Application of Ultrasound and Curing Agent during Osmotic Dehydration to Improve the Quality Properties of Freeze-Dried Yellow Peach (Amygdalus persica) Slices

Abstract

This study aimed to improve the quality of freeze-dried yellow peaches (Amygdalus persica). Yellow peaches were pretreated with osmotic dehydration for 15 min prior to vacuum-freeze drying and supplemented with different ultrasonic power levels (180 W, 240 W, 300 W) and a curing agent (calcium lactobionate, CaLa) to investigate the effects on the quality of freeze-dried yellow peach slices. After vacuum freeze-drying the yellow peach slices for 48 h, their moisture, color, texture, microstructure, total phenol (TP) content and oligomeric proantho-cyanidin (OPC) content were determined. It was found that the auxiliary ultrasonic power with various levels, especially powered at 240 W, produced very favorable effects on the quality characteristics of freeze-dried yellow peaches. The average pore size of USOD-240 W samples was reduced by 57.07% compared with that of the FD samples. In terms of nutrient maintenance, USOD-240 W can also prevent nutrient loss to the greatest extent. The TP content (5.40 mg/g) and OPC content (14.42 mg/g) were always highest in each pretreatment. The addition of CaLa can further improve the quality of yellow peach slices. Overall, the application of ultrasound and CaLa to improve the quality of freeze-dried yellow peach slices along with osmotic dehydration before freeze-drying is a method worth considering.