TY - JOUR
T1 - Calcium hydroxy palmitate
T2 - possible precursor phase in calcium precipitation by palmitate
AU - Vavrusova, Martina
AU - Raitio, Riikka Julia
AU - Orlien, Vibeke
AU - Skibsted, Leif Horsfelt
PY - 2013/6/15
Y1 - 2013/6/15
N2 - Calcium(II) precipitates with palmitate (Pal-), a process affecting calcium absorption in the gut, in a first-order reaction, as followed by a calcium electrode in neutral aqueous solution for excess of calcium(II), with a rate constant showing a minimum at physiological ionic strength of 0.32 ± 0.09 d-1 at 25 °C with a stoichiometry of 1.79 ± 0.03, lower than the expected 1:2. During ageing of precipitate, pH increases in the supernatant, while pH decreases for precipitation with excess of palmitate. Increasing pH, as in some aged food products, decreases the solubility, and Ksp′ = [Ca2+][Pal-][OH-] is found constant rather than Ksp = [Ca2+][Pal-] 2 in agreement with an initial precipitation of Ca(OH)(Pal), which slowly may convert into Ca(Pal)2 · Ca(OH)(Pal) has a solubility minimum at physiological ionic strength with Ksp′ = (1.4 ± 0.4)10-16 M3. X-ray diffraction showed a d-spacing of 44.15 Å (different from 45.2 Å reported for Ca(Pal)2), and infrared spectroscopy confirmed the presence of a hydroxy group.
AB - Calcium(II) precipitates with palmitate (Pal-), a process affecting calcium absorption in the gut, in a first-order reaction, as followed by a calcium electrode in neutral aqueous solution for excess of calcium(II), with a rate constant showing a minimum at physiological ionic strength of 0.32 ± 0.09 d-1 at 25 °C with a stoichiometry of 1.79 ± 0.03, lower than the expected 1:2. During ageing of precipitate, pH increases in the supernatant, while pH decreases for precipitation with excess of palmitate. Increasing pH, as in some aged food products, decreases the solubility, and Ksp′ = [Ca2+][Pal-][OH-] is found constant rather than Ksp = [Ca2+][Pal-] 2 in agreement with an initial precipitation of Ca(OH)(Pal), which slowly may convert into Ca(Pal)2 · Ca(OH)(Pal) has a solubility minimum at physiological ionic strength with Ksp′ = (1.4 ± 0.4)10-16 M3. X-ray diffraction showed a d-spacing of 44.15 Å (different from 45.2 Å reported for Ca(Pal)2), and infrared spectroscopy confirmed the presence of a hydroxy group.
U2 - 10.1016/j.foodchem.2012.12.012
DO - 10.1016/j.foodchem.2012.12.012
M3 - Journal article
SN - 0308-8146
VL - 138
SP - 2415
EP - 2420
JO - Food Chemistry
JF - Food Chemistry
IS - 4
ER -