Application of response surface methodology for the optimization of Process variables on the Wet extraction of inulin from sisal boles

Abstract

In sisal industry, only four percent of the leaves weight is used for production of sisal fibers. The leaves are only 2% of the whole plant meaning that 98% of the plant, including leaves stubs, sisal pole and sisal bole, is discarded as waste. Despite the fact that sisal bole contains 30% sugars in juice extract, currently they are burnt or broken down and ploughed under. The remaining sisal bole bagasse is a sustainably available and valuable biomass reserve potential for production of fermentable sugars and other lignin delivered products. This study focuses on investigating the potential to produce inulin from sisal waste including sisal boles. In this investigation, a 2-factors 3 - levels Response Surface Methodology (RSM) with Central Composite Design (CCD) was used to evaluate the main effects and interactions of the independent parameters, namely temperature and time, on the inulin yield response parameter during extraction with Minitab Version 21. The developed Second Order Quadratic mathematical regression model was used to analyze the main and interaction effects of the process variables on the inulin yield and optimizing the parameters. The inulin concentration was analyzed using HPLC with C-18 carbohydrate (4.6×45 mm) column and an RID detector. The optimal extraction conditions for inulin were obtained at a temperature of 70°C and reaction time of 86.67 minutes in which the optimum yield was 35.20%. The physicochemical properties of inulin were also determined, and results revealed that the produced inulin had a moisture content of 6.104 ± 0.104%, water-solubility of 124.92 ± 1.76 g/L and pH of 6.62 ± 0.38 indicating that this study’s inulin exhibited close similarities with the commercial ones. This study has revealed that Sisal bole has a relatively good potency of producing inulin nearing to the leading biomass sources like chicory and Jerusalem artichoke roots.