Optimization of Multilevel Ethanol Leaching Process of Porang Flour (Amorphophallus muelleri) Using Response Surface Methodology

Porang flour is a processed product derived from porang tuber (Amorphophallus oncophyllus), contains polysaccharide hydrocolloid such as glucomannan and it can beused as gelatinization, viscosity, filming, emulsifier and stabilizer agent. Porang flour has low content of glucomannan, contributing to its dark brown color and contains high level of calcium oxalate which can cause itching, irritation and other health effects. In this study, the multilevel ethanol optimization and maceration method were used toextract the glucomannan content from porang flour by the leaching process. Response surface methodology (RSM), Central Composite Design (CCD) on three independent variables leaching time (X1), stirring speed (X2) and ratio of solvent to flour (X3) with response of glucomannan content and calcium oxalate) were used as a tools to study the optimum responses. Responses model were quadratic with optimal condition as follows: leaching time was 4 h 6 min and 18 sec, stirring speed was at 443.45 rpm and ratio of solvent to flour was 8.92 ml/g. Under these conditions, the experimental yield of glucomannan content and calcium oxalate were 79.19 % and 0.08 %, respectively, which were very close to the predicted values of 79.26 % and 0.07 %, respectively.