Malting, germination, and fermentation influence on the thermochemical, functional, anti-nutritional, and antimicrobial properties of buckwheat flour: an untargeted HRAMS-based metabolite study.

Common buckwheat (Fagopyrum esculentum Moench) is a gluten-free pseudocereal known for its nutritional abundance; however, its utilization is restricted due to the presence of antinutritional factors. To overcome this, our study utilized bioprocessing techniques such as fermentation, germination, and malting, which significantly modified the compositional, structural, functional, and metabolomic properties relative to control (CBW). Tannin content reduced from 497.81 ± 11.93 to 98.66 ± 2.28 mg TAE/100 g in malted (MBW) condition and phytate from 17.48 ± 0.09 to 8.84 ± mg/100 g in germinated (GBW48) sample. The Antioxidant capacity increased significantly in Lactiplantibacillus plantarum fermented flour (FBW48) (DPPH 50.78 ± 0.28 mg AAE/100 g; FRAP 5.33 ± 0.10 mmol Fe2+/100 g; ABTS 39.80 ± 0.72 mg AAE/100 g), and the highest total phenolic content (373.59 ± 8.44 mg GAE/100 g) and GBW48 showed the highest flavonoid content (232.69 ± 3.33 mg QE/100 g). During antimicrobial activity all treatments significantly inhibited, but naturally fermented buckwheat flour for 48 h (NFBW48) showed the highest zone of inhibition for Salmonella typhi (14.33 ± 0.58 mm) and GBW48 for Escherichia coli (12.33 ± 0.57 mm), whereas NFBW48 was the only condition that showed a zone of inhibition for Staphylococcus aureus (22.33 ± 1.15 mm). XRD analyses revealed the reduction in crystalline structure, altered TGA decomposition, modified DSC transitions, and FTIR shifts in OH (∼3400), CO (∼1740), and Amide II (∼1540 cm-1) supported by morphological studies, which showed extensive pore formation and granule disintegration in MBW and FBW48. Fermented flours showed reduced G' and G″ from starch disruption and protein hydrolysis, indicating a softer texture required for baked food formulations. HRAMS identified several metabolites depending on the various bioprocessing treatments, where FBW48 identified trans-cinnamic acid, isorhamnetin, nicotinic acid; GBW48 identified chrysin and matairesinol; and MBW identified vanillin, catechin gallate, 4-coumaric acid, vanillin, thiamine, and desthiobiotin, which were initially not present in CBW. These metabolites are correlated with enhanced antioxidant capacity, and reduced anti-nutrient component, which further supports bioprocessed buckwheat flours as functional food ingredients.