The Preparation and Characterization of Quinoa Protein Gels and Application in Eggless Bread

• Published in: Foods Vol. 13; no. 8; p. 1271
• Main Authors: Xu, Qianqian, Zhang, Xinxia, Zuo, Zhongyu, Zhang, Ming, Li, Ting, Wang, Li
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.04.2024
• Subjects: Amino acids; Bread; Chemical bonds; Coiling; Disulfide bonds; eggless bread; Eggs; Food; Fourier transforms; Gels; Gluten; Hydration; Molecular weight; pH effects; Polysaccharides; Pores; Protein structure; Proteins; Quinoa; quinoa protein gels; Secondary structure; Sulfhydryl groups; Ultrasonic imaging; Ultrasound; Viscoelasticity; Viscosity; Water hardness; Xanthan; Xanthan gum; China; quinoa protein gels; eggless bread; ultrasound
• ISSN: 2304-8158; 2304-8158
• DOI: 10.3390/foods13081271

The properties of xanthan gum protein gels composed of quinoa protein (XG-QPG) and ultrasound-treated quinoa protein (XG-UQPG) were compared for the preparation of high-quality quinoa protein gels. The gel qualities at different pH values were compared. The gels were used to produce eggless bread. Microscopically, the secondary structure of the proteins in XG-QPG (pH 7.0) was mainly α-helix, followed by random coiling. In contrast, the content of β-sheet in XG-UQPG was higher, relative to the viscoelastic properties of the gel. Moreover, the free sulfhydryl groups and disulfide bonds of XG-QPG (pH 7.0) were 48.30 and 38.17 µmol/g, while XG-UQPG (pH 7.0) was 31.95 and 61.58 µmol/g, respectively. A high disulfide bond content was related to the formation of gel networks. From a macroscopic perspective, XG-QPG (pH 7.0) exhibited different pore sizes, XG-UQPG (pH 7.0) displayed a loose structure with uniform pores, and XG-UQPG (pH 4.5) exhibited a dense structure with small pores. These findings suggest that ultrasound can promote the formation of a gel by XG-UQPG (pH 7.0) that has a loose structure and high water-holding capacity and that XG-UQPG (pH 4.5) forms a gel with a dense structure and pronounced hardness. Furthermore, the addition of the disulfide bond-rich XG-UQPG (pH 7.0) to bread promoted the formation of gel networks, resulting in elastic, soft bread. In contrast, XG-UQPG (pH 4.5) resulted in firm bread. These findings broaden the applications of quinoa in food and provide a good egg substitute for quinoa protein gels.