Structural and functional modulation of Fagopyrum tataricum by multifrequency ultrasonication, germination and soaking: impact on polyphenols and techno-functional properties.

The current study investigated the effect of multifrequency ultrasonication (MFUT), germination (G), soaking (S) and their combined effect treatments MFUT + G and MFUT + G + S on metabolite profile, structural modifications and techno-functional properties of Fagopyrum tataricum. Relative to the untreated native group, MFUT + G + S significantly (p < 0.05) outperformed individual treatments and MFUT + G. MFUT + G + S treatment increased PAL (phenylalanine ammonia-lyase), PPO (polyphenol oxidase), POD (peroxidase), and SOD (Superoxide dismutase) activities by 7.07, 9.60, 6.81, and 10.92 folds, respectively, while reduced tannins and phytic acid by 66.37 % and 60.07 %, respectively. These biochemical modifications enhanced polyphenolic accumulation (particularly chlorogenic acid, vanillic acid, syringic acid, rutin, and catechins), antioxidant activity and protein digestibility by 173.98 %, 284.89 %, and 102.21 %, respectively. FTIR and XRD confirmed structural modifications indicated by diminished starch crystallinity index (31.98-13.40 %) and α-helix (10.97-10.25 %) accompanied by enhanced β-sheets (20.71-35.83 %). Furthermore, MFUT + G + S exhibited reduced pasting properties and particle size, alongside increased surface hydrophobicity, zeta-potential and uniform particle dispersity. Collectively, these structural modifications enhanced water holding capacity (295.65 %), water absorption index (30.45 %), swelling power (35.94 %), emulsifying activity (68.04 %) and emulsifying stability (55.30 %) as well as superior thermal and textural stability. Furthermore, E-nose sensor response indicated an improved aroma pattern of MFUT + G + S. Collectively, these findings demonstrate that sequential application of MFUT and soaking pretreatments enhance both the functional quality and digestibility of germinated Fagopyrum tataricum flour.