Ingham Bridget, Kirby Nigel, Wang Cheng, Brady Mike, Carr Alistair
Callaghan Innovation, PO Box 31-310, Lower Hutt 5040, New Zealand.
Australian Synchrotron, 800 Blackburn Road, Clayton, VIC 3168, Australia.
J Synchrotron Radiat. 2018 Jul 1;25(Pt 4):1106-1112. doi: 10.1107/S1600577518007774. Epub 2018 Jun 25.
Anomalous small-angle X-ray scattering (ASAXS) and resonant soft X-ray scattering (RSoXS) are two related techniques that can enable element-specific structural information to be obtained. The development of iron-fortified milk products can greatly benefit from such techniques, allowing the structure of iron and other minerals (such as native calcium) within the casein micelle to be determined. Each method has advantages and disadvantages: for ASAXS, the sample preparation is straightforward, but the signal is relatively low and information about the structure of Ca is difficult to access. RSoXS can be used to study both Ca and Fe, and the element-specific signals observed are proportionally much higher; however, the measurements are challenging due to the difficulty of precise control of the solution thickness using currently available vacuum-compatible liquid cells. Nevertheless, complementary results from both techniques indicate Fe is co-located with Ca, i.e. within the colloidal calcium phosphate nanoclusters that are present within native casein micelles in milk.
反常小角X射线散射（ASAXS）和共振软X射线散射（RSoXS）是两种相关技术，能够获取特定元素的结构信息。铁强化乳制品的开发可从这些技术中大大受益，从而确定酪蛋白胶束中铁和其他矿物质（如天然钙）的结构。每种方法都有优缺点：对于ASAXS，样品制备简单，但信号相对较低，且难以获取有关钙结构的信息。RSoXS可用于研究钙和铁，观察到的特定元素信号要高得多；然而，由于使用目前可用的真空兼容液体池精确控制溶液厚度存在困难，测量具有挑战性。尽管如此，两种技术的互补结果表明铁与钙共定位，即在牛奶中天然酪蛋白胶束内存在的胶体磷酸钙纳米簇中。
