Heat treatment of dark buckwheat flour improves the quality and starch digestibility of buckwheat-dried noodles through structural compactness

Buckwheat, a nutrient-rich pseudocereal, faces challenges in noodle production due to gluten deficiency and suboptimal textural properties. This study systematically evaluated the effects of heat-moisture treatment (HMT) and dry heat treatment (DHT) on the physicochemical characteristics of dark buckwheat flour (DBF), rheological behavior of composite dough, noodle quality, and starch digestibility. The results showed that DHT-modified DBF exhibited improved solubility (25 °C, 6.75–8.80 %; 100 °C, 15.16–16.65 %), swelling power (25 °C, 3.69–4.19 g/g; 100 °C, 9.19–10.78 g/g), and enthalpy values (6.39–7.70 J/g). DHT-modified noodles showed superior mechanical properties (fracture strength and flexibility) and cooking quality (water absorption and cooking loss). Both treatments improved the hardness (3.91–12.10 %), springiness (1.03–3.94 %), and chewiness (3.68–36.31 %), tensile strength (11.45–35.73 %), and breaking length (9.91–44.62 %) of the noodles. Scanning electron microscopy (SEM) imaging confirmed that thermal treatments promoted gel matrix formation, and reduced pore size (52.03 %), pore area (79.31 %), and porosity (91.77 %), while increasing structural compactness. Both treatments reduced starch digestibility, with DHT2 achieving the lowest hydrolysis extent (C_∞, 39.02 %) and rate (k₁, 0.0073 min⁻¹) of hydrolysis. This research elucidates that structural compactness is a key factor affecting food quality and starch digestibility, providing a theoretical basis for the development of low glycemic index buckwheat foods.