Quality assessment of commercial glucomannan products in Indonesia

Abstract Glucomannan is a hydrocolloid substance widely used in various industries. This study investigated the quality of commercial glucomannan samples from 4 regions in Indonesia, namely Semarang (GK1), Surabaya (GK2), Bandung (GK3), and Sleman-Yogyakarta (GK4). The results showed that the GK1 had a higher whiteness index of 80.97%, viscosity of 18,466 cP, and swelling capacity of GK1 31.08 g/mL. The GK2 had the highest solubility of 95.93%. The chemical compositions of GK 1 were moisture content of 10.72%, ash 1.56%, protein 0.89%, fat 0.21%, glucomannan 82.15%, and starch 0.80%. The molecular weight Mw of GK2, 5.9×10⁵, was the highest value, but for the Mn 4.43×10⁵, and PDI (Mw/Mn) 2.44 were obtained from GK1. Calcium (Ca) was defined as calcium oxalate found in all samples, with the highest value in GK4 (4.19%), but lead (Pb) was not found in all samples. The FTIR spectra of all samples indicated the glucomannan compound. The rheological analysis indicated shear-thinning (pseudoplastic) flow patterns for GK1, GK2, and GK3, while the GK4 sample could not be measured because it was not soluble and formed a gel or viscous solution. The morphology of GK4 displayed the druse crystal and fine particles, indicating the presence of calcium oxalate crystals and starch granules. Overall result indicated the glucomannan samples were influenced by the geographical plantation and obtained by various extraction methods, such as chemical and mechanical methods. The characteristics of glucomannan impacted its application.