Effect of Drying temperatures on Quality of Cassumunar Ginger(Plai) Rhizome (Zingiber montanum (Koenig) Link ex. Dietr.)

Abstract

The objective of this research was to study the effect of drying temperatures on the rhizome quality of Zingiber montanum. The experiment was designed as CRD with three replications and four treatments namely drying temperatures at 40, 60, 80 and 100๐C in hot air oven and was conducted at the Horticulture Department, Faculty of Agriculture, Kasetsart University, during July, 2008 to September, 2009. The rhizomes were made into a thin sliced at 1.5-2 mm thick. Drying time needed to reduce the moisture of the rhizome to be less than 13% were 123, 54, 30, and 24 hrs and mean drying rates 3.03, 6.76, 11.56, and 14
49 (kgH2O/kg db.h), respectively. The percentage of volatile oil content were 2.47, 2.33, 1.31 and 0.52%, the decreased volatile oil content was significantly related to increased dying temperature. Antioxidant activity was highly significantly decreased to 75.09, 68.20, 65.54, and  59.49% as the temperature was decreased as temperatures were compared with fresh rhizome slices. Drying temperature was highly significant in negative relation to the quality of sliced rhizomes except for red (a*) colour measurements which was just statistically significant.