Abstract
Lipid crystallization critically shapes food quality, yet its molecular regulation by emulsifiers remains poorly quantified. This study employs ultrasonic phase velocity, integrated with differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS), to elucidate sucrose fatty acid ester (SFE) modulation of hydrogenated coconut oil (HCO) crystallization. Compressibility drives acoustic responses, contributing ∼ 70 % to phase velocity changes versus ∼ 30 % from density. Phase velocity correlates strongly with crystallization enthalpy (R(2) > 0.99), detecting onset 15-30 min earlier than DSC. Three SFEs (C12:0, C18:0, C18:1) exhibit distinct mechanisms: laurate integrates into crystals, expanding lamellar structures; stearate forms pre-crystalline assemblies, delaying crystallization by up to 40 %; and oleate disrupts ordering with its bent structure. A three-regime model (breakpoints at 1.2 % and 3.8 %) explains 91 % of crystallization variance. These insights enable emulsifier selection for optimizing chocolate texture and spread stability, potentially reducing costs by 15-20 %, while establishing ultrasonic phase velocity as a precise (0.035 % resolution), non-destructive tool for real-time molecular monitoring in complex food systems.