The enhancement of sappanwood extract drying with foaming agent under different temperature

Sappanwood (Caesalpinia sappan Linn) contains brazilin, a natural antioxidant. It can be extracted and dried to obtain a dry extract powder. However, sappanwood extract drying is difficult due to its tendency to form a jelly-like structure, which strongly traps water molecules. This research studies the effect of foaming agents (egg albumin and gum Arabic) as well as the drying temperatures (40, 60, and 80 ℃) on the drying kinetics and physicochemical properties of the sappanwood extract powder. The water removal can be well expressed by the Page model. The addition of a foaming agent as well as the increase in drying temperature significantly speed up the drying process. However, at a temperature of 80℃, the effect of the foaming agents was less significant, and the dry extract became dark brown due to the occurrence of the Maillard reaction. By considering those trade-off phenomena, optimization with response surface methodology (RSM) was performed. The results indicated that sappanwood extract could be fully dried using a mixture of 5% egg albumin and 25% gum Arabic as the foaming agent at 64.1 ℃, the in just 64.7 minutes or 7 times shorter compared to the drying without foaming agent. Under these drying conditions, the total phenolic compound retention was up to 87.25%.