Optimization of the Novel Bisulfite Steeping Method by Response Surface Methodology for Natural Starch Synthesis From Oil Palm Trunk Biomass

Abstract

Malaysia is the 2nd largest in palm oil export, and after overcoming economic age (average 25 years), the palm oil trees entail to replace usually. Therefore, a massive quantity of palm oil trunk biomass, containing a significant amount of starch, is available as bio-waste annually. The efficient extraction of this starch (carbohydrate polymer) would be worthwhile concerning the environment, economy, conversion of biowaste to bioresources, and waste dumping challenges. Central composite design executed an experimental model design, evaluated the impacts of process variables and their interaction through response surface methodology to optimize the novel bisulfite steeping method for starch synthesis. Design-Expert software performed the data analysis. The developed quadratic models for four factors (Strength of Sodium bisulfite solution, steeping hour, mixing ratio with the bisulfite solution and ultra-pure water) and one response (%Yield), demonstrated that a significant starch yield (13.54%) is achievable utilizing 0.74% bisulfite solution, 5.6 steeping hours, for 1.6 and 0.6 mixing ratio with the bisulfite solution and ultra-pure water respectively. Experimental outcomes were quite consistent with the predicted model, which eventually sustains the significance of this method. Malvern Zetasizer test revealed a bimodal granular distribution for starch, with 7.15µm of hydrodynamic size. Starch morphology was determined by scanning electron microscopy. X-ray diffraction investigation exhibits an A-type model, specifying persistent characteristics of extracted starch.