The work investigated the influences of blanching (B) and ultrasonic assisted blanching (UB) as pretreatment on mass transfer, drying kinetics, color, contents of nutrient, and aroma compounds of hot-air dried perilla leaves. The samples were pretreated at two temperatures (70 ℃, 80 ℃) and two durations of pretreatment (1 min, 3 min). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) was used to distinguish sample characteristics of different pretreatments. The results showed that the condition of UB pretreatment had a higher drying rate compared to B pretreatment. The effective moisture diffusivity ( D_eff ) of pretreatment for UB is higher than B. The UB pretreatment method yielded the lower ΔE value and higher preserved content of chlorophyll, flavonoid and rosemary acid at the pretreatment temperature of 70℃. Moreover, GC-MS results showed the lower perilla ketone relative content under the same conditions. According to the results, the quality of the dried perilla leaves after performing low-temperature UB pretreatment (70 ℃) was improved relatively.

Spatial-channel transformer network based on mask-RCNN for efficient mushroom instance segmentation