| Abstract
| - Apparent binding constants of aroma compounds limonene, α- and β-ionone, and terpenyl acetate,with β-lactoglobulin (BLG), were determined, using dynamic coupled column liquid chromatography,for pH values varying from 3 to 11. Ka values varied from 2.61 to 3.21 × 103 M-1 for limonene,indicating a strong interaction with BLG. Similarly, significant and close apparent binding constantswere obtained for α- and β-ionone, 1.7 × 102 and 4.5 to 5.4 × 102 M-1, respectively. These dataindicated that a similar mechanism is involved for the binding of these two molecules. The weakervalues obtained at low pH, for α-ionone relative to β-ionone, can be explained by the existence ofsteric hindrance. An increase of the apparent binding constant was observed, for all the compoundsstudied, when the pH was increased from 3 to 9. At this pH, an apparent binding constant wasobtained for terpenyl acetate (1.04 × 102 M-1), whereas this determination was not possible at pH3 and 6. The apparent binding constant increase was in agreement with the decrease of aromacompound relative activity coefficient in the presence of BLG, previously observed at this pH. Itindicated a best accessibility to the same binding site. The binding constants of all the aromacompounds studied decreased at pH 11 as a result of the important release of the BLG structurepreviously reported. Keywords: β-Lactoglobulin; aroma compounds; binding constants; dynamic coupled column liquidchromatography (DCCLC); pH effect
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