ภัทรนิษฐ์ วงษ์ศุภลักษณ์. Drying Characteristics of Ginger Undergoing Microwave-Vacuum Drying. Master's Degree(Food Engineering). King Mongkut's University of Technology Thonburi. KMUTT Library. : King Mongkut's University of Technology Thonburi, 2010.
Drying Characteristics of Ginger Undergoing Microwave-Vacuum Drying
Abstract:
Ginger is normally dried by conventional methods, i.e., hot air drying, sun drying,
biomass drying and tray drying, which adversely affect the quality of finished product
due to lengthy drying time and high drying temperature. Microwave-vacuum drying, on
the other hand, is one of the techniques recently proposed to dry many agricultural
products when quality is of concern. However, there is so far no information on the
drying characteristics of ginger undergoing microwave-vacuum drying. In this study,
therefore, ginger with dimensions of 1.5 cm in both width and length and 3 mm in
thickness was treated at various microwave power levels (279, 204 and 115 W) and
absolute pressures (160, 360, 560 and 760 mmHg). It was observed that the drying time
decreased with an increase in the microwave power level and a decrease in the absolute
pressure. The drying characteristics of ginger slice could be well described by the
Modified Page model. The drying conditions significantly affected color, texture,
shrinkage, and microstructure of the dried ginger. At lower absolute pressure and higher
microwave power, less change of color, and less maximum force and shrinkage of dried
ginger were observed. Based on scanning electron microscopic results, more puffed
ginger structure was observed at higher microwave power and lower absolute pressure.
Microwave-vacuum drying at 279 W with 160 mmHg gave the shortest drying time and
the best overall quality of dried ginger slice in this study.