Designing food matrix structure by adjusting the ratio of soluble/insoluble wheat bran dietary fiber to mitigate the inhibition on wheat protein digestion: Application in noodles

This study investigated the effect of changing the ratio of soluble (SDF) and insoluble (IDF) wheat bran dietary fiber on matrix structure and protein digestion in wheat noodles. Results showed that SDF at a low ratio (≤ 3.5) induced a compact matrix structure, which decreased protein digestibility to 67.70 % and total amino acids release to 140.67 mg/g protein, respectively. The compaction of the noodle matrix could be attributed to the promotion of cross-linking between D-type low molecular weight gluten and γ-gliadin by a small amount of SDF, reducing lacunarity from 0.28 to 0.16. A high SDF ratio (>3.5) induced a more fragmented matrix structure, increasing protein digestibility to 76.88 %. Notably, at a higher SDF ratio (>4.5), the concentration-dependent static quenching on enzymatic sites of SDF became prominent, slightly reducing gastric protein digestibility. In summary, an SDF ratio of 2.0–2.5 helps to reduce the inhibition of SDF on protein digestion.