As the most common type of anemia, iron-deficiency anemia has attracted more and more attention. With the change of nutrition and health needs and the enhancement of safety awareness, there has been increasing interest in the research and development of oral iron supplements with good iron supplementation effect, easy absorption, small side effects and high safety. This paper reviews recent progress in the development and research of iron supplements. In this paper, the raw material source, structure, action mechanism, preparation, application, and digestion and absorption mechanism of iron protein succinate are reviewed, and future prospects of polypeptide-iron complexes and iron protein succinate are discussed. We anticipate that this review will provide a theoretical basis for the research and development of iron supplements.

Using high-amylose maize starch G50 and G70 as raw material, type Ⅲ resistant starch was obtained by successive steps of acid hydrolysis, pasting, debranching and recrystallization, and annealing and autoclaving treatments were used to improve the yield of resistant starch. Scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), rapid viscosity analysis (RVA) were used to evaluate the morphology, crystalline structure, thermal properties and pasting properties of starch granules, and the digestion properties of starch were tested by the Englyst method. The results showed that the yields of type Ⅲ resistant starch from high-amylose maize starch G50 and G70 after acid hydrolysis were 77.9% and 84.5%, respectively, and were reduced to 54.4% and 70.2% after recrystallization, respectively. For G50 and G70, the morphology of starch granules was destroyed after modification, and aggregates with different sizes and irregular shapes were formed. The crystalline type of starch changed from B + V to A + V, and the crystallinity increased. The pasting temperature of starch increased, and the viscosity almost disappeared after heating. The solubility of G50 and G70 significantly increased after acid hydrolysis, pasting, debranching and recrystallization, while the solubility and swelling power of type Ⅲ resistant starch decreased after annealing and autoclaving treatments. In vitro digestion tests showed that the modified G50 and G70 had stronger resistance to digestion than the raw ones, and the resistant starch content of G70-derived type Ⅲ resistant starch autoclaved after addition of 20% water was the highest (80.5%). In conclusion, the modification treatment can effectively increase the content of resistant starch in high-amylose maize starch G50 and G70, and the content of resistant starch is significantly positively correlated with the crystallinity and pasting temperature.