The effect of reducing agent DTT on pasting, hydration and microstructure properties of foxtail millet

• Published in: Journal of cereal science 2020-09, Vol.95, p.103044, Article 103044
• Main Authors: Zhang, Fan, Laraib, Yousaf, Chai, Xiaojiao, Shen, Yinan, Wang, Xianrui, Li, Shutian, Guo, Erhu, Diao, Xianmin, Shen, Qun
• Format: Article
• Language: English
• Subjects: Disulfide bonds; Foxtail millet; Hydration; Pasting
• ISSN: 0733-5210; 1095-9963
• DOI: 10.1016/j.jcs.2020.103044

Protein-protein crosslinks, especially disulfide bonds, widely exist and influence the quality of cereal-based food. In order to investigate the effect of disulfide bonds on pasting properties of foxtail millet, ten typical varieties were selected and separated into three groups according to their eating quality, and then reducing agent dithiothreitol (DTT) was used to disrupt disulfide bonds. Disulfide and sulfhydryl groups’ variations, pasting, and hydration properties were determined. Scanning electron microscope (SEM) and confocal laser scanning microscopy (CLSM) were also used to analyze the microstructure of foxtail millet paste. Results showed that foxtail millet with poor eating quality was more prone to form disulfide bond linkage at a higher rate and degree during cooking. Disrupting disulfide bonds increased peak viscosity, breakdown, water absorption, and swelling power of granules. Meanwhile, pasting temperature, setback, and final viscosity decreased significantly. The larger size of swollen starch granules and breakage of protein networks were found under CLSM, and firmer lamellar structures with less connections and pores were illustrated under SEM in DTT-treated paste. After DTT-treatment, disulfide bonds were believed to restrict hydration and pasting properties of foxtail millet, and strengthen the swollen granules and paste rigidity as well as a high level of starch reassociation. [Display omitted] •Disulfide-sulfhydryl changes were depicted in all varieties before and after cooking.•The rate and degree of change of disulfide bonds were related to the variety characteristics.•Disulfide bonds decreased water absorption and swelling power of foxtail millet.•Disulfide bond framework reinforced swollen granules, paste rigidity and reassociation of starch.