Identification of glucomannan molecules derived from Porang (Amorphophallus muelleri Blume) flour by various purification process and the optical transparency

Porang flour derived from porang tubers (Amorphophallus muelleri Blume) of the Araceae family and has contains high levels of glucomannan, ranging between 15 and 64% dry weight. Furthermore, porang flour includes oxalic acid, especially potassium oxalate monohydrate (K₂C₂O₄.H₂O), which is unnecessary in many applications due to it is hazardous to organisms. As a result, purification methods porang flour is a crucial step in removing these harmful chemicals. Therefore, the purpose of this research is to identify the chemical components of glucomannan and potassium oxalate monohydrate in porang flour samples before and after purification, as well as to investigate potential applications. Purification was accomplished using centrifugation and soaking for 30 minutes and 7 days. Furthermore, the content of glucomannan and potassium oxalate monohydrate in porang flour samples was determined by investigating the surface morphology, various chemical elements, molecular bonds and structures, and optical properties. EDX characterization showed that carbon (C) and oxygen (O) content increased while potassium (K) content de-creased significantly in samples purified using centrifugation and soaking methods. In addition, the FTIR spectrum confirmed the existence of H₂O functional group peaks, which explains the presence of potassium oxalate monohydrate in porang flour samples without purification and after soaking for 30 minutes and 7 days, respectively. According to the ¹HNMR results, the centrifugation purification method on porang flour significantly reduces the oxalate structure. The results of the ¹HNMR peak analysis showed that all samples contained Mannose and Glucose compounds such as α-D-Manose, β-D Mannose, α-D-glucose, β-D-Glucose, β-D-NAcetylmannosamine (β-D-ManNAc), α-D-NAcetylmannosamine (α-D-ManNAc), β-D-NAcetylglucosamine (β-D-GlcNAc) and α-D-NAcetylglucosamine (α-D-GlcNAc).The UV–Vis spectroscopy characteristics of the porang flour sample soaked for 7 days showed a lower absorption peak than the sample soaked for 30 minutes without purification. This shows that purification with a 7-day soaking method yields low oxalic acid levels, especially potassium oxalate monohydrate. As a result, purification by soaking for 7 days is an efficient method to produce porang flour with low potassium oxalate monohydrate levels. As a result, the purification method has the potential to be used in a variety of applications using porang flour, especially as a biomaterial in the medical field.