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

Jun Mei,Yuanming Chu,Jing Xie,Zhaoyang Ding,Saichao Wei

doi:10.3390/agriculture11111069

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.

Highlights

As a juicy, flavorful and delicate seasonal fruit, yellow peaches (Amygdalus persica) are popular among consumers
Osmotic dehydration occurs between fruits and vegetables and hypertonic solution
The ultrasound-assisted (180, 240, 300 W) group showed a significant increase in Water loss (WL) (6.81–7.11%) compared to ultrasonic technology with osmotic dehydration (USOD)-0 W (4.19%), due to the cavitation effect of the ultrasound promoting the generation of microchannels and enhancing water transfer

Summary

Introduction

Flavorful and delicate seasonal fruit, yellow peaches (Amygdalus persica) are popular among consumers. Yellow peaches are a respiratory leap type of fruit that ripens and softens rapidly after harvesting. They are very susceptible to flavor deterioration and rotting during transportation and storage, which has a negative impact on the fruit’s commercial value [2]. It is necessary to further process yellow peaches to extend their shelf life and increase their added value. Vacuum freeze-drying is a common way to process yellow peaches and the original color and flavor of the food can be well maintained due to its combination of low temperature and low pressure. Vacuum freeze-drying plays a positive role in maintaining the shelf life and overall quality of fruits such as strawberries and persimmons [3,4]. The disadvantages of vacuum freeze-drying are its high cost and long processing time [5]

Objectives

Methods

Results