Simultaneous thermo-enzymatic modification of pea starch at atmospheric and high temperature-pressure conditions: Implications for structure and resistance to digestibility

This study evaluated the simultaneous effect of processing temperature (95, 120, and 140 °C), α-amylase-mediated hydrolysis (0-75% peak viscosity reduction), and 72 h storage on the structure and functionality of pea starch. Pasting properties and gel hardness were significantly affected by all factors, with peak viscosity decreasing from 2924 to 682 cP and setback approaching zero at high hydrolysis levels. Gel hardness showed a non-linear response: low hydrolysis enhanced gel strength at 120 °C (1725 ± 31 g), whereas extensive hydrolysis consistently weakened gel formation. Storage promoted retrogradation, increasing gel hardness up to 3126 ± 21 g and enhancing thermal stability in selected systems. RS content varied between 11.08 and 21.63 g/100 g, with the highest values observed at 95 °C under mild hydrolysis, while excessive hydrolysis and high-temperature treatment reduced RS formation. FTIR and DSC analyses confirmed a progressive loss of short-range order and crystallinity, with gelatinization enthalpy decreasing from 6.28 to 0.35 J/g as hydrolysis increased. SEM confirmed a progressive transition from porous, interconnected networks to compact, collapsed matrices as temperature and hydrolysis increased. Partial depolymerization promoted molecular reorganization without compromising network formation. These findings demonstrate that thermo-enzymatic processing modulates starch structure, digestibility, and gelation for tailored food and biopolymer applications.