Preparation and characterization of nanoparticle and nanocrystal from sago starch

There is an emerging interest in the development of starch-biomaterial for various applications such as in food emulsions. Starch has several advantages to be modified as they are low-cost material, submicron in size with a high surface area to volume ratio and abundance of functional groups for surface modifications. The objective of this study was to prepare and investigate the morphological, structural and physicochemical properties of nanoparticles (SNP) and nanocrystals (SNC) extracted from sago starch. SNP was prepared by enzymatic hydrolysis with 5% pullulanase at 58°C for 24 hrs, meanwhile SNC was produced by acid hydrolysis with aqueous sulphuric acid (H2SO4) for 5 days at 40°C. Both SNP and SNC showed a size lower than 1000 nm and a homogenous polydispersity index. The X-ray diffraction analysis showed that the relative crystallinity increased significantly (p<0.05) and allowed stronger hydrogen bond interaction in both SNP and SNC. Besides that, swelling power, solubility and yield of SNP were significantly higher (p<0.05) than SNC as it was greatly influenced by the amorphous and crystalline regions of the starch particles after hydrolysis. Moreover, SNP have a less distinct shape with a size larger than SNC favoured by self-aggregation and lower zeta potential value. Overall, SNP prepared by enzymatic hydrolysis showed the most promising materials to meet industrial demands due to the environmental friendliness (no pollution), high yield and less preparation time needed. Therefore, the newly fabricated SNP have potential as an emulsifier, encapsulating agents and others regardless of any food system.