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.

Potato flour as a functional ingredient in bread: evaluation of bread quality and starch characteristics

“…Murayama et al (2015) also seen small but significant (P < 0.05) reduction in loaf volume for potato breads compared to bread made with 100% wheat flour. According to a previous study by Cao et al (2019), the addition of potato will also interact with the gluten network by disrupting disulphide bonds. It was found that polyphenolic groups in the potato pulp participated in redox reactions that ultimately lead to the reduction of the disulphide groups.…”

“…It was found that polyphenolic groups in the potato pulp participated in redox reactions that ultimately lead to the reduction of the disulphide groups. The reduction of disulphide groups in the dough will reduce dough strength leading to lower volume (Cao et al, 2019). However, the decrease in volume was largest between the control bread and the bread with 5% potato flour, compared to the reductions between the 5% potato flour and 10% potato flour breads and between the 10% potato flour and 15% potato flour breads.…”

Effects of catechins on the polymerisation behaviour, conformation and viscoelasticity of wheat gluten

“…These phenolic groups participate in redox reactions through forming quinones and providing electrons, similar to potato pulp and tannins reported previously by Cao et al . (2020) and Wang et al . (2015).…”

“…Therefore, the addition of catechins might result in a reduction in SS content and may explain the increase in free SH content. The greater the SS content, the more stable the network structure of gluten (Cao et al ., 2020). Hence, a low SS content indicates that adding catechins may destroy the gluten network structure.…”

“…SS bonds maintain the structure and functional properties of gluten, and are therefore crucial to the quality of the final product (Liu et al ., 2018). In general, SS bonds intrinsically existing in gliadin and glutelin are disrupted and recombined during the formation process of gluten, and some free SH groups combine with each other to form SS bonds that play an important part in the formation of stable gluten network structures (Guo et al ., 2018; Cao et al ., 2020). Changes in free SH content give an indication of variation in SS bonds that contribute to gluten aggregation (Wang et al ., 2014a; Tang et al ., 2019).…”