Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark.
Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark.
Food Chem. 2022 Apr 16;374:131701. doi: 10.1016/j.foodchem.2021.131701. Epub 2021 Nov 30.
Uptake of calcium from food depends on solubility of calcium salts in the intestines, and precipitation of calcium phosphates decreases bioaccessibility of food calcium. Citrate as a high affinity complex binder for calcium was found spontaneously to create strongly supersaturated solutions by rapid dissolution of calcium hydrogen phosphate characterized by short lag phases for precipitation. Gluconate with weaker affinity for calcium binding showed longer lag phases for precipitation from supersaturated solutions. For citrate/gluconate combinations, the highest degree of supersaturation with longest lag phases for precipitation were found by trial-and-error experiments for a citrate/gluconate ratio of 1:10 for dissolution of calcium hydrogen phosphate resulting in supersaturation factors around three and without precipitation for more than a month. The aim of the present study was to provide a physicochemical explanation of this robust supersaturation. Calcium speciation based on electrochemical calcium activity measurement identified a low [Ca]·[HCitr] product as critical for supersaturation.
食物中钙的吸收取决于钙盐在肠道中的溶解度，而磷酸钙的沉淀会降低食物钙的生物利用度。柠檬酸作为一种与钙具有高亲和力的络合剂，被发现能够通过快速溶解磷酸氢钙来自发地形成强过饱和溶液，其特点是沉淀的滞后期很短。而对于与钙结合亲和力较弱的葡萄糖酸盐，其过饱和溶液的沉淀滞后期则较长。对于柠檬酸/葡萄糖酸盐的组合，通过反复试验发现，柠檬酸/葡萄糖酸盐的比例为 1:10 时，溶解磷酸氢钙可以达到最高的过饱和度，并具有最长的沉淀滞后期，从而导致过饱和度因子约为 3，并且在一个多月的时间内没有发生沉淀。本研究的目的是为这种稳定的过饱和度提供一种物理化学解释。基于电化学钙活度测量的钙形态分析表明，低[Ca]·[HCitr]产物是过饱和度的关键。
