Chemical and physicochemical characterization of sago starch and sago pith residue for agroindustrial applications

Abstract Sago starch and its processing by-product, sago pith residue (SPR), are plentiful yet underexploited agricultural resources. The goal of this study was to determine the chemical composition and physicochemical properties of sago starch and SPR to assess their potential applications. Sago starch had a swelling power of 3.59 g/g, water solubility of 0.39%, and contained 12.87% moisture, 82.86% starch, and 28.54% amylose. The pasting analysis showed that the pasting temperature was 69.2 °C, the peak viscosity was 491 BU, the lowest viscosity was 198 BU, the breakdown viscosity was 293 BU, the setback was 150 BU, and the final viscosity was 336 BU. Sago starch had lower breakdown and setback viscosities than tapioca starch, which means that sago starch had better thermal stability and reduced retrogradation. SPR was composed of 37.71% lignin, 15.06% cellulose, 8.21% hemicellulose, and 30.20% residual starch. It had a water-holding capacity of 23.68 g/g, oil-holding capacity of 2.49 g/g, and swelling capacity of 16.8 mL/g. Polarized light microscopy validated the semi-crystalline characteristics of sago starch and the disrupted structure of SPR. These results suggest that sago starch could be used to produce biodegradable films, edible coatings, drilling starch, and glucose or its derivatives. SPR, on the other hand, could be used as a dietary fiber supplement, absorbent material, and bio-based composite filler. This supports the use of both in sustainable agroindustrial applications.