The Comparative Heat Stability of Bovine β-Lactoglobulin in Buffer and Complex Media

✍ Scribed by Galani, Despina; Apenten, Richard K. Owusu

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 287 KB
• Volume: 74
• Category: Article
• ISSN: 0022-5142
• DOI: 10.1002/(sici)1097-0010(199705)74:1<89::aid-jsfa773>3.0.co;2-p

✦ Synopsis

The heat stability of b-lactoglobulin (b-lg) is usually described with reference to a concentration-dependent pseudo-rate constant k. Kinetic and thermodynamic parameters for the irreversible denaturation of b-lg, in a whey protein mixture dissolved in Tris-HCl bu †er, were examined over a wide temperature range 75È120¡C and for degrees of denaturation up to

The Ðrst-order kinetic model best described b-lg denaturation over the temperature range 75È85¡C, whereas the second-order model applies in the range 90È120¡C. A comparison between b-lg thermostability in bu †er and literature data pertaining to more complex heating media (whey and milk), over the range 75È120¡C, was carried out on the basis of changes in activation free energy which itself takes into account changes in both activation enthalpy (*Gj), (*Hj) and activation entropy It was found that the thermal stability of b-lg in (*Sj). di †erent media, and irrespective of the kinetic model assumed in the present study, can be ranked : bu †er ? whey [ milk for the temperature range 75È85¡C. On the contrary, at the higher temperature range, 90È120¡C, the ranking is buffer \ whey \ milk, when using the second-order model to describe the present data. For such comparisons to be valid the initial concentration of b-lg in various studies, as well as the reaction order applied, should be taken into consideration.