Sun Drying and Far-Infrared Drying Characteristics of Lily

Abstract The sun drying and far-infrared drying characteristics of lily were experimentally investigated. Fresh lily was blanched and treated with boiling water at 100 °C before drying. The effects of blanching time, drying method and drying temperature on drying rate, nutrient contents (total phenol, total flavonoid and starch contents), hardness and color were analyzed. The results showed that fresh lily without blanching pretreatment had deep browning color, wrinkled skin and long drying time under any drying temperature and drying method. However, the drying rate of samples with blanching pretreatment was significantly increased and the drying time was shortened. The drying rate of solar drying was much lower than that of infrared drying, however the drying quality is better. With the increase of blanching time, the browning degree and the nutrient contents under both drying methods were reduced, while the foaming rate was increased. The hardness after solar drying was moderate, while the hardness of far-infrared drying gradually increased with the increase of drying temperature. The blanching time of 4–6 min was the ideal pretreatment time. Under this pretreatment time, a sample with fair color and moderate hardness and nutrient contents can be obtained under the far-infrared drying temperature of 60–90 °C. The far-infrared drying was more suitable than the sun drying and the most suitable drying process was as follows: fresh lilies were blanched at 100 °C for 5 minutes, and then dried at 70°C for 7.5 hours.