TY - JOUR
T1 - Aqueous Solubility of Calcium L-Lactate, Calcium D-Gluconate, and Calcium D-Lactobionate
T2 - importance of Complex Formation for Solubility Increase by Hydroxycarboxylate Mixtures
AU - Vavrusova, Martina
AU - Munk, Merete Bøgelund
AU - Skibsted, Leif Horsfelt
PY - 2013/8/28
Y1 - 2013/8/28
N2 - Among the calcium hydroxycarboxylates important for cheese quality, d-lactobionate [Ksp = (7.0 ± 0.3) × 10-3 mol3 L-3] and l-lactate [Ksp = (5.8 ± 0.2) × 10-3 mol3 L-3] were found more soluble than d-gluconate [Ksp = (7.1 ± 0.2) × 10 -4 mol3 L-3], as indicated by the solubility products determined electrochemically for aqueous 1.0 M NaCl at 25.0 C. Still, solubility of calcium l-lactate increases by 45% in the presence of 0.50 M sodium d-gluconate and by 37% in the presence of 0.50 M sodium d-lactobionate, while solubility of calcium d-gluconate increases by 66 and 85% in the presence of 0.50 M sodium l-lactate and 0.50 M sodium d-lactobionate, respectively, as determined by complexometric titration. Sodium l-lactate and sodium d-gluconate have only little influence on solubility of calcium d-lactobionate. The increased solubility is described quantitatively by calcium binding to d-gluconate (K1 = 14 ± 3 mol-1 L) in 1.0 M NaCl at 25 C, d-lactobionate (K1 = 11 ± 2 mol-1 L), and l-lactate (K1 = 8 ± 2 mol-1 L), as indicated by the association constants determined electrochemically. In mixed hydroxycarboxylate solutions, calcium binding is quantitatively described by the geometric mean of the individual association constants for both aqueous 1.0 and 0.20 M NaCl, indicating a 1:1 stoichiometry for complex formation.
AB - Among the calcium hydroxycarboxylates important for cheese quality, d-lactobionate [Ksp = (7.0 ± 0.3) × 10-3 mol3 L-3] and l-lactate [Ksp = (5.8 ± 0.2) × 10-3 mol3 L-3] were found more soluble than d-gluconate [Ksp = (7.1 ± 0.2) × 10 -4 mol3 L-3], as indicated by the solubility products determined electrochemically for aqueous 1.0 M NaCl at 25.0 C. Still, solubility of calcium l-lactate increases by 45% in the presence of 0.50 M sodium d-gluconate and by 37% in the presence of 0.50 M sodium d-lactobionate, while solubility of calcium d-gluconate increases by 66 and 85% in the presence of 0.50 M sodium l-lactate and 0.50 M sodium d-lactobionate, respectively, as determined by complexometric titration. Sodium l-lactate and sodium d-gluconate have only little influence on solubility of calcium d-lactobionate. The increased solubility is described quantitatively by calcium binding to d-gluconate (K1 = 14 ± 3 mol-1 L) in 1.0 M NaCl at 25 C, d-lactobionate (K1 = 11 ± 2 mol-1 L), and l-lactate (K1 = 8 ± 2 mol-1 L), as indicated by the association constants determined electrochemically. In mixed hydroxycarboxylate solutions, calcium binding is quantitatively described by the geometric mean of the individual association constants for both aqueous 1.0 and 0.20 M NaCl, indicating a 1:1 stoichiometry for complex formation.
U2 - 10.1021/jf402124n
DO - 10.1021/jf402124n
M3 - Journal article
C2 - 23906043
SN - 0021-8561
VL - 61
SP - 8207
EP - 8214
JO - Journal of Agricultural and Food Chemistry
JF - Journal of Agricultural and Food Chemistry
IS - 34
ER -