Effects of Oat Bran Flour and Tartary Buckwheat Bran Flour on Structure, Cooking Quality and Digestive Characteristics of Wheat Noodles

This study aimed to explore the effects of oat bran flour and Tartary buckwheat bran flour addition on the structure, quality and digestive characteristics of wheat noodles, so as to confirm their application values in the production of wheat-based food products.

Three types of noodles were prepared with three recombinant flours containing 30% oat bran flour + 70% wheat flour, 30% Tartary buckwheat bran flour + 70% wheat flour, and 15% oat bran flour + 15% Tartary buckwheat bran flour + 70% wheat flour, respectively, with pure wheat noodle as control. The cooking quality, sensory quality and digestive characteristics of different noodles were determined and compared firstly. Then the structural characteristics of protein and starch in noodles were analyzed and compared by Fourier infrared spectrometer, X-ray diffractometer, Size-exclusion high performance liquid chromatography, Scanning electron microscope and Laser confocal scanning microscope, respectively.

The introduction of oat bran flour and Tartary buckwheat bran flour weakened the cooking and sensory quality of noodles, but improved the starch digestion resistance of noodles. The noodle containing 30% oat bran flour showed the lowest glycemic index (GI) of 47.9 among all the noodles. Protein denaturation and reconstruction during noodle cooking facilitated the binding between protein and other molecules higher proportion α-helix and lower proportion β-sheets was found in the protein of cooked oat bran noodles, which led to the transformation of protein aggregates into a loose and extended protein network that enforced the wrapping effect of protein to starch. After cooking, the starch crystal in noodles was destroyed, leading to the reduced orderliness. The addition of oat bran flour and buckwheat bran flour promoted the starch-lipid interactions in noodles, which contributed to the formation of resistant starch. Compared with buckwheat bran four, oat bran flour was more beneficial to maintaining the short-range order of starch and promoting the formation of more V-type crystals in noodle. In addition, the high content of β-glucan in oat bran flour further contributed to the interactions between starch and other molecules.

The addition of oat bran flour and Tartary buckwheat bran flour decreased the cooking and sensory quality of wheat noodle, but reduced the GI value of the noodle. The noodles containing 30% oat bran flour was a low GI food. The addition of oat bran flour and buckwheat bran flour in noodles contributed to the formation of resistant starch deriving from complex starch-protein and starch-lipid interactions during starch gelatinization. Oat bran flour was conductive to maintaining the thermal stability of protein network and improving the digestion resistance of starch in noodle by enhancing the interactions between starch and other molecules.