Enzymatic retting of kenaf bast fiber: effect of enzyme combination, retting time and solid to water volume ratio

Traditionally in producing kenaf bast fibers was used water retting, chemical retting, mechanical retting before enzymatic retting are introduced. Water retting requires 14 to 28 days to degrade pectic materials, hemicellulose, and lignin. For chemical and mechanical retting, the fibers produced are very low quality fiber where the process can harm the quality of fiber. While, for enzymatic retting was found that can produce high quality fiber in shorter time.For this study, by using enzymatic retting, kenaf bast fibers were retted from enzyme solution of 100% pectinase and combination of enzyme pectinase, xylanase, and cellulase by using ratio of 60: 20: 20. The green kenaf ribbon retted significant variations following treatment at different enzyme solution concentration (10, 30, 50, 70, and 100 mL), retting time (24, 48, 72 and 96 hours), and with interaction between both parameters. It was that a retting time of 24 hours from retting process in enzyme combinations of pectinase, xylanase, and cellulase with enzyme concentration of 100 mL are produced good quality kenaf bast fiber in term of whiteness and clean fiber. Fourier transform infrared (FTIR) spectroscopy were used to investigate the decreased of lignin and hemicellulose in the retting process. While, Thermogravimetric (TGA) indicated that kenaf bast fiber that retted from enzyme combination of pectinase, xylanases, and cellulase for 24 hours displayed a superior thermal stability. Moreover, chemical anylsis of kenaf bast fibers after enzymatic retting process are conducted using gas chromatography-mass spectrometry (GC-MS). Two sample of residue from different combination enzyme was analyzed by using GC-MS to investigate the highest compound in residue are found that removed that prove on removing of lignin and pectin. The analysis was shown that fiber from retted process by using enzyme combination of pectinase, xylanases, and cellulase is highest compound of residue removal. Thus, the enzymatic retting process can produce fiber with high quality fiber in shorter time compared to chemical treatment that can harm the quality of fiber.