Foams Stabilized by β‑Lactoglobulin Amyloid Fibrils: Effect of pH

• Published in: Journal of agricultural and food chemistry Vol. 65; no. 48; pp. 10658 - 10665
• Main Authors: Peng, Dengfeng, Yang, Jinchu, Li, Jing, Tang, Cuie, Li, Bin
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 06.12.2017
• Subjects: pH; charges; surface behaviors; β-lactoglobulin fibrils; stability; foams
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/acs.jafc.7b03669

β-Lactoglobulin fibrils could serve as a surface-active component and form adsorption layers at the air/water interface. In this study, the physical parameters related to the surface adsorption, foaming, and surface properties of β-lactoglobulin fibrils as a function of pH (2–8) were investigated. Results showed that an increase of pH from 2 to 5 led to a rise of the viscoelastic modulus of the surface adsorption layer and half-life time (t 1/2) of foams, but it decreased foamability. When the pH was close to its isoelectric point (5.2), fibrils had the lowest electrostatic repulsion and entangled at the air/water interface resulting in a tightly packaged adsorption layer around bubbles to prevent coalescence and coarsening. When the pH (7–8) was higher than the pI of fibrils, the negatively charged β-lactoglobulin fibrils possessed good foamability (∼80%) and high foam stability (t 1/2 ≈ 8 h) simultaneously even at low concentration (1 mg/mL). It demonstrated that β-lactoglobulin fibrils with negative charges presented a good foaming behavior and could be a potential new foaming agent in the food industry.