Physicochemical Characteristics of 'Wushan Plum' Subjected to Three Drying Methods.

In this study, the effects of hot air drying (HAD), freeze-drying (FD), and air-impingement jet drying (JD) on the physicochemical characteristics of 'Wushan plum' were analyzed. The results indicated three drying methods affected the browning, ascorbic acids, phenolic compounds, and antioxidant activities. The ascorbic acid content in HAD, FD, and JD samples was1.75±0.38, 5.88±0.56, and 4.73±0.75 mg/100 g, respectively, and the content of total phenolic compounds was 2.76±0.10, 3.05±0.04, and 2.83±0.24 mg/g, respectively. HAD samples had the lowest antioxidant activities as determined by DPPH⋅, ABTS⋅, and FRAP assays. In addition, 11 phenolic compounds in 'Wushan plum' were quantified by UPLC-QqQ-MS/MS. The results showed that quercetin glycoside was the main compound, and its content was significantly reduced by these three drying methods. In all, this result indicated that JD would be a good choice for dying 'Wushan plum' considering the drying time, drying efficiency, and the integrated quality of the dried sample.