High-efficiency preparation of starch nanocrystals with small size and high crystallinity by ethanol-acid penetration and dry-heating pretreatment

Ethanol-acid penetration and drying-heating treatment was developed to shorten the preparation time and improve the quality of starch nanocrystals (SNCs). After treatment by optimized parameters, including 40 % ethanol solution, 10.6 mM chloric acid, and heating time of 1.5 h or 2.0 h, the starches exhibited weakened internal structure and relatively complete crystalline structure. Compared with the regular preparation of only acid hydrolysis, the regular final yield (8.5 % after 5 days) was reached in 48 h and 12 h of the starch heated at 1.5 h and 2.0 h, respectively. The micromorphology, molecular weight, and crystalline structure evaluation demonstrated that the collected nanoparticles were indeed SNCs with smaller size and higher relative crystallinity than regular SNCs. Further analysis found that the SNCs had better crystalline lamellae, higher thermal stability, and lower proportion of phosphorus and sulfur atoms than regular SNCs. This provided a potential method for the high-efficiency preparation of SNCs.