Influence of potato pulp on gluten network structure in wheat dough and steamed bread

Abstract Background and objectives Steamed bread is the traditional fermented wheat product in China and has popularity in other Asian, European, and some North American countries. Wheat flour replaced by potato pulp can be an effective way to improve nutritive values of steamed bread and promote potato consumption. The aim of this study was to investigate the influences of potato pulp on disulfide bond (S–S) contents, protein secondary structures, starch crystallinity, and microstructures of dough and steamed bread. Spectrophotometry, Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM) were used for analyses. Findings The dough and steamed bread samples added with 10% potato pulp had higher S–S contents than the other tested samples. Compared with the control, the free sulfhydryl contents in the dough (3.2 μmol/g) and steamed bread (2.7 μmol/g) added with 30% potato pulp significantly increased, whereas those of the S–S decreased to 10.0 and 10.9 μmol/g, respectively. The contents of β‐sheet and α‐helix in the dough and steamed bread containing 10% potato pulp were higher than those in samples without the potato pulp. The relative crystallinity of starch in the dough significantly decreased with increasing potato pulp level ( p < .05). The CLSM and SEM images showed that potato pulp significantly affected the microstructure. Sample with 10% potato pulp possessed improved gluten network structures. However, samples with high potato pulp contents (>20%) possessed more gas cells and a loose gluten network structure. Conclusions The results showed that the addition of potato pulp affected gluten network structural characteristics in wheat flour dough and steamed bread, but appropriate level of potato pulp could be produced for gluten network enhancement. Significance and novelty The study would contribute to better understanding of the effect of potato pulp on the structural characterization of gluten network in steamed bread making and provide theoretical basis for in‐depth application to wheat‐based products.