Optimization of boiling granulation technology of Puerariae radix

To explore the use of boiling granulation technology for the optimization of high dietary fiber Puerariae radix powder with granulation process, in this study, the main parameters (i.e., atomizing pressure, inlet air temperature, peristaltic pump speed) of granulation process were optimized by the response surface methodology on the basis of single factor experiments. Based on that, the regression model was generated. The single factor experiment results showed that the parameters of boiling granulation were relative better when atomizing pressure at 0.20 MPa, inlet air temperature at 60℃, peristaltic pump speed at 3 r/min. We analyzed the above single factor experiment results by response surface methodology to obtain the optimal granulation process regression modelThe variance analysis of the regression model, the regression probability was P<0.0100. On the other hand, the test for lack of fit of the regression model was P=0.5100>0.1000, showing that the response surface test results and the regression model fitted well, and the test error was small. Therefore, the regression model can be used to analyze and predict the tested results. The determination coefficient of the regression model was R2=0.9881. The CV was 2.21% indicating that the confidence of the model was high, and the model could better reflect the real test results. Therefore, this regression model could be used to analyze the change of response parameters. The F value from the variance analysis indicated the effect of the three factors on the dissolution rate of Puerariae radix powder after boiling granulation with B>A>C. The analysis also showed that the effect factors of A, B and C on the dissolution rate of Puerariae radix powder were very significant (P<0.01), while A and B, A and C or B and C had no significant difference on the dissolution rate of Puerariae radix powder (P>0.05). Through the method of the response surface analysis software to forecast the optimum technological condition of the regression model, it was concluded that the theoretical optimum boiling granulation process parameters were: atomizing pressure 0.19 MPa, inlet air temperature 59.21℃, peristaltic pump speed 3.13 r/min, and the predictive dissolution rate of Puerariae radix powder after granulation was 66.48%±0.383%. To verified this, and based on the actual convenience operation of the plant, we put conditions of the best boiling granulation process as atomizing pressure 0.19 MPa, inlet air temperature 59℃, peristaltic pump speed 3 r/min. The verification test showed that the dissolution rate of Puerariae radix powder was 66.49%±2.44% for the best boiling granulation conditions with three replicates. However the regression model predictive response dissolution rate of Puerariae radix powder was 66.48%±0.383%, the relative error was below 1%, the differentiation was not significant, indicating this optimization of boiling granulation technology of Puerariae radix was practicable. Under the optimal condition the dissolution rate of Puerariae radix powder was 33.98 percentage points higher compared to 32.51%±0.63% before boiling granulation, and the product yield reached 91.62%. The relative error between the estimating date of regressive model and actual date was less than 1%, showing that the granulation conditions were reasonable. Under the best granulation conditions, there was no significant difference at the Puerarin content. Our results offer theory utilization evidence for the further development of the instant Puerariae radix powder. © 2016, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.