Wheat bran incorporation in bread has multiple health benefits, but also a detrimental effect on overall bread quality. Bran is hypothesised to withdraw water from gluten, resulting in less optimal viscoelastic dough properties and a lower gas retention capacity, in turn resulting in a decreased bread loaf volume. In this study, wheat bran samples having different water retention capacities were produced and used to investigate this hypothesis. Gluten-starch model systems were used and the effect of substitution of part of the starch by bran in combination with different water absorptions and mixing times was evaluated. The properties of the gluten network in the doughs were investigated using rheological and microstructural analyses and these properties were linked to the final bread loaf volume. A proper gluten network microstructure, as visualised with CLSM, could be achieved in the presence of wheat bran. However, significant effects of the type of wheat bran, water absorption and mixing time on dough rheology and loaf volume were observed. Wheat bran addition decreased the strain hardening of dough despite optimisation of water absorption and mixing time. The deleterious effect of wheat bran on dough rheology increased by adding modified wheat bran with high water retention capacity and surface area. The results indicate that dynamic water redistribution after mixing and gas cell incorporation can have an effect on dough rheology when wheat bran is added to dough. The strain hardening behaviour of dough proved itself a valuable predictor of bread loaf volume also in the presence of (modified) wheat bran.

The proteins in the starchy endosperm of wheat determine wheat quality and exhibit a quantitative gradient decreasing from the outer to inner endosperm. Here, we investigate how protein-rich sub-aleurone cells contribute to the protein content and gradient by studying three cultivars, each cultivated at three levels of nitrogen (N)-fertilization. The observed increased protein content with increased N-fertilization was cultivar-dependent. Image analysis showed that the underlying protein gradient could be described by a declining biexponential curve, with protein contents up to 32.0% in the sub-aleurone. Cultivars did not differ in protein content in the center of the cheeks and only differed in the outer endosperm when N-fertilization is applied. N-Fertilization resulted in relatively higher increases in protein content in the outer compared to inner endosperm. Hence, sub-aleurone cells could affect the classification of cultivars by baking quality. Cultivar selection and N-fertilization could furthermore be promising techniques to produce protein-rich miller’s bran.