Calcium binding to lactose, inulin and their constituting monosaccharides and perspective for calcium bioaccessibility
Research output: Contribution to journal › Journal article › Research › peer-review
Calcium ions bind to lactose, galactose, glucose and fructose in a 1:1 ratio and to low-chain inulin in a 2:1 ratio; shown by conductivity using Job's method of continuous variation. The binding constant, Ka, for aqueous solution at 25.0 °C increases along the series of simple saccharides glucose (4 L mol−1) < fructose (6 L mol−1) < galactose (8 L mol−1) < lactose (10 L mol−1) as determined from equilibrated calcium iodate solubility. Isothermal titration calorimetry showed that calcium binding was athermal and binding accordingly entropy controlled. For lactose, the binding to the α-anomer increased during 5 h equilibration, while the binding for the β-anomer decreased to reach a common equilibrium as measured electrochemically. Quantum chemical calculations confirmed that the β-anomer of lactose and glucose binds calcium stronger than the α-anomer. For inulin, binding has Ka = 35 L mol−1 for each of two calcium in a moderately endothermic process.
Original language | English |
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Article number | 105042 |
Journal | International Dairy Journal |
Volume | 118 |
Number of pages | 8 |
ISSN | 0958-6946 |
DOIs | |
Publication status | Published - 2021 |
ID: 259067227