Experimental and Numerical Investigation of Spray-Drying Parameters on the Dried Powder Properties of Ginkgo biloba Seeds

Abstract

The operating parameters for spray drying play a significant role in determining the properties of the dried product. Ginkgo biloba (GB) seeds are a popular food and additive in the food and medicine market; in this study we spray dried these seeds. According to the L₁₆4⁴ orthogonal experimental design, a total of 16 tests was performed in a compact spray dryer. Parameters, i.e., inlet air temperature, air flow rate, outlet air temperature, and feed concentration, were selected as affecting factors. The dried product was evaluated with respect to residual moisture content, color difference, mean particle size, and protein content. The effects of these four parameters on the product properties were investigated. The experimental results showed that operating air temperature, especially the outlet air temperature, significantly affected the residual moisture and protein content in the dried product. High outlet air temperature can reduce the product quality. On the other hand, the mean particle size of GB powder was mainly affected by the feed concentration. Increasing feed concentration increased mean particle size. Color difference of GB seed powder was significantly affected by the inlet and outlet air temperatures and feed concentration. Furthermore, the optimal conditions of GB seed spray drying, i.e., inlet air temperature 190°C, air flow rate 120 m³/h, outlet air temperature 110°C, feed concentration 10%, were obtained from an L₁₆4⁴ orthogonal experiment. At last, correlation equations for GB seed powder properties with operating parameters were obtained using multivariable regression analysis.

Keywords:

• Orthogonal experimental design
• Product property
• Spray drying

ACKNOWLEDGMENTS

This project was sponsored by the Scientific Research Foundation for 948 Program Fund (Project No. 2006-4-114); the project from State Scientific and Technical Ministry, P.R. China (Project No. 2006JG001900); and the special project of Central Research (CAFINT2008K01 and CAFINT2008K05).

Notes

T ₁: Inlet air temperature; Q: air flow rate; T ₂: outlet air temperature; D: feed concentration.