Intermittent Ultrasound‑Assisted Anti‑Solvent Crystallization for Sucralose Production with Ultra-low Aspect Ratio and Larger Crystal Size

Abstract

The simultaneous achievements of lower aspect ratio and larger crystal size is urgent for the production of high-quality sucralose. In this work, non-toxic ethanol-based anti-solvent crystallization (ASC) of sucralose were conducted, during which carboxylic acids bearing different alkyl lengths (isovaleric acid (IVA), hexanoic acid (HNA), octanoic acid (ONA), decanoic acid (DNA)) have been used as anti-solvents. The longer alkyl lengths of carboxylic acids can render higher sucralose yield. Because the better flexibility can provide larger free void spaces with more easiness of emulsion shrinking, resulting in higher crystallization ratio and rate. And the optimal ASC conditions have been optimized, based on which low aspect ratio (1.5585) and small particle size (15.755 μm) can be obtained using ONA as anti-solvent. Based on the single crystal structure analysis, ONA-treated product bearing relatively weaker O-H···O/C-H···Cl hydrogen bonds was adopted for further ultrasound‑assisted ASC process. Interestingly, upon the intermittent sonication mode, the sucralose product with ultra-low aspect ratio (1.244) and larger crystal size (42.722 μm) can be obtained, which is attributed to the relatively stronger sp3-C-H···Cl0 hydrogen bonds on {011} face than O-H···O bonds on {101}/{110} faces. This work will provide theoretical guide for the production of high-quality sucralose.