Alcoholic-Alkali Modification of Corn Starch: A Framework for GCWS Design and Functional Tailoring

Granular cold-water-soluble starch (GCWS) offers a major advancement, combining cold-water solubility with retention of native-like granule structure and paste characteristics. Among the various preparation methods, suspending starch granules in alcohol containing a trace amount of alkalireferred to as alcoholic-alkali treatment (AAT)has been demonstrated to be particularly effective. This study systematically examined the effects of ethanol concentration (50-90%), NaOH content (1-6%), and treatment temperature (30-50 °C) on corn starch. Morphological and optical analyses revealed progressive granule shrinkage, agglomeration, fusion, and birefringence loss, with complete disruption observed in ≥3% NaOH in 50-70% ethanol. Differential scanning calorimetry showed a decline in gelatinization enthalpy under stronger alkaline conditions, culminating in the loss of ordered structures with ≥5% NaOH. Functional assessments confirmed that GCWS achieved cold-water swelling factors up to 19.4, a solubility of 12.8-29.6% at 25 °C, paste transmittance exceeding 70%, and viscosities up to 810 cP at 35 °C, outperforming untreated starch. Statistical analysis identified ethanol concentration as the primary determinant of swelling and viscosity, while NaOH content governed solubility and paste transmittance. Collectively, these findings establish optimized AAT parameters for GCWS production and provide mechanistic insights into processing-functionality relationships. The results demonstrate that precise modulation of AAT conditions enables rational design of GCWS with enhanced solubility, clarity, and viscosity, offering a robust framework for tailoring starch performance to diverse industrial applications.