Insights into the mechanism on Glucono-delta-lactone induced gelation of soybean protein at subunit level

• Published in: Food hydrocolloids 2022-04, Vol.125, p.107402, Article 107402
• Main Authors: Ju, Qian, Wu, Chang, Yuan, Yanqiu, Hu, Yayun, Zhou, Shuyi, Luan, Guangzhong
• Format: Article
• Language: English
• Subjects: Gelation; Microstructure; Rheology; Soybean protein; Subunit
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/j.foodhyd.2021.107402

To elucidate the gelation process and gel properties of coagulation in soybean protein at subunit level, the dispersions of subunits (αα′- and β-subunit) of β-conglycinin and polypeptides (acidic and basic polypeptides) of glycinin were coagulated by Glucono-delta-lactone (GDL), and the gelation processes were monitored with a dynamic rheometer. The rheological properties, microstructure, water distribution, and secondary structure of the gels were determined as well. The results showed that the β-subunit and basic polypeptide coagulated faster, while αα′-subunit and acidic polypeptide developed firmer and finer gels, who had stronger ability of water holding and contained higher content of β-sheet structure. The GDL-induced subunits/polypeptides gel network were dominated by hydrophobic interactions and disulfide bonds. It is proposed that the mechanism on gelation of soybean protein at subunit level as: with acidification of GDL, the basic polypeptide and β-subunit initially aggregate and form a proto-gel matrix. Subsequently, with the developing of gelation, α- and α′-subunits, especially acidic polypeptide, who is the last one to coagulate, complements to form finer and firmer network, and finally grows together to a mature gel. Besides the gelation rate, the higher content of β-sheet secondary structure and better water holding ability of acidic polypeptide and αα′-subunits would also contribute to the firmness of gel. The elucidation of the gelation mechanism at subunit level would support innovation of gelling technique and benefit the soybean industry. [Display omitted] •The Glucono-delta-lactone induced coagulation of αα'-, β-subunits of β-conglycinin, and acidic, basic polypeptide of glycinin were compared.•The β-subunit and basic polypeptide showed faster gelation rate, while αα′-subunits and acidic polypeptide formed stronger and homogeneous gel network.•The gelation mechanism of soybean protein at subunit level: “proto-gel matrix to mature gel” was proposed.