Multi-objective Optimization of Spray Drying of Jujube (Zizyphus jujuba Miller) Powder Using Response Surface Methodology

Optimum technology of spray-dried jujube powder was studied using a Box-Benhnken design. Effects of weight ratio of maltodextrin and the dry matter weight of jujube pulp (WR, 3–5), inlet air temperature (T, 140–160 °C), and shift of feed flow rate (FFR, 3–5) on the quality attributes (moisture content, lightness, the total color difference, vitamin C (VC) content and hygroscopicity) of jujube powder were systematically studied by response surface methodology and perturbation plot. Analysis of variance showed that a second-order polynomial equation could predict the experimental data well (R2 > 0.92). Moisture content and the total color difference (∆E) were significantly affected by WR, T, and FFR. The higher WR and lower FFR resulted in a decrease in moisture content and ∆E. WR and FFR had extremely significant effects on VC content and hygroscopicity (P < 0.01); with lower WR and FFR, higher values of VC content and hygroscopicity would be received. The effect of WR was the most significant variable among others. The optimum conditions that maximizing VC content and minimizing contents of moisture, ∆E, and hygroscopicity of jujube powder were found as WR of 3, inlet air temperature of 140 °C, and FFR of 3 ( i.e., 11 ml/min). Under these conditions, the response values were moisture content of 3.36 %, lightness of 83.32, ∆E of 9.92, VC content of 205.10 mg/100 g, and hygroscopicity of 18.59 %, respectively.