components of the product were well maintained. The DPPH free radical scavenging rate was the highest, and it was closer to the color of fresh roses. The change of moisture content of rose petals during far infrared-assisted heat pump drying could be well fitted by tian model equation. Studies had shown that the far-infrared assisted heat pump technology for drying edible rose petals was safe, efficient, low energy consumption, and high-quality products. This technology was expected to be piloted in the industry.