Optimization of process parameters in bio-retting kenaf bast fiber

Kenaf (Hibiscus cannabinus) belongs to family Malvaceae that suitable cultivated in Malaysia. This plant has two layers which are inner core and outer bast layer can be used as raw material for the production of high quality of fiber. The method commonly used is traditional retting by soaking the kenaf stem into water where the microorganisms required a long time to degrade the non-cellulosic substances and create the putrid odor. To overcome this problem, a new method is needed which is enzymatic retting that is the latest technology promotes the green technology and produced the good quality on fiber but high processing cost due to the usage of enzyme. The combinations of enzymes were developed by using the ratio of enzyme studied are pectinase: xylanase: cellulase (60: 20: 20) and pectinase: xylanase (60: 40). The optimum process parameter for both combinations for this study found that the optimum retting time are 48 hours for (pectinase: xylanase: cellulase) and 96 hours for (pectinase: xylanase) by using 70 mL of water at pH 3.5 with temperature is 50 °C. The optimum process parameters were determined by comparing the fibers produced based on the physical characterization. The observations of fibers were further studied based on the colour, fineness and cleanliness of fiber produced. Fourier transform infrared red (FTIR) studies showed that the peaks that represent lignin and hemicellulose region decreased after retting for both combinations. Thermogravimetric analysis (TGA) is to observe the improvement for thermal stability of fiber produced after enzymatic retting. Gas chromatography mass spectrometry (GCMS) determined the compound that presence in the solution enzyme after retted which are acetic acid, acetamide and ammonium acetate. From this study, it was found that the enzymatic retting is method for retting because can produce high quality of fiber and reduce the retting time.