Production of blueberry pulp powder by microwave-assisted foam-mat drying: Effects of formulations of foaming agents on drying characteristics and physicochemical properties

Foaming agents influence the feasibility of microwave-assisted foam-mat drying (MFD) for the production of blueberry pulp powder (BPP). In this study, the effects of the foaming agents on the drying characteristics of foamed blueberry pulp (FBP) and physicochemical indicators of BPP were investigated by using the formulations containing egg white powder (EWP, 0, 4, 8 g/100 g), maltodextrin (MD, 0, 5, 10 g/100 g) and carboxymethylcellulose (CMC, 0, 0.5, 1 g/100 g). Results showed that the co-addition of EWP and MD obviously influenced the drying rate of FBP. The solubility and porosity of BPP increased significantly (P < 0.05) with increasing concentrations of EWP, MD and CMC. The physicochemical indicators of BPP were evaluated using the principal component analysis method because of the significant differences in color, browning index (BI) and total anthocyanin content (TAC) for BPP under different formulations of foaming agents. The optimal formulation consisted of EWP, MD and CMC with the ratio of 16:20:1 can achieve high drying rate and desired physicochemical quality with high solubility and porosity, relatively high TAC and BI. This study may provide guidance for the production of high physicochemical quality powder with high moisture content, heat sensitivity as well as high viscosity like blueberry pulp.