Effect of ultrasound-assisted osmotic dehydration pretreatment on the drying characteristics and quality properties of Sanhua plum (Prunus salicina L.)

Sanhua plum is difficult to dehydrate because of its epicuticular wax and dense pulp. Therefore, it is necessary to pretreat Sanhua plum to enhance its dehydration efficiency. In this study, ultrasound-assisted osmotic dehydration pretreatment was used for Sanhua plum, and the effect of ultrasound-assisted osmotic dehydration pretreatment on the drying characteristics and quality properties of Sanhua plum was investigated. The results showed that ultrasound pretreatment significantly increased water loss and solid gain of Sanhua plum during osmotic dehydration. Furthermore, Sanhua plum treated with ultrasound-assisted osmotic dehydration showed reduced drying time, improved drying rate, and increased effective water diffusivity. Sanhua plum with low ultrasound intensity treatment exhibited higher antioxidant capacity and total phenolic retention. Textural result indicated that ultrasound treatment could decrease the hardness and chewiness of Sanhua plum. Moreover, ultrasound-treated Sanhua plum improved color retention in comparison with untreated samples. In conclusion, lower ultrasound-intensity pretreatment not only reduced the drying time of Sanhua plum, but also better retained the quality properties of Sanhua plum. This study provides a promising pretreatment for Sanhua plum dehydration.