Comparison of pregelatinization methods on physicochemical, functional and structural properties of tartary buckwheat flour and noodle quality

The microstructural, physicochemical, nutritional, functional and protein structural properties of buckwheat flour as affected by different pregelatinization treatment including roasting, steaming, extrusion, boiling and microwave before milling were investigated. Scanning electron microscopy studies showed that flours treated by boiling and extrusion displayed more swollen and more compacted flour particles than raw, roasted and microwave treated flours. Native buckwheat flours displayed lower values of gelatinization degree, swelling power and hydration capacity than pretreated flours, while pretreated flours were darker and more reddish than native flour. Regarding the functional ingredients, native flours have more total flavonoid, rutin and content than quercetin treated flours with the exception of steaming and extrusion. The different pregelatinization treated buckwheat flours showed a remarkably decrease in their viscosities as revealed by rapid visco analyzer (RVA). Furthermore, the primary structure of buckwheat protein did no change with different pretreatments, whereas the extrusion treatment seemed to induce a conjugation between protein molecules. The pregelatinized buckwheat flours were also observed to have potential for producing high quality and functional noodles.