A new physical starch modification method: Pressure annealing treatment (PAT)

The effects of pressure annealing treatment (PAT), a novel non-thermal starch modification method, were investigated using four starches from different botanical sources (corn, tapioca, wheat, and potato). PAT was conducted under sub-gelatinization conditions optimized by response surface methodology to maintain granule integrity while inducing internal molecular rearrangement. PAT starches showed no visible morphological changes, but exhibited starch-specific differences in physicochemical properties, such as particle size distribution, relative crystallinity, gelatinization behavior, and hydration properties. PAT increased crystallinity in corn and tapioca starches, while decreasing it in potato starch. Thermal stability varied depending on starch type. Swelling power and solubility showed moderate changes. In pasting properties, PAT generally enhanced peak viscosity but caused diverse effects on viscosity parameters depending on starch type. In vitro digestibility analysis showed increased slowly digestible starch (SDS) in corn and tapioca, and increased resistant starch (RS) in wheat. These findings demonstrate that PAT induces distinct structural and functional modifications across starch types, highlighting its potential as a clean-label and tunable strategy for starch modification.