Abstract:
The purpose of this research was to compare the two silk degumming processes as follows: 1) the two-step process using Zingibain enzyme (a protease enzyme) from ginger and a dilution of Sodium Carbonate and 2) the one-step process using the normal Sodium Carbonate solution.
In the two-step process, fresh gingers, aged 8 to 12 months, were extracted and dried through freeze-drying process into a stable Zingibain enzyme powder to degum White Thai silk fibers (100/120 denier yarn count). The Zingibain enzyme at 0.6% of the fiber weight was added in the first bath at pH 4.0 at 60°C for 60 minutes. After that, the fibers were rinsed with fresh water and bathed in 0.2 g/l Na2CO3 with nonionic detergent of 5 g/l at 85oC for 60 minutes. Finally, the fibers were washed with hot water, rinsed with fresh water and neutralized with diluted acetic acid. In the second process, the fibers were bathed in 2 g/l Na2CO3 solution with nonionic detergent 10 g/l at 98oC for 60 minutes. Then, the fibers were washed with hot water and rinsed with fresh water and neutralized with diluted acetic acid.
The result of this study revealed that the two-step process using the Zingibain enzyme from ginger and a dilution of Sodium Carbonate gave better result than the one-step process. In addition, the Zingibain enzyme from ginger at 0.6% of the fiber weight and a dilution of Sodium Carbonate at 0.2 g/l Na2CO3 with nonionic detergent of 5 g/l was a suitable mixture composition. The weight loss of the fibers, using the two-step method, was at 23.75% which was higher than 22.10% of that the one-step process. However, the fibers of the two-step process were softer than that of the one-step process. Likewise, the tensile strength of the fibers treated by the two-step process was decreased by 12.89% while the tensile strength of the fibers treated by the one-step process was decreased by 21.11%. Finally, the fibers treated by the one-step process were crimped which were not suitable for weaving process.