Use of ultrasound spectroscopy to examine the effect of cysteine on β-lactoglobulin interactions

• Published in: Colloid and polymer science 2009-12, Vol.287 (12), p.1487-1491
• Main Author: Yuno-Ohta, Naoko
• Format: Article
• Language: English
• Subjects: Applied sciences; Biological and medical sciences; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Exact sciences and technology; Food Science; Fundamental and applied biological sciences. Psychology; In solution. Condensed state. Thin layers; Molecular biophysics; Nanotechnology and Microengineering; Natural polymers; Physical Chemistry; Physico-chemical properties of biomolecules; Physicochemistry of polymers; Polymer Sciences; Proteins; Short Communication; Soft and Granular Matter
• ISSN: 0303-402X; 1435-1536
• DOI: 10.1007/s00396-009-2125-x

We investigated the effects of cysteine on β-lactoglobulin interactions using ultrasound spectroscopy, rheological measurements, and differential scanning calorimetry. Changes in ultrasonic velocity and attenuation were monitored using ultrasound spectroscopy, and we discuss the effects of cysteine on gel formation together with the results obtained using other methods. A decrease in ultrasonic velocity occurred around 54 °C, suggesting that the compressibility of the system increases at approximately this temperature. An increase in ultrasonic attenuation was observed at approximately 54 °C, which is much lower than the commonly observed denaturation temperature of 75–80 °C. The temperature coincided with the onset of phase transition by differential scanning calorimetry and the initial rise in temperature of dynamic modulus for rheological measurements under heat treatment. We conclude that cysteine promotes the polymerization processes of denatured proteins during the initial stage of gelation. The ultrasonic spectroscopic analysis is a useful tool to monitor protein molecule interactions prior to gelation.