Effects of Physical Pretreatment Methods and Hot Air Temperatures on the Hot Air Drying Characteristics and Quality of Yangxincai (Sedum aizoon L.)

In order to solve the problems of long drying time, high energy consumption and low drying efficiency, the drying experiment was conducted which study the effects of physical pretreatment methods (flattening, cutting, flattening + cutting) and hot air temperatures (60, 70, 80 ℃) on the drying characteristics of the whole plant, stem and leaf of Yangxincai. The drying model was established. The effects of different treatments was analyzed on the quality of Yangxincai . Experiment results showed that increasing hot air temperature and conducting flattening, flattening + cutting pretreatment could increase the drying rate and lower the drying time (P<0.05). Under flattening + cutting treatment, the drying time of hot air at 80 ℃ was only 47%, 21% of that at 70, 60 ℃, respectively. Under hot air temperature 80 ℃, the drying time of flattening and flattening + cutting treatment was only 40%, 35% of untreatment. The fitting degree of Weibull model was higher than 0.99 with experiment data. Increasing the hot air temperature and conducting physical pretreatment could reduce the soluble protein loss and make VC concentration decrease. The content of soluble protein was the highest, reaching 6.577 gprot/L under the hot air temperature 80 ℃ and flattening + cutting treatment. The content of V_C reached the highest level of 8.503 mg/100 g under the hot air temperature 80 ℃ and cutting treatment. Under the same treatment conditions, the content of soluble protein in dried stems and leaves was higher than the whole plant. The best drying method of Yangxincai was hot air temperature 80 ℃ and flattening + cutting treatment. The results of this study can provide a theoretical basis for the optimization of the drying process of Yangxincai, and improve the economic benefit of drying process.