Partial debranching and microwave treatment stabilize amylopectin-flavor interactions for better tsampa processing outcomes

This study investigated the synergistic mechanism of partial debranching and microwave treatment on the complexation between highland barley amylopectin and 2-ethyl-6-methyl pyrazine (EMP) in an aqueous system, a key roasted aroma compound in tsampa. Pullulanase-mediated partial debranching optimized the chain length distribution by reducing steric hindrance, which alone enhanced EMP binding. Subsequent microwave treatment (300, 500, 700 W) further promoted complexation through distinct, power-dependent mechanisms that fundamentally differ from conventional water bath heating. Unlike the random thermal motion of water bath heating, microwave irradiation induced high-frequency dipole rotation and orientational polarization, driving starch chain rearrangement and conformational tightening. Especially, at 700 W, partial chain cleavage generated linear fragments that readily formed V -type inclusion complexes, doubling EMP encapsulation compared to native starch. Molecular dynamics simulations confirmed that microwave treatment induced tighter chain folding and stronger intermolecular interactions than water bath heating. This work demonstrates that microwave irradiation actively reorganizes starch architecture rather than merely providing thermal energy, offering a novel strategy for starch-based flavor encapsulation.