Quality Study of the Preparation of Virgin Brown Sugar Powder by Vacuum Drying

The vacuum drying (VD) process of virgin brown sugar powder (VBSP) was optimized by response surface methodology. The influences of drying temperature (75–85 °C), vacuum pressure (30–50 kPa) and material thickness (0.7–1.3 cm) on the response values of drying rate and total phenolic content (TPC) were investigated. The optimal conditions of 85 °C, 46 kPa and 1.01 cm were obtained. The sensory, physical and chemical properties of VBSP under optimal conditions showed that significant changes in colour, aw and moisture state, but not in sugar composition, were found. The TPC, protein content and free amino acid content were slightly reduced, while certain increases in the DPPH radical scavenging activity, N-nitro clearance and reducing power were observed. The results indicated that VD could provide good sensory and physicochemical properties to VBSP, in addition to cost and efficiency advantages.