Characterization of β-Lactoglobulin A Gelation in the Presence of Sodium Caprate by Ultrasound Spectroscopy and Electron Microscopy

• Published in: Biomacromolecules 2007-08, Vol.8 (8), p.2542-2548
• Main Authors: Yuno-Ohta, Naoko, Corredig, Milena
• Format: Article
• Language: English
• Subjects: Applied sciences; Biological and medical sciences; Decanoic Acids - chemistry; Electrophoresis, Polyacrylamide Gel; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gels; In solution. Condensed state. Thin layers; Lactoglobulins - chemistry; Microscopy, Electron; Microscopy, Electron, Transmission; Molecular biophysics; Natural polymers; Physico-chemical properties of biomolecules; Physicochemistry of polymers; Proteins; Spectrum Analysis; Temperature; Ultrasonics
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm0701393

The effect of sodium caprate (a fatty acid salt) on the formation of β-lactoglobulin A gels was studied at constant temperature (30 or 35 °C) using ultrasonic spectroscopy. During incubation at these temperatures, ultrasonic attenuation increased with the addition of sodium caprate, and reached a plateau after 5−7 h of incubation. Comparing β-lactoglobulin A with and without sodium caprate, a decrease in net ultrasonic velocity was observed. These results suggested that aggregation occurred during incubation with sodium caprate, and the sample showed an increase in compressibility. Transmission electron microscopy with negative staining showed the formation of filamentous aggregates of β-lactoglobulin A at around 3−4.5 h of incubation with sodium caprate. These results demonstrated that sodium caprate induced the formation of structures with unique gel properties compared to those formed by heating β-lactoglobulin in the presence of NaCl alone.