Pre-baking-steaming of oat induces stronger macromolecular interactions and more resistant starch in oat-buckwheat noodle.

Pre-hydrothermal treatment is widely used to improve the quality of oat or buckwheat noodles. Noodle preparations containing pre-baked-steamed oat and untreated buckwheat (BUN) exhibited the highest sensory score (45.2) among six oat-buckwheat noodle preparations produced with different pre-hydrothermal treatments. Further comparison between the BUN and the noodle prepared with untreated oat and buckwheat showed that, the pre-baking-steaming of oat not only produced a more extended and thermally stable protein network involving rearranged gluten and oat globulins in cooked BUN, but also enhanced the short-range molecular order of gelatinized starch through the formation of nascent double helixes and binary/ternary complexes (starch-lipid, starch-protein and starch-lipid-protein). Overall, these stronger macromolecular interactions in cooked BUN led to an extensive and compact protein-starch network that promoted the formation of more resistant starch (41%). Our findings elucidated the molecular mechanism that underpin the positive effect of oat pretreatment on noodle quality and digestibility.