Spray-drying of ginger juice and physicochemical properties of ginger powders

The maturity of ginger rhizomes was studied by measuring their moisture content, fibre, density, and 6-gingerol content. Ginger rhizomes were harvested and divided into three groups according to their age of 4-6, 7-9, and 10-12 months. The results revealed that as ginger rhizomes age, moisture content and density decreased, while fibre and 6-gingerol content increased. Therefore, ginger maturity with the age of 10-12 months was used in the drying process. The effects of the drying aids maltodextrin and liquid glucose and inlet air temperatures on the properties of ginger powders were assessed. Moisture content, water activity, bulk density, water adsorption index, 6-gingerol content, and colour values of ginger powders decreased with increasing inlet air temperatures. Particle size, solubility, and water solubility index increased with increasing inlet air temperatures (p <= 0.05). Moisture content, water activity, water adsorption index, and particle size decreased with increasing the drying aids. Solubility, water solubility index, and yield increased with increasing the drying aids. The addition of 5% liquid glucose and an inlet air temperature of 120 degrees C resulted in good properties and the highest 6-gingerol content of the ginger powders. It was noted that liquid glucose could function as a drying aid and as an encapsulating agent.