Amylose Leaching in Application for Starch Nanocrystals (SNCs) Isolation

ABSTRACT The amylose‐leaching method was applied to annealed maize starch to accelerate the isolation of starch nanocrystals (SNCs) via sulfuric acid hydrolysis. Due to disrupting the outer shell integrity of the starch granules, this pretreatment enhanced the diffusion rate of hydrolysis products into the solution. After 20 h of hydrolysis, the resulting particles exhibited an average size of 170 nm with PDI of 0.422 and a crystallinity index of 27%. Extending hydrolysis to 50 h yielded a suspension nearly free of large granule residues, achieving a 17% SNC yield. Scanning electron microscopy (SEM) and static laser light scattering (SLS) revealed particles ranging from 100 to 200 nm with two distinct morphologies: spherical particles in the early stages of hydrolysis (1 h) and thin plates forming ribbon‐like agglomerates after prolonged treatment (>20 h). X‐ray diffraction (XRD) analysis showed that amylose leaching induces a transition in the crystal lattice type from orthorhombic to hexagonal. The hexagonal lattice nanocrystals are hypothesized to form through the dissolution of native crystallites followed by recrystallization. The thermal pretreatment method—combining annealing and amylose leaching—reduces the time required for SNC isolation and demonstrates the potential of leveraging retrogradation for more efficient SNC production.